PNC MORTGAGE SECURITIES CORP
424B5, 1997-11-25
FINANCE SERVICES
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<PAGE>
PROSPECTUS SUPPLEMENT
 
(To Prospectus Dated November 24, 1997)
 
                                  PNC MORTGAGE
 
                                SECURITIES CORP.
 
           DEPOSITOR, A MASTER SERVICER AND CERTIFICATE ADMINISTRATOR
 
               MORTGAGE PASS-THROUGH CERTIFICATES, SERIES 1997-8
                                  $828,189,236
                                 (APPROXIMATE)
 
  PRINCIPAL AND/OR INTEREST PAYABLE ON THE 25TH DAY OF EACH MONTH BEGINNING IN
                                 DECEMBER 1997
THESE CERTIFICATES DO NOT REPRESENT AN OBLIGATION OF OR INTEREST IN PNC MORTGAGE
   SECURITIES CORP. OR ANY OF ITS AFFILIATES, INCLUDING PNC BANK CORP.
        NEITHER THESE CERTIFICATES NOR THE UNDERLYING MORTGAGE LOANS
             ARE GUARANTEED BY ANY AGENCY OR INSTRUMENTALITY OF THE
                                 UNITED STATES.
 
    The Mortgage Pass-Through Certificates, Series 1997-8 (the "CERTIFICATES"),
will consist of the following thirty-eight classes: (i) Class I-A-1, (ii) Class
II-A-1, Class II-A-2, Class II-A-3, Class II-A-4, Class II-A-5, Class II-A-6,
Class II-A-7, Class II-A-8, Class II-A-9 and Class II-A-10 (the "GROUP II-A
CERTIFICATES"), (iii) Class III-PT (together with the Class I-A-1 and Group II-A
Certificates, the "CLASS A CERTIFICATES"), (iv) Class I-P, Class II-P and Class
III-P (the "CLASS P CERTIFICATES"), (v) Class I-X-1 and Class I-X-2 (the "CLASS
I-X CERTIFICATES"), Class II-X and Class III-X (together with the Class I-X
Certificates, the "CLASS X CERTIFICATES"), (vi) Class I-B-1, Class I-B-2 and
Class I-B-3 (the "GROUP I SENIOR SUBORDINATE CERTIFICATES"), (vii) Class I-B-4,
Class I-B-5 and Class I-B-6 (the "GROUP I JUNIOR SUBORDINATE CERTIFICATES" and,
together with the Group I Senior Subordinate Certificates, the "GROUP I-B
CERTIFICATES"), (viii) Class II-B-1, Class II-B-2 and Class II-B-3 (the "GROUP
II SENIOR SUBORDINATE CERTIFICATES"), (ix) Class II-B-4, Class II-B-5 and Class
II-B-6 (the "GROUP II JUNIOR SUBORDINATE CERTIFICATES" and, together with the
Group II Senior Subordinate Certificates, the "GROUP II-B CERTIFICATES"), (x)
Class III-B-1, Class III-B-2 and Class III-B-3 (the "GROUP III SENIOR
SUBORDINATE CERTIFICATES"), (xi) Class III-B-4, Class III-B-5 and Class III-B-6
(the "GROUP III JUNIOR SUBORDINATE CERTIFICATES" and, together with the Group
III Senior Subordinate Certificates, the "GROUP III-B CERTIFICATES"), and (xii)
Class R (the "RESIDUAL CERTIFICATES" and, together with the Class A, Class X and
Class P Certificates, the "SENIOR CERTIFICATES"). The Class I-A-1, Class I-P,
Class I-X and Group I-B Certificates are sometimes referred to as the "GROUP I
CERTIFICATES", the Group II-A, Class II-P, Class II-X, Group II-B and Class R
Certificates are sometimes referred to as the "GROUP II CERTIFICATES" and the
Class III-PT, Class III-P, Class III-X and Group III-B Certificates are
sometimes referred to as the "GROUP III CERTIFICATES". The Group I Certificates,
the Group II Certificates and the Group III Certificates are each a "CERTIFICATE
GROUP". The Class II-A-8 and Class II-A-9 Certificates are sometimes referred to
as the "LOCKOUT CERTIFICATES". The Class I-X-1 and Class I-X-2 Certificates are
sometimes referred to as the "LIBOR CERTIFICATES". The Class I-X-1 Certificates
are sometimes referred to as the "FLOATER CERTIFICATES" and the Class I-X-2
Certificates are sometimes referred to as the "INVERSE FLOATER CERTIFICATES".
The Group I Senior Subordinate Certificates, Group II Senior Subordinate
Certificates and Group III Senior Subordinate Certificates are collectively
referred to as the "SENIOR SUBORDINATE CERTIFICATES". The Group I Junior
Subordinate Certificates, Group II Junior Subordinate Certificates and Group III
Junior Subordinate Certificates are collectively referred to as the "JUNIOR
SUBORDINATE CERTIFICATES". The Group I-B, Group II-B and Group III-B
Certificates are collectively referred to as the "SUBORDINATE CERTIFICATES" or
"CLASS B CERTIFICATES". Only the Senior Certificates and the Senior Subordinate
Certificates (collectively, the "OFFERED CERTIFICATES") are offered hereby. The
Junior Subordinate Certificates are not offered hereby. It is a condition to the
issuance of the Offered Certificates that they receive the ratings indicated
under "Certificate Ratings" herein.
- --------------------------------------------------------------------------------
<TABLE>
<CAPTION>
                                         APPROXIMATE
                                        INITIAL CLASS        REMITTANCE
CLASS                                 PRINCIPAL BALANCE       RATE(1)
<S>                                   <C>                 <C>
- ------------------------------------
 
Class I-A-1.........................    $  363,533,005         7.250%
Class II-A-1........................        85,246,108         7.000%
Class II-A-2........................        72,411,210         7.000%
Class II-A-3........................        65,563,181         7.000%
Class II-A-4........................         6,388,029       7.000%(2)
Class II-A-5........................        10,490,109       7.000%(3)
Class II-A-6........................           555,409       7.000%(4)
Class II-A-7........................         7,423,000         7.000%
Class II-A-8........................        59,639,283         7.000%
Class II-A-9........................         4,901,652         7.000%
Class II-A-10.......................        10,086,644         7.000%
Class III-PT........................       100,539,062         6.750%
Class I-X-1.........................                --    Variable Rate(5)
Class I-X-2.........................                --    Variable Rate(6)
Class II-X..........................                --       7.000%(7)
 
<CAPTION>
                                         APPROXIMATE
                                        INITIAL CLASS        REMITTANCE
CLASS                                 PRINCIPAL BALANCE       RATE(1)
<S>                                   <C>                 <C>
 
Class III-X.........................                --       6.750%(8)
Class I-P...........................           152,576          (9)
Class II-P..........................           142,701          (9)
Class III-P.........................           201,782          (9)
Class I-B-1.........................        10,725,313         7.250%
Class I-B-2.........................         6,825,198         7.250%
Class I-B-3.........................         4,290,125         7.250%
Class II-B-1........................        11,132,668         7.000%
Class II-B-2........................         3,254,164         7.000%
Class II-B-3........................         1,712,718         7.000%
Class III-B-1.......................         2,244,486         6.750%
Class III-B-2.......................           417,579         6.750%
Class III-B-3.......................           313,184         6.750%
Class R.............................                50         7.000%
</TABLE>
 
- --------------------------------------------------------------------------------
                                         (FOOTNOTES CONTINUED ON FOLLOWING PAGE)
 
    The Offered Certificates are being offered by Donaldson, Lufkin & Jenrette
Securities Corporation (the "UNDERWRITER") from time to time in negotiated
transactions or otherwise at varying prices to be determined at the time of
sale. Sales may be made to investors at the same price or at different prices.
See "Method of Distribution" herein. The aggregate proceeds to PNC Mortgage
Securities Corp. (the "Company") from the sale of the Offered Certificates,
before deducting expenses estimated to be $620,000, will be 101.87816% of the
initial aggregate Certificate Principal Balance of the Offered Certificates plus
accrued interest. The difference between the aggregate purchase price for the
Offered Certificates paid to the Company and the aggregate proceeds from the
sale of the Offered Certificates realized by the Underwriter will constitute
underwriting discounts and commissions. The Company has agreed to indemnify the
Underwriter against certain liabilities, including liabilities under the
Securities Act of 1933. See "Method of Distribution" herein.
 
See "Risk Factors" immediately following "Summary Information" herein and
immediately following "Summary of Prospectus" in the Prospectus for a discussion
of certain factors that should be considered before purchasing any of the
Offered Certificates.
  THESE SECURITIES HAVE NOT BEEN APPROVED OR DISAPPROVED BY THE SECURITIES AND
 EXCHANGE COMMISSION OR THE SECURITIES COMMISSION OF ANY STATE NOR HAS ANY
         SUCH COMMISSION PASSED UPON THE ACCURACY OR ADEQUACY OF THIS
          PROSPECTUS. ANY REPRESENTATION TO THE CONTRARY IS A CRIMINAL
                                    OFFENSE.
 
    The Offered Certificates are offered by the Underwriter, as specified
herein, subject to receipt and acceptance by it, and subject to its right to
reject any order in whole or in part and to certain other conditions. It is
expected that delivery of the Offered Certificates (other than the Class R,
Senior Subordinate, Class X and Class P Certificates) will be made through the
facilities of The Depository Trust Company, and that delivery of the Class R
(other than the portion of the Class R Certificates retained by the Company),
Senior Subordinate, Class X and Class P Certificates will be made at the offices
of the Underwriter, on or about November 25, 1997. (Additional cover page
information is contained on the following four pages.)
 
              DONALDSON, LUFKIN & JENRETTE
                                SECURITIES CORPORATION
 
          The date of this Prospectus Supplement is November 24, 1997
<PAGE>
(CONTINUED FROM PREVIOUS PAGE)
 
(1) INTEREST DISTRIBUTED TO THE OFFERED CERTIFICATES (OTHER THAN THE CLASS P
    CERTIFICATES, WHICH WILL NOT BE ENTITLED TO RECEIVE DISTRIBUTIONS OF
    INTEREST) ON EACH DISTRIBUTION DATE WILL HAVE ACCRUED DURING THE PRECEDING
    CALENDAR MONTH AT THE APPLICABLE PER ANNUM REMITTANCE RATE, EXCEPT FOR THE
    LIBOR CERTIFICATES WHICH WILL ACCRUE INTEREST DURING THE PERIOD FROM THE
    25TH DAY OF THE MONTH PRIOR TO EACH DISTRIBUTION DATE TO THE 24TH DAY OF THE
    MONTH OF SUCH DISTRIBUTION DATE.
 
(2) ON EACH DISTRIBUTION DATE ON OR BEFORE THE CLASS II-A-4 ACCRETION
    TERMINATION DATE (AS DEFINED HEREIN), AN AMOUNT EQUAL TO THE CLASS II-A-4
    ACCRUAL AMOUNT (AS DEFINED HEREIN) WILL BE ADDED TO THE CLASS II-A-4
    PRINCIPAL BALANCE, AND SUCH AMOUNT WILL BE DISTRIBUTED AS PRINCIPAL TO OTHER
    CLASSES OF CERTIFICATES AS DESCRIBED HEREIN AND WILL NOT BE DISTRIBUTED AS
    INTEREST TO THE CLASS II-A-4 CERTIFICATES.
 
(3) THE CLASS II-A-5 CERTIFICATES ARE COMPRISED OF COMPONENT II-A-5-1 AND
    COMPONENT II-A-5-2 (EACH AS DEFINED HEREIN). THE INTEREST AND PRINCIPAL
    DISTRIBUTABLE TO THE CLASS II-A-5 CERTIFICATES WILL BE BASED ON THE INTEREST
    AND PRINCIPAL ALLOCABLE TO EACH COMPONENT (AS DEFINED HEREIN) THEREOF. ON
    EACH DISTRIBUTION DATE PRIOR TO THE COMPONENT II-A-5-1 ACCRETION TERMINATION
    DATE (AS DEFINED HEREIN), AN AMOUNT EQUAL TO THE COMPONENT II-A-5-1 ACCRUAL
    AMOUNT (AS DEFINED HEREIN) WILL BE ADDED TO THE COMPONENT II-A-5-1 PRINCIPAL
    BALANCE, AND SUCH AMOUNT WILL BE DISTRIBUTED AS PRINCIPAL TO COMPONENTS AND
    CLASSES OF CERTIFICATES AS DESCRIBED HEREIN AND WILL NOT BE DISTRIBUTED AS
    INTEREST TO COMPONENT II-A-5-1. ON EACH DISTRIBUTION DATE PRIOR TO THE
    COMPONENT II-A-5-2 ACCRETION TERMINATION DATE (AS DEFINED HEREIN), AN AMOUNT
    EQUAL TO THE COMPONENT II-A-5-2 ACCRUAL AMOUNT (AS DEFINED HEREIN) WILL BE
    ADDED TO THE COMPONENT II-A-5-2 PRINCIPAL BALANCE, AND SUCH AMOUNT WILL BE
    DISTRIBUTED AS PRINCIPAL TO ANOTHER CLASS OF CERTIFICATES AS DESCRIBED
    HEREIN AND WILL NOT BE DISTRIBUTED AS INTEREST TO COMPONENT II-A-5-2.
 
(4) ON EACH DISTRIBUTION DATE ON OR BEFORE THE CLASS II-A-6 ACCRETION
    TERMINATION DATE (AS DEFINED HEREIN), AN AMOUNT EQUAL TO THE CLASS II-A-6
    ACCRUAL AMOUNT (AS DEFINED HEREIN) WILL BE ADDED TO THE CLASS II-A-6
    PRINCIPAL BALANCE, AND SUCH AMOUNT WILL BE DISTRIBUTED AS PRINCIPAL TO OTHER
    CLASSES OF CERTIFICATES AS DESCRIBED HEREIN AND WILL NOT BE DISTRIBUTED AS
    INTEREST TO THE CLASS II-A-6 CERTIFICATES.
 
(5) THE INITIAL REMITTANCE RATE FOR THE CLASS I-X-1 CERTIFICATES WILL BE 5.250%
    PER ANNUM. THEREAFTER, THE CLASS I-X-1 CERTIFICATES WILL ACCRUE INTEREST AT
    A PER ANNUM RATE EQUAL TO FOUR MULTIPLIED BY LIBOR (AS DEFINED HEREIN) MINUS
    17.500%, SUBJECT TO A MINIMUM AND MAXIMUM REMITTANCE RATE OF 0% AND 14.500%
    PER ANNUM, RESPECTIVELY. THE CLASS I-X-1 CERTIFICATES WILL ACCRUE INTEREST
    ON THE CLASS I-X-1 NOTIONAL AMOUNT (AS DEFINED IN "DESCRIPTION OF THE
    CERTIFICATES--DISTRIBUTIONS OF INTEREST" HEREIN). THE CLASS I-X-1 NOTIONAL
    AMOUNT AS OF THE CUT-OFF DATE (AS DEFINED HEREIN) WILL BE APPROXIMATELY
    $21,674,172. THE CLASS I-X-1 CERTIFICATES WILL NOT BE ENTITLED TO RECEIVE
    DISTRIBUTIONS OF PRINCIPAL.
 
(6) THE INITIAL REMITTANCE RATE FOR THE CLASS I-X-2 CERTIFICATES WILL BE 9.250%
    PER ANNUM. THEREAFTER, THE CLASS I-X-2 CERTIFICATES WILL ACCRUE INTEREST AT
    A PER ANNUM RATE EQUAL TO 32.000% MINUS FOUR MULTIPLIED BY LIBOR, SUBJECT TO
    A MINIMUM AND MAXIMUM REMITTANCE RATE OF 0% AND 14.500% PER ANNUM,
    RESPECTIVELY. THE CLASS I-X-2 CERTIFICATES WILL ACCRUE INTEREST ON THE CLASS
    I-X-2 NOTIONAL AMOUNT (AS DEFINED IN "DESCRIPTION OF THE
    CERTIFICATES--DISTRIBUTIONS OF INTEREST" HEREIN). THE CLASS I-X-2 NOTIONAL
    AMOUNT AS OF THE CUT-OFF DATE WILL BE APPROXIMATELY $21,674,172. THE CLASS
    I-X-2 CERTIFICATES WILL NOT BE ENTITLED TO RECEIVE DISTRIBUTIONS OF
    PRINCIPAL.
 
(7) THE REMITTANCE RATE ON THE CLASS II-X CERTIFICATES WILL BE 7.000% PER ANNUM.
    THE CLASS II-X CERTIFICATES WILL ACCRUE INTEREST ON THE CLASS II-X NOTIONAL
    AMOUNT (AS DEFINED IN "DESCRIPTION OF THE CERTIFICATES--DISTRIBUTIONS OF
    INTEREST" HEREIN). THE CLASS II-X NOTIONAL AMOUNT AS OF THE CUT-OFF DATE
    WILL BE APPROXIMATELY $35,143,021. THE CLASS II-X CERTIFICATES WILL NOT BE
    ENTITLED TO RECEIVE DISTRIBUTIONS OF PRINCIPAL.
 
(8) THE REMITTANCE RATE ON THE CLASS III-X CERTIFICATES WILL BE 6.750% PER
    ANNUM. THE CLASS III-X CERTIFICATES WILL ACCRUE INTEREST ON THE CLASS III-X
    NOTIONAL AMOUNT (AS DEFINED IN "DESCRIPTION OF THE
    CERTIFICATES--DISTRIBUTIONS OF INTEREST" HEREIN). THE CLASS III-X NOTIONAL
    AMOUNT AS OF THE CUT-OFF DATE WILL BE APPROXIMATELY $9,303,707. THE CLASS
    III-X CERTIFICATES WILL NOT BE ENTITLED TO RECEIVE DISTRIBUTIONS OF
    PRINCIPAL.
 
(9) THE CLASS I-P, CLASS II-P AND CLASS III-P CERTIFICATES WILL NOT BE ENTITLED
    TO RECEIVE DISTRIBUTIONS OF INTEREST.
 
                                      S-2
<PAGE>
    The Certificates will evidence all the beneficial ownership interest in a
trust (the "TRUST") established by the Company, the assets of which will consist
of a pool of conventional fixed-rate one- to four-family residential and
cooperative apartment mortgage loans with original terms to maturity of not more
than 30 years (the "MORTGAGE LOANS") deposited by the Company, and certain other
assets, as described herein. Certain of the Mortgage Loans will be master
serviced by the Company (the "PNC LOANS") and certain of the Mortgage Loans will
be master serviced by IndyMac, Inc. (the "INDYMAC LOANS", and each of the
Company and IndyMac, in such capacity, a "MASTER SERVICER"). The Mortgage Pool
(as described herein) consists of three groups of Mortgage Loans ("LOAN GROUP
I", "LOAN GROUP II" and "LOAN GROUP III", and each, a "LOAN GROUP"). The
Mortgage Loans in Loan Group I are sometimes referred to as the "GROUP I LOANS",
the Mortgage Loans in Loan Group II are sometimes referred to as the "GROUP II
LOANS" and the Mortgage Loans in Loan Group III are sometimes referred to as the
"GROUP III LOANS". The Group I Certificates will correspond to the Group I
Loans, which consist of fixed-rate Mortgage Loans with terms to maturity of not
more than 30 years. The Group II Certificates will correspond to the Group II
Loans, which consist of fixed-rate Mortgage Loans with terms to maturity of not
more than 30 years. The Group III Certificates will correspond to the Group III
Loans, which consist of fixed-rate Mortgage Loans with terms to maturity of not
more than 15 years. Distributions of interest and principal on the Group I
Certificates, the Group II Certificates and the Group III Certificates will be
solely based on interest and principal received or advanced with respect to the
Group I Loans, Group II Loans and Group III Loans, respectively. The rights of
the holders of the Class B Certificates of a Certificate Group to receive
distributions with respect to the Mortgage Loans in the related Loan Group will
be based solely on interest and principal received or advanced with respect to
such Loan Group, and will be subordinate to the rights of the holders of Class B
Certificates of such Certificate Group with lower numerical designations and the
Senior Certificates of such Certificate Group to the extent described herein and
in the Prospectus.
 
    The Company intends to cause an election to be made to treat the Trust as a
"real estate mortgage investment conduit" (a "REMIC") for federal income tax
purposes. All of the certificates issued by the Trust, other than the Class R
Certificates, will represent ownership of REMIC "regular interests". The Class R
Certificates will represent ownership of the REMIC "residual interest" in the
Trust. See "CERTAIN FEDERAL INCOME TAX CONSEQUENCES" herein and in the
Prospectus.
 
    The Offered Certificates evidence interests only in the Trust and are
payable solely from amounts received with respect thereto.
 
    The Company has the right to effect early retirement of the Certificates
under certain circumstances. See "Description of the Certificates--Optional
Termination of the Trust" herein.
 
    The yield to maturity on any Class of Certificates generally will depend on
the rate and timing of principal payments (including prepayments, defaults and
liquidations) on the Mortgage Loans in the related Loan Group.
 
    The Class II-A-4 Certificates will be especially sensitive to the rate of
prepayments on the Group II Loans because such Certificates will receive
distributions of principal on any Distribution Date only to the extent of a
percentage of the Group II Senior Principal Distribution Amount (as defined
herein) remaining, if any, after (i) the Lockout Certificates receive their
distributions from the Lockout Principal Distribution Amount (as defined
herein), if any, for such Distribution Date, (ii) the Class R Principal Balance
has been reduced to zero, (iii) the Class II-A-1 Certificates (the "PAC")
receive principal on such Distribution Date to the extent of the Class II-A-1
Certificates' planned principal balance for such Distribution Date as set forth
in Appendix A (each, a "PLANNED PRINCIPAL BALANCE"), and (iv) the Class II-A-2
Certificates receive principal distributions to the extent of the Class II-A-2
Certificates' targeted principal balance for such Distribution Date as set forth
in Appendix B (for any TAC (as defined herein), a "TARGETED PRINCIPAL BALANCE").
Furthermore, if the Group II Senior Principal Distribution Amount on any
Distribution Date is not sufficient to reduce the Class II-A-1 Principal Balance
to its Planned Principal
 
                                      S-3
<PAGE>
Balance and the Class II-A-2 Principal Balance to its Targeted Principal
Balance, the Class II-A-4 Certificates will receive no principal distributions
on such Distribution Date.
 
    The Class II-A-6 Certificates will be especially sensitive to the rate of
prepayments on the Group II Loans because such Certificates will receive
distributions of principal on any Distribution Date only to the extent of a
percentage of the Group II Senior Principal Distribution Amount remaining, if
any, after (i) the Lockout Certificates receive their distributions from the
Lockout Principal Distribution Amount, if any, for such Distribution Date, (ii)
the Class R Principal Balance has been reduced to zero, (iii) the Class II-A-1
Certificates receive principal on such Distribution Date to the extent of the
Class II-A-1 Certificates' Planned Principal Balance for such Distribution Date
as set forth on Appendix A, and (iv) the Class II-A-10 Certificates receive
principal distributions to the extent of the Class II-A-10 Certificates'
Targeted Principal Balance for such Distribution Date as set forth on Appendix
B. Furthermore, if the Group II Senior Principal Distribution Amount on any
Distribution Date is not sufficient to reduce the Class II-A-1 Principal Balance
to its Planned Principal Balance and the Class II-A-10 Principal Balance to its
Targeted Principal Balance, the Class II-A-6 Certificates will receive no
principal distributions on such Distribution Date.
 
    The Class II-A-5 Certificates will be especially sensitive to the rate of
prepayments on the Group II Loans because Component II-A-5-2 will receive
distributions of principal on any Distribution Date only to the extent of a
percentage of the Group II Senior Principal Distribution Amount remaining, if
any, after (i) the Lockout Certificates receive their distributions from the
Lockout Principal Distribution Amount, if any, for such Distribution Date, (ii)
the Class R Principal Balance has been reduced to zero, (iii) the Class II-A-1
Certificates receive principal on such Distribution Date to the extent of the
Class II-A-1 Certificates' Planned Principal Balance for such Distribution Date
as set forth on Appendix A, and (iv) the Class II-A-3 Certificates receive
principal distributions to the extent of the Class II-A-3 Certificates' Targeted
Principal Balance for such Distribution Date as set forth on Appendix B.
Furthermore, if the Group II Senior Principal Distribution Amount on any
Distribution Date is not sufficient to reduce the Class II-A-1 Principal Balance
to its Planned Principal Balance and the Class II-A-3 Principal Balance to its
Targeted Principal Balance, Component II-A-5-2 will receive no principal
distributions on such Distribution Date. However, if a Collateral Reduction
Trigger Date (as defined herein) occurs, Component II-A-5-1 and Component
II-A-5-2 will receive a percentage of the Group II Senior Principal Distribution
Amount prior to distributions of principal to the Class II-A-3 Certificates. See
"Description of the Certificates--Distributions of Principal--Group II
Certificate Principal Distributions--GROUP II SENIOR PRINCIPAL DISTRIBUTION
AMOUNT" herein.
 
    The Class II-A-10, Class II-A-2 and Class II-A-3 Certificates are "TACS". If
a higher than expected rate of Principal Prepayments is to occur with respect to
the Group II Loans, and the Class II-A-6 Certificates are retired, the Class
II-A-10 Certificates would receive distributions of principal in excess of the
related Targeted Principal Balances. Similarly, if a higher than expected rate
of Principal Prepayments is to occur with respect to the Group II Loans, and the
Class II-A-4 Certificates are retired, the Class II-A-2 Certificates would
receive distributions of principal in excess of the related Targeted Principal
Balances. Similarly, if a higher than expected rate of Principal Prepayments is
to occur with respect to the Group II Loans, and Component II-A-5-2 is retired,
the Class II-A-3 Certificates would receive distributions of principal in excess
of the related Targeted Principal Balance.
 
    The yields to maturity on the Classes of Class X Certificates will be
extremely sensitive to the level of Principal Prepayments on certain of the
Mortgage Loans in the related Loan Group. The interest payable to the Class I-X
Certificates is based on the weighted average of the Stripped Interest Rates (as
defined herein) of the Group I Mortgage Loans having Pass-Through Rates in
excess of 7.250% per annum (the "GROUP I PREMIUM RATE MORTGAGE LOANS"). The
interest payable to the Class II-X Certificates is based on the weighted average
of the Stripped Interest Rates of the Group II Mortgage Loans having Pass-
Through Rates in excess of 7.000% per annum (the "GROUP II PREMIUM RATE MORTGAGE
LOANS"). The interest payable to the Class III-X Certificates is based on the
weighted average of the Stripped Interest
 
                                      S-4
<PAGE>
Rates of the Group III Mortgage Loans having Pass-Through Rates in excess of
6.750% per annum (the "GROUP III PREMIUM RATE MORTGAGE LOANS" and, together with
the Group I Premium Rate Mortgage Loans and Group II Premium Rate Mortgage
Loans, the "PREMIUM RATE MORTGAGE LOANS"). Therefore, the yield to maturity on
any Class of the Class X Certificates will generally decrease as a result of
faster than expected Principal Prepayments on the related Premium Rate Mortgage
Loans. Prospective investors should fully consider the risks associated with an
investment in any Class of the Class X Certificates, including the possibility
that if the rate of Principal Prepayments on the related Premium Rate Mortgage
Loans is rapid, such investors may not fully recoup their initial investments.
 
    The yields to maturity on the Classes of Class P Certificates will be
extremely sensitive to the level of Principal Prepayments on certain of the
Mortgage Loans in the related Loan Group. The principal payable to the Class I-P
Certificates is derived from Group I Mortgage Loans having Pass-Through Rates
lower than 7.250% per annum (the "CLASS I-P MORTGAGE LOANS"). The principal
payable to the Class II-P Certificates is derived from Group II Mortgage Loans
having Pass-Through Rates lower than 7.000% per annum (the "CLASS II-P MORTGAGE
LOANS"). The principal payable to the Class III-P Certificates is derived from
Group III Mortgage Loans having Pass-Through Rates lower than 6.750% per annum
(the "CLASS III-P MORTGAGE LOANS" and, together with the Class I-P Mortgage
Loans and Class II-P Mortgage Loans, the "CLASS P MORTGAGE LOANS"). Therefore,
the yield to maturity on each Class of Class P Certificates will be adversely
affected by slower than expected prepayments of the related Class P Mortgage
Loans.
 
    For each Loan Group, because the interest payable on the Classes of Class X
Certificates related to such Loan Group and the principal distributable to the
Classes of Class P Certificates related to such Loan Group are derived from
different groups of Mortgage Loans within such Loan Group, it is possible that
faster than expected Principal Prepayments on the Mortgage Loans related to a
Class of Class X Certificates may occur at the same time as slower than expected
Principal Prepayments on the Mortgage Loans related to the Class of Class P
Certificates of the same Certificate Group. This occurrence would result in a
lower yield to maturity for both the Class X Certificates and Class P
Certificates related to a single Loan Group. See "Yield and Prepayment
Considerations" herein.
 
    Moreover, since the Class I-X-1 and Class I-X-2 Certificates are LIBOR
Certificates, the yield to investors in such Certificates will be sensitive to
fluctuations in LIBOR. The yield to maturity on the Class I-X-2 Certificates
will be extremely sensitive to fluctuations in LIBOR, and the Remittance Rate on
such Certificates will vary inversely with LIBOR. If prevailing rates of LIBOR
are sufficiently high, investors in the Class I-X-2 Certificates may not recoup
their initial investments, regardless of the rate of Principal Prepayments on
the Group I Premium Rate Mortgage Loans. Changes in LIBOR may not correlate with
changes in prevailing mortgage interest rates. It is possible that lower
prevailing mortgage interest rates, which might be expected to result in faster
prepayments, could occur concurrently with an increased level of LIBOR.
Conversely, higher prevailing mortgage interest rates (which would be expected
to result in slower prepayments) could occur concurrently with a lower level of
LIBOR.
 
    The rights of the holders of the Senior Subordinate Certificates of each
Certificate Group to receive distributions of interest and principal are
subordinated to the rights of the holders of the Senior Certificates of such
Certificate Group to receive distributions of interest and principal. In
addition, the rights of the holders of each Class of Senior Subordinate
Certificates of a Certificate Group to receive distributions of interest and
principal are subordinated to the rights of the holders of each other Class of
Senior Subordinate Certificates of such Certificate Group with a lower numerical
class designation to receive distributions of interest and principal.
Furthermore, following the reduction of the aggregate Class Principal Balance of
the Junior Subordinate Certificates of a Certificate Group to zero, the yield to
maturity on each Class of the Senior Subordinate Certificates of such
Certificate Group will be extremely sensitive to certain realized losses on the
Mortgage Loans in the related Loan Group because a disproportionate amount of
such losses (rather than a pro rata portion thereof) generally will be allocable
to such Classes in the order of reverse numerical Class designation. Similarly,
following the reduction of the aggregate Class Principal Balance of the Class B
Certificates of a Certificate Group to zero, the yield to
 
                                      S-5
<PAGE>
maturity on the Senior Certificates of such Certificate Group will be extremely
sensitive to all realized losses on the Mortgage Loans in the related Loan
Group. See "Description of the Certificates--Subordination and Allocation of
Losses" herein.
 
    Although the Lockout Certificates are Senior Certificates, the Class II-A-8
and Class II-A-9 Certificates will generally not be entitled to receive
principal distributions (other than the Lockout Liquidation Amount (as defined
herein)) until the Distribution Date in December 2002, and thereafter will not
be entitled to receive the disproportionate allocation of Principal Prepayments
in Loan Group II that the other Senior Certificates in Certificate Group II are
entitled to receive. See "Description of the Certificates--Distributions of
Principal" and "Yield and Prepayment Considerations" herein.
 
    HOLDERS OF THE CLASS II-A-7 CERTIFICATES WILL BE ENTITLED TO RECEIVE
DISTRIBUTIONS OF INTEREST ON EACH DISTRIBUTION DATE AS DESCRIBED HEREIN UNDER
"DESCRIPTION OF THE CERTIFICATES--DISTRIBUTIONS OF INTEREST". HOWEVER, UNLESS
THE CREDIT SUPPORT DEPLETION DATE HAS OCCURRED, SUCH HOLDERS WILL NOT BE
ENTITLED TO RECEIVE DISTRIBUTIONS OF PRINCIPAL UNTIL THE CLASS PRINCIPAL
BALANCES OF THE CLASS II-A-1, CLASS II-A-2, CLASS II-A-3, CLASS II-A-4, CLASS
II-A-5, CLASS II-A-6, CLASS II-A-10 AND CLASS R CERTIFICATES HAVE BEEN REDUCED
TO ZERO. THE TABLE INCLUDED IN APPENDIX C INDICATES THE DATES ON WHICH
DISTRIBUTIONS OF PRINCIPAL TO THE CLASS II-A-7 CERTIFICATES ARE EXPECTED TO
COMMENCE, AND THE DATES ON WHICH SUCH DISTRIBUTIONS ARE EXPECTED TO END, BASED
ON VARIOUS ASSUMPTIONS REGARDING THE PREPAYMENT EXPERIENCE OF THE GROUP II
LOANS. HOWEVER, THERE CAN BE NO ASSURANCE THAT THE GROUP II LOANS WILL PERFORM
ACCORDING TO SUCH ASSUMPTIONS. IN ADDITION, BECAUSE THE CLASS II-A-7
CERTIFICATES WILL BE OUTSTANDING FOR A RELATIVELY LONG PERIOD OF TIME, THERE IS
A GREATER LIKELIHOOD THAT THEY WILL REMAIN OUTSTANDING AFTER THE TERMINATION OF
THE CREDIT SUPPORT PROVIDED BY THE GROUP II-B CERTIFICATES AND THEREFORE BE MORE
SUSCEPTIBLE TO LOSSES ON THE GROUP II LOANS. INVESTORS IN THE CLASS II-A-7
CERTIFICATES SHOULD CONSULT WITH THEIR FINANCIAL ADVISORS REGARDING THE RISKS
ASSOCIATED WITH SUCH AN INVESTMENT.
 
    The Offered Certificates, other than the Class II-A-7, Class X and Class R
Certificates, are offered in minimum denominations equivalent to not less than
$25,000 initial Certificate Principal Balance each and multiples of $1 in excess
thereof, except that one Class I-P, one Class II-P and one Class III-P
Certificate may be issued in a different amount. The Class II-A-7 Certificates
are offered in minimum denominations equivalent to not less than $1,000 initial
Certificate Principal Balance each and multiples of $1 in excess thereof. The
Class X Certificates are offered in minimum denominations equivalent to not less
than $100,000 initial Class Notional Amount each and multiples of $1 in excess
thereof, except that one Class I-X-1, one Class I-X-2, one Class II-X and one
Class III-X Certificate may be issued in a different amount. The Class R
Certificates will be offered in registered, certificated form in a single
denomination of 99.99% Percentage Interest. The remaining 0.01% Percentage
Interest of the Class R Certificates will be retained by the Company as set
forth herein under "Certain Federal Income Tax Consequences". There is at
present no market for any Class of Certificates and there can be no assurance
that a secondary market for any Class of Certificates will develop or, if it
does develop, that it will provide Certificateholders of such Class with
liquidity of investment or will continue for the life of such Class of
Certificates.
 
    The Offered Certificates offered by this Supplement constitute a separate
Series of Certificates being offered by the Company from time to time pursuant
to the Prospectus dated November 24, 1997 of which this Supplement is a part and
which accompanies this Supplement. The Prospectus contains important information
regarding this offering which is not contained herein, and prospective investors
are urged to read the Prospectus and this Supplement in full.
 
    UNTIL THE EXPIRATION OF 90 DAYS AFTER THE DATE OF THIS SUPPLEMENT, ALL
DEALERS EFFECTING TRANSACTIONS IN THE OFFERED CERTIFICATES, WHETHER OR NOT
PARTICIPATING IN THIS DISTRIBUTION, MAY BE REQUIRED TO DELIVER A SUPPLEMENT AND
THE PROSPECTUS TO WHICH IT RELATES. THIS IS IN ADDITION TO THE OBLIGATION OF
DEALERS TO DELIVER A SUPPLEMENT AND PROSPECTUS WHEN ACTING AS UNDERWRITERS AND
WITH RESPECT TO THEIR UNSOLD ALLOTMENTS OR SUBSCRIPTIONS.
 
                                      S-6
<PAGE>
    NO PERSON HAS BEEN AUTHORIZED TO GIVE ANY INFORMATION OR TO MAKE ANY
REPRESENTATIONS OTHER THAN THOSE CONTAINED IN THIS SUPPLEMENT AND THE PROSPECTUS
TO WHICH IT RELATES, AND, IF GIVEN OR MADE, SUCH INFORMATION OR REPRESENTATIONS
MUST NOT BE RELIED UPON. THIS SUPPLEMENT DOES NOT CONSTITUTE AN OFFER TO SELL OR
A SOLICITATION OF AN OFFER TO BUY ANY SECURITIES OTHER THAN THE OFFERED
CERTIFICATES OFFERED HEREBY NOR AN OFFER OF THE OFFERED CERTIFICATES TO ANY
PERSON IN ANY STATE OR OTHER JURISDICTION IN WHICH SUCH OFFER WOULD BE UNLAWFUL.
THE DELIVERY OF THIS SUPPLEMENT AT ANY TIME DOES NOT IMPLY THAT INFORMATION
HEREIN IS CORRECT AS OF ANY TIME SUBSEQUENT TO ITS DATE; HOWEVER, IF ANY
MATERIAL CHANGE OCCURS WHILE THIS SUPPLEMENT IS REQUIRED BY LAW TO BE DELIVERED,
THIS SUPPLEMENT WILL BE AMENDED OR SUPPLEMENTED ACCORDINGLY.
 
                                      S-7
<PAGE>
                               TABLE OF CONTENTS
<PAGE>
                              SUMMARY INFORMATION
 
    THE FOLLOWING SUMMARY IS QUALIFIED IN ITS ENTIRETY BY REFERENCE TO THE
DETAILED INFORMATION APPEARING ELSEWHERE HEREIN AND IN THE PROSPECTUS.
CAPITALIZED TERMS USED HEREIN AND NOT OTHERWISE DEFINED HEREIN HAVE THE MEANINGS
ASSIGNED IN THE PROSPECTUS.
 
<TABLE>
<S>                            <C>
Title of Securities..........  Mortgage Pass-Through Certificates, Series 1997-8 (the
                               "CERTIFICATES")
 
Depositor and Certificate
 Administrator...............  PNC Mortgage Securities Corp. (the "COMPANY"). In acting as
                               administrator of the Certificates (in such capacity, the
                               "CERTIFICATE ADMINISTRATOR"), the Company will perform
                               certain securities administration functions for the Trust
                               under the Pooling Agreement (as defined below), including,
                               among other things, monitoring the amounts on deposit in the
                               Collection Account established in accordance with the
                               Pooling Agreement and maintained with the Trustee,
                               calculating amounts payable to Certificateholders on each
                               Distribution Date and preparing and distributing to
                               Certificateholders periodic statements and other reports as
                               provided in the Pooling Agreement, all in exchange for a
                               fee.
 
Trustee......................  U.S. Bank National Association
 
Cut-Off Date.................  November 1, 1997
 
Closing Date.................  On or about November 25, 1997
 
Certificates.................  The Offered Certificates will be issued pursuant to a
                               Pooling and Servicing Agreement (the "Pooling Agreement"),
                               dated as of the Cut-Off Date, among the Company, as
                               Depositor, Certificate Administrator and Master Servicer,
                               IndyMac, Inc., as Master Servicer, and the Trustee. The
                               approximate initial Class Principal Balances, Remittance
                               Rates, and types of the Offered Certificates will be as
                               follows:
</TABLE>
 
<TABLE>
<CAPTION>
                                                       APPROXIMATE
                                                      INITIAL CLASS     REMITTANCE
                                         CLASS      PRINCIPAL BALANCE      RATE                  TYPE
                                      ------------  ------------------  -----------  ----------------------------
<S>                                   <C>           <C>                 <C>          <C>
                                      Class I-A-1      $363,533,005         7.250%              Senior
                                      Class II-A-1       85,246,108         7.000%         Super Senior/PAC
                                      Class II-A-2       72,411,210         7.000%            Senior/TAC
                                      Class II-A-3       65,563,181         7.000%            Senior/TAC
                                      Class II-A-4        6,388,029         7.000%          Senior/Accrual
                                      Class II-A-5       10,490,109         7.000%      Sr./Component/Accrual
                                      Class II-A-6          555,409         7.000%          Senior/Accrual
                                      Class II-A-7        7,423,000         7.000%              Senior
                                      Class II-A-8       59,639,283         7.000%          Senior/Lockout
                                      Class II-A-9        4,901,652         7.000%     Mezzanine/Senior/Lockout
                                      Class                                                   Senior/TAC
                                      II-A-10            10,086,644         7.000%
                                      Class III-PT      100,539,062         6.750%              Senior
                                      Class I-X-1                --       Variable       Senior/Interest Only
                                      Class I-X-2                --       Variable       Senior/Interest Only
                                      Class II-X                 --         7.000%       Senior/Interest Only
                                      Class III-X                --         6.750%       Senior/Interest Only
                                      Class I-P             152,576             --      Senior/Principal Only
                                      Class II-P            142,701             --      Senior/Principal Only
                                      Class III-P           201,782             --      Senior/Principal Only
</TABLE>
 
                                      S-9
<PAGE>
 
<TABLE>
<CAPTION>
                                                       APPROXIMATE
                                                      INITIAL CLASS     REMITTANCE
                                         CLASS      PRINCIPAL BALANCE      RATE                  TYPE
                                      ------------  ------------------  -----------  ----------------------------
<S>                                   <C>           <C>                 <C>          <C>
                                      Class I-B-1        10,725,313         7.250%        Senior Subordinate
                                      Class I-B-2         6,825,198         7.250%        Senior Subordinate
                                      Class I-B-3         4,290,125         7.250%        Senior Subordinate
                                      Class II-B-1       11,132,668         7.000%        Senior Subordinate
                                      Class II-B-2        3,254,164         7.000%        Senior Subordinate
                                      Class II-B-3        1,712,718         7.000%        Senior Subordinate
                                      Class                                               Senior Subordinate
                                      III-B-1             2,244,486         6.750%
                                      Class                                               Senior Subordinate
                                      III-B-2               417,579         6.750%
                                      Class                                               Senior Subordinate
                                      III-B-3               313,184         6.750%
                                      Class R                    50         7.000%         Senior/Residual
</TABLE>
 
<TABLE>
<S>                            <C>
                               COMPONENTS. The Class II-A-5 Certificates will be comprised
                               of two components (each, a "COMPONENT"), each of which will
                               have a specified principal balance (a "COMPONENT PRINCIPAL
                               BALANCE") which functions in a manner comparable to that of
                               a Class Principal Balance on which interest will accrue at a
                               designated Remittance Rate. Holders of the Class II-A-5
                               Certificates will be entitled to receive distributions on
                               any Distribution Date to the extent of the amount
                               distributed with respect to the related Components on such
                               Distribution Date. Holders of the Class II-A-5 Certificates
                               may not transfer the Components separately.
 
                               The Components comprising the Class II-A-5 Certificates will
                               have the designations, initial Component Principal Balances
                               and characteristics set forth below:
</TABLE>
 
<TABLE>
<CAPTION>
                                                                              APS PROXIMATE
                                                                            INITIAL COMPONENT
                                                  DESIGNATION               PRINCIPAL BALANCE         TYPE
                                      -----------------------------------  -------------------  ----------------
<S>                                   <C>                                  <C>                  <C>
                                      Component II-A-5-1.................     $   2,596,302       Senior/Accrual
                                      Component II-A-5-2.................     $   7,893,807       Senior/Accrual
</TABLE>
 
<TABLE>
<S>                            <C>
                               The Certificates will evidence all the beneficial ownership
                               interest in a trust (the "TRUST") established by the
                               Company, into which the mortgage loans (the "MORTGAGE
                               LOANS") will be deposited. The Company will cause an
                               election to be made to treat the Trust as a real estate
                               mortgage investment conduit (a "REMIC"). See "Description of
                               the Certificates" herein.
 
Master Servicers.............  With respect to approximately 4,354 Mortgage Loans (the "PNC
                               LOANS"), with an aggregate principal balance as of the
                               Cut-Off Date of approximately $769,753,210, the Company will
                               act as Master Servicer, and with respect to approximately
                               564 Mortgage Loans (the "INDYMAC LOANS"), with an aggregate
                               principal balance as of the Cut-Off Date of approximately
                               $67,196,433, IndyMac, Inc. ("INDYMAC") will act as Master
                               Servicer. Notwithstanding anything to the contrary in the
                               Prospectus, the Master Servicers will provide all customary
                               servicing functions with respect to the related Mortgage
                               Loans pursuant to the Pooling Agreement. Each Master
                               Servicer will be entitled to: (i) a monthly master servicing
                               fee with respect to each Mortgage Loan serviced by such
                               Master Servicer, (ii) any interest or investment income
                               earned on funds deposited in certain accounts as described
                               herein, and (iii) certain additional servicing compensation
                               as described herein.
</TABLE>
 
                                      S-10
<PAGE>
 
<TABLE>
<S>                            <C>
The Mortgage Pool............  The Mortgage Pool consists of three groups of Mortgage Loans
                               ("LOAN GROUP I", "LOAN GROUP II" and "LOAN GROUP III", and
                               each, a "LOAN GROUP").
 
                               GROUP I LOANS. The Group I Loans consist of approximately
                               3,453 Mortgage Loans with an aggregate principal balance as
                               of the Cut-Off Date of approximately $390,011,349. The
                               principal balance at origination of each Group I Loan ranged
                               from a minimum of approximately $22,500 to a maximum of
                               approximately $247,500, with an average principal balance at
                               origination of approximately $113,091. The Group I Loans
                               have terms to maturity from the date of origination of not
                               more than 30 years, with an average remaining term to
                               maturity (adjusted for Curtailments) of approximately 356.1
                               months as of the Cut-Off Date.
 
                               GROUP II LOANS. The Group II Loans consist of approximately
                               1,032 Mortgage Loans with an aggregate principal balance as
                               of the Cut-Off Date of approximately $342,543,635. The
                               principal balance at origination of each Group II Loan
                               ranged from a minimum of approximately $214,650 to a maximum
                               of approximately $2,500,000, with an average principal
                               balance at origination of approximately $332,468. The Group
                               II Loans have terms to maturity from the date of origination
                               of not more than 30 years, with a weighted average remaining
                               term to maturity (adjusted for Curtailments) of
                               approximately 357.7 months as of the Cut-Off Date.
 
                               GROUP III LOANS. The Group III Loans consist of
                               approximately 433 Mortgage Loans with an aggregate principal
                               balance as of the Cut-Off Date of approximately
                               $104,394,658. The principal balance at origination of each
                               Group III Loan ranged from a minimum of approximately
                               $22,000 to a maximum of approximately $1,000,000, with an
                               average principal balance at origination of approximately
                               $244,103. The Group III Loans have terms to maturity from
                               the date of origination of not more than 15 years, with a
                               weighted average remaining term to maturity (adjusted for
                               Curtailments, except with respect to Balloon Loans (as
                               defined herein) and disregarding the amortization schedules
                               of Balloon Loans) of approximately 176.0 months as of the
                               Cut-Off Date.
 
                               For a further description of the Mortgage Loans, see
                               "Description of the Mortgage Pool" herein.
 
Initial Aggregate Certificate
 Principal Balance of the
 Offered Certificates........  The aggregate initial Certificate Principal Balance will be
                               approximately equal to the aggregate principal balance of
                               the Mortgage Loans as of the Cut-Off Date. The Group I
                               Certificates that are Senior Certificates will comprise
                               approximately 93.25%, the Group I Senior Subordinate
                               Certificates will comprise approximately 5.60%, and the
                               Group I Junior Subordinate Certificates will comprise
                               approximately 1.15%, of the initial aggregate principal
                               balance of the Group I Loans as of the Cut-Off Date. The
                               Group II Certificates that are Senior Certificates will
                               comprise approximately 94.25%, the Group II Senior
                               Subordinate Certificates will comprise approximately
</TABLE>
 
                                      S-11
<PAGE>
 
<TABLE>
<S>                            <C>
                               4.70%, and the Group II Junior Subordinate Certificates will
                               comprise approximately 1.05%, of the initial aggregate
                               principal balance of the Group II Loans as of the Cut-Off
                               Date. The Group III Certificates that are Senior
                               Certificates will comprise approximately 96.50%, the Group
                               III Senior Subordinate Certificates will comprise
                               approximately 2.85%, and the Group III Junior Subordinate
                               Certificates will comprise approximately 0.65%, of the
                               initial aggregate principal balance of the Group III Loans
                               as of the Cut-Off Date.
 
Loan Group I Initial Weighted
 Average Mortgage Interest
 Rate........................  8.363% (approximate).
 
Loan Group II Initial
 Weighted Average Mortgage
 Interest Rate...............  8.001% (approximate).
 
Loan Group III Initial
 Weighted Average Mortgage
 Interest Rate...............  7.615% (approximate).
 
The Trust....................  The assets of the Trust will consist of a pool (the
                               "MORTGAGE POOL") of Mortgage Loans with an aggregate
                               outstanding principal balance as of the Cut-Off Date of
                               approximately $836,949,643. The Trust will also contain (i)
                               certain insurance policies related to the Mortgage Loans,
                               (ii) any property which secured a Mortgage Loan and which is
                               acquired by foreclosure or by deed in lieu of foreclosure
                               after the Cut-Off Date, (iii) amounts held in the
                               Certificate Account, and (iv) certain other assets. See "The
                               Trust" herein.
 
Book-Entry Registration......  Except in certain limited circumstances as described herein,
                               the Class A Certificates generally will be available only in
                               book-entry form through the facilities of The Depository
                               Trust Company ("DTC"). See "Description of the
                               Certificates--Book-Entry Registration" herein.
 
Priority of Distributions....  Commencing in December 1997, on the 25th day of each month,
                               or if such 25th day is not a business day, on the
                               immediately succeeding business day (each, a "DISTRIBUTION
                               DATE"), distributions with respect to a Certificate Group
                               prior to the Credit Support Depletion Date (as defined
                               below) for such Certificate Group will in general be made to
                               the extent of the Available Distribution Amount (as defined
                               in "Description of the Certificates--Available Distribution
                               Amount" herein) for the related Loan Group in the order and
                               priority as follows: (1) first, to the related Class P
                               Certificates, a certain portion of the principal received in
                               respect of each related Class P Mortgage Loan, as described
                               in "Description of the Certificates--Distributions of
                               Principal" herein; (2) second, to the Senior Certificates of
                               such Certificate Group entitled to interest, accrued and
                               unpaid interest, as described in "Description of the
                               Certificates--Distributions of Interest" herein; PROVIDED,
                               HOWEVER, that with respect to the Group II Certificates (i)
                               on or before the Class II-A-4 Accretion Termination Date (as
                               defined herein), interest otherwise distributable to the
                               Class II-A-4 Certificates will be distributed, as principal,
                               to certain Classes of Certificates as described in
                               "Description of the
</TABLE>
 
                                      S-12
<PAGE>
 
<TABLE>
<S>                            <C>
                               Certificates--Priority of Distributions--CLASS II-A-4
                               ACCRUAL" herein, (ii) prior to the Component II-A-5-1
                               Accretion Termination Date (as defined herein), interest
                               otherwise distributable to Component II-A-5-1 will be
                               distributed, as principal, to a Class of Certificates and a
                               Component as described in "Description of the
                               Certificates--Priority of Distributions--COMPONENT II-A-5-1
                               ACCRUAL" herein, (iii) prior to the Component II-A-5-2
                               Accretion Termination Date (as defined herein), interest
                               otherwise distributable to Component II-A-5-2 will be
                               distributed, as principal, to a Class of Certificates and a
                               Component as described in "Description of the
                               Certificates--Priority of Distributions--COMPONENT II-A-5-2
                               ACCRUAL" herein and (iv) on or before the Class II-A-6
                               Accretion Termination Date (as defined herein), interest
                               otherwise distributable to the Class II-A-6 Certificates
                               will be distributed, as principal, to a Class of
                               Certificates as described in "Description of the
                               Certificates--Priority of Distributions--CLASS II-A-6
                               ACCRUAL" herein; (3) third, to the Senior Certificates of
                               such Certificate Group entitled to principal, principal in
                               the order described in "Description of the Certificates--
                               Distributions of Principal--Group I Senior Principal
                               Distribution Amount", "--Group II Senior Principal
                               Distribution Amount" or "--Group III Senior Principal
                               Distribution Amount" herein, as applicable; (4) fourth, to
                               the Class P Certificates of such Certificate Group,
                               principal to make up for certain losses on the related Class
                               P Mortgage Loans, as described in "Description of the
                               Certificates-- Distributions of Principal--CLASS I-P
                               PRINCIPAL DISTRIBUTION AMOUNT", "--CLASS II-P PRINCIPAL
                               DISTRIBUTION AMOUNT" or "--CLASS III-P PRINCIPAL
                               DISTRIBUTION AMOUNT" herein, as applicable; (5) fifth, to
                               each Class of Subordinate Certificates of such Certificate
                               Group, interest and then principal in increasing order of
                               numerical Class designation, with both interest and
                               principal being paid to one Class before any payments are
                               made to the next Class, as described in "Description of the
                               Certificates--Priority of Distributions" herein; and (6)
                               sixth, to the Class R Certificates, the remainder (which is
                               expected to be zero) of the Available Distribution Amount
                               for such Distribution Date.
 
                               The "CREDIT SUPPORT DEPLETION DATE" for each Certificate
                               Group is the first Distribution Date on which the aggregate
                               Class Principal Balance of the Subordinate Certificates of
                               such Certificate Group has been or will be reduced to zero.
 
                               With respect to each Certificate Group, on each Distribution
                               Date on or after the Credit Support Depletion Date for such
                               Certificate Group, distributions will in general be made to
                               the extent of the Available Distribution Amount for the
                               related Loan Group in the order and priority as follows: (1)
                               first, to the related Class P Certificates, a certain
                               portion of the principal received in respect of each related
                               Class P Mortgage Loan, as described in "Description of the
                               Certificates--Distributions of Principal" herein; (2)
                               second, to the Senior Certificates of such Certificate Group
                               entitled to interest, accrued and unpaid interest, as
                               described in "Description of the Certificates--Distributions
                               of Interest" herein; (3) third, to the Senior Certificates
                               of such Certificate Group entitled to principal, principal
</TABLE>
 
                                      S-13
<PAGE>
 
<TABLE>
<S>                            <C>
                               pro rata according to their respective Class Principal
                               Balances, as described in "Description of the
                               Certificates--Distributions of Principal" herein; and (4)
                               fourth, to the Class R Certificates, the remainder (which is
                               expected to be zero) of the Available Distribution Amount on
                               such Distribution Date.
 
                               For a description of the order and priority of
                               distributions, see "Description of the
                               Certificates--Priority of Distributions" herein.
 
Interest.....................  With respect to each Class of Certificates (except the Class
                               P Certificates, which are not entitled to interest),
                               interest will be passed through monthly on each Distribution
                               Date, commencing in December 1997, except that (1) interest
                               accrued on the Class II-A-4 Certificates on or before the
                               Class II-A-4 Accretion Termination Date will be added to the
                               Class II-A-4 Principal Balance, (2) interest accrued on
                               Component II-A-5-1 prior to the Component II-A-5-1 Accretion
                               Termination Date will be added to the Component II-A-5-1
                               Principal Balance, (3) interest accrued on Component
                               II-A-5-2 prior to the Component II-A-5-2 Accretion
                               Termination Date will be added to the Component II-A-5-2
                               Principal Balance and (4) interest accrued on the Class
                               II-A-6 Certificates on or before the Class II-A-6 Accretion
                               Termination Date will be added to the Class II-A-6 Principal
                               Balance. With respect to each Distribution Date, an amount
                               of interest will accrue or accrete, as applicable, on each
                               Class of Certificates (other than the Class P Certificates),
                               or, with respect to the Class II-A-5 Certificates, on each
                               Component of such Certificates, generally equal to 1/12th of
                               the applicable Remittance Rate for such Class or Component
                               multiplied by the related Class Principal Balance, Component
                               Principal Balance or Class Notional Amount, as applicable.
                               The Remittance Rates for the Offered Certificates entitled
                               to interest (other than the LIBOR Certificates) are fixed as
                               set forth on the cover page hereof. For a description of how
                               the Class X Notional Amounts are determined, see
                               "Description of the Certificates--Distributions of Interest"
                               herein. Interest to be distributed on the Certificates on
                               any Distribution Date will consist of accrued and unpaid
                               interest as of previous Distribution Dates and interest
                               accrued during the preceding calendar month, except for the
                               LIBOR Certificates which accrue interest during the period
                               commencing on the 25th day of the preceding calendar month
                               and ending on the 24th day of the month of such Distribution
                               Date. All distributions of interest for each Class of
                               Certificates will generally be made only to the extent of
                               the Available Distribution Amount for the related Loan Group
                               as described under "Description of the
                               Certificates--Priority of Distributions" herein.
 
                               See "Description of the Certificates--Distributions of
                               Interest" herein.
 
LIBOR........................  The Remittance Rates for the LIBOR Certificates will be
                               determined by the Certificate Administrator based on the
                               average of quotations of the London Interbank Offered Rate
                               for one-month U.S. dollar deposits ("LIBOR") as provided by
                               the Reference Banks (as defined herein), as further
                               described herein. See "Description of the
                               Certificates--LIBOR" herein.
</TABLE>
 
                                      S-14
<PAGE>
 
<TABLE>
<S>                            <C>
Compensating Interest........  Subject to the limitations described in this Prospectus
                               Supplement under "Yield and Prepayment Considerations", the
                               Company, as Master Servicer, is obligated to remit to the
                               Certificate Account on the day prior to each Distribution
                               Date with respect to the PNC Loans in each Loan Group an
                               amount equal to the lesser of (a) any shortfall for the
                               related month in interest collections resulting from the
                               timing of Payoffs on such Mortgage Loans made from the 15th
                               day of the calendar month preceding such Distribution Date
                               to the last day of such month and (b) the applicable monthly
                               Master Servicing Fee payable to the Company, any
                               reinvestment income realized by the Company, as Master
                               Servicer, relating to Payoffs on such Mortgage Loans made
                               during the related Prepayment Period (as defined herein) and
                               interest payments on such Payoffs received during the period
                               of the first day through the 14th day of the month of such
                               Distribution Date. In addition, on the day prior to each
                               Distribution Date, with respect to the IndyMac Loans in each
                               Loan Group, IndyMac is obligated to remit to the Certificate
                               Account an amount equal to the lesser of (i) any shortfall
                               for the related month in interest collections resulting from
                               the timing of Payoffs or Curtailments made during the
                               related Prepayment Period, and (ii) two-thirds of the
                               applicable monthly Master Servicing Fee payable to IndyMac
                               with respect to such Mortgage Loans. The sum of the amounts
                               so remitted will hereinafter be referred to as "COMPENSATING
                               INTEREST". Compensating Interest paid with respect to a Loan
                               Group will be allocated to each Class of Certificates of the
                               related Certificate Group pro rata according to the amount
                               of interest accrued thereon, and any remaining shortfall in
                               interest collections resulting from the timing of Payoffs
                               and Curtailments will be applied pro rata according to the
                               amount of interest to which each Class of Certificates of
                               the related Certificate Group would otherwise be entitled in
                               reduction thereof.
 
                               See "Description of the Certificates--Distributions of
                               Interest" herein.
 
Principal (including
 Principal Prepayments)......  GENERAL. On each Distribution Date, Certificateholders will
                               generally be entitled to receive principal distributions
                               from the related Available Distribution Amount to the extent
                               and priority described herein. All distributions of
                               principal will be made only to the extent of the related
                               Available Distribution Amount as described herein under
                               "Description of the Certificates--Priority of
                               Distributions". The Group I Certificates will receive
                               principal collected from Group I Loans, the Group II
                               Certificates will receive principal collected from Group II
                               Loans and the Group III Certificates will receive principal
                               collected from Group III Loans.
 
                               The Class X Certificates will not receive any distributions
                               of principal.
 
                               DISTRIBUTIONS TO THE CLASS P CERTIFICATES. On each
                               Distribution Date, each Class of the Class P Certificates
                               will receive a portion of the principal received on or in
                               respect of the Class P Mortgage Loans of the related Loan
                               Group. In addition, on each Distribution Date for so long as
                               any Class of Class B Certificates of the related Certificate
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                                      S-15
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                               Group remains outstanding, the Class P Certificates for such
                               Certificate Group will receive distributions of principal
                               equal to a portion of certain losses on the related Class P
                               Mortgage Loans. For a more detailed description of the
                               principal distributions to the Class P Certificates, see
                               "Description of the Certificates--Distributions of
                               Principal--CLASS I-P PRINCIPAL DISTRIBUTION AMOUNT",
                               "--CLASS II-P PRINCIPAL DISTRIBUTION AMOUNT" or "--CLASS
                               III-P PRINCIPAL DISTRIBUTION AMOUNT" herein, as applicable.
 
                               DISTRIBUTIONS TO THE CLASS I-A-1 CERTIFICATES. On each
                               Distribution Date, an amount, up to the amount of the Group
                               I Senior Principal Distribution Amount (as defined in
                               "Description of the Certificates-- Distributions of
                               Principal--GROUP I SENIOR PRINCIPAL DISTRIBUTION AMOUNT"
                               herein) for such Distribution Date, will be distributed as
                               principal to the Class I-A-1 Certificates.
 
                               DISTRIBUTIONS TO THE GROUP II-A AND CLASS R CERTIFICATES. On
                               each Distribution Date prior to the Credit Support Depletion
                               Date, an amount, up to the amount of the Group II Senior
                               Principal Distribution Amount (as defined in "Description of
                               the Certificates-- Distributions of Principal--GROUP II
                               SENIOR PRINCIPAL DISTRIBUTION AMOUNT" herein) for such
                               Distribution Date, will be distributed as principal to the
                               Group II-A and Class R Certificates in the order of priority
                               described in "Description of the Certificates--Distributions
                               of Principal--GROUP II SENIOR PRINCIPAL DISTRIBUTION AMOUNT"
                               herein. On each Distribution Date on and after the Credit
                               Support Depletion Date, principal will not be distributed in
                               that order and priority. Instead, an amount up to the Group
                               II Senior Principal Distribution Amount for such
                               Distribution Date will be distributed as principal to the
                               Group II-A and Class R Certificates, PRO RATA according to
                               their respective Class Principal Balances.
 
                               DISTRIBUTIONS ON THE CLASS II-A-7 CERTIFICATES. UNLESS THE
                               CREDIT SUPPORT DEPLETION DATE HAS OCCURRED, THE CLASS II-A-7
                               CERTIFICATES WILL NOT BE ENTITLED TO RECEIVE DISTRIBUTIONS
                               OF PRINCIPAL UNTIL THE CLASS PRINCIPAL BALANCES OF THE CLASS
                               II-A-1, CLASS II-A-2, CLASS II-A-3, CLASS II-A-4, CLASS
                               II-A-5, CLASS II-A-6, CLASS II-A-10 AND CLASS R CERTIFICATES
                               HAVE BEEN REDUCED TO ZERO.
 
                               DISTRIBUTIONS TO THE CLASS III-PT CERTIFICATES. On each
                               Distribution Date, an amount, up to the amount of the Group
                               III Senior Principal Distribution Amount (as defined in
                               "Description of the Certificates-- Distributions of
                               Principal--GROUP III SENIOR PRINCIPAL DISTRIBUTION AMOUNT"
                               herein) for such Distribution Date, will be distributed as
                               principal to the Class III-PT Certificates.
 
                               DISTRIBUTIONS TO THE CLASS B CERTIFICATES. On each
                               Distribution Date, an amount, up to the Subordinate
                               Principal Distribution Amount for the applicable Certificate
                               Group (as defined in "Description of the
                               Certificates--Distributions of Principal--GROUP I
                               SUBORDINATE PRINCIPAL DISTRIBUTION AMOUNT", "--GROUP II
                               SUBORDINATE PRINCIPAL DISTRIBUTION AMOUNT" or "--GROUP III
                               SUBORDINATE PRINCIPAL DISTRIBUTION AMOUNT" herein) for such
                               Distribution Date, will be distributed as principal to the
                               related Class of Class B Certificates.
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                                      S-16
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                               With respect to the Class B Certificates of each Certificate
                               Group, notwithstanding the foregoing, on any Distribution
                               Date on which the Subordination Level (as defined herein)
                               for any Class of Class B Certificates in a Certificate Group
                               is less than such percentage as of the Cut-Off Date, the
                               portion of the Subordinate Principal Prepayments
                               Distribution Amount (as defined herein) for such Certificate
                               Group otherwise allocable to the Class or Classes of the
                               Class B Certificates in the related Certificate Group junior
                               to such Class will be allocated to the most senior Class of
                               Class B Certificates in such Certificate Group for which the
                               Subordination Level is less than such percentage as of the
                               Cut-Off Date and to the Class or Classes of Class B
                               Certificates in such Certificate Group senior thereto, pro
                               rata according to the Class Principal Balances of such
                               Classes. See "Description of the Certificates--Priority of
                               Distributions" herein.
 
                               The rights of the holders of the Class B Certificates of a
                               Certificate Group to receive distributions of interest and
                               principal are subordinated to the rights of the holders of
                               the Senior Certificates in such Certificate Group to receive
                               distributions of interest and principal. See "Description of
                               the Certificates--Subordination and Allocation of Losses"
                               herein.
 
                               PREPAYMENT PERIOD. With respect to each Distribution Date
                               and each Payoff (as defined herein) of a PNC Loan, the
                               related "PREPAYMENT PERIOD" will commence on the 15th day of
                               the month preceding the month in which the related
                               Distribution Date occurs (or, in the case of the first
                               Distribution Date, commencing on the Cut-Off Date) and will
                               end on the 14th day of the month in which such Distribution
                               Date occurs. With respect to each Distribution Date and each
                               Payoff of an IndyMac Loan, the related "PREPAYMENT PERIOD"
                               will be the calendar month preceding the month in which the
                               related Distribution Date occurs. With respect to each
                               Curtailment, regardless of the Master Servicer of the
                               applicable Mortgage Loan, the related "PREPAYMENT PERIOD"
                               will be the calendar month preceding the month in which the
                               related Distribution Date occurs.
 
                               For a more detailed description of how distributions of
                               principal will be allocated among the various Classes of
                               Certificates, see "Description of the
                               Certificates--Distributions of Principal" herein.
 
Subordination and Allocation
 of Losses...................  The Class B Certificates of each Certificate Group will be
                               subordinate in right of payment to and provide credit
                               support to the Senior Certificates of such Certificate
                               Group, the Junior Subordinate Certificates of each
                               Certificate Group will be subordinate in right of payment to
                               and provide credit support to the Senior Subordinate
                               Certificates of such Certificate Group and each Class of
                               Senior Subordinate Certificates in each Certificate Group
                               will be subordinate in right of payment to and provide
                               credit support to each Class of Senior Subordinate
                               Certificates in the related Certificate Group with a lower
                               numerical Class designation. The support provided by the
                               Class B Certificates of each Certificate Group is intended
                               to enhance the likelihood of regular receipt by the Senior
                               Certificates of such
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                                      S-17
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                               Certificate Group of the full amount of the monthly
                               distributions of interest (except with respect to the
                               related Class P Certificates, which are not entitled to
                               interest) and principal (except with respect to the related
                               Class X Certificates, which are not entitled to principal)
                               to which they are entitled and to afford such Certificates
                               protection against certain losses. The protection afforded
                               to the Senior Certificates of each Certificate Group by the
                               Class B Certificates of such Certificate Group will be
                               accomplished by the preferential right on each Distribution
                               Date of such Senior Certificates to receive distributions of
                               interest (except with respect to the related Class P
                               Certificates) and principal (except with respect to the
                               related Class X Certificates) prior to distributions of
                               interest or principal to such Class B Certificates. The
                               protection afforded a Class of Senior Subordinate
                               Certificates of a Certificate Group by the Classes of Senior
                               Subordinate Certificates of such Certificate Group with
                               higher numerical Class designations will be similarly
                               accomplished by the preferential right of those Classes with
                               lower numerical Class designations to receive distributions
                               of principal and interest prior to distributions of
                               principal and interest to those Classes of Senior
                               Subordinate Certificates in such Certificate Group with
                               higher numerical Class designations. The support provided by
                               the Junior Subordinate Certificates of each Certificate
                               Group to the Senior Subordinate Certificates of such
                               Certificate Group is intended to enhance the likelihood of
                               regular receipt by such Senior Subordinate Certificates of
                               the full amount of monthly distributions of interest and
                               principal to which they are entitled and to afford such
                               Certificateholders protection against certain losses. The
                               protection afforded to the Senior Subordinate Certificates
                               of each Certificate Group by the Junior Subordinate
                               Certificates of such Certificate Group will be accomplished
                               by the preferential right on each Distribution Date of such
                               Senior Subordinate Certificates to receive distributions of
                               interest and principal, prior to distributions of interest
                               and principal to such Junior Subordinate Certificates.
 
                               Except for Special Hazard Losses, Fraud Losses and
                               Bankruptcy Losses in excess of the designated amounts of the
                               applicable Special Hazard Coverage, Fraud Coverage and
                               Bankruptcy Coverage (each, as defined herein) for a Loan
                               Group, any loss realized with respect to a Mortgage Loan in
                               a Loan Group will be allocated among the Certificates in the
                               related Certificate Group (i) for losses allocable to
                               principal (a) first, to the related Junior Subordinate
                               Certificates, until the aggregate of the Class Principal
                               Balances thereof has been reduced to zero, (b) second, to
                               the Class I-B-3, Class II-B-3 or Class III-B-3 Certificates,
                               as applicable, until the Class Principal Balance thereof has
                               been reduced to zero, (c) third, to the Class I-B-2, Class
                               II-B-2 or Class III-B-2 Certificates, as applicable, until
                               the Class Principal Balance thereof has been reduced to
                               zero, (d) fourth, to the Class I-B-1, Class II-B-1 or Class
                               III-B-1 Certificates, as applicable, until the Class
                               Principal Balance thereof has been reduced to zero, and (e)
                               fifth, to the Senior Certificates of the related Certificate
                               Group (other than the related Class X and Class P
</TABLE>
 
                                      S-18
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                               Certificates), pro rata, according to their Class Principal
                               Balances (or Component Principal Balances in the case of
                               Component II-A-5-1 and Component II-A-5-2) in reduction of
                               their respective Class or Component Principal Balances, as
                               applicable, PROVIDED, HOWEVER, that if the loss is
                               recognized with respect to a Class P Mortgage Loan, the
                               applicable Class P Fraction of such loss will first be
                               allocated to the Class P Certificates of the related
                               Certificate Group and the remainder of such loss will be
                               allocated as described above in this clause (i); and (ii)
                               for losses allocable to interest (a) first, to the related
                               Junior Subordinate Certificates, in reduction of accrued but
                               unpaid interest thereon and then in reduction of the Class
                               Principal Balances of such Certificates, (b) second, to the
                               Class I-B-3, Class II-B-3 or Class III-B-3 Certificates, as
                               applicable, in reduction of accrued but unpaid interest
                               thereon and then in reduction of the Class Principal Balance
                               of such Class of Certificates, (c) third, to the Class
                               I-B-2, Class II-B-2 or Class III-B-2 Certificates, as
                               applicable, in reduction of accrued but unpaid interest
                               thereon and then in reduction of the Class Principal Balance
                               of such Class of Certificates, (d) fourth, to the Class
                               I-B-1, Class II-B-1 or Class III-B-1 Certificates, as
                               applicable, in reduction of accrued but unpaid interest
                               thereon and then in reduction of the Class Principal Balance
                               of such Class of Certificates, and (e) fifth, to the Senior
                               Certificates of the related Certificate Group (other than
                               the related Class P Certificates), pro rata according to
                               accrued but unpaid interest thereon and then pro rata
                               according to their Class Principal Balances (or Component
                               Principal Balances in the case of Component II-A-5-1 and
                               Component II-A-5-2) in reduction of their respective Class
                               or Component Principal Balances, as applicable; PROVIDED,
                               FURTHER, that all losses allocated to principal and interest
                               that would otherwise be allocable to the Class II-A-1
                               Certificates on any Distribution Date will be allocated to
                               the Class II-A-9 Certificates, until the Class II-A-9
                               Principal Balance has been reduced to zero.
 
                               The allocation of the principal portion of losses relating
                               to a Mortgage Loan in a given Loan Group to all Classes of
                               Certificates in the related Certificate Group (other than
                               the related Class P and Class X Certificates) pro rata
                               according to their respective Class or Component Principal
                               Balances (except if the loss is recognized with respect to a
                               Class P Mortgage Loan, in which event the applicable Class P
                               Fraction (as defined herein) of such loss will first be
                               allocated to the Class P Certificates of the related
                               Certificate Group, and the remainder of such loss will be
                               allocated as described above), and the allocation of the
                               interest portion of such losses to the Certificates in the
                               related Certificate Group pro rata according to the amount
                               of interest accrued on each such Class or Component (other
                               than the related Class P Certificates) in reduction thereof
                               and then in reduction of their related Class or Component
                               Principal Balances, is hereinafter referred to as "PRO RATA
                               ALLOCATION".
 
                               Special Hazard Losses, Fraud Losses and Bankruptcy Losses
                               for Mortgage Loans in a Loan Group in excess of the
                               applicable coverage will be allocated to all outstanding
                               Classes of Certificates in the
</TABLE>
 
                                      S-19
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                               related Certificate Group by Pro Rata Allocation. Each of
                               the coverages for such losses may be reduced periodically,
                               as described herein. See "Description of the
                               Certificates--Subordination and Allocation of Losses"
                               herein.
 
                               See also "Description of the Certificates--Distributions of
                               Principal" herein.
 
Credit Enhancements..........  SUBORDINATION. The subordination of the Class B Certificates
                               of each Certificate Group to the Senior Certificates of such
                               Certificate Group and the further subordination among the
                               Class B Certificates of each Certificate Group described
                               above and in "Description of the Certificates--Subordination
                               and Allocation of Losses" herein, will provide credit
                               enhancement to the related Senior Certificates and each
                               related Class B Certificate with a lower numerical Class
                               designation.
 
                               SHIFTING OF INTERESTS. The Senior Certificates of a
                               Certificate Group entitled to principal, other than the
                               Lockout Certificates (unless the applicable Credit Support
                               Depletion Date has occurred), will receive 100% of Principal
                               Prepayments received with respect to the Mortgage Loans in
                               the related Loan Group until the fifth anniversary of the
                               first Distribution Date. During the next four years, such
                               Senior Certificates, other than the Lockout Certificates
                               (unless the applicable Credit Support Depletion Date has
                               occurred), will receive a disproportionately large, but
                               decreasing, share of Principal Prepayments received with
                               respect to the Mortgage Loans in the related Loan Group.
                               This will result in an acceleration of the amortization of
                               such Senior Certificates, other than the Lockout
                               Certificates, subject to the priorities described in
                               "Description of the Certificates--Distributions of
                               Principal" herein, enhancing the likelihood that holders of
                               such Classes of Certificates will be paid the full amount of
                               principal to which they are entitled. For a more detailed
                               description of how Principal Prepayments with respect to a
                               Loan Group are allocated among the Classes of Certificates
                               of the related Certificate Group, see "Description of the
                               Certificates-- Distributions of Principal" herein.
 
Advances.....................  With respect to each Mortgage Loan, the related Master
                               Servicer will make Advances on each Distribution Date to the
                               Certificate Account to cover any shortfall between (i)
                               payments scheduled to be received in respect of such
                               Mortgage Loan and (ii) the amounts actually deposited in the
                               Certificate Account on account of such payments; provided
                               that such Master Servicer determines, in good faith, on such
                               Distribution Date that such Advances will be recoverable
                               from Insurance Proceeds, Liquidation Proceeds (as defined in
                               the Prospectus) or other amounts received with respect to
                               such Mortgage Loan. Advances are reimbursable to each Master
                               Servicer from cash in the Certificate Account relating to
                               Mortgage Loans in the applicable Loan Group master serviced
                               by such Master Servicer prior to payments to the
                               Certificateholders if such Master Servicer determines that
                               any such Advances previously made are not recoverable from
                               Insurance Proceeds, Liquidation Proceeds or other amounts
                               recoverable with respect to the applicable Mortgage Loan
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                                      S-20
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                               and so notifies the Certificate Administrator. See
                               "Description of the Certificates--Advances" herein.
 
Class II-A-7 Certificates....  Holders of the Class II-A-7 Certificates will be entitled to
                               receive distributions of interest on each Distribution Date
                               as described herein under "Description of the
                               Certificates--Distributions of Interest." However, unless
                               the Credit Support Depletion Date has occurred, such holders
                               will not be entitled to receive distributions of principal
                               until the Class Principal Balances of the Class II-A-1,
                               Class II-A-2, Class II-A-3, Class II-A-4, Class II-A-5,
                               Class II-A-6, Class II-A-10 and Class R Certificates have
                               been reduced to zero. The table included in Appendix C
                               herein indicates the dates on which distributions of
                               principal to the Class II-A-7 Certificates are expected to
                               commence, and the dates on which such distributions are
                               expected to end, based on various assumptions regarding the
                               loss and prepayment experience of the Group II Loans.
                               However, there can be no assurance that the Group II Loans
                               will perform as expected. In addition, because the Class
                               II-A-7 Certificates will be outstanding for a relatively
                               long period of time, there is a greater likelihood that they
                               will remain outstanding after the termination of the credit
                               support provided by the Group II-B Certificates and
                               therefore be more susceptible to losses on the Group II
                               Loans. Investors in the Class II-A-7 Certificates should
                               consult with their financial advisors regarding the risks
                               associated with such an investment.
 
Yield and Prepayment
 Considerations..............  The effective yield to maturity of each Class of
                               Certificates will depend upon, among other things, the price
                               at which such Certificates are purchased, the applicable
                               Remittance Rate, the actual characteristics of the Mortgage
                               Loans in the related Loan Group, the rate of principal
                               payments (including Principal Prepayments) on the Mortgage
                               Loans in the related Loan Group and the rate of liquidations
                               on the Mortgage Loans in the related Loan Group. A higher
                               than anticipated rate of principal payments (including
                               Principal Prepayments) and liquidations would reduce the
                               aggregate principal balance of the Mortgage Loans more
                               quickly than expected, thereby reducing the aggregate
                               interest payments with respect to such Mortgage Loans.
                               Therefore, a higher rate of principal payments (including
                               Principal Prepayments) and liquidations in a Loan Group
                               could result in a lower than expected yield to maturity on
                               related Classes of Certificates purchased at a premium.
                               Conversely, a lower than anticipated rate of principal
                               payments (including Principal Prepayments) and liquidations
                               in a Loan Group could reduce the return on any related Class
                               of Certificates purchased at a discount, in that payments of
                               principal with respect to the Mortgage Loans in such Loan
                               Group would occur later than anticipated. Principal
                               distributions to the Group I Certificates, Group II
                               Certificates and Group III Certificates relate to principal
                               payments on the Group I Loans, Group II Loans and Group III
                               Loans, respectively.
 
                               The actual rate of payments of principal (including
                               Principal Prepayments) and liquidations on the Mortgage
                               Loans may be influenced by a variety of economic,
                               geographic, social and other
</TABLE>
 
                                      S-21
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                               factors. In general, if interest rates generally rise above
                               the interest rates on the Mortgage Loans, the rate of
                               prepayment would be expected to decrease. Conversely, if
                               prevailing interest rates fall significantly below the
                               interest rates on the Mortgage Loans, the Mortgage Loans are
                               likely to be subject to higher prepayment rates than if
                               prevailing rates remain at or above the interest rates on
                               the Mortgage Loans. See "Risk Factors" and "Yield and
                               Prepayment Considerations" herein.
 
                               For a discussion of special yield and prepayment
                               considerations applicable to certain Classes of
                               Certificates, see "Risk Factors" herein.
 
Ratings......................  It is a condition to the issuance of the Offered
                               Certificates that they receive the ratings from one or more
                               of Standard & Poor's, a division of The McGraw-Hill
                               Companies, Inc. ("S&P"), Fitch Investors Service, L.P.
                               ("FITCH"), and Duff & Phelps Credit Rating Co. ("DCR"),
                               indicated under "Certificate Ratings" herein. See also "Risk
                               Factors" and "Yield and Prepayment Considerations" herein.
                               The ratings on the Offered Certificates address the
                               likelihood of the receipt by holders of Offered Certificates
                               of all distributions with respect to the underlying Mortgage
                               Loans to which they are entitled and do not address the
                               likely actual rate of Principal Prepayments, which rate
                               could, if different than originally anticipated, adversely
                               affect the yield realized by Certificateholders or cause the
                               Class X Certificateholders to fail to recoup their initial
                               investments.
 
Last Scheduled Distribution
 Date........................  The Last Scheduled Distribution Date for the Group I
                               Certificates is the Distribution Date in January 2028, which
                               is the Distribution Date in the month after the scheduled
                               maturity date for the latest maturing Mortgage Loan in Loan
                               Group I.
 
                               The Last Scheduled Distribution Date for the Group II
                               Certificates is the Distribution Date in December 2027,
                               which is the Distribution Date in the month after the
                               scheduled maturity date for the latest maturing Mortgage
                               Loan in Loan Group II.
 
                               The Last Scheduled Distribution Date for the Group III
                               Certificates is the Distribution Date in December 2012,
                               which is the Distribution Date in the month after the
                               scheduled maturity date for the latest maturing Mortgage
                               Loan in Loan Group III.
 
                               The actual rate of principal payments on the Certificates
                               will depend on the rate of payments of principal (including
                               Principal Prepayments) on the Mortgage Loans in the related
                               Loan Group which, in turn, may be influenced by a variety of
                               economic, geographic and social factors, as well as the
                               level of prevailing interest rates. No assurance can be
                               given as to the actual payment experience on the Mortgage
                               Loans. See "Description of the Certificates--Last Scheduled
                               Distribution Date" and "Yield and Prepayment Considerations"
                               herein.
 
Legal Investment.............  As of the date of their issuance, the Offered Certificates,
                               other than the Class I-B-2, Class II-B-2, Class III-B-2,
                               Class I-B-3, Class II-B-3 and Class III-B-3 Certificates,
                               will constitute "mortgage related
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                                      S-22
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                               securities" for purposes of the Secondary Mortgage Market
                               Enhancement Act of 1984 ("SMMEA"). SMMEA provides that
                               states may override its provisions on legal investment and
                               restrict or condition investment in mortgage related
                               securities by taking statutory action prior to October 4,
                               1991. Certain states have enacted legislation which has
                               overridden the provisions of SMMEA. See "Certain Legal
                               Investment Aspects" herein.
 
                               Institutions whose investment activities are subject to
                               review by certain regulatory authorities may be or may
                               become subject to restrictions on investment in the Offered
                               Certificates, and such restrictions may be retroactively
                               imposed. The Federal Financial Institutions Examination
                               Council, the Federal Deposit Insurance Corporation, the
                               Office of the Comptroller of the Currency, the Board of
                               Governors of the Federal Reserve System, the Office of
                               Thrift Supervision and the National Credit Union
                               Administration have adopted guidelines, and have proposed
                               policies, regarding the suitability of investments in
                               various types of derivative mortgage-backed securities,
                               including securities such as the Offered Certificates. In
                               addition, several states have adopted or are considering
                               regulations that would prohibit regulated institutions
                               subject to their jurisdiction from holding mortgage-backed
                               securities such as the Offered Certificates, including such
                               securities previously purchased. Investors should consult
                               their own legal advisors in determining whether and to what
                               extent the Offered Certificates constitute legal investments
                               for such investors.
 
ERISA Considerations.........  See "ERISA Considerations" herein and in the Prospectus.
 
Certain Federal Income Tax
 Consequences................  For federal income tax purposes, the Company will cause an
                               election to be made to treat the Trust as a "real estate
                               mortgage investment conduit" (a "REMIC"). The certificates
                               issued by the Trust, other than the Class R Certificates,
                               will be designated as REMIC regular interests. As REMIC
                               regular interests, such certificates will generally be
                               treated as representing ownership of debt for federal income
                               tax purposes. Certificateholders will be required to include
                               in income all interest and original issue discount ("OID")
                               on such certificates in accordance with the accrual method
                               of accounting regardless of the Certificateholders' usual
                               methods of accounting. For federal income tax purposes, the
                               Class R Certificates will be the "residual interest" in the
                               Trust.
 
                               The Class II-A-4, Class II-A-5, Class II-A-6, Class III-PT,
                               Class X and Class P Certificates will, and the Class II-A-7,
                               Class II-A-8, Class II-A-9 and Senior Subordinate
                               Certificates may, be treated as having been issued with OID
                               for federal income tax purposes. Certain Classes of
                               Certificates may be treated for federal income tax purposes
                               as having been issued at a premium. The prepayment
                               assumption that will be used in determining the rate of
                               accrual of market discount and premium, if any, for federal
                               income tax purposes is 100% of the Basic Prepayment
                               Assumption for Loan Group I, 250% of the Basic Prepayment
                               Assumption for Loan Group II and 235% of the Basic
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                                      S-23
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                               Prepayment Assumption for Loan Group III as described herein
                               under "Yield and Prepayment Considerations". No
                               representation is made that the Mortgage Loans in any Loan
                               Group will prepay at any given percentage of the Basic
                               Prepayment Assumption.
 
                               If actual prepayments differ sufficiently from the
                               prepayment assumption, the calculation of OID for certain
                               Classes of Offered Certificates might produce a negative
                               number for certain accrual periods. In such event,
                               Certificateholders will not be entitled to a deduction for
                               such amount, but will be required to carry such amount
                               forward as an offset to OID, if any, accruing in future
                               accrual periods.
 
                               Under the REMIC Regulations (as defined herein), the
                               Residual Certificates will not be regarded as having
                               "significant value" for purposes of applying the rules
                               relating to "excess inclusions". In addition, the Residual
                               Certificates may constitute "noneconomic" residual interests
                               for purposes of the REMIC Regulations. Transfers of the
                               Residual Certificates will be restricted under the Pooling
                               Agreement to United States Persons (as defined in the
                               Prospectus) in a manner designed to prevent a transfer of a
                               noneconomic residual interest from being disregarded under
                               the REMIC Regulations. See "Certain Federal Income Tax
                               Consequences--Special Tax Considerations Applicable to the
                               Residual Certificates" herein and "Certain Federal Income
                               Tax Consequences--Taxation of Owners of REMIC Residual
                               Certificates--Excess Inclusions" and "--Noneconomic REMIC
                               Residual Certificates" in the Prospectus.
 
                               The Residual Certificateholders may be required to report an
                               amount of taxable income with respect to the early years of
                               the REMIC's term that significantly exceeds distributions on
                               the Residual Certificates during such years, with
                               corresponding tax deductions or losses deferred until the
                               later years of the REMIC's term. Accordingly, on a present
                               value basis, the tax detriments occurring in the earlier
                               years may substantially exceed the sum of any tax benefits
                               in the later years. As a result, the Residual
                               Certificateholders' after-tax rate of return may be zero or
                               negative, even if their pre-tax rate of return is positive.
 
                               The Offered Certificates will generally be treated as
                               "qualifying real property loans" for mutual savings banks
                               and domestic building and loan associations, "loans secured
                               by an interest in real property" for domestic building and
                               loan associations, and "real estate assets" for real estate
                               investment trusts ("REITS") in the same proportion that the
                               assets in the REMIC would be so treated. In addition,
                               interest on the Offered Certificates will generally be
                               treated as "interest on obligations secured by mortgages on
                               real property" for REITs to the extent that such
                               Certificates are treated as "real estate assets". See
                               "Certain Federal Income Tax Consequences" in the Prospectus.
 
                               For further information regarding the federal income tax
                               consequences of investing in the Offered Certificates, see
                               "Certain Federal Income Tax Consequences" herein and in the
                               Prospectus.
</TABLE>
 
                                      S-24
<PAGE>
                                  RISK FACTORS
 
EFFECT OF PRINCIPAL PREPAYMENTS
 
    The rate of principal payments, amount of each interest payment and yield to
maturity on each Class of the Certificates are directly related to the rate of
payments of principal on the Mortgage Loans in the related Loan Group, which may
be in the form of scheduled amortization, principal prepayments or liquidations.
In general, when the level of prevailing mortgage interest rates declines
significantly below the interest rates on the Mortgage Loans, the rate of
prepayment is likely to increase, although the prepayment rate is influenced by
a number of other factors, including general economic conditions and homeowner
mobility. The rate of payment of principal will also be affected by any
repurchase by the Company of the Mortgage Loans in the related Loan Group. See
"Maturity, Average Life and Prepayment Assumptions" and "Description of
Certificates--Termination" in the Prospectus and "Description of the
Certificates--Optional Termination of the Trust" and "Yield and Prepayment
Considerations" herein. In such event, the repurchase price paid by the Company
would be passed through to related Certificateholders on the Distribution Date
following the month of repurchase. All of the Mortgage Loans contain
"due-on-sale" clauses. Consequently, acceleration of maturity as a result of
transfers of Mortgaged Properties will affect the level of Principal Prepayments
on the Mortgage Loans.
 
    "PRINCIPAL PREPAYMENTS" include prepayments in full on a Mortgage Loan
("PAYOFFS") and partial principal prepayments on a Mortgage Loan
("CURTAILMENTS").
 
    The Class II-A-2, Class II-A-3 and Class II-A-10 Certificates (the
"ACCRETION DIRECTED CLASSES") and Component II-A-5-2 (the "ACCRETION DIRECTED
COMPONENT") will receive distributions of principal otherwise payable as
interest to Class II-A-4 (on or before the Class II-A-4 Accretion Termination
Date (as defined herein)), Class II-A-6 (on or before the Class II-A-6 Accretion
Termination Date (as defined herein)), Component II-A-5-1 (prior to the
Component II-A-5-1 Accretion Termination Date (as defined herein)) and Component
II-A-5-2 (prior to the Component II-A-5-2 Accretion Termination Date (as defined
herein)). Because the Accretion Directed Classes and Accretion Directed
Component receive such distributions of principal, they may amortize faster than
otherwise would be the case. The Class II-A-4, Class II-A-5 and Class II-A-6
Certificates are referred to as the "ACCRUAL CERTIFICATES" herein.
 
    If any Certificate is purchased at a discount from its original Certificate
Principal Balance, and if a purchaser of such Certificate calculates the yield
to maturity based on an assumed rate of principal payments (including Principal
Prepayments) and liquidations faster than that actually received on the Mortgage
Loans in the related Loan Group, the actual yield to maturity will be lower than
that so calculated. If any Certificate is purchased at a premium from its
original Certificate Principal Balance, and if a purchaser of such Certificate
calculates the yield to maturity based on an assumed rate of principal payments
(including Principal Prepayments) and liquidations slower than that actually
received on the Mortgage Loans in the related Loan Group, the actual yield to
maturity will be lower than that so calculated.
 
    Principal distributions on the Class II-A-1 Certificates (the "PAC") on any
Distribution Date will generally be payable in amounts determined on the basis
of the planned principal balances for the Class II-A-1 Certificates for such
Distribution Date as set forth in Appendix A (each, a "PLANNED PRINCIPAL
BALANCE"). The Planned Principal Balances for the Class II-A-1 Certificates were
determined assuming that the prepayment rate of the Group II Loans occur each
month at a constant level between approximately 65% and 350% of the Basic
Prepayment Assumption (as defined herein). However, as discussed herein, actual
principal distributions may deviate from the described amounts, because the
actual prepayment rate of such Group II Loans each month may not occur at a
constant level between approximately 65% and 350% of the Basic Prepayment
Assumption. If the Class Principal Balances of the Class II-A-2, Class II-A-3,
Class II-A-4, Class II-A-5, Class II-A-6 and Class II-A-10 Certificates are
reduced to zero before the Class II-A-1 Principal Balance is reduced to zero,
the weighted average life of the Class II-A-1 Certificates will become
significantly more sensitive to changes in the prepayment rate of the Group II
Loans, and principal distributions thereon will be more likely to deviate from
the described amounts.
 
                                      S-25
<PAGE>
    Principal distributions on the Class II-A-2, Class II-A-3 and Class II-A-10
Certificates (the "TACS") on any Distribution Date will generally be payable in
amounts determined on the basis of their respective targeted principal balances
for such Distribution Date as set forth in Appendix B (each, a "TARGETED
PRINCIPAL BALANCE"). The Targeted Principal Balances of such Classes were
determined assuming that the prepayment rate of the Group II Loans remains
constant at 250% of the Basic Prepayment Assumption. However, as discussed
herein, actual principal distributions may deviate from the described amounts,
because the actual prepayment rate of the Group II Loans each month may not
remain constant at 250% of the Basic Prepayment Assumption. If the Class II-A-4
Principal Balance has been reduced to zero, the rate of principal distributions
and the weighted average life of the Class II-A-2 Certificates will become
significantly more sensitive to changes in the prepayment rate of the Group II
Loans. If the Component II-A-5-2 Principal Balance has been reduced to zero, the
rate of principal distributions and the weighted average life of Class II-A-3
Certificates will become significantly more sensitive to changes in the
prepayment rate of the Group II Loans. If the Class II-A-6 Principal Balance has
been reduced to zero, the rate of principal distributions and the weighted
average life of the Class II-A-10 Certificates will become significantly more
sensitive to changes in the prepayment rate of the Group II Loans.
 
    Principal Prepayments on the Group II Loans and other unscheduled payments
of principal may result in principal available for distribution on a
Distribution Date to the Class II-A-1 Certificates and the TACs on such
Distribution Date in an amount greater than the amount necessary to reduce the
applicable Class Principal Balances of the Class II-A-1 Certificates and the
TACs to their scheduled amounts. The excess principal after distribution to the
Class II-A-1 Certificates will be distributed as follows: (a) a percentage will
be distributed to the Class II-A-2 Certificates to the extent of Class II-A-2's
Targeted Principal Balance, then to the Class II-A-4 Certificates, until the
Class II-A-4 Principal Balance has been reduced to zero and then to the Class
II-A-2 Certificates until the Class II-A-2 Principal Balance has been reduced to
zero; (b) a percentage will be distributed to the Class II-A-10 Certificates to
the extent of Class II-A-10's Targeted Principal Balance, then to the Class
II-A-6 Certificates, until the Class II-A-6 Principal Balance has been reduced
to zero and then to the Class II-A-10 Certificates until the Class II-A-10
Principal Balance has been reduced to zero; and (c) the remainder of such excess
will be distributed to the Class II-A-3 Certificates to the extent of its
Targeted Principal Balance, then to Component II-A-5-2, until the Component
II-A-5-2 Principal Balance has been reduced to zero, then to the Class II-A-3
Certificates until the Class II-A-3 Principal Balance has been reduced to zero
and then to Component II-A-5-1, until the Component II-A-5-1 Principal Balance
has been reduced to zero (provided, however, that on or after the Collateral
Reduction Trigger Date (as defined herein) Component II-A-5-1 will receive
distributions before Component II-A-5-2, which will receive distributions before
the Class II-A-3 Certificates). Any excess after all such payments will be
distributed to the Class II-A-1 Certificates without regard to its Planned
Principal Balance. Accordingly, the rate of payments on the Group II Loans is
expected to have a greater effect on the weighted average life of the Class
II-A-4, Class II-A-5 and Class II-A-6 Certificates, and under certain prepayment
scenarios, the TACs, than on the weighted average lives of the Class II-A-1
Certificates. If the rate of Principal Prepayments and other unscheduled
payments of principal causes the principal available for distribution on the
Group II Certificates on any Distribution Date to be less than the amounts
necessary to reduce the Class Principal Balance of the Class II-A-1 Certificates
to its Planned Principal Balance, the Class II-A-2, Class II-A-3, Class II-A-4,
Class II-A-5, Class II-A-6, Class II-A-7 and Class II-A-10 Certificates will not
receive any distributions of principal (other than the principal they may
receive as Accretion Directed Classes or Accretion Directed Components).
Similarly, prior to the Collateral Reduction Trigger Date, if the principal
available for distribution to the Class II-A-2, Class II-A-10 and Class II-A-3
Certificates is less than the amount necessary to reduce their Class Principal
Balances to their respective Targeted Principal Balances, the Class II-A-4,
Class II-A-5 and Class II-A-6 Certificates will not receive any distributions of
principal (other than the principal they may receive as Accretion Directed
Classes). See "Yield and Prepayment Considerations" herein.
 
    The yields to maturity on the Class X Certificates will be extremely
sensitive to the level of Principal Prepayments on certain of the Mortgage Loans
in the related Loan Group. The interest payable to the
 
                                      S-26
<PAGE>
Class I-X Certificates is based on the weighted average of the Stripped Interest
Rates (as defined herein) of the Group I Mortgage Loans having Pass-Through
Rates in excess of 7.250% per annum (the "GROUP I PREMIUM RATE MORTGAGE LOANS").
The interest payable to the Class II-X Certificates is based on the weighted
average of the Stripped Interest Rates of the Group II Mortgage Loans having
Pass-Through Rates in excess of 7.000% per annum (the "GROUP II PREMIUM RATE
MORTGAGE LOANS"). The interest payable to the Class III-X Certificates is based
on the weighted average of the Stripped Interest Rates of the Group III Mortgage
Loans having Pass-Through Rates in excess of 6.750% per annum (the "GROUP III
PREMIUM RATE MORTGAGE LOANS" and, together with the Group I Premium Rate
Mortgage Loans and Group II Premium Rate Mortgage Loans, the "PREMIUM RATE
MORTGAGE LOANS"). Therefore, the yield to maturity on any Class of the Class X
Certificates will generally decrease as a result of faster than expected
Principal Prepayments on the related Premium Rate Mortgage Loans. Prospective
investors should fully consider the risks associated with an investment in any
Class of the Class X Certificates, including the possibility that if the rate of
Principal Prepayments on the related Premium Rate Mortgage Loans is rapid, such
investors may not fully recoup their initial investments.
 
    Moreover, since the Class I-X-1 and Class I-X-2 Certificates are LIBOR
Certificates, the yield to investors in such Certificates will be sensitive to
fluctuations in LIBOR. The yield to maturity on the Class I-X-2 Certificates
will be extremely sensitive to fluctuations in LIBOR, and the Remittance Rate on
such Certificates will vary inversely with LIBOR. If prevailing rates of LIBOR
are sufficiently high, investors in the Class I-X-2 Certificates may not recoup
their initial investments, regardless of the rate of Principal Prepayments on
the Group I Premium Rate Mortgage Loans. Changes in LIBOR may not correlate with
changes in prevailing mortgage interest rates. It is possible that lower
prevailing mortgage interest rates, which might be expected to result in faster
prepayments, could occur concurrently with an increased level of LIBOR.
Conversely, higher prevailing mortgage interest rates (which would be expected
to result in slower prepayments) could occur concurrently with a lower level of
LIBOR.
 
    The yields to maturity on the Class P Certificates will be extremely
sensitive to the level of Principal Prepayments on certain of the Mortgage Loans
in the related Loan Group. The principal payable to the Class I-P Certificates
is derived from Group I Mortgage Loans having Pass-Through Rates lower than
7.250% per annum (the "CLASS I-P MORTGAGE LOANS"). The principal payable to the
Class II-P Certificates is derived from Group II Mortgage Loans having
Pass-Through Rates lower than 7.000% per annum (the "CLASS II-P MORTGAGE
LOANS"). The principal payable to the Class III-P Certificates is derived from
Group III Mortgage Loans having Pass-Through Rates lower than 6.750% per annum
(the "CLASS III-P MORTGAGE LOANS" and, together with the Class I-P Mortgage
Loans and Class II-P Mortgage Loans, the "CLASS P MORTGAGE LOANS"). Therefore,
the yield to maturity on any Class of the Class P Certificates will be adversely
affected by slower than expected prepayments of the related Class P Mortgage
Loans.
 
    For each Loan Group, because the interest payable on the Class X
Certificates related to such Loan Group and the principal distributable to the
Class P Certificates related to such Loan Group are derived from different
groups of Mortgage Loans within such Loan Group, it is possible that faster than
expected Principal Prepayments on the Mortgage Loans related to a Class of Class
X Certificates may occur at the same time as slower than expected Principal
Prepayments on the Mortgage Loans related to the Class of Class P Certificates
of the same Certificate Group. This occurrence would result in a lower yield to
maturity for both the Class X Certificates and Class P Certificates related to a
single Loan Group. See "Yield and Prepayment Considerations" herein.
 
    The yield to maturity on each Class of the Senior Subordinate Certificates
in a Certificate Group will be extremely sensitive to realized losses on the
Mortgage Loans in the related Loan Group (other than Special Hazard Losses,
Fraud Losses and Bankruptcy Losses in excess of the applicable coverage therefor
provided by the Class B Certificates of such Certificate Group), because a
disproportionately large amount of such losses (rather than a pro rata portion
thereof) generally will be allocable to such Classes of Certificates following
the reduction of the aggregate of the Class Principal Balances of the Junior
Subordinate Certificates of such Certificate Group to zero, as described under
"Description of the Certificates--Subordination and Allocation of Losses"
herein.
 
                                      S-27
<PAGE>
CLASS II-A-7 CERTIFICATES
 
    Holders of the Class II-A-7 Certificates will be entitled to receive
distributions of interest on each Distribution Date as described herein under
"Description of the Certificates--Distributions of Interest". However, unless
the Credit Support Depletion Date has occurred, such holders will not be
entitled to receive distributions of principal until the Class Principal
Balances of the Class II-A-1, Class II-A-2, Class II-A-3, Class II-A-4, Class
II-A-5, Class II-A-6, Class II-A-10 and Class R Certificates have been reduced
to zero. The table included in Appendix C herein indicates the dates on which
distributions of principal to the Class II-A-7 Certificates are expected to
commence, and the dates on which such distributions are expected to end, based
on various assumptions regarding the loss and prepayment experience of the Group
II Loans. However, there can be no assurance that the Group II Loans will
perform according to such assumptions. In addition, because the Class II-A-7
Certificates will be outstanding for a relatively long period of time, there is
a greater likelihood that they will remain outstanding after the termination of
the credit support provided by the Group II-B Certificates and therefore be more
susceptible to losses on the Group II Loans. Investors in the Class II-A-7
Certificates should consult with their financial advisors regarding the risks
associated with such an investment.
 
BOOK-ENTRY SYSTEM
 
    Since transactions in the Class A Certificates (the "BOOK-ENTRY
CERTIFICATES") generally can be effected only through The Depository Trust
Company ("DTC"), participating organizations, indirect participants and certain
banks, the ability of a Certificateholder to pledge a Book-Entry Certificate to
persons or entities that do not participate in the DTC system, or otherwise to
take actions with respect to such Certificates, may be limited due to a lack of
a physical certificate representing the Book-Entry Certificates. In addition,
the Certificateholders may experience some delay in their receipt of
distributions of interest and principal on the Book-Entry Certificates, since
such distributions will be forwarded by the Trustee (or its duly appointed
paying agent, if any) to DTC, and DTC will credit such distributions to the
accounts of DTC Participants (as defined herein) which will thereafter credit
them to the accounts of Certificateholders either directly or indirectly through
indirect participants. Also, issuance of the Book-Entry Certificates in
book-entry form may reduce the liquidity thereof in any secondary trading market
that may develop therefor because investors may be unwilling to purchase
securities for which they cannot obtain delivery of physical certificates. See
"Description of the Certificates -- Book-Entry Registration" herein.
 
                                   THE TRUST
 
    The primary assets of the Trust will consist of a pool of Mortgage Loans
(the "MORTGAGE POOL"). The Trust will also contain (i) certain insurance
policies related to the Mortgage Loans, (ii) any property which secured a
Mortgage Loan and which is acquired by foreclosure or by deed in lieu of
foreclosure after the Cut-Off Date, (iii) amounts held in the Certificate
Account, and (iv) certain other assets. Funds otherwise required to be held in
the Certificate Account may be held in an investment account and invested for
the benefit of the Master Servicers in Eligible Investments pursuant to the
terms of the Pooling Agreement, as described herein. The Mortgage Loans will be
assigned to the Trustee, together with all principal and interest due on the
Mortgage Loans after the Cut-Off Date. The Trustee will, concurrently with such
assignment, authenticate and deliver the Certificates. Each Mortgage Loan will
be identified in a schedule appearing as an exhibit to the Pooling Agreement
(the "MORTGAGE LOAN SCHEDULE") which will specify with respect to each Mortgage
Loan, among other things, the applicable Master Servicer, the applicable Loan
Group, the original principal balance and the outstanding principal balance as
of the close of business on the Cut-Off Date, the term of the Mortgage Note and
the Mortgage Interest Rate.
 
                                      S-28
<PAGE>
                       DESCRIPTION OF THE MORTGAGE POOL*
 
    The Mortgage Pool will consist of Mortgage Loans that will have an aggregate
principal balance outstanding as of November 1, 1997 (the "CUT-OFF DATE"), after
deducting payments due on or before that date, of approximately $836,949,643.
The Group I Loans, Group II Loans and Group III Loans have an aggregate
principal balance outstanding as of the Cut-Off Date, after deducting payments
due on or before that date, of approximately $390,011,349, $342,543,635 and
$104,394,658, respectively. Certain of the risks of loss on certain Mortgage
Loans will be covered up to specified limits by Primary Insurance Policies.
 
    The Mortgage Loans are secured by first mortgages or first deeds of trust or
other similar security instruments creating first liens on one- to four-family
residential properties or shares of stock relating to cooperative apartments
(the "MORTGAGED PROPERTIES"), which may include detached homes, duplexes,
townhouses, individual condominium units, individual units in planned unit
developments and other attached dwelling units which are part of buildings
consisting of more than four units (so long as the property subject to the lien
of the related Mortgage consists of no more than four units other than
cooperative apartments), and having the additional characteristics described
below and in the Prospectus.
 
    Each Mortgage Loan will have a first payment date during the period from
June 1991 through January 1998 inclusive, and will have an original term to
maturity of not more than 30 years in the case of Group I Loans and Group II
Loans and 15 years in the case of Group III Loans.
 
LOAN GROUP I
 
    As of the Cut-Off Date, the Mortgage Interest Rate on each Group I Loan will
be not less than 6.875% and not more than 9.750% per annum. As of the Cut-Off
Date, the weighted average of the Mortgage Interest Rates on the Group I Loans
will be approximately 8.363% per annum. As of the Cut-Off Date, the Pass-Through
Rate for each Group I Loan will be not less than 6.450% and not more than 9.450%
per annum. As of the Cut-Off Date, the weighted average of the Pass-Through
Rates for the Group I Loans will be approximately 8.053% per annum. As of the
Cut-Off Date, 2,893 of the Group I Loans with an aggregate principal balance of
$324,056,135 were PNC Loans, and 560 of the Group I Loans with an aggregate
principal balance of $65,955,214 were IndyMac Loans.
 
    All of the Group I Loans will have principal and interest payable on the
first day of each month (the "DUE DATE"). None of the Group I Loans will be
Buydown Loans. The latest original scheduled maturity of any Group I Loan will
be December 2027. Each of the Group I Loans will have original terms to maturity
 
- ------------------------
 
*   The description herein of the Mortgage Pool and the Mortgaged Properties is
    based upon the Mortgage Loans at the close of business on the Cut-Off Date,
    after deducting the scheduled principal payments due on or before such date,
    whether or not actually received. All references herein to "principal
    balance" refer to the principal balance as of the Cut-Off Date, unless
    otherwise specifically stated or required by the context. References herein
    to percentages of Mortgage Loans refer in each case to the percentage of the
    aggregate principal balance of the related Loan Group, based on the
    outstanding principal balances of the Mortgage Loans after giving effect to
    scheduled Monthly Payments due on or prior to the Cut-Off Date, whether or
    not received. References to weighted averages refer, in each case, to
    weighted averages by principal balance as of the Cut-Off Date of the related
    Mortgage Loans (determined as described in the preceding sentence). Prior to
    the issuance of the Certificates, Mortgage Loans may be removed from the
    Mortgage Pool as a result of principal prepayments in full ("PAYOFFS"),
    delinquencies or otherwise. In such event, other Mortgage Loans may be
    included in the Mortgage Pool. The Company believes that the information set
    forth herein with respect to the Mortgage Pool is representative of the
    characteristics of the Mortgage Pool as it will actually be constituted at
    the time the Certificates are issued, although the range of Mortgage
    Interest Rates and certain other characteristics of the Mortgage Loans in
    the Mortgage Pool may vary. See "--Additional Information" herein.
 
                                      S-29
<PAGE>
of not more than 30 years, and as of the Cut-Off Date, the weighted average
remaining term to maturity (adjusted for Curtailments) of the Group I Loans will
be approximately 356.1 months. At origination, based upon an appraisal of the
Mortgaged Property securing each Group I Loan, approximately 91.0% of the Group
I Loans will have had Loan-to-Value Ratios less than or equal to 80%, and
approximately 9.0% of the Group I Loans will have had Loan-to-Value Ratios
greater than 80% but less than or equal to 95%. No Group I Loan will have had a
Loan-to-Value Ratio at origination greater than 95%. At origination, the
weighted average of the Loan-to-Value Ratios of the Group I Loans was
approximately 73.5%. As of the Cut-Off Date, the weighted average of the
Loan-to-Value Ratios of the Group I Loans is approximately 73.4%. As of the
Cut-Off Date, approximately 8.8% of the Group I Loans are covered by a Primary
Insurance Policy. Approximately 96.9% of the Group I Loans with Loan-to-Value
Ratios as of the Cut-Off Date in excess of 80% were covered by a Primary
Insurance Policy. At origination, each Group I Loan will have had a principal
balance of not less than $22,500 nor more than $247,500, and the average
principal balance of the Group I Loans as of the Cut-Off Date will be
approximately $112,949. Approximately 70.4% of the Group I Loans will have been
secured by owner-occupied Mortgaged Properties which were the primary residences
of the related Mortgagors, based solely on representations of the Mortgagors
obtained at the origination of the related Group I Loans, and approximately 3.8%
of the Group I Loans will have been secured by owner-occupied Mortgaged
Properties which were second or vacation homes of the related Mortgagors, based
solely on such representations. Approximately 25.7% of the Group I Loans will
have been secured by Mortgaged Properties which were investor properties of the
related Mortgagors, based solely on such representations. Approximately 0.5% of
the Group I Loans are secured by interests in cooperative apartments. The
aggregate principal balance of Group I Loans originated under reduced and no
documentation programs (including certain Group I Loans for which verification
of income and deposits was not required), which generally limit the original
Loan-to-Value Ratio of the Group I Loans, will be approximately $270,348,220
which will be approximately 69.3% of Loan Group I. As of the Cut-Off Date, the
weighted average of the Loan-to-Value Ratios of such Group I Loans originated
under such reduced and no documentation programs is approximately 71.0%.
 
    Approximately 27.6% of the Group I Loans are secured by Mortgaged Properties
located in California; 7.6%, in Colorado; 6.3%, in Florida; 6.2%, in Arizona;
5.4%, in New York; and no other single state contains Mortgaged Properties
securing more than 5.0% of the Group I Loans. No more than 0.2% of the Group I
Loans will be secured by Mortgaged Properties located in any one California zip
code area, and no more than 0.3% of the Group I Loans will be secured by
Mortgaged Properties located in any other single zip code area. Approximately
45.8% of the Group I Loans will have been originated for the purpose of
refinancing existing mortgage debt, including cash-out refinancings.
Approximately 54.2% of the Group I Loans will have been originated for the
purpose of purchasing the Mortgaged Property.
 
LOAN GROUP II
 
    As of the Cut-Off Date, the Mortgage Interest Rate on each Group II Loan
will be not less than 7.000% and not more than 9.250% per annum. As of the
Cut-Off Date, the weighted average of the Mortgage Interest Rates on the Group
II Loans will be approximately 8.001% per annum. As of the Cut-Off Date, the
Pass-Through Rate for each Group II Loan will be not less than 6.700% and not
more than 8.960% per annum. As of the Cut-Off Date, the weighted average of the
Pass-Through Rates for the Group II Loans will be approximately 7.715% per
annum. As of the Cut-Off Date, 1,028 of the Group II Loans with an aggregate
principal balance of $341,302,416 were PNC Loans, and 4 of the Group II Loans
with an aggregate principal balance of $1,241,219 were IndyMac Loans.
 
    All of the Group II Loans will have principal and interest payable on the
Due Date. None of the Group II Loans will be Buydown Loans. The latest original
scheduled maturity of any Group II Loan will be November 2027. Each of the Group
II Loans will have original terms to maturity of not more than 30 years, and as
of the Cut-Off Date, the weighted average remaining term to maturity (adjusted
for Curtailments) of the Group II Loans will be approximately 357.7 months. At
origination, based upon an
 
                                      S-30
<PAGE>
appraisal of the Mortgaged Property securing each Group II Loan, approximately
86.8% of the Group II Loans will have had Loan-to-Value Ratios less than or
equal to 80%, and approximately 13.2% of the Group II Loans will have had
Loan-to-Value Ratios greater than 80% but less than or equal to 95%. No Group II
Loan will have had a Loan-to-Value Ratio at origination greater than 95%. At
origination, the weighted average of the Loan-to-Value Ratios of the Group II
Loans was approximately 74.2%. As of the Cut-Off Date, the weighted average of
the Loan-to-Value Ratios of the Group II Loans is approximately 74.1%. As of the
Cut-Off Date, approximately 12.6% of the Group II Loans are covered by a Primary
Insurance Policy. Approximately 96.4% of the Group II Loans with Loan-to-Value
Ratios as of the Cut-Off Date in excess of 80% were covered by a Primary
Insurance Policy. At origination, each Group II Loan will have had a principal
balance of not less than $214,650 nor more than $2,500,000 and the average
principal balance of the Group II Loans as of the Cut-Off Date will be
approximately $331,922. Approximately 93.9% of the Group II Loans will have been
secured by owner-occupied Mortgaged Properties which were the primary residences
of the related Mortgagors, based solely on representations of the Mortgagors
obtained at the origination of the related Group II Loans, and approximately
2.6% of the Group II Loans will have been secured by owner-occupied Mortgaged
Properties which were second or vacation homes of the related Mortgagors, based
solely on such representations. Approximately 3.5% of the Group II Loans will
have been secured by Mortgaged Properties which were investor properties of the
related Mortgagors, based solely on such representations. Approximately 0.3% of
the Group II Loans are secured by interests in cooperative apartments. The
aggregate principal balance of Group II Loans originated under reduced and no
documentation programs (including certain Group II Loans for which verification
of income and deposits was not required), which generally limit the original
Loan-to-Value Ratio of the Group II Loans, will be approximately $114,917,051,
which will be approximately 33.5% of Loan Group II. As of the Cut-Off Date, the
weighted average of the Loan-to-Value Ratios of such Group II Loans originated
under such reduced and no documentation programs is approximately 69.5%.
 
    Approximately 46.1% of the Group II Loans are secured by Mortgaged
Properties located in California; 5.1%, in New York; 5.1%, in Illinois; and no
other single state contains Mortgaged Properties securing more than 5% of the
Group II Loans. No more than 1.4% of the Group II Loans will be secured by
Mortgaged Properties located in any one California zip code area, and no more
than 0.8% of the Group II Loans will be secured by Mortgaged Properties located
in any other single zip code area. Approximately 47.5% of the Group II Loans
will have been originated for the purpose of refinancing existing mortgage debt,
including cash-out refinancings. Approximately 52.5% of the Group II Loans will
have been originated for the purpose of purchasing the Mortgaged Property.
 
LOAN GROUP III
 
    As of the Cut-Off Date, the Mortgage Interest Rate on each Group III Loan
will be not less than 6.500% and not more than 9.250% per annum. As of the
Cut-Off Date, the weighted average of the Mortgage Interest Rates on the Group
III Loans will be approximately 7.615% per annum. As of the Cut-Off Date, the
Pass-Through Rate for each Group III Loan will be not less than 6.260% and not
more than 8.970% per annum. As of the Cut-Off Date, the weighted average of the
Pass-Through Rates for the Group III Loans will be approximately 7.339% per
annum. As of the Cut-Off Date, all of the Group III Loans were PNC Loans.
 
    All of the Group III Loans will have principal and interest payable on the
Due Date. None of the Group III Loans will be Buydown Loans. The latest original
scheduled maturity of any Group III Loan will be November 2012. Each of the
Group III Loans will have original terms to maturity of not more than 15 years,
and as of the Cut-Off Date, the weighted average remaining term to maturity
(adjusted for Curtailments, except with respect to Balloon Loans) of the Group
III Loans will be approximately 176.0 months. The weighted average remaining
term to maturity for Loan Group III was determined without regard to the
amortization schedules of the Balloon Loans in Loan Group III. As of the Cut-Off
Date, approximately 4.0% of the Group III Loans, with an aggregate principal
balance of $4,194,955, by
 
                                      S-31
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the terms of the related Mortgages will not fully amortize by their stated
maturity dates (each, a "Balloon Loan"). At origination, based upon an appraisal
of the Mortgaged Property securing each Group III Loan, approximately 96.8% of
the Group III Loans will have had Loan-to-Value Ratios less than or equal to
80%, and approximately 3.2% of the Group III Loans will have had Loan-to-Value
Ratios greater than 80% but less than or equal to 95%. No Group III Loan will
have had a Loan-to-Value Ratio at origination greater than 95%. At origination,
the weighted average of the Loan-to-Value Ratios of the Group III Loans was
approximately 69.4%. As of the Cut-Off Date, the weighted average of the
Loan-to-Value Ratios of the Group III Loans is approximately 68.6%. As of the
Cut-Off Date, approximately 3.5% of the Group III Loans are covered by a Primary
Insurance Policy. All of the Group III Loans with Loan-to-Value Ratios as of the
Cut-Off Date in excess of 80% were covered by a Primary Insurance Policy. At
origination, each Group III Loan will have had a principal balance of not less
than $22,000 nor more than $1,000,000 and the average principal balance of the
Group III Loans as of the Cut-Off Date will be approximately $241,096.
Approximately 94.0% of the Group III Loans will have been secured by
owner-occupied Mortgaged Properties which were the primary residences of the
related Mortgagors, based solely on representations of the Mortgagors obtained
at the origination of the related Group III Loans, and approximately 3.1% of the
Group III Loans will have been secured by owner-occupied Mortgaged Properties
which were second or vacation homes of the related Mortgagors, based solely on
such representations. Approximately 2.9% of the Group III Loans will have been
secured by Mortgaged Properties which were investor properties of the related
Mortgagors, based solely on such representations. None of the Group III Loans
are secured by interests in cooperative apartments. The aggregate principal
balance of Group III Loans originated under reduced and no documentation
programs (including certain Group III Loans for which verification of income and
deposits was not required), which generally limit the original Loan-to-Value
Ratio of the Group III Loans, will be approximately $21,952,893, which will be
approximately 21.0% of Loan Group III. As of the Cut-Off Date, the weighted
average of the Loan-to-Value Ratios of such Group III Loans originated under
such reduced and no documentation programs is approximately 65.2%.
 
    Approximately 34.6% of the Group III Loans are secured by Mortgaged
Properties located in California; 5.6%, in Texas; 5.2% in Michigan; and no other
single state contains Mortgaged Properties securing more than 5% of the Group
III Loans. No more than 1.1% of the Group III Loans will be secured by Mortgaged
Properties located in any one California zip code area, and no more than 1.6% of
the Group III Loans will be secured by Mortgaged Properties located in any other
single zip code area. Approximately 57.4% of the Group III Loans will have been
originated for the purpose of refinancing existing mortgage debt, including
cash-out refinancings. Approximately 42.6% of the Group III Loans will have been
originated for the purpose of purchasing the Mortgaged Property.
 
INDYMAC
 
    IndyMac, Inc. (formerly known as Independent National Mortgage Corporation),
is a Delaware corporation ("INDYMAC"). The principal executive offices of
IndyMac are located at 155 North Lake Avenue, Pasadena, California 91101.
IndyMac operates a conduit program established in April 1993 to purchase
"conventional non-conforming mortgage loans" (i.e., loans which are not insured
by the FHA or partially guaranteed by the VA or which do not qualify for sale to
FNMA or FHLMC) secured by first liens on one- to four-family residential
properties. IndyMac purchases mortgage loans from banks, savings and loan
associations, mortgage bankers (which may or may not be affiliated with IndyMac)
and other mortgage loan originators.
 
ADDITIONAL INFORMATION
 
    A Current Report on Form 8-K relating to the Offered Certificates containing
a detailed description of the Mortgage Loans will be available to purchasers of
Offered Certificates on or before initial issuance of the Offered Certificates
and will be filed with the Securities and Exchange Commission within 15 days
 
                                      S-32
<PAGE>
after such initial issuance. The Current Report on Form 8-K will specify as of
the Cut-Off Date the aggregate principal balance of the Mortgage Loans and will
set forth in detail the following information regarding the Mortgage Loans of
each Loan Group: the number of Mortgage Loans, the range of Mortgage Interest
Rates, the range of Mortgage Loan original principal balances, the years in
which initial Monthly Payments on the Mortgage Loans are due, the weighted
average remaining term to maturity of the Mortgage Loans, the range of
Loan-to-Value Ratios of the Mortgage Loans as of the Cut-Off Date, the types of
Mortgaged Properties, the stated owner occupancy status of the Mortgaged
Properties at the time the Mortgage Loans were originated, the geographic
distribution by state of the Mortgage Properties, the scheduled maturity years
of the Mortgage Loans (adjusted for Curtailments), the original terms to
maturity of the Mortgage Loans, the Mortgagors' purpose of financing, the number
of Mortgage Loans originated under a reduced documentation program, if any, and
the number of Buydown Loans, if any, in each case, for each Loan Group.
 
                        DESCRIPTION OF THE CERTIFICATES
 
GENERAL
 
    The Certificates will be issued pursuant to a Pooling and Servicing
Agreement (the "POOLING AGREEMENT") to be dated as of the Cut-Off Date between
the Company, as Depositor, Certificate Administrator and Master Servicer,
IndyMac, as Master Servicer, and U.S. Bank National Association, as trustee (the
"TRUSTEE"), a form of which is filed as an exhibit to the Registration Statement
of which this Prospectus Supplement is a part. Reference is made to the
Prospectus for important additional information regarding the terms and
conditions of the Pooling Agreement and the Certificates. It is a condition to
the issuance of the Offered Certificates that they receive the ratings from one
or more of Standard & Poor's, a division of The McGraw-Hill Companies, Inc.
("S&P"), Fitch Investors Service, L.P. ("FITCH") and Duff & Phelps Credit Rating
Co. ("DCR") indicated under "Certificate Ratings" herein. As of the date of
their issuance, the Offered Certificates, other than the Class I-B-2, Class
II-B-2, Class III-B-2, Class I-B-3, Class II-B-3 and Class III-B-3 Certificates,
will qualify as "mortgage related securities" within the meaning of the
Secondary Mortgage Market Enhancement Act of 1984.
 
    Each Master Servicer will be obligated to make Advances with respect to
delinquent payments on the related Mortgage Loans as described herein under
"--Advances".
 
    The Certificates will evidence all the beneficial ownership in a trust (the
"TRUST") established by the Company into which the mortgage loans (the "MORTGAGE
LOANS") will be deposited. The Mortgage Pass-Through Certificates, Series 1997-8
(the "CERTIFICATES"), will consist of the following thirty-eight classes: (i)
Class I-A-1, (ii) Class II-A-1, Class II-A-2, Class II-A-3, Class II-A-4, Class
II-A-5, Class II-A-6, Class II-A-7, Class II-A-8, Class II-A-9 and Class II-A-10
(the "GROUP II-A CERTIFICATES"), (iii) Class III-PT (together with the Class
I-A-1 and Group II-A Certificates, the "CLASS A CERTIFICATES"), (iv) Class I-P,
Class II-P and Class III-P (the "CLASS P CERTIFICATES"), (v) Class I-X-1 and
Class I-X-2 (the "CLASS I-X CERTIFICATES"), Class II-X and Class III-X (together
with the Class I-X Certificates, the "CLASS X CERTIFICATES"), (vi) Class I-B-1,
Class I-B-2 and Class I-B-3 (the "GROUP I SENIOR SUBORDINATE CERTIFICATES"),
(vii) Class I-B-4, Class I-B-5 and Class I-B-6 (the "GROUP I JUNIOR SUBORDINATE
CERTIFICATES" and, together with the Group I Senior Subordinate Certificates,
the "GROUP I-B CERTIFICATES"), (viii) Class II-B-1, Class II-B-2 and Class
II-B-3 (the "GROUP II SENIOR SUBORDINATE CERTIFICATES"), (ix) Class II-B-4,
Class II-B-5 and Class II-B-6 (the "GROUP II JUNIOR SUBORDINATE CERTIFICATES"
and, together with the Group II Senior Subordinate Certificates, the "GROUP II-B
CERTIFICATES"), (x) Class III-B-1, Class III-B-2 and Class III-B-3 (the "GROUP
III SENIOR SUBORDINATE CERTIFICATES"), (xi) Class III-B-4, Class III-B-5 and
Class III-B-6 (the "GROUP III JUNIOR SUBORDINATE CERTIFICATES" and, together
with the Group III Senior Subordinate Certificates, the "GROUP III-B
CERTIFICATES"), and (xii) Class R (the "RESIDUAL CERTIFICATES" and, together
with the Class A, Class X and Class P Certificates, the "SENIOR CERTIFICATES").
The Class I-A-1, Class I-P, Class I-X and Group I-B Certificates are sometimes
referred to as the "GROUP I CERTIFICATES", the Group II-A, Class II-P, Class
II-X, Group II-B and Class R Certificates are sometimes
 
                                      S-33
<PAGE>
referred to as the "GROUP II CERTIFICATES" and the Class III-PT, Class III-P,
Class III-X and Group III-B Certificates are sometimes referred to as the "GROUP
III CERTIFICATES". The Group I Certificates, the Group II Certificates and the
Group III Certificates are each a "CERTIFICATE GROUP". The Class II-A-8 and
Class II-A-9 Certificates are sometimes referred to as the "LOCKOUT
CERTIFICATES". The Class I-X-1 and Class I-X-2 Certificates are sometimes
referred to as the "LIBOR CERTIFICATES". The Class I-X-1 Certificates are
sometimes referred to as the "FLOATER CERTIFICATES" and the Class I-X-2
Certificates are sometimes referred to as the "INVERSE FLOATER CERTIFICATES".
The Group I Senior Subordinate Certificates, Group II Senior Subordinate
Certificates and Group III Senior Subordinate Certificates are collectively
referred to as the "SENIOR SUBORDINATE CERTIFICATES". The Group I Junior
Subordinate Certificates, Group II Junior Subordinate Certificates and Group III
Junior Subordinate Certificates are collectively referred to as the "JUNIOR
SUBORDINATE CERTIFICATES". The Group I-B, Group II-B and Group III-B
Certificates are collectively referred to as the "SUBORDINATE CERTIFICATES" or
"CLASS B CERTIFICATES". Only the Senior Certificates and the Senior Subordinate
Certificates (collectively, the "OFFERED CERTIFICATES") are offered hereby. The
Junior Subordinate Certificates are not offered hereby. The "CLASS PRINCIPAL
BALANCE" for any Class of Certificates (other than the Class II-A-5
Certificates) will equal the aggregate amount of principal to which such Class
is entitled, after giving effect to prior (i) distributions of principal to such
Class, (ii) allocations of losses required to be borne by such Class and (iii)
in the case of the Accrual Classes, increases resulting from all interest
accrued and added to the Class Principal Balance thereof. The "CLASS PRINCIPAL
BALANCE" of the Class II-A-5 Certificates will equal the sum of the Component
Principal Balances (as defined below) thereof.
 
    The Class II-A-5 Certificates will be comprised of two components (each, a
"COMPONENT"), each of which will have a specified principal balance (a
"COMPONENT PRINCIPAL BALANCE"), which functions in a manner comparable to that
of a Class Principal Balance, on which interest will accrue at a designated
Remittance Rate. Holders of Class II-A-5 Certificates will be entitled to
receive distributions on any Distribution Date to the extent of the amount
distributed with respect to the related Components on such Distribution Date.
Holders of Class II-A-5 Certificates may not transfer such Components
separately. The Class II-A-5 Certificates will be comprised of Component
II-A-5-1 and Component II-A-5-2 with initial Component Principal Balances of
$2,596,302 and $7,893,807, respectively. The Class Principal Balance of the
Class II-A-5 Certificates will equal the sum of the Component Principal Balances
thereof. The Component Principal Balance for each Component will equal the
aggregate amount of principal to which such Component is entitled, after giving
effect to prior (i) distributions of principal to such Component, (ii)
allocations of losses required to be borne by such Component and (iii) increases
resulting from all interest accrued and added to the Component Principal
Balances thereof.
 
    The "CERTIFICATE PRINCIPAL BALANCE" for any Certificate will be the portion
of the corresponding Class Principal Balance represented by such Certificate.
The aggregate initial Certificate Principal Balance will be approximately equal
to the aggregate principal balance of the Mortgage Loans as of the Cut-Off Date.
The Group I Certificates that are Senior Certificates will comprise
approximately 93.25%, the Group I Senior Subordinate Certificates will comprise
approximately 5.60%, and the Group I Junior Subordinate Certificates will
comprise approximately 1.15%, of the initial aggregate principal balance of the
Group I Loans as of the Cut-Off Date. The Group II Certificates that are Senior
Certificates will comprise approximately 94.25%, the Group II Senior Subordinate
Certificates will comprise approximately 4.70%, and the Group II Junior
Subordinate Certificates will comprise approximately 1.05%, of the initial
aggregate principal balance of the Group II Loans as of the Cut-Off Date. The
Group III Certificates that are Senior Certificates will comprise approximately
96.50%, the Group III Senior Subordinate Certificates will comprise
approximately 2.85%, and the Group III Junior Subordinate Certificates will
comprise approximately 0.65%, of the initial aggregate principal balance of the
Group III Loans as of the Cut-Off Date. The Offered Certificates, other than the
Class II-A-7, Class X and Class R Certificates, are offered in minimum
denominations equivalent to not less than $25,000 initial Certificate Principal
Balance each and multiples of $1 in excess thereof, except that one Class I-P,
one Class II-P and one Class III-P Certificate may be issued in a different
amount. The Class II-A-7 Certificates are offered in minimum
 
                                      S-34
<PAGE>
denominations equivalent to not less than $1,000 initial Certificate Principal
Balance each and multiples of $1 in excess thereof. The Class X Certificates are
offered in minimum denominations equivalent to not less than $100,000 initial
Class Notional Amount each and multiples of $1 in excess thereof, except that
one Class I-X-1, one Class I-X-2, one Class II-X and one Class III-X Certificate
may be issued in a different amount. The Class R Certificates will be offered in
registered, certificated form in a single denomination of 99.99% Percentage
Interest. The remaining 0.01% Percentage Interest of the Class R Certificates
will be retained by the Company as set forth herein under "Certain Federal
Income Tax Consequences".
 
BOOK-ENTRY REGISTRATION
 
    Each Class of Book-Entry Certificates will initially be represented by a
global Certificate registered in the name of the nominee of DTC. DTC has advised
the Company that DTC's nominee will be Cede & Co. ("CEDE"). Accordingly, Cede is
expected to be the holder of record of the Book-Entry Certificates. No
Book-Entry Certificateholder will be entitled to receive a certificate
representing such person's interest in such Certificate. Unless and until
Definitive Certificates (as defined below) are issued under the limited
circumstances described herein, all references herein to actions by Book-Entry
Certificateholders shall refer to actions taken by DTC upon instructions from
DTC Participants (as defined below), and all references herein to distributions,
notices, reports, and statements to Book-Entry Certificateholders shall refer to
distributions, notices, reports, and statements to Cede, as the registered
holder of such Certificates, for distribution to Book-Entry Certificateholders
in accordance with DTC procedures.
 
    Certificateholders may hold their Book-Entry Certificates through DTC, if
they are DTC Participants (as defined below), or indirectly through
organizations which are DTC Participants. Transfers between DTC Participants
will occur in the ordinary way in accordance with DTC rules. Cede, as nominee of
DTC,will hold the global Certificates for the Book-Entry Certificates.
 
    DTC has advised the Company that it is a limited-purpose trust company
organized under the New York Banking Law, a "banking organization" within the
meaning of the New York Banking Law, a member of the Federal Reserve System, a
"clearing corporation" within the meaning of the New York Uniform Commercial
Code and a "clearing agency" registered pursuant to the provisions of Section
17A of the Securities Exchange Act of 1934, as amended. DTC holds securities
that its participants ("DTC PARTICIPANTS") deposit with DTC. DTC also
facilitates the settlement among DTC Participants of securities transactions,
such as transfers and pledges, in deposited securities through electronic
computerized book-entry changes in DTC Participants' accounts, thereby
eliminating the need for physical movement of securities certificates. DTC
Participants include the Underwriter, securities brokers and dealers, banks,
trust companies, clearing corporations and certain other organizations. Indirect
access to the DTC system also is available to other entities, such as banks,
brokers, dealers, and trust companies that clear through or maintain a custodial
relationship with a DTC Participant, either directly or indirectly ("INDIRECT
DTC PARTICIPANTS").
 
    Certificateholders that are not DTC Participants or Indirect DTC
Participants but desire to purchase, sell, or otherwise transfer ownership of or
other interests in Book-Entry Certificates may do so only through DTC
Participants and Indirect DTC Participants. In addition, unless Definitive
Certificates are issued, Certificateholders will receive all distributions of
principal and interest on the Book-Entry Certificates through DTC Participants.
Under a book-entry format, Certificateholders will receive payments after the
related Distribution Date because, while payments are required to be forwarded
to Cede, as nominee for DTC, on each such date, DTC will forward such payments
to DTC Participants which thereafter will be required to forward them to
Indirect DTC Participants or Certificateholders. It is anticipated that the sole
"Certificateholder" (as such term is used in the Pooling Agreement) for each
Class of Book-Entry Certificates will be Cede, as nominee of DTC, and that
Book-Entry Certificateholders will not be recognized by the Trustee as
Certificateholders under the Pooling Agreement. Book-Entry Certificateholders
will be permitted to exercise the rights of Certificateholders under the Pooling
Agreement only indirectly through DTC Participants, who in turn will exercise
their rights through DTC.
 
                                      S-35
<PAGE>
    Under the rules, regulations and procedures creating and affecting DTC and
its operations (the "RULES"), DTC is required to make book-entry transfers among
DTC Participants on whose behalf it acts with respect to the Book-Entry
Certificates and is required to receive and transmit payments of principal and
interest, if any, on such Book-Entry Certificates. DTC Participants and Indirect
DTC Participants with whom Book-Entry Certificateholders have accounts with
respect to the Book-Entry Certificates similarly are required to make book-entry
transfers and receive and transmit such payments on behalf of their respective
Book-Entry Certificateholders. Accordingly, although owners of Book-Entry
Certificates will not possess Definitive Certificates, the Rules provide a
mechanism by which owners of the Book-Entry Certificates through their DTC
Participants will receive payments and will be able to transfer their interest.
 
    Because DTC can only act on behalf of DTC Participants, who in turn act on
behalf of Indirect DTC Participants and certain banks, the ability of a
Book-Entry Certificateholder to pledge Book-Entry Certificates to persons or
entities that do not participate in the DTC system, or otherwise take actions in
respect of such Book-Entry Certificates, may be limited due to the lack of a
physical certificate for such Book-Entry Certificates.
 
    DTC has advised the Company that it will take any action permitted to be
taken by a Book-Entry Certificateholder under the Pooling Agreement only at the
direction of one or more DTC Participants to whose account with DTC the
Certificates are credited. Additionally, DTC has advised the Company that it
will take such actions with respect to a Book-Entry Certificate only at the
direction of and on behalf of the DTC Participant whose holdings include that
Certificate. DTC may take conflicting actions with respect to other Book-Entry
Certificates to the extent that such actions are taken on behalf of DTC
Participants whose holdings include such Book-Entry Certificates.
 
    Although DTC has agreed to the foregoing procedures in order to facilitate
transfers of Book-Entry Certificates among DTC Participants, it is under no
obligation to perform or continue to perform such procedures and such procedures
may be discontinued at any time.
 
DEFINITIVE CERTIFICATES
 
    The Book-Entry Certificates will be issued in fully registered, certificated
form to Certificateholders or their nominees ("DEFINITIVE CERTIFICATES"), rather
than to DTC or its nominee, only if (i) the Company advises the Trustee in
writing that DTC is no longer willing or able to discharge properly its
responsibilities as Depository with respect to the Book-Entry Certificates and
the Trustee or the Company is unable to locate a qualified successor, (ii) the
Company, at its option, elects to terminate the book-entry system through DTC or
(iii) after the occurrence of an Event of Default, Certificateholders of
Book-Entry Certificates evidencing not less than 66% of the aggregate
outstanding Certificate Principal Balance advise the Trustee and DTC through DTC
Participants in writing that the continuation of a book-entry system through DTC
(or a successor thereto) is no longer in the best interests of the
Certificateholders.
 
    Upon notice of the occurrence of any of the events described in the
immediately preceding paragraph, DTC is required to notify all DTC Participants
of the availability of Definitive Certificates. Upon surrender by DTC of the
global Certificates and receipt from DTC of instructions for re-registration,
the Trustee will issue the Book-Entry Certificates in the form of Definitive
Certificates, and thereafter the Trustee will recognize the holders of such
Definitive Certificates as Certificateholders under the Pooling Agreement.
 
    Distributions of principal and interest on the Definitive Certificates, as
well as the other Classes of Certificates, will be made by the Trustee (or its
duly appointed paying agent, if any) directly to holders of such Certificates in
accordance with the procedures set forth herein and in the Pooling Agreement.
Distributions of principal and interest on each Distribution Date will be made
to holders in whose names such Certificates were registered at the close of
business on the related Record Date. Distributions will be made by wire transfer
in immediately available funds for the account of each such holder or, if a
holder has not provided wire instructions, by check mailed to the address of
such holder as it appears on the register
 
                                      S-36
<PAGE>
maintained by the Certificate Registrar. The final payment on any Certificate
(whether Class X, Class P, Class R, Class B, Definitive or the global
Certificates registered in the name of Cede) will be made only upon presentation
and surrender of such Certificate at the offices of the Trustee or its agent or
such office or agency as is specified in the notice of final distribution to
holders of Certificates being retired. The Trustee will provide such notice to
registered Certificateholders not later than the fifteenth day of the month in
which all remaining outstanding Certificates will be retired.
 
    Definitive Certificates, as well as the other Classes of Certificates, will
be transferable and exchangeable at the offices of the Trustee in New York City.
A reasonable service charge may be imposed for any registration of transfer or
exchange, and the Trustee or such agent may require payment of a sum sufficient
to cover any tax or other governmental charge imposed in connection therewith.
 
PRIORITY OF DISTRIBUTIONS
 
    Commencing in December 1997, on the 25th day of each month, or if such 25th
day is not a business day, on the immediately succeeding business day (each, a
"DISTRIBUTION DATE"), distributions will be made in the order and priority as
follows:
 
    (a) with respect to the Group I and Class R Certificates, prior to the Group
       I Credit Support Depletion Date (as defined herein), to the extent of the
       Available Distribution Amount for Loan Group I remaining following prior
       distributions, if any, on such Distribution Date:
 
       (i)  first, to the Class I-P Certificates, the Class I-P Fraction (as
           defined herein) of all principal received on or in respect of each
           Class I-P Mortgage Loan;
 
       (ii)  second, to the Class I-A-1 and Class I-X Certificates, accrued and
           unpaid interest at their respective Remittance Rates on their
           respective Class Principal Balances (or Class Notional Amounts, in
           the case of the Class I-X Certificates);
 
       (iii)  third, to the Class I-A-1 Certificates, as principal, the Group I
           Senior Principal Distribution Amount (as defined in "--Distributions
           of Principal--GROUP I SENIOR PRINCIPAL DISTRIBUTION AMOUNT" herein);
 
       (iv)  fourth, to the Class I-P Certificates, to the extent of amounts
           otherwise available to pay the Group I Subordinate Principal
           Distribution Amount (as defined herein) (without regard to clause (B)
           of such definition) on such Distribution Date, the sum of (a)
           principal in an amount equal to the Class I-P Fraction of certain
           principal losses on the Class I-P Mortgage Loans, as described in
           "--Distributions of Principal--CLASS I-P DISTRIBUTION AMOUNT" herein
           and (b) the sum of amounts, if any, by which the amount described in
           clause (a) above on each prior Distribution Date exceeded the amount
           actually distributed in respect thereof on such prior Distribution
           Dates and not subsequently distributed; PROVIDED that any amounts
           distributed in respect of losses pursuant to this paragraph shall not
           cause a further reduction in the Class I-P Principal Balance;
 
       (v)  fifth, to the Class I-B-1 Certificates, accrued and unpaid interest
           at the Class I-B-1 Remittance Rate on the Class I-B-1 Principal
           Balance;
 
       (vi)  sixth, to the Class I-B-1 Certificates, their pro rata share of the
           Group I Subordinate Principal Distribution Amount;
 
       (vii)  seventh, to the Class I-B-2 Certificates, accrued and unpaid
           interest at the Class I-B-2 Remittance Rate on the Class I-B-2
           Principal Balance;
 
       (viii) eighth, to the Class I-B-2 Certificates, their pro rata share of
           the Group I Subordinate Principal Distribution Amount;
 
                                      S-37
<PAGE>
       (ix)  ninth, to the Class I-B-3 Certificates, accrued and unpaid interest
           at the Class I-B-3 Remittance Rate on the Class I-B-3 Principal
           Balance;
 
       (x)  tenth, to the Class I-B-3 Certificates, their pro rata share of the
           Group I Subordinate Principal Distribution Amount;
 
       (xi)  eleventh, to the Group I Junior Subordinate Certificates, interest
           and principal in the same manner as for the Group I Senior
           Subordinate Certificates, first to the Class I-B-4 Certificates, then
           to the Class I-B-5 Certificates and then to the Class I-B-6
           Certificates;
 
       (xii)  twelfth, to each Class of the Group I-B Certificates in order of
           seniority, the remaining portion, if any, of the Available
           Distribution Amount for Loan Group I, up to the amount of
           unreimbursed realized losses previously allocated to such Class, if
           any, PROVIDED that distribution of any amount pursuant to this
           paragraph shall not cause a further reduction in the Class Principal
           Balances of the Group I-B Certificates; and
 
       (xiii) thirteenth, to the Class R Certificates, the remaining portion, if
           any (which is expected to be zero), of the Available Distribution
           Amount for Loan Group I for such Distribution Date;
 
    (b) with respect to the Group II Certificates, prior to the Group II Credit
       Support Depletion Date, to the extent of the Available Distribution
       Amount for Loan Group II remaining following prior distributions, if any,
       on such Distribution Date:
 
       (i)  first, to the Class II-P Certificates, the Class II-P Fraction (as
           defined herein) of all principal received on or in respect of each
           Class II-P Mortgage Loan;
 
       (ii)  second, (a) to the Group II-A, Class II-X and Class R Certificates,
           accrued and unpaid interest at their respective Remittance Rates on
           their respective Class Principal Balances (or Class Notional Amount
           in the case of the Class II-X Certificates and the respective
           Component Principal Balances in the case of Component II-A-5-1 and
           Component II-A-5-2), provided, however, that no such distributions
           will be made to the Class II-A-4 Certificates on or before the Class
           II-A-4 Accretion Termination Date, to Component II-A-5-1 prior to the
           Component II-A-5-1 Accretion Termination Date, to Component II-A-5-2
           prior to the Component II-A-5-2 Accretion Termination Date and to the
           Class II-A-6 Certificates on or before the Class II-A-6 Accretion
           Termination Date, (b) on or before the Class II-A-4 Accretion
           Termination Date, to the Classes in the manner described under
           "--CLASS II-A-4 ACCRUAL" herein, as principal, the Class II-A-4
           Accrual Amount (as defined herein), (c) prior to the Component
           II-A-5-1 Accretion Termination Date, to the Classes and Components in
           the manner described under "--COMPONENT II-A-5-1 ACCRUAL" herein, as
           principal, the Component II-A-5-1 Accrual Amount (as defined herein),
           (d) prior to the Component II-A-5-2 Accretion Termination Date, to
           the Classes and Components in the manner described under "--COMPONENT
           II-A-5-2 ACCRUAL" herein, as principal, the Component II-A-5-2
           Accrual Amount (as defined herein) and (e) on or before the Class
           II-A-6 Accretion Termination Date, to the Classes in the manner
           described under "--CLASS II-A-6 ACCRUAL" herein, as principal, the
           Class II-A-6 Accrual Amount (as defined herein).
 
       (iii)  third, to the Group II-A and Class R Certificates, as principal,
           the Group II Senior Principal Distribution Amount in the order
           described in "--Distributions of Principal-- GROUP II SENIOR
           PRINCIPAL DISTRIBUTION AMOUNT" herein;
 
       (iv)  fourth, to the Class II-P Certificates, to the extent of amounts
           otherwise available to pay the Group II Subordinate Principal
           Distribution Amount (as defined herein) (without regard to clause (B)
           of such definition) on such Distribution Date, the sum of (a)
           principal in an amount equal to the Class II-P Fraction of certain
           principal losses on the Class II-P
 
                                      S-38
<PAGE>
           Mortgage Loans, as described in "--Distributions of Principal--CLASS
           II-P PRINCIPAL DISTRIBUTION AMOUNT" herein and (b) the sum of
           amounts, if any, by which the amount described in clause (a) above on
           each prior Distribution Date exceeded the amount actually distributed
           in respect thereof on such prior Distribution Dates and not
           subsequently distributed; PROVIDED that any amounts distributed in
           respect of losses pursuant to this paragraph shall not cause a
           further reduction in the Class II-P Principal Balance;
 
       (v)  fifth, to the Class II-B-1 Certificates, accrued and unpaid interest
           at the Class II-B-1 Remittance Rate on the Class II-B-1 Principal
           Balance;
 
       (vi)  sixth, to the Class II-B-1 Certificates, their pro rata share of
           the Group II Subordinate Principal Distribution Amount;
 
       (vii)  seventh, to the Class II-B-2 Certificates, accrued and unpaid
           interest at the Class II-B-2 Remittance Rate on the Class II-B-2
           Principal Balance;
 
       (viii) eighth, to the Class II-B-2 Certificates, their pro rata share of
           the Group II Subordinate Principal Distribution Amount;
 
       (ix)  ninth, to the Class II-B-3 Certificates, accrued and unpaid
           interest at the Class II-B-3 Remittance Rate on the Class II-B-3
           Principal Balance;
 
       (x)  tenth, to the Class II-B-3 Certificates, their pro rata share of the
           Group II Subordinate Principal Distribution Amount;
 
       (xi)  eleventh, to the Group II Junior Subordinate Certificates, interest
           and principal in the same manner as for the Group II Senior
           Subordinate Certificates, first to Class II-B-4 Certificates, then to
           Class II-B-5 Certificates and then to Class II-B-6 Certificates;
 
       (xii)  twelfth, to each Class of the Group II-B Certificates in order of
           seniority, the remaining portion, if any, of the Available
           Distribution Amount for Loan Group II, up to the amount of
           unreimbursed realized losses previously allocated to such Class, if
           any, PROVIDED that distribution of any amount pursuant to this
           paragraph shall not cause a further reduction in the Class Principal
           Balances of the Group II-B Certificates; and
 
       (xiii) thirteenth, to the Class R Certificates, the remaining portion, if
           any (which is expected to be zero), of the Available Distribution
           Amount for Loan Group II for such Distribution Date; and
 
    (c) with respect to the Group III and Class R Certificates, prior to the
       Group III Credit Support Depletion Date (as defined herein), to the
       extent of the Available Distribution Amount for Loan Group III remaining
       following prior distributions, if any, on such Distribution Date:
 
       (i)  first, to the Class III-P Certificates, the Class III-P Fraction (as
           defined herein) of all principal received on or in respect of each
           Class III-P Mortgage Loan;
 
       (ii)  second, to the Class III-PT and Class III-X Certificates, accrued
           and unpaid interest at their respective Remittance Rates on their
           respective Class Principal Balances (or Class Notional Amount, in the
           case of the Class III-X Certificates);
 
       (iii)  third, to the Class III-PT Certificates, as principal, the Group
           III Senior Principal Distribution Amount (as defined in
           "--Distributions of Principal--GROUP III SENIOR PRINCIPAL
           DISTRIBUTION AMOUNT" herein);
 
       (iv)  fourth, to the Class III-P Certificates, to the extent of amounts
           otherwise available to pay the Group III Subordinate Principal
           Distribution Amount (as defined herein) (without regard to clause (B)
           of such definition) on such Distribution Date, the sum of (a)
           principal in an amount equal to the Class III-P Fraction of certain
           principal losses on the Class III-P
 
                                      S-39
<PAGE>
           Mortgage Loans, as described in "--Distributions of Principal--CLASS
           III-P DISTRIBUTION AMOUNT" herein and (b) the sum of amounts, if any,
           by which the amount described in clause (a) above on each prior
           Distribution Date exceeded the amount actually distributed in respect
           thereof on such prior Distribution Dates and not subsequently
           distributed; PROVIDED that any amounts distributed in respect of
           losses pursuant to this paragraph shall not cause a further reduction
           in the Class III-P Principal Balance;
 
       (v)  fifth, to the Class III-B-1 Certificates, accrued and unpaid
           interest at the Class III-B-1 Remittance Rate on the Class III-B-1
           Principal Balance;
 
       (vi)  sixth, to the Class III-B-1 Certificates, their pro rata share of
           the Group III Subordinate Principal Distribution Amount;
 
       (vii)  seventh, to the Class III-B-2 Certificates, accrued and unpaid
           interest at the Class III-B-2 Remittance Rate on the Class III-B-2
           Principal Balance;
 
       (viii) eighth, to the Class III-B-2 Certificates, their pro rata share of
           the Group III Subordinate Principal Distribution Amount;
 
       (ix)  ninth, to the Class III-B-3 Certificates, accrued and unpaid
           interest at the Class III-B-3 Remittance Rate on the Class III-B-3
           Principal Balance;
 
       (x)  tenth, to the Class III-B-3 Certificates, their pro rata share of
           the Group III Subordinate Principal Distribution Amount;
 
       (xi)  eleventh, to the Group III Junior Subordinate Certificates,
           interest and principal in the same manner as for the Group III Senior
           Subordinate Certificates, first to the Class III-B-4 Certificates,
           then to the Class III-B-5 Certificates and then to the Class III-B-6
           Certificates;
 
       (xii)  twelfth, to each Class of the Group III-B Certificates in order of
           seniority, the remaining portion, if any, of the Available
           Distribution Amount for Loan Group III, up to the amount of
           unreimbursed realized losses previously allocated to such Class, if
           any, PROVIDED that distribution of any amount pursuant to this
           paragraph shall not cause a further reduction in the Class Principal
           Balances of the Group III-B Certificates; and
 
       (xiii) thirteenth, to the Class R Certificates, the remaining portion, if
           any (which is expected to be zero), of the Available Distribution
           Amount for Loan Group III for such Distribution Date.
 
    With respect to the Class B Certificates of each Certificate Group,
notwithstanding the foregoing, on any Distribution Date on which the
Subordination Level (as defined herein) for any Class of Class B Certificates in
a Certificate Group is less than such percentage as of the Cut-Off Date, the
portion of the Subordinate Principal Prepayments Distribution Amount for such
Certificate Group otherwise allocable to the Class or Classes of the Class B
Certificates in the related Certificate Group junior to such Class will be
allocated to the most senior Class of Class B Certificates in such Certificate
Group for which the Subordination Level is less than such percentage as of the
Cut-Off Date and to the Class or Classes of Class B Certificates in such
Certificate Group senior thereto, pro rata according to the Class Principal
Balances of such Classes.
 
    The "SUBORDINATION LEVEL" on any specified date with respect to any Class of
Class B Certificates is the percentage obtained by dividing the sum of the Class
Principal Balances of all Classes of Certificates in the related Certificate
Group which are subordinate in right of payment to such Class by the sum of the
Class Principal Balances of all Classes of Certificates in the related
Certificate Group as of such date prior to giving effect to distributions or
allocations of realized losses on the Mortgage Loans in the related Loan Group
on such date.
 
                                      S-40
<PAGE>
    On each Distribution Date on or after the Group I Credit Support Depletion
Date, distributions will be made with respect to the Group I and Class R
Certificates as follows, subject, in each case, to the extent of the Available
Distribution Amount of Loan Group I remaining following prior distributions, if
any, on such Distribution Date:
 
    (i) first, to the Class I-P Certificates, the Class I-P Fraction of all
        principal received on or in respect of each Class I-P Mortgage Loan;
 
    (ii) second, to the Class I-A-1 and Class I-X Certificates, accrued and
         unpaid interest at their respective Remittance Rates on their Class
         Principal Balance (or Class Notional Amounts, in the case of the Class
         I-X Certificates);
 
   (iii) third, to the Class I-A-1 Certificates, the Group I Senior Principal
         Distribution Amount; and
 
    (iv) fourth, to the Class R Certificates, the remaining portion, if any
         (which is expected to be zero), of the Available Distribution Amount
         for Loan Group I for such Distribution Date.
 
    The "GROUP I CREDIT SUPPORT DEPLETION DATE" is the first Distribution Date
on which the aggregate of the Class Principal Balances of the Group I-B
Certificates has been or will be reduced to zero.
 
    On each Distribution Date on or after the Group II Credit Support Depletion
Date, distributions will be made with respect to the Group II Certificates,
subject, in each case, to the extent of the Available Distribution Amount of
Loan Group II remaining following prior distributions, if any, on such
Distribution Date:
 
    (i) first, to the Class II-P Certificates, the Class II-P Fraction of all
        principal received on or in respect of each Class II-P Mortgage Loan;
 
    (ii) second, to the Group II-A, Class II-X and Class R Certificates, accrued
         and unpaid interest at their respective Remittance Rates on their
         respective Class Principal Balances (or Class Notional Amount in the
         case of the Class II-X Certificates, or the respective Component
         Principal Balances in the case of Component II-A-5-1 and Component
         II-A-5-2);
 
   (iii) third, to the Group II-A and Class R Certificates, the Group II Senior
         Principal Distribution Amount, pro rata according to their respective
         Class Principal Balances (or Component Principal Balances in the case
         of Component II-A-5-1 and Component II-A-5-2); and
 
    (iv) fourth, to the Class R Certificates, the remaining portion, if any
         (which is expected to be zero), of the Available Distribution Amount
         for Loan Group II for such Distribution Date.
 
    The "GROUP II CREDIT SUPPORT DEPLETION DATE" is the first Distribution Date
on which the aggregate of the Class Principal Balances of the Group II-B
Certificates has been or will be reduced to zero.
 
    On each Distribution Date on or after the Group III Credit Support Depletion
Date, distributions will be made with respect to the Group III and Class R
Certificates, subject, in each case, to the extent of the Available Distribution
Amount of Loan Group III remaining following prior distributions, if any, on
such Distribution Date:
 
    (i) first, to the Class III-P Certificates, the Class III-P Fraction of all
        principal received on or in respect of each Class III-P Mortgage Loan;
 
    (ii) second, to the Class III-PT and Class III-X Certificates, accrued and
         unpaid interest at their respective Remittance Rates on their Class
         Principal Balance (or Class Notional Amount, in the case of the Class
         III-X Certificates);
 
   (iii) third, to the Class III-PT Certificates, the Group III Senior Principal
         Distribution Amount; and
 
    (iv) fourth, to the Class R Certificates, the remaining portion, if any
         (which is expected to be zero), of the Available Distribution Amount
         for Loan Group III for such Distribution Date.
 
                                      S-41
<PAGE>
    The "GROUP III CREDIT SUPPORT DEPLETION DATE" is the first Distribution Date
on which the aggregate of the Class Principal Balances of the Group III-B
Certificates has been or will be reduced to zero.
 
    CLASS II-A-4 ACCRUAL. The "CLASS II-A-4 ACCRETION TERMINATION DATE" is the
earlier to occur of (i) the Distribution Date on which the Class II-A-2
Principal Balance has been reduced to zero and (ii) the Group II Credit Support
Depletion Date. On each Distribution Date on or before the Class II-A-4
Accretion Termination Date, an amount (for any Distribution Date, the "CLASS
II-A-4 ACCRUAL AMOUNT") equal to the accrued interest that would otherwise be
distributable in respect of the Class II-A-4 Certificates on such Distribution
Date will be added to the Class II-A-4 Principal Balance (such amount to
thereafter accrue interest at the Class II-A-4 Remittance Rate) and such amount
will be distributed, as principal, to the following Certificates:
 
    (1) first, to the Class II-A-2 Certificates, to the extent necessary to
       reduce the Class II-A-2 Principal Balance to its Targeted Principal
       Balance for such Distribution Date; and
 
    (2) second, to the Class II-A-4 Certificates, until the Class II-A-4
       Principal Balance has been reduced to zero.
 
    CLASS II-A-6 ACCRUAL. The "CLASS II-A-6 ACCRETION TERMINATION DATE" is the
earlier to occur of (i) the Distribution Date on which the Class II-A-10
Principal Balance has been reduced to zero and (ii) the Group II Credit Support
Depletion Date. On each Distribution Date on or before the Class II-A-6
Accretion Termination Date, an amount (for any Distribution Date, the "CLASS
II-A-6 ACCRUAL AMOUNT") equal to the accrued interest that would otherwise be
distributable in respect of the Class II-A-6 Certificates on such Distribution
Date will be added to the Class II-A-6 Principal Balance (such amount to
thereafter accrue interest at the Class II-A-6 Remittance Rate) and such amount
will be distributed, as principal, to the following Certificates:
 
    (1) first, to the Class II-A-10 Certificates, to the extent necessary to
       reduce the Class II-A-10 Principal Balance to its Targeted Principal
       Balance for such Distribution Date; and
 
    (2) second, to the Class II-A-6 Certificates, until the Class II-A-6
       Principal Balance has been reduced to zero.
 
    COMPONENT II-A-5-1 ACCRUAL. The "COMPONENT II-A-5-1 ACCRETION TERMINATION
DATE" is the earlier to occur of (i) the Distribution Date following the
Distribution Date on which Component II-A-5-1 receives any amount of principal,
(ii) the Distribution Date following the Group II Credit Support Depletion Date
and (iii) the Collateral Reduction Trigger Date (as defined under
"--Distributions of Principal--Group II Certificate Principal
Distributions--GROUP II SENIOR PRINCIPAL DISTRIBUTION AMOUNT" herein). On each
Distribution Date prior to the Component II-A-5-1 Accretion Termination Date, an
amount (the "COMPONENT II-A-5-1 ACCRUAL AMOUNT") equal to the accrued interest
that would otherwise be distributable in respect of Component II-A-5-1 on such
Distribution Date will be added to the Component II-A-5-1 Principal Balance
(such amount to thereafter accrue interest at the Component II-A-5-1 Remittance
Rate) and such amount will be distributed, as principal, to the following
Certificates and Components:
 
    (1) first, to the Class II-A-3 Certificates, to the extent necessary to
       reduce the Class II-A-3 Principal Balance to its Targeted Principal
       Balance for such Distribution Date;
 
    (2) second, to Component II-A-5-2, until the Component II-A-5-2 Principal
       Balance has been reduced to zero;
 
    (3) third, to the Class II-A-3 Certificates, until the Class II-A-3
       Principal Balance has been reduced to zero; and
 
    (4) fourth, to Component II-A-5-1, until the Component II-A-5-1 Principal
       Balance has been reduced to zero.
 
                                      S-42
<PAGE>
    COMPONENT II-A-5-2 ACCRUAL. The "COMPONENT II-A-5-2 ACCRETION TERMINATION
DATE" is the earlier to occur of (i) the Distribution Date following the
Distribution Date on which Component II-A-5-2 receives any amount of principal,
(ii) the Distribution Date following the Group II Credit Support Depletion Date
and (iii) the Collateral Reduction Trigger Date. On each Distribution Date prior
to the Component II-A-5-2 Accretion Termination Date, after the Component
II-A-5-1 Accrual Amount has been distributed as described above, an amount (for
any Distribution Date, the "COMPONENT II-A-5-2 ACCRUAL AMOUNT") equal to the
accrued interest that would otherwise be distributable in respect of Component
II-A-5-2 on such Distribution Date will be added to the Component II-A-5-2
Principal Balance (such amount to thereafter accrue interest at the Component
II-A-5-2 Remittance Rate) and such amount will be distributed, as principal, to
the following Certificates and Components:
 
    (1) first, to the Class II-A-3 Certificates, to the extent necessary to
       reduce the Class II-A-3 Principal Balance to its Targeted Principal
       Balance for such Distribution Date; and
 
    (2) second, to Component II-A-5-2, until the Component II-A-5-2 Principal
       Balance has been reduced to zero.
 
    Distributions of interest and principal to the Group I Certificates, the
Group II Certificates and the Group III Certificates will be based solely on
payments received with respect to Group I Loans, Group II Loans and Group III
Loans, respectively.
 
DISTRIBUTIONS OF INTEREST
 
    With respect to each Class of Certificates (except the Class P Certificates,
which are not entitled to interest), interest will be passed through monthly on
each Distribution Date, commencing in December 1997, except that (1) interest
accrued on the Class II-A-4 Certificates on or before the Class II-A-4 Accretion
Termination Date will be added to the Class II-A-4 Principal Balance, (2)
interest accrued on Component II-A-5-1 prior to the Component II-A-5-1 Accretion
Termination Date will be added to the Component II-A-5-1 Principal Balance, (3)
interest accrued on Component II-A-5-2 prior to the Component II-A-5-2 Accretion
Termination Date will be added to the Component II-A-5-2 Principal Balance and
(4) interest accrued on the Class II-A-6 Certificates on or before the Class
II-A-6 Accretion Termination Date will be added to the Class II-A-6 Principal
Balance. With respect to each Distribution Date, an amount of interest will
accrue or accrete, as applicable, on each Class of Certificates (other than the
Class P Certificates), or, with respect to the Class II-A-5 Certificates, on
each Component of such Class of Certificates, generally equal to 1/12th of the
applicable Remittance Rate for such Class or Component multiplied by the related
Class Principal Balance, Component Principal Balance or Class Notional Amount,
as applicable. Interest to be distributed on the Certificates on any
Distribution Date will consist of accrued and unpaid interest as of previous
Distribution Dates and interest accrued during the preceding calendar month,
except for the LIBOR Certificates which accrue interest as described below. All
distributions of interest for each Class of Certificates (or in the case of the
Class II-A-5 Certificates, each Component of such Class) will generally be made
only to the extent of the Available Distribution Amount for the related Loan
Group as described herein under "--Priority of Distributions".
 
    The Remittance Rates for the Offered Certificates (other than the LIBOR
Certificates) are fixed as set forth on the cover page hereof. The Remittance
Rates for Component II-A-5-1 and Component II-A-5-2 will each be 7.000% per
annum.
 
    The Remittance Rates for the LIBOR Certificates are adjustable monthly based
on changes in LIBOR (as defined herein), as described herein. Interest to be
distributed to the LIBOR Certificates on any Distribution Date will consist of
interest accrued during the period commencing on the 25th day of the preceding
calendar month and ending on the 24th day of the month of such Distribution
Date. The initial Remittance Rate for the Class I-X-1 Certificates will be
5.250% per annum. Thereafter, the Class I-X-1 Certificates will accrue interest
at a per annum rate equal to four multiplied by LIBOR minus 17.500%, subject to
a minimum and maximum Remittance Rate of 0% and 14.500% per annum, respectively.
The
 
                                      S-43
<PAGE>
initial Remittance Rate for the Class I-X-2 Certificates will be 9.250% per
annum. Thereafter, the Class I-X-2 Certificates will accrue interest at a per
annum rate equal to 32.000% minus four multiplied by LIBOR, subject to a minimum
and maximum Remittance Rate of 0% and 14.500% per annum, respectively.
 
    Each Class of Class X Certificates will accrue interest on the applicable
Class Notional Amount.
 
    The "CLASS I-X NOTIONAL AMOUNT" with respect to any Distribution Date will
equal the product of (x) the aggregate scheduled principal balance, as of the
second preceding Due Date after giving effect to payments scheduled to be
received as of such Due Date, whether or not received, or with respect to the
initial Distribution Date, as of the Cut-Off Date, of the Group I Premium Rate
Mortgage Loans and (y) a fraction, the numerator of which is the weighted
average of the Stripped Interest Rates (as defined below) for the Group I
Premium Rate Mortgage Loans as of such Due Date and the denominator of which is
7.250%. The "CLASS I-X-1 NOTIONAL AMOUNT" with respect to any Distribution Date
will equal one-half of the Class I-X Notional Amount. The "CLASS I-X-2 NOTIONAL
AMOUNT" with respect to any Distribution Date will equal one-half of the Class
I-X Notional Amount. The Class I-X-1 and Class I-X-2 Notional Amounts as of the
Cut-Off Date will each be approximately $21,674,172.
 
    The "CLASS II-X NOTIONAL AMOUNT" with respect to any Distribution Date will
equal the product of (x) the aggregate scheduled principal balance, as of the
second preceding Due Date after giving effect to payments scheduled to be
received as of such Due Date, whether or not received, or with respect to the
initial Distribution Date, as of the Cut-Off Date, of the Group II Premium Rate
Mortgage Loans and (y) a fraction, the numerator of which is the weighted
average of the Stripped Interest Rates for the Group II Premium Rate Mortgage
Loans as of such Due Date and the denominator of which is 7.000%. The Class II-X
Notional Amount as of the Cut-Off Date will be approximately $35,143,021.
 
    The "CLASS III-X NOTIONAL AMOUNT" with respect to any Distribution Date will
equal the product of (x) the aggregate scheduled principal balance, as of the
second preceding Due Date after giving effect to payments scheduled to be
received as of such Due Date, whether or not received, or with respect to the
initial Distribution Date, as of the Cut-Off Date, of the Group III Premium Rate
Mortgage Loans and (y) a fraction, the numerator of which is the weighted
average of the Stripped Interest Rates for the Group III Premium Rate Mortgage
Loans as of such Due Date and the denominator of which is 6.750%. The Class
III-X Notional Amount as of the Cut-Off Date will be approximately $9,303,707.
 
    The "STRIPPED INTEREST RATE" means (i) for each Group I Loan, the excess, if
any, of the Pass-Through Rate for such Mortgage Loan over 7.250%, (ii) for each
Group II Loan, the excess, if any, of the Pass-Through Rate for such Mortgage
Loan over 7.000% and (iii) for each Group III Loan, the excess, if any, of the
Pass-Through Rate for such Mortgage Loan over 6.750%. The "Pass-Through Rate"
for each Mortgage Loan is equal to the Mortgage Interest Rate thereon less the
sum of the rates at which the related Master Servicing Fee, Servicing Fee and
Certificate Administrator Fee (each, as defined herein) are calculated.
 
    COMPENSATING INTEREST. The Company, as Master Servicer, is obligated to
remit to the Certificate Account on the day prior to each Distribution Date with
respect to the PNC Loans in each Loan Group an amount equal to the lesser of (a)
any shortfall for the related month in interest collections resulting from the
timing of Payoffs on the related Mortgage Loans made from the 15th day of the
calendar month preceding such Distribution Date to the last day of such month
and (b) the applicable monthly Master Servicing Fee payable to the Company, any
reinvestment income realized by the Company, as Master Servicer, relating to
Payoffs on the related Mortgage Loans made during the related Prepayment Period
and interest payments on such Payoffs received during the period of the first
day through the 14th day of the month of such Distribution Date. In addition, on
the day prior to each Distribution Date, with respect to the IndyMac Loans in
each Loan Group, if any, IndyMac is obligated to remit to the Certificate
Account an amount equal to the lesser of (i) any shortfall for the related month
in interest collections resulting from the timing of Payoffs or Curtailments
made during the related Prepayment Period, and (ii) two-thirds of the applicable
monthly Master Servicing Fee payable to IndyMac with respect to such
 
                                      S-44
<PAGE>
Mortgage Loans. See "Yield and Prepayment Considerations" herein and "Yield
Considerations-- Effective Interest Rate" in the Prospectus.
 
LIBOR
 
    The LIBOR Certificates will bear interest at their respective Remittance
Rates, which are based on the London Interbank Offered Rate for one-month U.S.
dollar deposits ("LIBOR") determined by the Certificate Administrator on the
basis of quotations provided by the reference banks meeting the criteria set
forth herein (the "REFERENCE BANKS"). The initial Reference Banks will be
Barclays Bank PLC, Bankers Trust Company and The Bank of Tokyo, Ltd. The
Certificate Administrator will determine LIBOR and the Remittance Rates for the
LIBOR Certificates for a given accrual period, other than the initial accrual
period, on the second business day prior to the day on which such accrual period
commences (a "LIBOR DETERMINATION DATE"). For this purpose a "business day" is
any day on which banks in London and New York City are open for the transaction
of international business. The Remittance Rates for the LIBOR Certificates, and
the outstanding Class Notional Amounts for each Class of LIBOR Certificates
(expressed as percentages of the initial Class Notional Amounts) applicable to
the then current and the immediately preceding accrual period will appear on
Telerate (as defined below). The specific Telerate page number upon which such
information appears may be obtained from the Certificate Administrator.
 
    With respect to any accrual period commencing on or after December 25, 1997,
the determination of LIBOR will be made in accordance with the following
provisions:
 
    (i) On each LIBOR Determination Date, the Certificate Administrator will
        determine LIBOR on the basis of LIBOR quotations provided by each of the
        Reference Banks as of approximately 11:00 a.m. (London time) on the
        LIBOR Determination Date in question, as such quotations appear on the
        Telerate Page 3750 ("TELERATE") (as defined in the International Swap
        Dealers Association Inc. Code of 1987 Interest Rate and Currency
        Exchange Definitions).
 
    (ii) If, on any LIBOR Determination Date, at least two of the Reference
         Banks provide quotations, LIBOR will be determined as the arithmetic
         mean (rounded upward, if necessary, to the nearest multiple of 1/16 of
         1%) of such offered quotations.
 
   (iii) If, on any LIBOR Determination Date, only one or none of the Reference
         Banks provides quotations, LIBOR will be the higher of:
 
       (a) LIBOR as determined on the previous LIBOR Determination Date (or, in
           the case of the first LIBOR Determination Date, 5.6875%); or
 
       (b) the Reserve Rate (as defined below).
 
    The "RESERVE RATE" will be the rate per annum (rounded upward, if necessary,
to the nearest multiple of 1/16 of 1%) that the Certificate Administrator
determines to be either (1) the arithmetic mean of the offered quotations that
the leading banks in New York City selected by the Certificate Administrator are
quoting on the relevant LIBOR Determination Date for one-month U.S. dollar
deposits to the principal London office of each of the Reference Banks or those
of them (being at least two in number) to which such offered quotations are, in
the opinion of the Certificate Administrator, being so made, or (2) in the event
that the Certificate Administrator can determine no such arithmetic mean, the
arithmetic mean of the offered quotations that leading banks in New York City
selected by the Certificate Administrator are quoting on such LIBOR
Determination Date to leading European banks for one-month U.S. dollar deposits;
provided, however, that if the banks selected by the Certificate Administrator
are not quoting as mentioned above, LIBOR for the next accrual period will be
LIBOR as specified in (iii)(a) above.
 
    Each Reference Bank (i) shall be a leading bank engaged in transactions in
Eurodollar deposits in the international Eurocurrency market, (ii) shall not
control, be controlled by, or be under common control with, the Certificate
Administrator and (iii) shall have an established place of business in London.
If any
 
                                      S-45
<PAGE>
such Reference Bank should be unwilling or unable to act as such or if the
Certificate Administrator should terminate the designation of any such Reference
Bank, the Certificate Administrator will promptly designate another leading bank
meeting the criteria specified above.
 
    The establishment of LIBOR on each LIBOR Determination Date by the
Certificate Administrator and the Certificate Administrator's calculation of the
Remittance Rates for the LIBOR Certificates for the related accrual period
shall, in the absence of manifest error, be final and binding.
 
    Listed below are some historical values of LIBOR since January 1992. Such
values were not determined in accordance with the provisions set forth above and
are intended only to provide a historical summary of the movement in yields on
LIBOR; the monthly figures set forth below are the value of LIBOR as derived
from various sources.
 
<TABLE>
<CAPTION>
                                                                                YEAR
                                                  ----------------------------------------------------------------
MONTH                                               1997       1996       1995       1994       1993       1992
- ------------------------------------------------  ---------  ---------  ---------  ---------  ---------  ---------
<S>                                               <C>        <C>        <C>        <C>        <C>        <C>
January.........................................    5.43750%   5.43750%   6.09375%   3.12500%   3.18750%   4.18750%
February........................................    5.43750    5.31250    6.12500    3.56250    3.18750    4.25000
March...........................................    5.68750    5.43750    6.12500    3.68750    3.18750    4.25000
April...........................................    5.68750    5.43750    6.06250    4.00000    3.12500    3.93750
May.............................................    5.68750    5.43750    6.06250    4.37500    3.25000    4.00000
June............................................    5.68750    5.49609    6.12500    4.56250    3.18750    3.93750
July............................................    5.62500    5.46484    5.87500    4.50000    3.18750    3.37500
August..........................................    5.65625    5.43750    5.87500    4.87500    3.18750    3.50000
September.......................................    5.65625    5.43359    5.87500    5.06250    3.18750    3.12500
October.........................................    5.64844    5.37500    5.83203    5.06250    3.18750    3.25000
November........................................               5.56250    5.97656    6.06250    3.56250    4.25000
December........................................               5.50000    5.68750    6.00000    3.25000    3.31250
</TABLE>
 
DISTRIBUTIONS OF PRINCIPAL
 
    GENERAL. On each Distribution Date, Certificateholders of each Certificate
Group will be entitled to receive principal distributions from the related
Available Distribution Amount to the extent and in the priority described
herein. See " -- Priority of Distributions" herein. The Group I Certificates
will receive principal collected from Group I Loans, the Group II Certificates
will receive principal collected from the Group II Loans and the Group III
Certificates will receive principal collected from the Group III Loans.
 
    The Class X Certificates will not receive any distributions of principal.
 
    GROUP I CERTIFICATE PRINCIPAL DISTRIBUTIONS
 
    CLASS I-P PRINCIPAL DISTRIBUTION AMOUNT. On each Distribution Date, the
Class I-P Certificates will receive a portion of the Available Distribution
Amount for Loan Group I attributable to principal received on or in respect of
any Group I Loan with a Pass-Through Rate of less than 7.250% (a "CLASS I-P
MORTGAGE LOAN"), equal to the amount of such principal so attributable
multiplied by a fraction, the numerator of which is 7.250% minus the
Pass-Through Rate on such Class I-P Mortgage Loan and the denominator of which
is 7.250% (the "Class I-P Fraction"). In addition, on each Distribution Date for
so long as any of the Group I-B Certificates remains outstanding, the Class I-P
Certificates will also be allocated principal, to the extent of amounts
available to pay the Group I Subordinate Principal Distribution Amount (without
regard to clause (B) of such definition) on such Distribution Date, in an amount
generally equal to (i) the Class I-P Fraction of any loss on a Class I-P
Mortgage Loan other than a Special Hazard Loss in excess of the Group I Special
Hazard Coverage, a Fraud Loss in excess of the Group I Fraud Coverage or a
Bankruptcy Loss in excess of the Group I Bankruptcy Coverage (each, as defined
herein) and (ii) the sum of amounts, if any, by which the foregoing amount on
each prior Distribution Date exceeded the amount actually distributed in respect
thereof on such prior Distribution Dates and not
 
                                      S-46
<PAGE>
subsequently distributed; PROVIDED, that such payments in respect of losses
shall not cause a further
reduction of the outstanding Class I-P Principal Balance. The aggregate of the
amounts payable to the Class I-P Certificates described in this paragraph are
referred to herein as the "CLASS I-P PRINCIPAL DISTRIBUTION AMOUNT".
 
    GROUP I SENIOR PRINCIPAL DISTRIBUTION AMOUNT. The "GROUP I SENIOR PRINCIPAL
DISTRIBUTION AMOUNT" for any Distribution Date will equal the sum of (i) the
Group I Senior Percentage (as defined below) of the Principal Payment Amount (as
defined below) for Loan Group I (exclusive of the portion thereof attributable
to the Class I-P Principal Distribution Amount), (ii) the Group I Senior
Prepayment Percentage (as defined under "--Principal Prepayments" below) of the
Principal Prepayment Amount (as defined below) for Loan Group I (exclusive of
the portion thereof attributable to the Class I-P Principal Distribution
Amount), and (iii) the Group I Senior Liquidation Amount (as defined below).
 
    The "GROUP I SENIOR PERCENTAGE" for any Distribution Date will equal the
Class I-A-1 Principal Balance divided by the aggregate Class Principal Balance
of the Group I Certificates (less the Class I-P Principal Balance), in each case
immediately prior to the Distribution Date.
 
    The "GROUP I SENIOR LIQUIDATION AMOUNT" is the aggregate, for each Group I
Loan which became a Liquidated Mortgage Loan during the calendar month preceding
the month of the Distribution Date, of the lesser of (i) the Group I Senior
Percentage of the principal balance of such Mortgage Loan (exclusive of the
Class I-P Fraction thereof, with respect to any Class I-P Mortgage Loan) and
(ii) the Group I Senior Prepayment Percentage of the Liquidation Principal with
respect to such Mortgage Loan.
 
    "LIQUIDATION PRINCIPAL" is the principal portion of Liquidation Proceeds
received with respect to each Mortgage Loan which became a Liquidated Mortgage
Loan (as defined herein) (but not in excess of the principal balance thereof)
during the calendar month preceding the month of the Distribution Date,
exclusive of the portion thereof attributable to the applicable Class P
Principal Distribution Amount. A "LIQUIDATED MORTGAGE LOAN" is a Mortgage Loan
as to which the applicable Master Servicer or a servicer has determined that all
amounts which it expects to recover from or on account of such Mortgage Loan,
whether from Insurance Proceeds, Liquidation Proceeds or otherwise have been
recovered.
 
    The "GROUP I SUBORDINATE PERCENTAGE" for any Distribution Date will equal
the excess of 100% over the Group I Senior Percentage for such date. The Group I
Senior Percentage and the Group I Subordinate Percentage as of the Cut-Off Date
will be approximately 93.25% and 6.75%, respectively.
 
    GROUP I SUBORDINATE PRINCIPAL DISTRIBUTION AMOUNT. On each Distribution
Date, an amount, up to the Group I Subordinate Principal Distribution Amount (as
defined below) for such Distribution Date, will be distributed as principal to
the Group I-B Certificates. On each Distribution Date, except Distribution Dates
on which the Subordination Level for any Class of the Group I-B Certificates is
less than such Subordination Level as of the Cut-Off Date, each Class of the
Group I-B Certificates will be entitled to receive its pro rata (by Class
Principal Balance) share of the Group I Subordinate Principal Distribution
Amount, to the extent of the Available Distribution Amount for Loan Group I
remaining after distributions of interest and principal to the Senior
Certificates in Certificate Group I, distributions of interest and principal to
all Classes of the Group I-B Certificates senior to such Class and distributions
of interest to such Class. See "--Priority of Distributions" herein. The
relative seniority, from highest to lowest, of the Group I-B Certificates shall
be as follows: Class I-B-1, Class I-B-2, Class I-B-3, Class I-B-4, Class I-B-5
and Class I-B-6.
 
    The "GROUP I SUBORDINATE PRINCIPAL DISTRIBUTION AMOUNT" for any Distribution
Date will be equal to the excess of (A) the sum of (i) the Group I Subordinate
Percentage of the Principal Payment Amount for Loan Group I (exclusive of the
portion thereof attributable to the Class I-P Principal Distribution Amount),
(ii) the Group I Subordinate Principal Prepayments Distribution Amount and (iii)
the Group I Subordinate Liquidation Amount over (B) the amounts required to be
distributed to the Class I-P Certificates pursuant to clause (iv) of paragraph
(a) under "--Priority of Distributions" herein on such
 
                                      S-47
<PAGE>
Distribution Date. The "GROUP I SUBORDINATE PRINCIPAL PREPAYMENTS DISTRIBUTION
AMOUNT" as of any Distribution Date is the Group I Subordinate Prepayment
Percentage of the Principal Prepayment Amount for Loan Group I (exclusive of the
portion thereof attributable to the Class I-P Principal Distribution Amount).
Any reduction in the Group I Subordinate Principal Distribution Amount pursuant
to clause (B) above, shall first offset the amount calculated pursuant to clause
(A)(i), second clause (A)(iii) and then clause (A)(ii), in each case of the
definition thereof.
 
    The "GROUP I SUBORDINATE LIQUIDATION AMOUNT" will equal the excess, if any,
of the aggregate Liquidation Principal for all Group I Loans which became
Liquidated Mortgage Loans during the calendar month preceding the month of the
Distribution Date, over the Group I Senior Liquidation Amount for such
Distribution Date.
 
    The "GROUP I SUBORDINATE PREPAYMENT PERCENTAGE" for any Distribution Date
will equal the excess of 100% over the Group I Senior Prepayment Percentage;
PROVIDED, HOWEVER, that if the Class I-A-1 Principal Balance has been reduced to
zero, then the Group I Subordinate Prepayment Percentage will equal 100%.
 
    The rights of the holders of the Group I-B Certificates to receive
distributions of interest and principal are subordinated to the rights of the
holders of the Group I Certificates that are Senior Certificates to receive
scheduled distributions of interest and principal. See "--Subordination and
Allocation of Losses" herein.
 
    GROUP II CERTIFICATE PRINCIPAL DISTRIBUTIONS
 
    CLASS II-P PRINCIPAL DISTRIBUTION AMOUNT. On each Distribution Date, the
Class II-P Certificates will receive a portion of the Available Distribution
Amount for Loan Group II attributable to principal received on or in respect of
any Group II Loan with a Pass-Through Rate of less than 7.000% (a "CLASS II - P
MORTGAGE LOAN"), equal to the amount of such principal so attributable
multiplied by a fraction, the numerator of which is 7.000% minus the
Pass-Through Rate on such Class II-P Mortgage Loan and the denominator of which
is 7.000% (the "CLASS II-P FRACTION"). In addition, on each Distribution Date
for so long as any of the Group II-B Certificates remains outstanding, the Class
II-P Certificates will also be allocated principal, to the extent of amounts
available to pay the Group II Subordinate Principal Distribution Amount (without
regard to clause (B) of such definition) on such Distribution Date, in an amount
generally equal to (i) the Class II-P Fraction of any loss on a Class II-P
Mortgage Loan other than a Special Hazard Loss in excess of the Group II Special
Hazard Coverage, a Fraud Loss in excess of the Group II Fraud Coverage or a
Bankruptcy Loss in excess of the Group II Bankruptcy Coverage (each, as defined
herein) and (ii) the sum of amounts, if any, by which the foregoing amount on
each prior Distribution Date exceeded the amount actually distributed in respect
thereof on such prior Distribution Dates and not subsequently distributed;
PROVIDED, that such payments in respect of losses shall not cause a further
reduction of the outstanding Class II-P Principal Balance. The aggregate of the
amounts payable to the Class II-P Certificates described in this paragraph are
referred to herein as the "CLASS II-P PRINCIPAL DISTRIBUTION AMOUNT".
 
    GROUP II SENIOR PRINCIPAL DISTRIBUTION AMOUNT. On each Distribution Date
prior to the Group II Credit Support Depletion Date, an amount, up to the amount
of the Group II Senior Principal Distribution Amount (as defined below) for such
Distribution Date, will be distributed as principal to the following Classes of
Group II-A and Class R Certificates in the following order of priority:
 
    (i) first, to the Class II-A-8 and Class II-A-9 Certificates, pro rata, an
        amount, up to the amount of the Lockout Principal Distribution Amount
        (as defined below) for such Distribution Date, until the Principal
        Balances of the Class II-A-8 and Class II-A-9 Certificates have been
        reduced to zero;
 
    (ii) second, to the Class R Certificates, the portion of the Group II Senior
         Principal Distribution Amount remaining after the distribution
         described above, until the Class R Principal Balance has been reduced
         to zero;
 
                                      S-48
<PAGE>
   (iii) third, to the Class II-A-1 Certificates, the portion of the Group II
         Senior Principal Distribution Amount remaining after the distributions
         described above, to the extent necessary to reduce the Class II-A-1
         Principal Balance to its Planned Principal Balance for such
         Distribution Date;
 
    (iv) fourth, the portion of the Group II Senior Principal Distribution
         Amount remaining after the distributions described above, concurrently,
         as follows, until the Class Principal Balances thereof have been
         reduced to zero:
 
       (A) 6.4304540193% sequentially as follows:
 
           (1) first, to the Class II-A-10 Certificates, to the extent necessary
               to reduce the Class II-A-10 Principal Balance to its Targeted
               Principal Balance for such Distribution Date (after giving effect
               to any distributions of principal received as an Accretion
               Directed Class);
 
           (2) second, to the Class II-A-6 Certificates, until the Class II-A-6
               Principal Balance has been reduced to zero; and
 
           (3) third, to the Class II-A-10 Certificates, until the Class II-A-10
               Principal Balance has been reduced to zero;
 
       (B) 47.6143919926% sequentially as follows:
 
           (1) first, to the Class II-A-2 Certificates, to the extent necessary
               to reduce the Class II-A-2 Principal Balance to its Targeted
               Principal Balance for such Distribution Date (after giving effect
               to any distributions of principal received as an Accretion
               Directed Class);
 
           (2) second, to the Class II-A-4 Certificates, until the Class II-A-4
               Principal Balance has been reduced to zero; and
 
           (3) third, to the Class II-A-2 Certificates, until the Class II-A-2
               Principal Balance has been reduced to zero; and
 
       (C) 45.9551539881% sequentially as follows:
 
           (1) prior to the Collateral Reduction Trigger Date, as follows:
 
                (a) first, to the Class II-A-3 Certificates, to the extent
                    necessary to reduce the Class II-A-3 Principal Balance to
                    its Targeted Principal Balance for such Distribution Date
                    (after giving effect to any distributions of principal
                    received as an Accretion Directed Class);
 
                (b) second, to Component II-A-5-2, until the Component II-A-5-2
                    Principal Balance has been reduced to zero;
 
                (c) third, to the Class II-A-3 Certificates, until the Class
                    II-A-3 Principal Balance has been reduced to zero; and
 
                (d) fourth, to Component II-A-5-1, until the Component II-A-5-1
                    Principal Balance has been reduced to zero;
 
           (2) on or after the Collateral Reduction Trigger Date, as follows:
 
                (a) first, to Component II-A-5-1, until the Component II-A-5-1
                    Principal Balance has been reduced to zero;
 
                (b) second, to Component II-A-5-2, until the Component II-A-5-2
                    Principal Balance has been reduced to zero; and
 
                                      S-49
<PAGE>
                (c) third, to the Class II-A-3 Certificates, until the Class
                    II-A-3 Principal Balance has been reduced to zero;
 
    (v) fifth, to the Class II-A-1 Certificates, the portion of the Group II
        Senior Principal Distribution Amount remaining after the distributions
        described above, until the Class II-A-1 Principal Balance has been
        reduced to zero;
 
    (vi) sixth, to the Class II-A-7 Certificates, the portion of the Group II
         Senior Principal Distribution Amount remaining after the distributions
         described above, until the Class II-A-7 Principal Balance has been
         reduced to zero; and
 
   (vii) seventh, to the Class II-A-8 and Class II-A-9 Certificates, pro rata,
         the portion of the Group II Senior Principal Distribution Amount
         remaining after the distributions described above, until the Class
         II-A-8 and Class II-A-9 Principal Balances have been reduced to zero.
 
    The "COLLATERAL REDUCTION TRIGGER DATE" will be the first Distribution Date
on which (X) the portion of the Available Distribution Amount for Loan Group II
representing payments in respect of principal for such Distribution Date exceeds
(Y) the product of (i) the Percentage Reduction Factor (as defined below) for
such Distribution Date and (ii) the aggregate Scheduled Principal Balance (as
defined below) of the Group II Mortgage Loans as of the preceding Distribution
Date (or as of the Cut-Off Date, in the case of the first Distribution Date).
 
    The "PERCENTAGE REDUCTION FACTOR" for each Distribution Date is set forth in
Appendix D herein. The Percentage Reduction Factor for each Distribution Date
represents the percentage by which the aggregate Scheduled Principal Balance of
all the Group II Loans would be reduced on such Distribution Date in relation to
the aggregate Scheduled Principal Balance of the Group II Loans as of the
preceding Distribution Date (or as of the Cut-Off Date, in the case of the first
Distribution Date) assuming that payments of principal of the Group II Loans
were to be received in each preceding calendar month (or in each preceding
Prepayment Period, in the case of prepayments and other unscheduled recoveries)
and, in the case of prepayments, at a constant rate of 251% of the BPA. However,
the precise percentage of the BPA at which the Collateral Reduction Trigger Date
occurs may be higher or lower than 251% of the BPA, depending in part upon the
respective rates at which principal payments (including scheduled payments
received or advanced, the principal portion of repurchase proceeds, Principal
Prepayments and other unscheduled recoveries of principal) have been made in the
past and in part upon the fact that the remaining terms to maturity, weighted
average lives and interest rates of the outstanding Group II Loans will change
over time from the corresponding characteristics initially used to compute the
Percentage Reduction Factor.
 
    The "SCHEDULED PRINCIPAL BALANCE" of a Mortgage Loan as of any Distribution
Date is the unpaid principal balance of such Mortgage Loan as specified in the
amortization schedule at the time relating thereto (before any adjustment to
such schedule by reason of bankruptcy or similar proceeding or any moratorium or
similar waiver or grace period) as of the first day of the month preceding the
month of such Distribution Date, after giving effect to any previously applied
Curtailments, the payment of principal due on such first day of the month and
any reduction of the principal balance of such Mortgage Loan by a bankruptcy
court, irrespective of any delinquency in payment by the related Mortgagor.
 
    The "GROUP II SENIOR PRINCIPAL DISTRIBUTION AMOUNT" for any Distribution
Date will equal the sum of (i) the Group II Senior Percentage (as defined below)
of the Principal Payment Amount for Loan Group II (exclusive of the portion
thereof attributable to the Class II-P Principal Distribution Amount), (ii) the
Group II Senior Prepayment Percentage (as defined under "--Principal
Prepayments" below) of the Principal Prepayment Amount for Loan Group II
(exclusive of the portion thereof attributable to the Class II-P Principal
Distribution Amount), and (iii) the Group II Senior Liquidation Amount (as
defined below).
 
    The "GROUP II SENIOR PERCENTAGE" for any Distribution Date will equal the
sum of the Class Principal Balances of the Group II-A and the Class R
Certificates divided by the aggregate of the Class Principal
 
                                      S-50
<PAGE>
Balances of the Group II Certificates (less the Class II-P Principal Balance) in
each case immediately prior to the Distribution Date.
 
    The "GROUP II SENIOR LIQUIDATION AMOUNT" is the aggregate, for each Group II
Loan which became a Liquidated Mortgage Loan during the calendar month preceding
the month of the Distribution Date, of the lesser of (i) the Group II Senior
Percentage of the principal balance of such Mortgage Loan (exclusive of the
Class II-P Fraction thereof, with respect to any Class II-P Mortgage Loan) and
(ii) the Group II Senior Prepayment Percentage of the Liquidation Principal with
respect to such Mortgage Loan.
 
    The "GROUP II SUBORDINATE PERCENTAGE" for any Distribution Date will equal
the excess of 100% over the Group II Senior Percentage for such date. The Group
II Senior Percentage and the Group II Subordinate Percentage as of the Cut-Off
Date will be approximately 94.25% and 5.75%, respectively.
 
    The "LOCKOUT PRINCIPAL DISTRIBUTION AMOUNT" for any Distribution Date will
equal the sum of (i) the Adjusted Lockout Percentage (as defined below) of the
Principal Payment Amount for Loan Group II (exclusive of the portion thereof
attributable to the Class II-P Principal Distribution Amount), (ii) the Lockout
Prepayment Percentage (as defined herein) of the Principal Prepayment Amount for
Loan Group II (exclusive of the portion thereof attributable to the Class II-P
Principal Distribution Amount) and (iii) the Lockout Liquidation Amount (as
defined below).
 
    The "ADJUSTED LOCKOUT PERCENTAGE" will equal (i) for any Distribution Date
prior to the Distribution Date in December 2002, 0% and (ii) for any
Distribution Date on or after the Distribution Date in December 2002, the
Lockout Percentage.
 
    The "LOCKOUT PERCENTAGE" for any Distribution Date will equal the sum of the
Class II-A-8 and Class II-A-9 Principal Balances divided by the aggregate Class
Principal Balance of the Group II Certificates (less the Class II-P Principal
Balance), in each case immediately prior to the Distribution Date. The Lockout
Percentage as of the Cut-Off Date will be approximately 18.85%.
 
    The "LOCKOUT LIQUIDATION AMOUNT" is the aggregate, for each Group II Loan
which became a Liquidated Mortgage Loan during the calendar month preceding the
month of the Distribution Date, of the lesser of (i) the Lockout Percentage of
the principal balance of such Mortgage Loan (exclusive of the Class II-P
Fraction thereof, if applicable) and (ii) the Lockout Percentage on any
Distribution Date occurring prior to the fifth anniversary of the first
Distribution Date, and the Lockout Prepayment Percentage (as defined herein) on
any Distribution Date thereafter, in each case, of the Liquidation Principal
with respect to such Mortgage Loan.
 
    The "LOCKOUT PREPAYMENT PERCENTAGE" will equal the product of (a) the
Lockout Percentage and (b) the Step Down Percentage.
 
    The "STEP DOWN PERCENTAGE" for any Distribution Date will be the percentage
indicated below:
 
<TABLE>
<CAPTION>
                   DISTRIBUTION DATE OCCURRING                         IN STEP DOWN PERCENTAGE
- -----------------------------------------------------------------  -------------------------------
<S>                                                                <C>
December 1997 through November 2002..............................                     0%
December 2002 through November 2003..............................                    30%
December 2003 through November 2004..............................                    40%
December 2004 through November 2005..............................                    60%
December 2005 through November 2006..............................                    80%
December 2006 and thereafter.....................................                   100%
</TABLE>
 
    GROUP II SUBORDINATE PRINCIPAL DISTRIBUTION AMOUNT. On each Distribution
Date, an amount, up to the Group II Subordinate Principal Distribution Amount
(as defined below) for such Distribution Date, will be distributed as principal
to the Group II-B Certificates. On each Distribution Date, except Distribution
Dates on which the Subordination Level for any Class of the Group II-B
Certificates is less than such Subordination Level as of the Cut-Off Date, each
Class of the Group II-B Certificates will be entitled to receive its pro rata
(by Class Principal Balance) share of the Group II Subordinate Principal
Distribution
 
                                      S-51
<PAGE>
Amount, to the extent of the Available Distribution Amount for Loan Group II
remaining after distributions of interest and principal to the Senior
Certificates in Certificate Group II, distributions of interest and principal to
all Classes of the Group II-B Certificates senior to such Class and
distributions of interest to such Class. See "--Priority of Distributions"
herein. The relative seniority, from highest to lowest, of the Group II-B
Certificates shall be as follows: Class II-B-1, Class II-B-2, Class II-B-3,
Class II-B-4, Class II-B-5 and Class II-B-6.
 
    The "GROUP II SUBORDINATE PRINCIPAL DISTRIBUTION AMOUNT" for any
Distribution Date will be equal to the excess of (A) the sum of (i) the Group II
Subordinate Percentage of the Principal Payment Amount for Loan Group II
(exclusive of the portion thereof attributable to the Class II-P Principal
Distribution Amount), (ii) the Group II Subordinate Principal Prepayments
Distribution Amount and (iii) the Group II Subordinate Liquidation Amount over
(B) the amounts required to be distributed to the Class II-P Certificates
pursuant to clause (iv) of paragraph (b) under "--Priority of Distributions"
herein on such Distribution Date. The "GROUP II SUBORDINATE PRINCIPAL
PREPAYMENTS DISTRIBUTION AMOUNT" as of any Distribution Date is the Group II
Subordinate Prepayment Percentage of the Principal Prepayment Amount for Loan
Group II (exclusive of the portion thereof attributable to the Class II-P
Principal Distribution Amount). Any reduction in the Group II Subordinate
Principal Distribution Amount pursuant to clause (B) above, shall first offset
the amount calculated pursuant to clause (A)(i), second clause (A)(iii) and then
clause (A)(ii), in each case of the definition thereof.
 
    The "GROUP II SUBORDINATE LIQUIDATION AMOUNT" will equal the excess, if any,
of the aggregate Liquidation Principal for all Group II Loans which became
Liquidated Mortgage Loans during the calendar month preceding the month of the
Distribution Date, over the Group II Senior Liquidation Amount for such
Distribution Date.
 
    The "GROUP II SUBORDINATE PREPAYMENT PERCENTAGE" for any Distribution Date
will equal the excess of 100% over the Group II Senior Prepayment Percentage;
PROVIDED, HOWEVER, that if the Class Principal Balances of the Group II-A and
Class R Certificates has been reduced to zero, then the Group II Subordinate
Prepayment Percentage will equal 100%.
 
    The rights of the holders of the Group II-B Certificates to receive
distributions of interest and principal are subordinated to the rights of the
holders of the Group II Certificates that are Senior Certificates to receive
scheduled distributions of interest and principal. See "--Subordination and
Allocation of Losses" herein.
 
    GROUP III CERTIFICATE PRINCIPAL DISTRIBUTIONS
 
    CLASS III-P PRINCIPAL DISTRIBUTION AMOUNT. On each Distribution Date, the
Class III-P Certificates will receive a portion of the Available Distribution
Amount for Loan Group III attributable to principal received on or in respect of
any Group III Loan with a Pass-Through Rate of less than 6.750% (a "CLASS III-P
MORTGAGE LOAN"), equal to the amount of such principal so attributable
multiplied by a fraction, the numerator of which is 6.750% minus the
Pass-Through Rate on such Class III-P Mortgage Loan and the denominator of which
is 6.750% (the "CLASS III-P FRACTION"). In addition, on each Distribution Date
for so long as any of the Group III-B Certificates remains outstanding, the
Class III-P Certificates will also be allocated principal, to the extent of
amounts available to pay the Group III Subordinate Principal Distribution Amount
(without regard to clause (B) of such definition) on such Distribution Date, in
an amount generally equal to (i) the Class III-P Fraction of any loss on a Class
III-P Mortgage Loan other than a Special Hazard Loss in excess of the Group III
Special Hazard Coverage, a Fraud Loss in excess of the Group III Fraud Coverage
or a Bankruptcy Loss in excess of the Group III Bankruptcy Coverage (each, as
defined herein) and (ii) the sum of amounts, if any, by which the foregoing
amount on each prior Distribution Date exceeded the amount actually distributed
in respect thereof on such prior Distribution Dates and not subsequently
distributed; PROVIDED, that such payments in respect of losses shall not cause a
further reduction of the outstanding Class III-P Principal Balance. The
aggregate of the amounts payable to the Class III-P Certificates described in
this paragraph are referred to herein as the "CLASS III-P PRINCIPAL DISTRIBUTION
AMOUNT".
 
                                      S-52
<PAGE>
    GROUP III SENIOR PRINCIPAL DISTRIBUTION AMOUNT. The "GROUP III SENIOR
PRINCIPAL DISTRIBUTION AMOUNT" for any Distribution Date will equal the sum of
(i) the Group III Senior Percentage (as defined below) of the Principal Payment
Amount (as defined below) for Loan Group III (exclusive of the portion thereof
attributable to the Class III-P Principal Distribution Amount), (ii) the Group
III Senior Prepayment Percentage (as defined under "--Principal Prepayments"
below) of the Principal Prepayment Amount (as defined below) for Loan Group III
(exclusive of the portion thereof attributable to the Class III-P Principal
Distribution Amount), and (iii) the Group III Senior Liquidation Amount (as
defined below).
 
    The "GROUP III SENIOR PERCENTAGE" for any Distribution Date will equal the
Class III-PT Principal Balance divided by the aggregate Class Principal Balance
of the Group III Certificates (less the Class III-P Principal Balance), in each
case immediately prior to the Distribution Date.
 
    The "GROUP III SENIOR LIQUIDATION AMOUNT" is the aggregate, for each Group
III Loan which became a Liquidated Mortgage Loan during the calendar month
preceding the month of the Distribution Date, of the lesser of (i) the Group III
Senior Percentage of the principal balance of such Mortgage Loan (exclusive of
the Class III-P Fraction thereof, with respect to any Class III-P Mortgage Loan)
and (ii) the Group III Senior Prepayment Percentage of the Liquidation Principal
with respect to such Mortgage Loan.
 
    The "GROUP III SUBORDINATE PERCENTAGE" for any Distribution Date will equal
the excess of 100% over the Group III Senior Percentage for such date. The Group
III Senior Percentage and the Group III Subordinate Percentage as of the Cut-Off
Date will be approximately 96.49% and 3.51%, respectively.
 
    GROUP III SUBORDINATE PRINCIPAL DISTRIBUTION AMOUNT. On each Distribution
Date, an amount, up to the Group III Subordinate Principal Distribution Amount
(as defined below) for such Distribution Date, will be distributed as principal
to the Group III-B Certificates. On each Distribution Date, except Distribution
Dates on which the Subordination Level for any Class of the Group III-B
Certificates is less than such Subordination Level as of the Cut-Off Date, each
Class of the Group III-B Certificates will be entitled to receive its pro rata
(by Class Principal Balance) share of the Group III Subordinate Principal
Distribution Amount, to the extent of the Available Distribution Amount for Loan
Group III remaining after distributions of interest and principal to the Senior
Certificates in Certificate Group III, distributions of interest and principal
to all of the Group III-B Certificates senior to such Class and distributions of
interest to such Class. See "--Priority of Distributions" herein. The relative
seniority, from highest to lowest, of the Group III-B Certificates shall be as
follows: Class III-B-1, Class III-B-2, Class III-B-3, Class III-B-4, Class
III-B-5 and Class III-B-6.
 
    The "GROUP III SUBORDINATE PRINCIPAL DISTRIBUTION AMOUNT" for any
Distribution Date will be equal to the excess of (A) the sum of (i) the Group
III Subordinate Percentage of the Principal Payment Amount for Loan Group III
(exclusive of the portion thereof attributable to the Class III-P Principal
Distribution Amount), (ii) the Group III Subordinate Principal Prepayments
Distribution Amount and (iii) the Group III Subordinate Liquidation Amount over
(B) the amounts required to be distributed to the Class III-P Certificates
pursuant to clause (iv) of paragraph (c) under "--Priority of Distributions"
herein on such Distribution Date. The "GROUP III SUBORDINATE PRINCIPAL
PREPAYMENTS DISTRIBUTION AMOUNT" as of any Distribution Date is the Group III
Subordinate Prepayment Percentage of the Principal Prepayment Amount for Loan
Group III (exclusive of the portion thereof attributable to the Class III-P
Principal Distribution Amount). Any reduction in the Group III Subordinate
Principal Distribution Amount pursuant to clause (B) above, shall first offset
the amount calculated pursuant to clause (A)(i), second clause (A)(iii) and then
clause (A)(ii), in each case of the definition thereof.
 
    The "GROUP III SUBORDINATE LIQUIDATION AMOUNT" will equal the excess, if
any, of the aggregate Liquidation Principal for all Group III Loans which became
Liquidated Mortgage Loans during the calendar month preceding the month of the
Distribution Date, over the Group III Senior Liquidation Amount for such
Distribution Date.
 
    The "GROUP III SUBORDINATE PREPAYMENT PERCENTAGE" for any Distribution Date
will equal the excess of 100% over the Group III Senior Prepayment Percentage;
PROVIDED, HOWEVER, that if the Class III-PT
 
                                      S-53
<PAGE>
Principal Balance has been reduced to zero, then the Group III Subordinate
Prepayment Percentage will equal 100%.
 
    The rights of the holders of the Group III-B Certificates to receive
distributions of interest and principal are subordinated to the rights of the
holders of the Group III Certificates that are Senior Certificates to receive
scheduled distributions of interest and principal. See "--Subordination and
Allocation of Losses" herein.
 
    For any Distribution Date and for any Loan Group, the "PRINCIPAL PAYMENT
AMOUNT" is the sum with respect to the Mortgage Loans in such Loan Group of (i)
scheduled principal payments on the Mortgage Loans due on the related Due Date,
(ii) the principal portion of repurchase proceeds received with respect to any
Mortgage Loan which was repurchased as permitted or required by the Pooling
Agreement during the calendar month preceding the month of the Distribution Date
and (iii) any other unscheduled payments of principal which were received on the
Mortgage Loans during the preceding calendar month, other than Payoffs,
Curtailments or Liquidation Principal. For any Distribution Date and for any
Loan Group, the "PRINCIPAL PREPAYMENT AMOUNT" is the sum with respect to the
Mortgage Loans in such Loan Group of all Curtailments and all Payoffs from the
Mortgage Loans in such Loan Group which were received during the applicable
Prepayment Period. Principal distributions to each Certificate Group will be
based on the Principal Payment Amount, Principal Prepayment Amount and
Liquidation Principal for the related Loan Group.
 
    With respect to each Distribution Date and each Payoff with respect to a PNC
Loan, the related "PREPAYMENT PERIOD" will commence on the 15th day of the month
preceding the month in which the related Distribution Date occurs (or, in the
case of the first Distribution Date, commencing on the Cut-Off Date) and will
end on the 14th day of the month in which such Distribution Date occurs. With
respect to each Distribution Date and each Payoff with respect to an IndyMac
Loan, the related "PREPAYMENT PERIOD" will be the calendar month preceding the
month in which the related Distribution Date occurs. With respect to each
Curtailment, and regardless of the Master Servicer of the applicable Mortgage
Loan, the related "PREPAYMENT PERIOD" will be the month preceding the month in
which the related Distribution Date occurs.
 
PRINCIPAL PREPAYMENTS
 
    The "GROUP I SENIOR PREPAYMENT PERCENTAGE", "GROUP II SENIOR PREPAYMENT
PERCENTAGE" and "GROUP III SENIOR PREPAYMENT PERCENTAGE" for any Distribution
Date occurring prior to the month of the fifth anniversary of the first
Distribution Date will equal 100%. The "GROUP I SENIOR PREPAYMENT PERCENTAGE",
"GROUP II SENIOR PREPAYMENT PERCENTAGE" and "GROUP III SENIOR PREPAYMENT
PERCENTAGE" in each of the months of the fifth through ninth anniversaries of
the first Distribution Date will be as follows: for any Distribution Date in or
after the month of the fifth anniversary of the month of the first Distribution
Date but before the sixth anniversary of the month of the first Distribution
Date, the Group I, Group II or Group III Senior Percentage, as applicable, for
such Distribution Date plus 70% of the related Subordinate Percentage for such
Distribution Date; for any Distribution Date in or after the month of the sixth
anniversary of the month of the first Distribution Date but before the seventh
anniversary of the month of the first Distribution Date, the Group I, Group II
or Group III Senior Percentage, as applicable, for such Distribution Date plus
60% of the related Subordinate Percentage for such Distribution Date; for any
Distribution Date in or after the month of the seventh anniversary of the month
of the first Distribution Date but before the eighth anniversary of the month of
the first Distribution Date, the Group I, Group II or Group III Senior
Percentage, as applicable, for such Distribution Date plus 40% of the related
Subordinate Percentage for such Distribution Date; and for any Distribution Date
in or after the month of the eighth anniversary of the month of the first
Distribution Date but before the ninth anniversary of the month of the first
Distribution Date, the Group I, Group II or Group III Senior Percentage, as
applicable, for such Distribution Date plus 20% of the related Subordinate
Percentage for such Distribution Date. For any Distribution Date in or after the
month of the ninth anniversary of the month of the first Distribution Date, the
Group I, Group II or Group III Senior Prepayment Percentage will be the Group I,
Group II or Group III Senior Percentage, respectively, for such Distribution
Date.
 
                                      S-54
<PAGE>
    Notwithstanding the foregoing, if on any Distribution Date the Group I,
Group II or Group III Senior Percentage for such Distribution Date exceeds the
initial Group I, Group II or Group III Senior Percentage, respectively, as of
the Cut-Off Date, then the Group I, Group II or Group III Senior Prepayment
Percentage, as applicable, for such Distribution Date will equal 100%. The
scheduled reductions in the Group I, Group II and Group III Senior Prepayment
Percentages for Distribution Dates occurring on or after the month of the fifth
anniversary of the month of the first Distribution Date will be subject to
certain conditions specified in the Pooling Agreement. Such conditions may
include requirements that no such reduction may occur if delinquencies or losses
on the Mortgage Loans in the related Loan Group exceed specified limits at the
time of, or on a date preceding, the Distribution Date for which such reduction
would otherwise be applicable. Notwithstanding the foregoing, on any
Distribution Date if the delinquencies or losses on the Mortgage Loans in a Loan
Group exceed such limits such that the Pooling Agreement restricts a reduction
of the Group I, Group II or Group III Senior Prepayment Percentage, as
applicable, then the Group I, Group II or Group III Senior Prepayment
Percentage, as applicable, for such Distribution Date will equal 100% for such
Distribution Date. If on any Distribution Date the allocation to the Group I,
Group II or Group III Senior Certificates (other than the related Class P
Certificates) in the percentage required would reduce the sum of the Class
Principal Balances of such Certificates below zero, the Group I, Group II or
Group III Senior Prepayment Percentage, as applicable, for such Distribution
Date will be limited to the percentage necessary to reduce such sum to zero.
 
SUBORDINATION AND ALLOCATION OF LOSSES
 
    The Class B Certificates of each Certificate Group will be subordinate in
right of payment to and provide credit support to the Senior Certificates of
such Certificate Group, the Junior Subordinate Certificates of each Certificate
Group will be subordinate in right of payment to and provide credit support to
the Senior Subordinate Certificates of such Certificate Group and each Class of
Senior Subordinate Certificates in each Certificate Group will be subordinate in
right of payment to and provide credit support to each Class of Senior
Subordinate Certificates in such Certificate Group with a lower numerical Class
designation. The support provided by the Class B Certificates of each
Certificate Group is intended to enhance the likelihood of regular receipt by
the Senior Certificates of such Certificate Group of the full amount of the
monthly distributions of interest (except with respect to the related Class P
Certificates, which are not entitled to interest) and principal (except with
respect to the related Class X Certificates, which are not entitled to
principal) to which they are entitled and to afford such Certificates protection
against certain losses. The protection afforded to the Senior Certificates of
each Certificate Group by the Class B Certificates of such Certificate Group
will be accomplished by the preferential right on each Distribution Date of such
Senior Certificates to receive distributions of interest (except with respect to
the related Class P Certificates) and principal (except with respect to the
related Class X Certificates) prior to distributions of interest or principal to
such Class B Certificates. The protection afforded a Class of Senior Subordinate
Certificates of a Certificate Group by the Classes of Senior Subordinate
Certificates of such Certificate Group with higher numerical Class designations
will be similarly accomplished by the preferential right of those Classes with
lower numerical Class designations to receive distributions of principal and
interest prior to distributions of principal and interest to those Classes of
Senior Subordinate Certificates in such Certificate Group with higher numerical
Class designations. The support provided by the Junior Subordinate Certificates
of each Certificate Group to the Senior Subordinate Certificates of such
Certificate Group is intended to enhance the likelihood of regular receipt by
such Senior Subordinate Certificates of the full amount of monthly distributions
of interest and principal to which they are entitled and to afford such
Certificateholders protection against certain losses. The protection afforded to
the Senior Subordinate Certificates of each Certificate Group by the Junior
Subordinate Certificates of such Certificate Group will be accomplished by the
preferential right on each Distribution Date of such Senior Subordinate
Certificates to receive distributions of interest and principal, prior to
distributions of interest and principal to such Junior Subordinate Certificates.
 
                                      S-55
<PAGE>
    Except for Special Hazard Losses, Fraud Losses and Bankruptcy Losses in
excess of the designated amounts of the applicable Special Hazard Coverage,
Fraud Coverage and Bankruptcy Coverage (each, as defined herein) for a Loan
Group, any loss realized with respect to a Mortgage Loan will be allocated among
the Certificates in the related Certificate Group (i) for losses allocable to
principal (a) first, to the related Junior Subordinate Certificates, until the
aggregate of the Class Principal Balances thereof has been reduced to zero, (b)
second, to the Class I-B-3, Class II-B-3 or Class III-B-3 Certificates, as
applicable, until the Class Principal Balance thereof has been reduced to zero,
(c) third, to the Class I-B-2, Class II-B-2 or Class III-B-2 Certificates, as
applicable, until the Class Principal Balance thereof has been reduced to zero,
(d) fourth, to the Class I-B-1, Class II-B-1 or Class III-B-1 Certificates, as
applicable, until the Class Principal Balance thereof has been reduced to zero,
and (e) fifth, to the Senior Certificates of the related Certificate Group
(other than the related Class X and Class P Certificates), pro rata, according
to their Class Principal Balances (or Component Principal Balances in the case
of Component II-A-5-1 and Component II-A-5-2) in reduction of their respective
Class or Component Principal Balances, as applicable, PROVIDED, HOWEVER, that if
the loss is recognized with respect to a Class P Mortgage Loan, the applicable
Class P Fraction of such loss will first be allocated to the related Class P
Certificates and the remainder of such loss will be allocated as described above
in this clause (i); and (ii) for losses allocable to interest (a) first, to the
related Junior Subordinate Certificates, in reduction of accrued but unpaid
interest thereon and then in reduction of the Class Principal Balances of such
Certificates, (b) second, to the Class I-B-3, Class II-B-3 or Class III-B-3
Certificates, as applicable, in reduction of accrued but unpaid interest thereon
and then in reduction of the Class Principal Balance of such Certificates, (c)
third, to the Class I-B-2, Class II-B-2 or Class III-B-2 Certificates, as
applicable, in reduction of accrued but unpaid interest thereon and then in
reduction of the Class Principal Balance of such Certificates, (d) fourth, to
the Class I-B-1, Class II-B-1 or Class III-B-1 Certificates, as applicable, in
reduction of accrued but unpaid interest thereon and then in reduction of the
Class Principal Balance of such Certificates, and (e) fifth, to the Senior
Certificates of the related Certificate Group (other than the Class P
Certificates), pro rata according to accrued but unpaid interest thereon and
then pro rata according to their Class Principal Balances (or Component
Principal Balances in the case of Component II-A-5-1 and Component II-A-5-2) in
reduction of their respective Class Principal or Component Balances, as
applicable; PROVIDED, FURTHER, that all losses allocated to principal and
interest that would otherwise be allocable to the Class II-A-1 Certificates on
any Distribution Date will be allocated to the Class II-A-9 Certificates, until
the Class II-A-9 Principal Balance has been reduced to zero.
 
    The allocation of the principal portion of losses relating to a Mortgage
Loan in a given Loan Group to all Classes of Certificates in the related
Certificate Group (other than the related Class P and Class X Certificates) pro
rata according to their respective Class or Component Principal Balances (except
if the loss is recognized with respect to a Class P Mortgage Loan, in which
event the applicable Class P Fraction of such loss will first be allocated to
the Class P Certificates of the related Certificate Group, and the remainder of
such loss will be allocated as described above), and the allocation of the
interest portion of such losses to the Certificates in the related Certificate
Group pro rata according to the amount of interest accrued but unpaid on each
such Class or Component (other than the related Class P Certificates) in
reduction thereof and then in reduction of their related Class or Component
Principal Balances, is hereinafter referred to as "PRO RATA ALLOCATION".
 
    On each Distribution Date, if the aggregate Class Principal Balance of all
outstanding Classes of Certificates in a Certificate Group exceeds the aggregate
principal balance of the Mortgage Loans in the related Loan Group (after giving
effect to distributions of principal and the allocation of all losses on the
Classes of Certificates in such Certificate Group on such Distribution Date),
such excess will be deemed a principal loss and will be allocated to the most
junior Class of Subordinate Certificates in such Certificate Group then
outstanding.
 
    Special Hazard Losses incurred on a Mortgage Loan in excess of the Special
Hazard Coverage for the related Loan Group will be allocated to the outstanding
Class or Classes of Certificates in the related Certificate Group by Pro Rata
Allocation. The "GROUP I SPECIAL HAZARD COVERAGE" is expected to equal
 
                                      S-56
<PAGE>
approximately $3,900,113 as of the Cut-Off Date. The "GROUP II SPECIAL HAZARD
COVERAGE" is expected to equal approximately $4,996,812 as of the Cut-Off Date.
The "GROUP III SPECIAL HAZARD COVERAGE" is expected to equal approximately
$1,976,393 as of the Cut-Off Date. On each anniversary of the Cut-Off Date, the
Special Hazard Coverage for each Loan Group will be reduced, but not increased,
to an amount equal to the lesser of (i) the greatest of (a) the aggregate
principal balance of the Mortgage Loans in the related Loan Group located in the
single California zip code area containing the largest aggregate principal
balance of such Mortgage Loans, (b) 1% of the aggregate unpaid principal balance
of the Mortgage Loans in the related Loan Group and (c) twice the unpaid
principal balance of the largest single Mortgage Loan in the related Loan Group,
in each case calculated as of the Due Date in the immediately preceding month
and (ii) the Special Hazard Coverage for such Loan Group as of the Cut-Off Date
as reduced by the Special Hazard Losses allocated to the Certificates in the
related Certificate Group since the Cut-Off Date.
 
    Fraud Losses incurred on a Mortgage Loan in excess of the Fraud Coverage for
the related Loan Group will be allocated to the outstanding Class or Classes of
Certificates in the related Certificate Group by Pro Rata Allocation. The "GROUP
I FRAUD COVERAGE" is expected to equal approximately $7,800,227 as of the
Cut-Off Date. The "GROUP II FRAUD COVERAGE" is expected to equal approximately
$6,850,873 as of the Cut-Off Date. The "GROUP III FRAUD COVERAGE" is expected to
equal approximately $1,043,946 as of the Cut-Off Date. Fraud Coverage for a Loan
Group will be reduced, from time to time, by the amount of Fraud Losses
allocated to the Certificates of the related Certificate Group. On each
anniversary of the Cut-Off Date, Fraud Coverage for a Loan Group will be reduced
to the lesser of (i) (a) with respect to Loan Group I and Loan Group II, on the
first, second, third and fourth anniversaries of the Cut-Off Date, 1.00% of the
aggregate principal balance of the Mortgage Loans in the related Loan Group as
of the Due Date in the preceding month and (b) with respect to Loan Group III,
on the first anniversary of the Cut-Off Date, 1.00%, and on the second, third
and fourth anniversaries of the Cut-Off Date, 0.50% of the aggregate principal
balance of the Group III Loans as of the Due Date in the preceding month and
(ii) the excess of the Fraud Coverage for such Loan Group as of the Cut-Off Date
over cumulative Fraud Losses allocated to the Certificates in such Certificate
Group since the Cut-Off Date. On the fifth anniversary of the Cut-Off Date,
Fraud Coverage for each Loan Group will be reduced to zero.
 
    Bankruptcy Losses incurred on a Mortgage Loan in excess of the Bankruptcy
Coverage for the related Loan Group will be allocated to the outstanding Class
or Classes of Certificates in the related Certificate Group by Pro Rata
Allocation. The "GROUP I BANKRUPTCY COVERAGE" is expected to equal approximately
$107,830 as of the Cut-Off Date. The "GROUP II BANKRUPTCY COVERAGE" is expected
to equal approximately $113,235 as of the Cut-Off Date. The "GROUP III
BANKRUPTCY COVERAGE" is expected to equal approximately $100,000 as of the
Cut-Off Date. Bankruptcy Coverage for a Loan Group will be reduced, from time to
time, by the amount of Bankruptcy Losses allocated to the Certificates in the
related Certificate Group.
 
    Special Hazard Coverage, Fraud Coverage or Bankruptcy Coverage for a Loan
Group may also be reduced upon written confirmation from the Rating Agencies
that such reduction will not adversely affect the then current ratings assigned
to the Offered Certificates of the related Certificate Group by the Rating
Agencies. Such a reduction, in the event of Special Hazard Losses, Fraud Losses
or Bankruptcy Losses on the Mortgage Loans in such Loan Group, could adversely
affect the level of protection afforded the Senior Certificates of the related
Certificate Group by subordination of the Class B Certificates of such
Certificate Group or the level of protection afforded the Senior Subordinate
Certificates of such Certificate Group by subordination of the related Junior
Subordinate Certificates.
 
THE CLASS R CERTIFICATES
 
    On each Distribution Date, in addition to payments of interest and principal
to the Class R Certificates described herein, any amounts remaining (which are
expected to be zero) in the Certificate Account from the Available Distribution
Amount for each Loan Group after distributions of interest and principal on the
Certificates and payment of expenses, if any, of the Trust will be distributed
to the Class R
 
                                      S-57
<PAGE>
Certificateholders, together with Excess Liquidation Proceeds (as defined
below), if any. Distributions of such remaining amounts to the Class R
Certificateholders will be subordinate to all payments required to be made with
respect to the other Offered Certificates on any Distribution Date.
 
    Any amounts remaining in the Certificate Account upon reduction of the
aggregate Certificate Principal Balance to zero, payment of any outstanding
expenses and termination of the Trust will be distributable to the Class R
Certificateholders. Such remaining assets are expected to be minimal. See
"--Optional Termination of the Trust" herein.
 
ADVANCES
 
    With respect to each Mortgage Loan, the related Master Servicer will make
Advances to the Certificate Account on each Distribution Date to cover any
shortfall between (i) payments scheduled to be received in respect of such
Mortgage Loan and (ii) the amounts actually deposited in the Certificate Account
on account of such payments; provided that such Master Servicer determines, in
good faith, on such Distribution Date that such Advances will be recoverable
from Insurance Proceeds, Liquidation Proceeds or other amounts received with
respect to such Mortgage Loan. Advances are reimbursable to a Master Servicer
from cash in the Certificate Account remitted by such Master Servicer with
respect to Mortgage Loans in the same Loan Group prior to payments to the
Certificateholders if such Master Servicer determines that such Advances
previously made are not recoverable from Insurance Proceeds, Liquidation
Proceeds or other amounts recoverable with respect to the applicable Mortgage
Loan and so notifies the Certificate Administrator. A Master Servicer has no
obligation to make Advances with respect to Mortgage Loans which are not master
serviced by it.
 
AVAILABLE DISTRIBUTION AMOUNT
 
    On each Distribution Date, the Available Distribution Amount for any
Distribution Date which will be determined separately with respect to each Loan
Group, and, in each case, will generally include scheduled principal and
interest payments due on the related Due Date, Curtailments received in the
previous calendar month (as set forth below), Payoffs received in the applicable
Prepayment Period to the extent set forth below and amounts received with
respect to liquidations of Mortgage Loans with respect to such Loan Group in the
previous calendar month, will be distributed by or on behalf of the Trustee to
the Certificateholders, as specified herein.
 
    The Due Date related to each Distribution Date is the first day of the month
in which such Distribution Date occurs. The determination date (the
"DETERMINATION DATE") is a day not later than the 10th day preceding the related
Distribution Date in the month in which such Distribution Date occurs.
 
    The "AVAILABLE DISTRIBUTION AMOUNT" for any Distribution Date for each Loan
Group, as more fully described in the Pooling Agreement, will equal the sum,
with respect to the Mortgage Loans in such Loan Group, of the following amounts:
 
    (1) the total amount of all cash received by or on behalf of the Master
Servicers with respect to such Mortgage Loans by the Determination Date for such
Distribution Date and not previously distributed (including advances made by
servicers, proceeds of Mortgage Loans in such Loan Group which are liquidated,
and scheduled amounts of distributions from Buydown Funds respecting Buydown
Loans, if any), except:
 
        (a) all scheduled payments of principal and interest collected but due
    on a date subsequent to the related Due Date;
 
        (b) all Curtailments received after the previous calendar month
    (together with any interest payment received with such prepayments to the
    extent that it represents the payment of interest accrued on such Mortgage
    Loans for the period subsequent to the previous calendar month);
 
        (c) all Payoffs received after the applicable Prepayment Period
    immediately preceding such Determination Date (together with any interest
    payment received with such Payoffs to the extent that
 
                                      S-58
<PAGE>
    it represents the payment of interest accrued on the Mortgage Loans for the
    period subsequent to the previous calendar month), and, with respect to PNC
    Loans, interest which was accrued and received on Payoffs received during
    the period from the first to the 14th day of the month of such Determination
    Date, which interest shall not be included in the calculation of the
    Available Distribution Amount for any Distribution Date;
 
        (d) Liquidation Proceeds and Insurance Proceeds received on such
    Mortgage Loans after the previous calendar month;
 
        (e) all amounts in the Certificate Account which are due and
    reimbursable to a servicer or the Master Servicers pursuant to the terms of
    the Pooling Agreement;
 
        (f) the sum of the Servicing Fee, the Master Servicing Fee and the
    Certificate Administrator Fee for each such Mortgage Loan; and
 
        (g) the excess, if any, of aggregate Liquidation Proceeds on such
    Mortgage Loans received during the previous calendar month over the amount
    that would have been received if Payoffs had been made with respect to such
    Mortgage Loans on the date such Liquidation Proceeds were received ("EXCESS
    LIQUIDATION PROCEEDS");
 
    (2) the total, to the extent not previously distributed, of the following
amounts, to the extent advanced or received, as applicable, by either Master
Servicer:
 
        (a) all Advances made by either Master Servicer to the Trustee with
    respect to such Distribution Date relating to such Mortgage Loans; and
 
        (b) any amounts payable as Compensating Interest by either Master
    Servicer on such Distribution Date relating to such Mortgage Loans; and
 
    (3) the total amount of any cash received by the Trustee or either Master
Servicer in respect of the obligation of the Company to repurchase any such
Mortgage Loans.
 
LAST SCHEDULED DISTRIBUTION DATE
 
    The Last Scheduled Distribution Date for the Group I Certificates is the
Distribution Date in January 2028, which is the Distribution Date in the month
after the scheduled maturity date for the latest maturing Mortgage Loan in Loan
Group I.
 
    The Last Scheduled Distribution Date for the Group II Certificates is the
Distribution Date in December 2027, which is the Distribution Date in the month
after the scheduled maturity date for the latest maturing Mortgage Loan in Loan
Group II.
 
    The Last Scheduled Distribution Date for the Group III Certificates is the
Distribution Date in December 2012, which is the Distribution Date in the month
after the scheduled maturity date for the latest maturing Mortgage Loan in Loan
Group III.
 
    The actual rate of principal payments on the Certificates will depend on the
rate of payments of principal (including Principal Prepayments) on the related
Mortgage Loans which, in turn, may be influenced by a variety of economic,
geographic and social factors, as well as the level of prevailing interest
rates. No assurance can be given as to the actual payment experience on the
Mortgage Loans.
 
OPTIONAL TERMINATION OF THE TRUST
 
    On any Distribution Date after the first date on which the aggregate
outstanding principal balance of the Mortgage Loans is less than 10% of the
aggregate principal balance of the Mortgage Loans as of the Cut-Off Date, the
Company may repurchase the Mortgage Loans and all property acquired in respect
of any Mortgage Loan remaining in the Trust, and thereby effect the termination
of the Trust and the retirement of the Certificates. The repurchase price will
equal, after deductions of related advances by the Master Servicers, the sum of
(1) 100% of the aggregate outstanding principal balance of such Mortgage Loans
(other than Liquidated Mortgage Loans), plus accrued interest thereon at the
applicable Pass-
 
                                      S-59
<PAGE>
Through Rates through the last day of the month of such repurchase, less any
Bankruptcy Losses realized with respect to the Mortgage Loans not already
allocated to the Certificates and (2) the fair market value of all other
property remaining in the Trust. The proceeds of such repurchase will be treated
as a prepayment of the Mortgage Loans for purposes of distributions to
Certificateholders. Accordingly, an optional termination of the Trust will cause
the outstanding principal balance of the Certificates to be paid in full through
the distribution of such proceeds and the allocation of the associated realized
losses, if any, on each Mortgaged Property in the Trust the fair market value of
which is less than the aggregate principal balance of the related Mortgage Loans
as of the time that the Trust acquired such Mortgaged Property, and upon such
payment in full the Trust will be terminated. In no event will the Trust
continue beyond the expiration of 21 years from the death of the survivor of
certain persons identified in the Pooling Agreement. See "Description of
Certificates--Termination" in the Prospectus.
 
                                   SERVICING
 
SERVICING COMPENSATION AND PAYMENT OF EXPENSES
 
    Each Master Servicer will receive a fee (the "MASTER SERVICING FEE") for its
services as Master Servicer under the Pooling Agreement. Each Master Servicer
will retain as its Master Servicing Fee an amount which will be calculated as a
per annum percentage for each related Mortgage Loan. The Master Servicing Fee
with respect to each Group I Loan will range from a minimum of 0.035% to a
maximum of 0.045%, with a weighted average of 0.040%. The Master Servicing Fee
with respect to each Group II Loan will range from a minimum of 0.035% to a
maximum of 0.095%, with a weighted average of 0.051%. The Master Servicing Fee
with respect to each Group III Loan will range from a minimum of 0.025% to a
maximum of 0.045%, with a weighted average of 0.040%.
 
    Each Master Servicer will pay all expenses incurred in connection with its
activities as Master Servicer. The Master Servicers are entitled to
reimbursement for certain expenses incurred by them in connection with the
liquidation of defaulted Mortgage Loans. In addition, the Master Servicers are
entitled to reimbursement of expenditures incurred by them in connection with
the restoration of a damaged Mortgaged Property.
 
    The Servicing Fee with respect to each Group I Loan will range from a
minimum of 0.200% to a maximum of 0.375%, with a weighted average of 0.266%. The
Servicing Fee with respect to each Group II Loan will range from a minimum of
0.150% to a maximum of 0.375%, with a weighted average of 0.229%. The Servicing
Fee with respect to each Group III Loan will range from a minimum of 0.200% to a
maximum of 0.250%, with a weighted average of 0.231%.
 
CERTIFICATE ADMINISTRATOR
 
    Pursuant to the Pooling Agreement, the Company (in its capacity as
Certificate Administrator) will calculate LIBOR and amounts payable to the
Certificateholders and provide certain other administrative services as
specified in the Pooling Agreement. The Certificate Administrator will receive a
fee (the "CERTIFICATE ADMINISTRATOR FEE") for its services as Certificate
Administrator under the Pooling Agreement. The Certificate Administrator Fee
with respect to each Mortgage Loan shall be 0.005% per annum. The Company, in
its capacity as Certificate Administrator and Master Servicer, will be
responsible for paying the fees of the Trustee. The Company will also pay all
expenses incurred in connection with its activities as Certificate Administrator
under the Pooling Agreement.
 
                                      S-60
<PAGE>
                      YIELD AND PREPAYMENT CONSIDERATIONS
 
GENERAL
 
    The effective yield to maturity of each Class of Certificates will depend
upon, among other things, the price at which such Certificates are purchased,
the applicable Remittance Rate, the actual characteristics of the Mortgage Loans
in the related Loan Group, the rate of principal payments (including Principal
Prepayments) on the Mortgage Loans in the related Loan Group and the rate of
liquidations on the Mortgage Loans in the related Loan Group. The effective
yield to maturity to holders of the Certificates (other than the LIBOR
Certificates) will be lower than the yield to maturity otherwise produced by the
applicable Remittance Rate and purchase price of such Certificates because
principal and interest distributions will not be payable to such
Certificateholders until the 25th day of the month following the month of
accrual (without any additional distribution of interest or earnings thereon
with respect to such delay). Distributions to the Group I Certificates, Group II
Certificates and Group III Certificates relate to payments on the Group I Loans,
Group II Loans and Group III Loans, respectively.
 
PRINCIPAL PREPAYMENTS AND COMPENSATING INTEREST
 
    When a Mortgagor prepays a Mortgage Loan in full between Due Dates for such
Mortgage Loan, the Mortgagor pays interest on the amount prepaid only to the
date of prepayment instead of for the entire month. Also, when a Curtailment is
made on a Mortgage Loan together with the scheduled Monthly Payment for a month
on or after the related Due Date, the principal balance of the Mortgage Loan is
reduced by the amount of the Curtailment as of such Due Date, but such principal
is not distributed to related Certificateholders until the Distribution Date in
the next month; therefore, one month of interest shortfall accrues on the amount
of such Curtailment.
 
    In order to reduce the adverse effect on Certificateholders from the
deficiency in interest payable as a result of a Payoff on a Mortgage Loan
between its Due Dates, each Master Servicer will pass through Compensating
Interest to the related Certificateholders to the limited extent and in the
manner set forth below. The Company, as Master Servicer, is obligated to remit
to the Certificate Account on the day prior to each Distribution Date with
respect to the PNC Loans in each Loan Group an amount equal to the lesser of (a)
any shortfall for the related month in interest collections resulting from the
timing of Payoffs on the related Mortgage Loans made from the 15th day of the
calendar month preceding such Distribution Date to the last day of such month
and (b) the applicable monthly Master Servicing Fee payable to the Company, any
reinvestment income realized by the Company, as Master Servicer, relating to
Payoffs on the related Mortgage Loans made during the related Prepayment Period
and interest payments on such Payoffs received during the period of the first
day through the 14th day of the month of such Distribution Date. Accordingly, no
Compensating Interest will be payable with respect to Payoffs in the related
Loan Group received during such period. Payoffs received during the period from
the 15th day through the last day of any month will be passed through on the
Distribution Date in the following month, and, in order to provide for a full
month's interest payment with respect to the prior month, Compensating Interest
will be passed through to related Certificateholders with respect to such
period. In addition, on the day prior to each Distribution Date, with respect to
the IndyMac Loans in each Loan Group, if any, IndyMac, as Master Servicer, is
obligated to remit to the Certificate Account an amount equal to the lesser of
(i) any shortfall for the related month in interest collections resulting from
the timing of Payoffs or Curtailments made during the calendar month preceding
such Distribution Date, and (ii) two-thirds of the applicable monthly Master
Servicing Fee payable to IndyMac.
 
    To the extent that the amount allocated to a Loan Group to pay Compensating
Interest is insufficient to cover the deficiency in interest payable as a result
of a Payoff or Curtailment on a Mortgage Loan, such remaining deficiency will be
allocated to the Certificates of the related Certificate Group pro rata
according to the amount of interest to which each related Class of Certificates
would otherwise be entitled in reduction thereof.
 
                                      S-61
<PAGE>
LOCKOUT CERTIFICATES
 
    Investors in the Lockout Certificates should be aware that because the
Lockout Certificates will generally not be entitled to receive principal
distributions prior to the Distribution Date occurring in December 2002 (other
than the Lockout Liquidation Amount), the weighted average lives of the Lockout
Certificates will be longer than would otherwise be the case, and the effect on
the market value of the Lockout Certificates arising out of changes in market
interest rates or market yields for similar securities will be greater than for
other Classes of Class A Certificates entitled to such distributions.
 
RATE OF PAYMENTS
 
    The rate of principal payments on the Certificates entitled to receive
principal generally is directly related to the rate of principal payments on the
Mortgage Loans in the related Loan Group, which may be in the form of scheduled
payments or Principal Prepayments. See "Risk Factors" herein and "Yield
Considerations" in the Prospectus. Mortgagors may prepay the Mortgage Loans at
any time without penalty. A higher than anticipated rate of Principal
Prepayments would reduce the aggregate principal balance of the Mortgage Loans
more quickly than expected. As a consequence, aggregate interest payments with
respect to the Mortgage Loans would be substantially less than expected.
Therefore, a higher rate of Principal Prepayments in a Loan Group could result
in a lower than expected yield to maturity on each related Class of Certificates
purchased at a premium and in certain circumstances such investors may not fully
recoup their initial investments. Conversely, a lower than anticipated rate of
Principal Prepayments in a Loan Group would reduce the return to investors on
any related Classes of Certificates purchased at a discount, in that principal
payments with respect to the Mortgage Loans would occur later than anticipated.
There can be no assurance that Certificateholders will be able to reinvest
amounts received with respect to the Certificates at a rate which is comparable
to the applicable Remittance Rate. Investors should fully consider all of the
associated risks.
 
SPECIAL SENSITIVITIES
 
    The Class II-A-4 Certificates will be especially sensitive to the rate of
prepayments on the Group II Loans because such Certificates will receive
distributions of principal on any Distribution Date only to the extent of a
percentage of the Group II Senior Principal Distribution Amount (as defined
herein) remaining, if any, after (i) the Lockout Certificates receive their
distributions from the Lockout Principal Distribution Amount, if any, for such
Distribution Date, (ii) the Class R Principal Balance has been reduced to zero,
(iii) the PAC receives principal on such Distribution Date to the extent of the
PAC's Planned Principal Balance, and (iv) the Class II-A-2 Certificates receive
principal distributions to the extent of the Class II-A-2 Certificates' Targeted
Principal Balance. Furthermore, if the Group II Senior Principal Distribution
Amount on any Distribution Date is not sufficient to reduce the Class II-A-1
Principal Balance to its Planned Principal Balance and the Class II-A-2
Principal Balance to its Targeted Principal Balance, the Class II-A-4
Certificates will receive no principal distributions on such Distribution Date.
 
    The Class II-A-6 Certificates will be especially sensitive to the rate of
prepayments on the Group II Loans because such Certificates will receive
distributions of principal on any Distribution Date only to the extent of a
percentage of the Group II Senior Principal Distribution Amount remaining, if
any, after (i) the Lockout Certificates receive their distributions from the
Lockout Principal Distribution Amount, if any, for such Distribution Date, (ii)
the Class R Principal Balance has been reduced to zero, (iii) the Class II-A-1
Certificates receive principal on such Distribution Date to the extent of the
Class II-A-1 Certificates' Planned Principal Balance, and (iv) the Class II-A-10
Certificates receive principal distributions to the extent of the Class II-A-10
Certificates' Targeted Principal Balance. Furthermore, if the Group II Senior
Principal Distribution Amount on any Distribution Date is not sufficient to
reduce the Class II-A-1 Principal Balance to its Planned Principal Balance and
the Class II-A-10 Principal Balance to its Targeted
 
                                      S-62
<PAGE>
Principal Balance, the Class II-A-6 Certificates will receive no principal
distributions on such Distribution Date.
 
    The Class II-A-5 Certificates will be especially sensitive to the rate of
prepayments on the Group II Loans because Component II-A-5-2 will receive
distributions of principal on any Distribution Date only to the extent of a
percentage of the Group II Senior Principal Distribution Amount remaining, if
any, after (i) the Lockout Certificates receive their distributions from the
Lockout Principal Distribution Amount, if any, for such Distribution Date, (ii)
the Class R Principal Balance has been reduced to zero, (iii) the Class II-A-1
Certificates receive principal on such Distribution Date to the extent of the
Class II-A-1 Certificates' Planned Principal Balance, and (iv) the Class II-A-3
Certificates receive principal distributions to the extent of the Class II-A-3
Certificates' Targeted Principal Balance (as described herein). Furthermore, if
the Group II Senior Principal Distribution Amount on any Distribution Date is
not sufficient to reduce the Class II-A-1 Principal Balance to its Planned
Principal Balance and the Class II-A-3 Principal Balance to its Targeted
Principal Balance, Component II-A-5-2 will receive no principal distributions on
such Distribution Date. However, if a Collateral Reduction Trigger Date occurs,
Component II-A-5-1 and Component II-A-5-2 will receive a percentage of the Group
II Senior Principal Distribution Amount prior to distributions of principal to
the Class II-A-3 Certificates. See "Description of the Certificates--
Distributions of Principal--Group II Certificate Principal Distributions--GROUP
II SENIOR PRINCIPAL DISTRIBUTION AMOUNT" herein.
 
    The Class II-A-10, Class II-A-2 and Class II-A-3 Certificates are TACs. If a
higher than expected rate of Principal Prepayments is to occur with respect to
the Group II Loans, and the Class II-A-6 Certificates are retired, the Class
II-A-10 Certificates would receive distributions of principal in excess of the
related Targeted Principal Balances. Similarly, if a higher than expected rate
of Principal Prepayments is to occur with respect to the Group II Loans, and the
Class II-A-4 Certificates are retired, the Class II-A-2 Certificates would
receive distributions of principal in excess of the related Targeted Principal
Balances. Similarly, if a higher than expected rate of Principal Prepayments is
to occur with respect to the Group II Loans, and Component II-A-5-2 is retired,
the Class II-A-3 Certificates would receive distributions of principal in excess
of the related Targeted Principal Balances.
 
BASIC PREPAYMENT ASSUMPTION
 
    Prepayments on mortgage loans are commonly measured relative to a prepayment
standard or model. The two prepayment models used in this Prospectus Supplement
(each, a "BASIC PREPAYMENT ASSUMPTION" or "BPA") represent an assumed rate of
prepayment each month relative to the then outstanding principal balance of a
pool of mortgage loans. For Loan Group I, a 100% Basic Prepayment Assumption
assumes a constant prepayment rate of 4.0% per annum of the then outstanding
principal balance of such mortgage loans in the first month of the life of the
mortgage loans and an additional 12/11% per annum in each month thereafter
through the eleventh month. Beginning in the twelfth month and in each month
thereafter during the life of the mortgage loans, a 100% BPA assumes a constant
prepayment rate of 16% per annum each month. For Loan Group II and Loan Group
III, a 100% Basic Prepayment Assumption assumes a per annum rate of prepayment
of 0.2% of the then outstanding principal balance of a pool of mortgage loans in
the first month after formation of such pool of mortgage loans, following which,
such annual prepayment rate increases by 0.2% each month until the 30th month
after formation of such pool of mortgage loans and remains constant at 6% per
annum in the 30th month after formation of such pool of mortgage loans and in
each month thereafter. As used in the tables below, a 50% BPA assumes prepayment
rates equal to 50% of the BPA. Correspondingly, a 250% BPA assumes prepayment
rates equal to 250% of the BPA, and so forth.
 
    Neither of the BPAs purports to be either an historical description of the
prepayment experience of any pool of mortgage loans or a prediction of the
anticipated rate of prepayment of any pool of mortgage loans, including the
Mortgage Pool, and there is no assurance that the Mortgage Loans in any Loan
Group will prepay at any given percentage of the applicable BPA. The actual rate
of Principal Prepayments on the
 
                                      S-63
<PAGE>
Mortgage Loans may be influenced by a variety of economic, geographic, social
and other factors. In general, if prevailing interest rates fall significantly
below the interest rates on the Mortgage Loans, the Mortgage Loans are likely to
be subject to higher prepayment rates than if prevailing rates remain at or
above the interest rates on the Mortgage Loans. Conversely, if interest rates
rise above the interest rates on the Mortgage Loans, the rate of prepayment
would be expected to decrease. A comparatively low interest-rate environment may
result in a higher than expected rate of prepayments on the Mortgage Loans and
an earlier than expected retirement of the Certificates.
 
    The Company makes no representation as to the specific factors that will
affect the prepayment of the Mortgage Loans or the relative importance of such
factors. Factors not identified by the Company or discussed herein may
significantly affect the prepayment rate of the Mortgage Loans. In particular,
the Company makes no representation as to the percentage of the principal amount
of the Mortgage Loans that will be paid as of any date or as to the overall rate
of prepayment.
 
    For purposes of the tables set forth in Appendix C, it is assumed that the
Mortgage Loans included in the Mortgage Pool on the Closing Date have the actual
characteristics of the Mortgage Loans described herein and that (i) scheduled
payments on all Mortgage Loans are received on the first day of each month
beginning December 1, 1997, (ii) any Payoffs on the Mortgage Loans are received
on the last day of each month beginning in November 1997 and include 30 days of
interest thereon, (iii) there are no defaults or delinquencies on the Mortgage
Loans, (iv) optional termination of the Trust does not occur, (v) there are no
partial prepayments on the Mortgage Loans and prepayments are computed after
giving effect to scheduled payments received on the following day, (vi) the
Mortgage Loans in each Loan Group prepay at the indicated constant percentages
of the applicable BPA, (vii) the date of issuance for the Certificates is
November 25, 1997, (viii) cash distributions are received by the
Certificateholders on the 25th day of each month when due and (ix) the scheduled
monthly payments for each Mortgage Loan are computed based upon its unpaid
principal balance, Mortgage Interest Rate and amortized remaining term such that
the Mortgage Loan will fully amortize on its maturity date (except that with
respect to each Balloon Loan in Loan Group III, it is assumed that any unpaid
principal balance as of its maturity date will be paid in full on its maturity
date) (collectively, the "MODELING ASSUMPTIONS"). The approximate Class
Principal Balances of the Junior Subordinate Certificates as of the Cut Off-Date
will be as follows: Class I-B-4, $2,145,062; Class I-B-5, $780,023; Class I-B-6,
$1,560,046; Class II-B-4, $1,541,446; Class II-B-5, $1,027,630; Class II-B-6,
$1,027,633; Class III-B-4, $260,987; Class III-B-5, $208,789; and Class III-B-6,
$208,788.
 
    Any discrepancy between the actual characteristics of the Mortgage Loans and
the characteristics of the Mortgage Loans set forth above may affect the
percentages of the initial Class Principal Balances set forth in the tables and
the weighted average lives of the Offered Certificates. In addition, to the
extent that the characteristics of the Mortgage Loans differ and the initial
Class Principal Balances differ, from those assumed in preparing the tables in
Appendix C, the outstanding Class Principal Balance of any Class of Offered
Certificates may be reduced to zero earlier or later than indicated by such
tables.
 
    Variations in actual prepayment experience may increase or decrease the
percentages of the original outstanding Class Principal Balances and the
weighted average lives shown in the tables in Appendix C. Such variations may
occur even if the average prepayment experience of all the Mortgage Loans equals
the indicated percentage of the Basic Prepayment Assumption. There is no
assurance, however, that prepayment of the Mortgage Loans of any Loan Group will
conform to any given percentage of the applicable Basic Prepayment Assumption.
 
    Based on the foregoing assumptions, the tables in Appendix C indicate the
projected weighted average lives of the Offered Certificates and set forth the
percentages of the initial outstanding Class Principal Balance of each such
Class of Offered Certificates that would be outstanding after each of the dates
shown at various constant percentages of the applicable Basic Prepayment
Assumption.
 
                                      S-64
<PAGE>
YIELD CONSIDERATIONS WITH RESPECT TO THE CLASS X AND CLASS P CERTIFICATES
 
    The yields to maturity on the Class X and Class P Certificates will be
extremely sensitive to the level of Principal Prepayments on certain of the
Mortgage Loans in the related Loan Group. Because the interest payable to each
Class of the Class X Certificates is based on the weighted average of the
Stripped Interest Rates of the related Premium Rate Mortgage Loans, the yield to
maturity on such Certificates will generally decrease as a result of faster than
expected Principal Prepayments on the related Premium Rate Mortgage Loans.
Prospective investors should fully consider the risks associated with an
investment in any Class of the Class X Certificates, including the possibility
that if the rate of Principal Prepayments on the related Premium Rate Mortgage
Loans is rapid, such investors may not fully recoup their initial investments.
Because the principal payable to each Class of the Class P Certificates is
derived from the related Class P Mortgage Loans, the yield to maturity on such
Certificates will be adversely affected by slower than expected prepayments of
such Mortgage Loans. For each Loan Group, because the interest distributable on
the Class X Certificates related to such Loan Group and the principal
distributable to the Class P Certificates related to such Loan Group are derived
from different groups of Mortgage Loans within such Loan Group, it is possible
that faster than expected Principal Prepayments on the Mortgage Loans related to
a Class of Class X Certificate may occur at the same time as slower than
expected Principal Prepayments on the Mortgage Loans related to the Class of
Class P Certificates of the same Certificate Group. This occurrence would result
in a lower yield to maturity for both the Class X Certificates and Class P
Certificates related to a single Loan Group.
 
    Moreover, since the Class I-X-1 and Class I-X-2 Certificates are LIBOR
Certificates, the yield to investors in such Certificates will be sensitive to
fluctuations in LIBOR. The yield to maturity on the Class I-X-2 Certificates
will be extremely sensitive to fluctuations in LIBOR, and the Remittance Rate on
such Certificates will vary inversely with LIBOR. If prevailing rates of LIBOR
are sufficiently high, investors in the Class I-X-2 Certificates may not recoup
their initial investments. Changes in LIBOR may not correlate with changes in
prevailing mortgage interest rates. It is possible that lower prevailing
mortgage interest rates, which might be expected to result in faster
prepayments, could occur concurrently with an increased level of LIBOR.
Conversely, higher prevailing mortgage interest rates (which would be expected
to result in slower prepayments) could occur concurrently with a lower level of
LIBOR.
 
    To illustrate the significance of different rates of prepayment and, in the
case of the Class I-X Certificates, different levels of LIBOR, on the
distributions on the Class X and Class P Certificates, the following tables
indicate the approximate pre-tax yields to maturity (on a corporate bond
equivalent basis) under the different percentages of the applicable BPA
indicated, and with respect to the Class I-X Certificates, different levels of
LIBOR. Because the rate of distribution of interest on the Class X Certificates
and the rate of distribution of principal on the Class P Certificates will be
directly related to the actual amortization (including prepayments) of the
Mortgage Loans in the related Loan Group, which will include Mortgage Loans that
have remaining terms to maturity shorter or longer than those assumed and
interest rates higher or lower than those assumed, the pre-tax yields to
maturity on the Class X and Class P Certificates are likely to differ from those
shown in the following tables even if all the Mortgage Loans in the related Loan
Group prepay at the indicated constant percentages of the applicable BPA and the
weighted average remaining terms to maturity of the Mortgage Loans in the
related Loan Group are as assumed and, for the Class I-X Certificates, LIBOR
remains at the levels assumed. Any differences between such assumptions and the
actual characteristics and performance of the Mortgage Loans and of the
Certificates may result in yields to maturity being different from those shown
in such tables. Discrepancies between assumed and actual characteristics and
performances underscore the hypothetical nature of the tables, which are
provided only to give a general sense of the sensitivity of yields to maturity
in varying prepayment scenarios and, for the Class I-X Certificates, different
levels of LIBOR. In addition, it is highly unlikely that the Mortgage Loans will
prepay at a constant level of the applicable BPA until maturity or that all of
such Mortgage Loans will prepay at the same rate or, for the Class I-X
Certificates, that the level of LIBOR will remain constant. The timing of
changes to the rate of Principal Prepayments
 
                                      S-65
<PAGE>
or rate of LIBOR may significantly affect the actual yield to maturity to an
investor, even if the average rate of Principal Prepayments or rate of LIBOR is
consistent with an investor's expectation. In general, the earlier a payment of
principal of the Mortgage Loans or change in LIBOR, the greater the effect on an
investor's yield to maturity. As a result, the effect on an investor's yield to
maturity of Principal Prepayments occurring at a rate higher (or lower) than the
rate anticipated by the investor during the period immediately following the
issuance of the Certificates or changes in the level of LIBOR, as applicable,
will not be equally offset by a subsequent like reduction (or increase) in the
rate of Principal Prepayments or level of LIBOR.
 
    In addition, the yield to maturity on the Class X Certificates may be
adversely affected if an optional termination of the Trust occurs.
 
    The sensitivity tables for the Class X and Class P Certificates set forth
below are based on the Modeling Assumptions and assume further that (i) the
Certificates are purchased at prices equal to those set forth in the tables and
(ii) in the case of the Class I-X Certificates, on the LIBOR Determination Date
in December 1997 and on each LIBOR Determination Date thereafter, the applicable
LIBOR will be the rate shown and on the first Distribution Date, the Class I-X
Certificateholders will receive 30 days of interest at their respective initial
Remittance Rates. There can be no assurance that the Mortgage Loans will have
the assumed characteristics, will prepay at any of the rates shown herein, that
the rate of LIBOR will correspond to the levels shown herein, or that the
purchase prices of the Certificates will be assumed or that the pre-tax yields
to maturity will correspond to any of the pre-tax yields shown herein. The
actual prices to be paid on the Class X and Class P Certificates have not been
determined and will be dependent on the characteristics of the Mortgage Pool as
ultimately constituted. In addition to any other factors an investor may deem
material, each investor must make its own decision as to the appropriate
prepayment assumptions to be used and, in the case of the Class I-X
Certificates, the appropriate rates of LIBOR to be assumed in deciding whether
or not to purchase a Class of Certificates.
 
                    SENSITIVITY OF PRE-TAX YIELD TO MATURITY
       OF THE CLASS I-X-1 CERTIFICATES TO PRINCIPAL PREPAYMENTS AND LIBOR
  AT AN ASSUMED PURCHASE PRICE OF 29.15625% OF THE CLASS I-X-1 NOTIONAL AMOUNT
 
<TABLE>
<CAPTION>
                                                                      PERCENTAGE OF THE BPA
                                                 ---------------------------------------------------------------
LIBOR                                                0%           50%         100%         150%         200%
<S>                                              <C>          <C>          <C>          <C>          <C>
3.6875%........................................       *            *            *            *            *
4.6875%........................................       (0.98 )%      (8.86 )%     (17.18 )%     (25.71 )%     (34.80 )%
5.6875%........................................       17.03 %       8.78 %       0.18 %      (8.83 )%     (18.30 )%
6.6875%........................................       32.26 %      23.81 %      15.01 %       5.82 %      (3.84 )%
7.6875%........................................       47.63 %      39.01 %      30.03 %      20.66 %      10.84 %
</TABLE>
 
- ------------------------
 
*   The pre-tax yield to maturity will be less than (99.99)%.
 
    On the basis of a constant prepayment rate of approximately 101% of the BPA
used with respect to Loan Group I, a purchase price of $6,319,376, which
includes accrued interest, a LIBOR rate of 5.6875% and the assumptions described
above, the pre-tax yield to maturity of the Class I-X-1 Certificates would be
approximately 0%. If the actual prepayment rate were to exceed the rates assumed
above, even for one month, while equaling such rates for all other months, an
investor in the Class I-X-1 Certificates would not fully recoup the initial
purchase price of such Certificates.
 
                                      S-66
<PAGE>
                    SENSITIVITY OF PRE-TAX YIELD TO MATURITY
       OF THE CLASS I-X-2 CERTIFICATES TO PRINCIPAL PREPAYMENTS AND LIBOR
  AT AN ASSUMED PURCHASE PRICE OF 26.15625% OF THE CLASS I-X-2 NOTIONAL AMOUNT
 
<TABLE>
<CAPTION>
                                                                      PERCENTAGE OF THE BPA
                                                 ---------------------------------------------------------------
LIBOR                                                0%           50%         100%         150%         200%
<S>                                              <C>          <C>          <C>          <C>          <C>
3.6875%........................................      60.01%       51.24%       42.13%       32.63%       22.67%
4.6875%........................................      54.41%       45.71%       36.67%       27.23%       17.33%
5.6875%........................................      36.87%       28.37%       19.53%       10.28%        0.58%
6.6875%........................................      19.68%       11.39%        2.75%       (6.29)%     (15.80)%
7.6875%........................................       0.05%       (7.86)%     (16.11)%     (24.76)%     (33.89)%
</TABLE>
 
    On the basis of a constant prepayment rate of approximately 203% of the BPA
used with respect to Loan Group I, a purchase price of $5,669,151, which
includes accrued interest, a LIBOR rate of 5.6875% and the assumptions described
above, the pre-tax yield to maturity of the Class I-X-2 Certificates would be
approximately 0%. If the actual prepayment rate were to exceed the rates assumed
above, even for one month, while equaling such rates for all other months, an
investor in the Class I-X-2 Certificates would not fully recoup the initial
purchase price of such Certificates.
 
                    SENSITIVITY OF PRE-TAX YIELD TO MATURITY
          OF THE CLASS II-X CERTIFICATES TO PRINCIPAL PREPAYMENTS AT A
                            SPECIFIED ASSUMED PRICE
 
<TABLE>
<CAPTION>
                                                                                  PERCENTAGE OF THE BPA
                                                             ---------------------------------------------------------------
ASSUMED PRICE                                                    0%          100%         250%         350%         500%
                                                             -----------  -----------  -----------  -----------  -----------
<S>                                                          <C>          <C>          <C>          <C>          <C>
$9,389,044.................................................      26.31%       21.21%       13.37%        8.03%       (0.16)%
</TABLE>
 
    On the basis of a constant prepayment rate of approximately 497% of the BPA
used with respect to Loan Group II, a purchase price of $9,389,044, which
includes accrued interest, and the assumptions described above, the pre-tax
yield to maturity of the Class II-X Certificates would be approximately 0%. If
the actual prepayment rate were to exceed the rates assumed above, even for one
month, while equaling such rates for all other months, an investor in the Class
II-X Certificates would not fully recoup the initial purchase price of such
Certificates.
 
                    SENSITIVITY OF PRE-TAX YIELD TO MATURITY
         OF THE CLASS III-X CERTIFICATES TO PRINCIPAL PREPAYMENTS AT A
                            SPECIFIED ASSUMED PRICE
 
<TABLE>
<CAPTION>
                                                                                   PERCENTAGE OF THE BPA
                                                              ---------------------------------------------------------------
ASSUMED PRICE                                                     0%          100%         235%         350%         500%
                                                              -----------  -----------  -----------  -----------  -----------
<S>                                                           <C>          <C>          <C>          <C>          <C>
$1,832,830..................................................      30.88%       25.93%       19.10%       13.13%        5.13%
</TABLE>
 
    On the basis of a constant prepayment rate of approximately 594% of the BPA
used with respect to Loan Group III, a purchase price of $1,832,830, which
includes accrued interest, and the assumptions described above, the pre-tax
yield to maturity of the Class III-X Certificates would be approximately 0%. If
the actual prepayment rate were to exceed the rates assumed above, even for one
month, while equaling such rates for all other months, an investor in the Class
III-X Certificates would not fully recoup the initial purchase price of such
Certificates.
 
                                      S-67
<PAGE>
                    SENSITIVITY OF PRE-TAX YIELD TO MATURITY
          OF THE CLASS I-P CERTIFICATES TO PRINCIPAL PREPAYMENTS AT A
                            SPECIFIED ASSUMED PRICE
 
<TABLE>
<CAPTION>
                                                                                   PERCENTAGE OF THE BPA
                                                              ---------------------------------------------------------------
ASSUMED PRICE                                                     0%           50%         100%         150%         200%
                                                              -----------  -----------  -----------  -----------  -----------
<S>                                                           <C>          <C>          <C>          <C>          <C>
$104,134....................................................       2.04%        4.79%        8.38%       12.32%       16.48%
</TABLE>
 
                    SENSITIVITY OF PRE-TAX YIELD TO MATURITY
          OF THE CLASS II-P CERTIFICATES TO PRINCIPAL PREPAYMENTS AT A
                            SPECIFIED ASSUMED PRICE
 
<TABLE>
<CAPTION>
                                                                                   PERCENTAGE OF THE BPA
                                                              ---------------------------------------------------------------
ASSUMED PRICE                                                     0%          100%         250%         350%         500%
                                                              -----------  -----------  -----------  -----------  -----------
<S>                                                           <C>          <C>          <C>          <C>          <C>
$91,686.....................................................       2.33%        4.38%        8.05%       10.48%       13.93%
</TABLE>
 
                    SENSITIVITY OF PRE-TAX YIELD TO MATURITY
         OF THE CLASS III-P CERTIFICATES TO PRINCIPAL PREPAYMENTS AT A
                            SPECIFIED ASSUMED PRICE
 
<TABLE>
<CAPTION>
                                                                                   PERCENTAGE OF THE BPA
                                                              ---------------------------------------------------------------
ASSUMED PRICE                                                     0%          100%         235%         350%         500%
                                                              -----------  -----------  -----------  -----------  -----------
<S>                                                           <C>          <C>          <C>          <C>          <C>
$137,716....................................................       4.70%        6.19%        8.45%       10.47%       13.10%
</TABLE>
 
    The pre-tax yields to maturity set forth in the preceding tables were
calculated by determining the monthly discount rates (whether positive or
negative) which, when applied to the assumed streams of cash flows to be paid on
the Class X and Class P Certificates, would cause the discounted present values
of such assumed streams of cash flows to equal the assumed purchase price,
including accrued interest, where applicable. These monthly discount rates were
converted to corporate bond equivalent rates, which are higher than the monthly
discount rates because they are based on semiannual compounding. These yields to
maturity do not take into account the different interest rates at which
investors may be able to reinvest funds received by them as distributions on the
Class X or Class P Certificates and thus do not reflect the return on any
investment in the Class X or Class P Certificates when any reinvestment rates
other than the discount rates are considered.
 
    There are no historical prepayment data available for the Mortgage Pool, and
comparable data are not available because the Mortgage Loans do not constitute a
representative sample of mortgage loans generally. In addition, historical data
available with respect to mortgage loans underlying mortgage pass-through
certificates issued by the Government National Mortgage Association ("GNMA"),
FNMA and FHLMC may not be comparable to prepayments expected to be experienced
by the Mortgage Pool because the Mortgage Loans may have characteristics which
differ from the mortgage loans underlying certificates issued by GNMA, FNMA and
FHLMC.
 
    The Company makes no representation that the Mortgage Loans will prepay in
the manner or at any of the rates assumed above. Each investor must make its own
decision as to the appropriate prepayment assumptions to be used in deciding
whether or not to purchase any of the Certificates. Since the rate of principal
payments (including prepayments) with respect to, and repurchases of, the
Mortgage Loans will significantly affect the yields to maturity on the Offered
Certificates, prospective investors are urged to consult their investment
advisors as to both the anticipated rate of future principal payments (including
prepayments) on the Mortgage Loans and the suitability of the Certificates to
their investment objectives.
 
                                      S-68
<PAGE>
YIELD CONSIDERATIONS WITH RESPECT TO THE SENIOR SUBORDINATE CERTIFICATES
 
    The tables beginning on page S-70 have been prepared using the Modeling
Assumptions, except that it has been assumed that (i) defaults occur monthly on
the last day of the previous month at rates which in the aggregate are equal to
the following percentages of the aggregate principal balance of the Mortgage
Loans in the applicable Loan Group as of the Cut-Off Date for the number of
months indicated (and none thereafter); (ii) the scheduled monthly payments for
each Mortgage Loan in the applicable Loan Group are computed based upon its
unpaid principal balance after giving effect to any default; (iii) certain
delinquency experience levels specified in the Pooling Agreement for the
determination of the Group I, Group II and Group III Senior Prepayment
Percentages, as applicable, and the Group I, Group II and Group III Subordinate
Prepayment Percentages, as applicable, are not exceeded; and (iv) prepayments
are calculated as assumed above but before giving effect to any such defaults
(unless such defaults would reduce the aggregate principal balance of the
Mortgage Loans in the applicable Loan Group below the aggregate amount of such
assumed prepayments, in which case prepayments are limited to the outstanding
principal balance of such Mortgage Loans after such defaults).
 
<TABLE>
<CAPTION>
                                           PRINCIPAL BALANCE OF DEFAULTED
                                           MORTGAGE LOANS IN LOAN GROUP I
                                           AND LOAN GROUP II AS A               PRINCIPAL BALANCE OF DEFAULTED
                                           PERCENTAGE OF THE AGGREGATE          MORTGAGE LOANS IN LOAN GROUP III
                                           PRINCIPAL BALANCE OF THE MORTGAGE    AS A PERCENTAGE OF THE AGGREGATE
NUMBER OF MONTHS                           LOANS IN LOAN GROUP I AND LOAN       PRINCIPAL BALANCE OF THE MORTGAGE
COMMENCING IN                              GROUP II, RESPECTIVELY, AS OF THE    LOANS IN LOAN GROUP III AS OF THE
NOVEMBER 1998                                        CUT-OFF DATE                            CUT-OFF DATE
- -----------------------------------------  -----------------------------------  -----------------------------------------
<S>                                        <C>                                  <C>
N.A......................................                    0.00%                                   0.00%
24.......................................                    0.85%                                   0.35%
24.......................................                    1.25%                                   0.75%
24.......................................                    3.00%                                   1.50%
</TABLE>
 
    For example, if defaulted Group III Loans total 0.35% of the aggregate
principal balance of the Group III Loans as of the Cut-Off Date as assumed for
purposes of the following tables (approximately $365,381, which is 0.35% of
$104,394,658), and such defaults occur at an amount per month equal to
approximately $15,224 (1/24th of $365,381) in each month of the 24-month period
commencing in November 1998, the effect on the pre-tax yield to maturity of the
Senior Subordinate Certificates from such aggregate defaults on the Group III
Loans over such 24-month period would be as shown in the tables below.
 
    In addition, it was assumed that (i) realized losses on liquidation of the
Mortgage Loans occur at a rate of 20% and 40%, with respect to the Group I and
Group II Loans, and 20% and 30%, with respect to the Group III Loans, of the
outstanding principal balance of such defaulted Mortgage Loans at the time of
default as indicated in the table (referred to as a "Loss Severity Percentage")
in the month in which the Mortgage Loans first default, (ii) there are no
Special Hazard Losses, Fraud Losses or Bankruptcy Losses, (iii) the Senior
Subordinate Certificates are purchased at the assumed purchase prices equal to
the indicated percentages of the applicable Class Principal Balance, plus
accrued interest from the Cut-Off Date and (iv) all scheduled payments on
Mortgage Loans are advanced by the applicable Master Servicer whether or not
received from the related Mortgagors.
 
    The rate of distributions in reduction of the Class Principal Balance of any
Class of Senior Subordinate Certificates will be related to the actual
amortization schedule of the Mortgage Loans; accordingly, the interest
distributions and distributions in reduction of the Class Principal Balances of
the Senior Subordinate Certificates may result in yields to maturity which
differ from those reflected below.
 
    The Mortgage Loans will not have the characteristics assumed, and it is
unlikely that they will prepay at any of the constant rates specified. The
assumed percentages of the applicable BPA, the principal balance of the
defaulted Mortgage Loans and the loss severities on the Mortgage Loans shown in
the tables below are for illustrative purposes only and the Company makes no
representations with respect to
 
                                      S-69
<PAGE>
the reasonableness of such assumptions or that the actual rates of prepayment
and liquidation and loss severity experience of the Mortgage Loans will in any
way correspond to any of the assumptions made herein. In addition, it is
unlikely that liquidations will occur in the month of default, and the timing of
such liquidations may cause the pre-tax yield to maturity of the Senior
Subordinate Certificates to differ from those shown below.
 
           PRE-TAX YIELD TO MATURITY OF THE CLASS I-B-1 CERTIFICATES
          AT AN ASSUMED PURCHASE PRICE OF 101.6875% OF THE CLASS I-B-1
         PRINCIPAL BALANCE PLUS ACCRUED INTEREST FROM THE CUT-OFF DATE
 
<TABLE>
<CAPTION>
DEFAULTED MORTGAGE
LOANS EXPRESSED AS A
PERCENTAGE OF THE
AGGREGATE PRINCIPAL
BALANCE OF THE GROUP I
LOANS AS OF THE CUT-OFF
DATE OVER THE 24-MONTH                       PERCENTAGE OF THE BPA              LOSS
PERIOD COMMENCING IN                 -------------------------------------    SEVERITY
NOVEMBER 1998                         0%      50%    100%    150%    200%    PERCENTAGE
- -----------------------------------  -----   -----   -----   -----   -----   ----------
<S>                                  <C>     <C>     <C>     <C>     <C>     <C>
0.00%..............................  7.14%   7.09%   7.06%   7.03%   7.01%        0%
0.85%..............................  7.14%   7.09%   7.06%   7.03%   7.01%       20%
0.85%..............................  7.14%   7.09%   7.06%   7.03%   7.01%       40%
1.25%..............................  7.14%   7.09%   7.06%   7.03%   7.01%       20%
1.25%..............................  7.14%   7.09%   7.06%   7.03%   7.01%       40%
3.00%..............................  7.14%   7.09%   7.06%   7.03%   7.01%       20%
3.00%..............................  7.14%   7.09%   7.06%   7.03%   7.01%       40%
</TABLE>
 
           PRE-TAX YIELD TO MATURITY OF THE CLASS II-B-1 CERTIFICATES
         AT AN ASSUMED PURCHASE PRICE OF 100.2500% OF THE CLASS II-B-1
         PRINCIPAL BALANCE PLUS ACCRUED INTEREST FROM THE CUT-OFF DATE
 
<TABLE>
<CAPTION>
DEFAULTED MORTGAGE
LOANS EXPRESSED AS A
PERCENTAGE OF THE
AGGREGATE PRINCIPAL
BALANCE OF THE GROUP II
LOANS AS OF THE CUT-OFF
DATE OVER THE 24-MONTH                       PERCENTAGE OF THE BPA              LOSS
PERIOD COMMENCING IN                 -------------------------------------    SEVERITY
NOVEMBER 1998                         0%     100%    250%    350%    500%    PERCENTAGE
- -----------------------------------  -----   -----   -----   -----   -----   ----------
<S>                                  <C>     <C>     <C>     <C>     <C>     <C>
0.00%..............................  7.03%   7.02%   7.00%   7.00%   6.99%        0%
0.85%..............................  7.03%   7.02%   7.00%   7.00%   6.99%       20%
0.85%..............................  7.03%   7.02%   7.00%   7.00%   6.99%       40%
1.25%..............................  7.03%   7.02%   7.00%   7.00%   6.99%       20%
1.25%..............................  7.03%   7.02%   7.00%   7.00%   6.99%       40%
3.00%..............................  7.03%   7.02%   7.00%   7.00%   6.99%       20%
3.00%..............................  7.03%   7.01%   7.00%   7.00%   6.99%       40%
</TABLE>
 
                                      S-70
<PAGE>
          PRE-TAX YIELD TO MATURITY OF THE CLASS III-B-1 CERTIFICATES
         AT AN ASSUMED PURCHASE PRICE OF 100.7500% OF THE CLASS III-B-1
         PRINCIPAL BALANCE PLUS ACCRUED INTEREST FROM THE CUT-OFF DATE
 
<TABLE>
<CAPTION>
DEFAULTED MORTGAGE
LOANS EXPRESSED AS A
PERCENTAGE OF THE
AGGREGATE PRINCIPAL
BALANCE OF THE GROUP III
LOANS AS OF THE CUT-OFF
DATE OVER THE 24-MONTH                       PERCENTAGE OF THE BPA              LOSS
PERIOD COMMENCING IN                 -------------------------------------    SEVERITY
NOVEMBER 1998                         0%     100%    235%    350%    500%    PERCENTAGE
- -----------------------------------  -----   -----   -----   -----   -----   ----------
<S>                                  <C>     <C>     <C>     <C>     <C>     <C>
0.00%..............................  6.65%   6.64%   6.63%   6.63%   6.62%        0%
0.35%..............................  6.65%   6.64%   6.63%   6.63%   6.62%       20%
0.35%..............................  6.65%   6.64%   6.63%   6.63%   6.62%       30%
0.75%..............................  6.65%   6.64%   6.63%   6.63%   6.62%       20%
0.75%..............................  6.65%   6.64%   6.63%   6.63%   6.62%       30%
1.50%..............................  6.65%   6.64%   6.63%   6.63%   6.62%       20%
1.50%..............................  6.65%   6.64%   6.63%   6.63%   6.62%       30%
</TABLE>
 
           PRE-TAX YIELD TO MATURITY OF THE CLASS I-B-2 CERTIFICATES
          AT AN ASSUMED PURCHASE PRICE OF 101.0000% OF THE CLASS I-B-2
         PRINCIPAL BALANCE PLUS ACCRUED INTEREST FROM THE CUT-OFF DATE
 
<TABLE>
<CAPTION>
DEFAULTED MORTGAGE
LOANS EXPRESSED AS A
PERCENTAGE OF THE
AGGREGATE PRINCIPAL
BALANCE OF THE GROUP I
LOANS AS OF THE CUT-OFF
DATE OVER THE 24-MONTH                       PERCENTAGE OF THE BPA              LOSS
PERIOD COMMENCING IN                 -------------------------------------    SEVERITY
NOVEMBER 1998                         0%      50%    100%    150%    200%    PERCENTAGE
- -----------------------------------  -----   -----   -----   -----   -----   ----------
<S>                                  <C>     <C>     <C>     <C>     <C>     <C>
0.00%..............................  7.21%   7.18%   7.15%   7.13%   7.12%        0%
0.85%..............................  7.21%   7.18%   7.15%   7.13%   7.12%       20%
0.85%..............................  7.21%   7.18%   7.15%   7.13%   7.12%       40%
1.25%..............................  7.21%   7.18%   7.15%   7.13%   7.12%       20%
1.25%..............................  7.21%   7.18%   7.15%   7.13%   7.12%       40%
3.00%..............................  7.21%   7.18%   7.15%   7.13%   7.12%       20%
3.00%..............................  7.21%   7.17%   7.15%   7.13%   7.12%       40%
</TABLE>
 
                                      S-71
<PAGE>
           PRE-TAX YIELD TO MATURITY OF THE CLASS II-B-2 CERTIFICATES
          AT AN ASSUMED PURCHASE PRICE OF 99.5000% OF THE CLASS II-B-2
         PRINCIPAL BALANCE PLUS ACCRUED INTEREST FROM THE CUT-OFF DATE
 
<TABLE>
<CAPTION>
DEFAULTED MORTGAGE
LOANS EXPRESSED AS A
PERCENTAGE OF THE
AGGREGATE PRINCIPAL
BALANCE OF THE GROUP II
LOANS AS OF THE CUT-OFF
DATE OVER THE 24-MONTH                       PERCENTAGE OF THE BPA              LOSS
PERIOD COMMENCING IN                 -------------------------------------    SEVERITY
NOVEMBER 1998                         0%     100%    250%    350%    500%    PERCENTAGE
- -----------------------------------  -----   -----   -----   -----   -----   ----------
<S>                                  <C>     <C>     <C>     <C>     <C>     <C>
0.00%..............................  7.11%   7.11%   7.11%   7.11%   7.11%        0%
0.85%..............................  7.11%   7.11%   7.11%   7.11%   7.11%       20%
0.85%..............................  7.11%   7.11%   7.11%   7.11%   7.11%       40%
1.25%..............................  7.11%   7.11%   7.11%   7.11%   7.11%       20%
1.25%..............................  7.11%   7.11%   7.11%   7.11%   7.11%       40%
3.00%..............................  7.11%   7.11%   7.11%   7.11%   7.11%       20%
3.00%..............................  7.11%   7.11%   7.11%   7.11%   7.11%       40%
</TABLE>
 
          PRE-TAX YIELD TO MATURITY OF THE CLASS III-B-2 CERTIFICATES
         AT AN ASSUMED PURCHASE PRICE OF 100.0000% OF THE CLASS III-B-2
         PRINCIPAL BALANCE PLUS ACCRUED INTEREST FROM THE CUT-OFF DATE
 
<TABLE>
<CAPTION>
DEFAULTED MORTGAGE
LOANS EXPRESSED AS A
PERCENTAGE OF THE
AGGREGATE PRINCIPAL
BALANCE OF THE GROUP III
LOANS AS OF THE CUT-OFF
DATE OVER THE 24-MONTH                       PERCENTAGE OF THE BPA              LOSS
PERIOD COMMENCING IN                 -------------------------------------    SEVERITY
NOVEMBER 1998                         0%     100%    235%    350%    500%    PERCENTAGE
- -----------------------------------  -----   -----   -----   -----   -----   ----------
<S>                                  <C>     <C>     <C>     <C>     <C>     <C>
0.00%..............................  6.77%   6.77%   6.77%   6.76%   6.76%        0%
0.35%..............................  6.77%   6.77%   6.77%   6.76%   6.76%       20%
0.35%..............................  6.77%   6.77%   6.77%   6.76%   6.76%       30%
0.75%..............................  6.77%   6.77%   6.77%   6.76%   6.76%       20%
0.75%..............................  6.77%   6.77%   6.77%   6.76%   6.76%       30%
1.50%..............................  6.77%   6.77%   6.77%   6.76%   6.76%       20%
1.50%..............................  6.77%   6.77%   6.77%   6.76%   6.76%       30%
</TABLE>
 
                                      S-72
<PAGE>
           PRE-TAX YIELD TO MATURITY OF THE CLASS I-B-3 CERTIFICATES
          AT AN ASSUMED PURCHASE PRICE OF 99.2500% OF THE CLASS I-B-3
         PRINCIPAL BALANCE PLUS ACCRUED INTEREST FROM THE CUT-OFF DATE
 
<TABLE>
<CAPTION>
DEFAULTED MORTGAGE
LOANS EXPRESSED AS A
PERCENTAGE OF THE
AGGREGATE PRINCIPAL
BALANCE OF THE GROUP I
LOANS AS OF THE CUT-OFF
DATE OVER THE 24-MONTH                       PERCENTAGE OF THE BPA              LOSS
PERIOD COMMENCING IN                 -------------------------------------    SEVERITY
NOVEMBER 1998                         0%      50%    100%    150%    200%    PERCENTAGE
- -----------------------------------  -----   -----   -----   -----   -----   ----------
<S>                                  <C>     <C>     <C>     <C>     <C>     <C>
0.00%..............................  7.39%   7.39%   7.40%   7.40%   7.40%        0%
0.85%..............................  7.39%   7.39%   7.40%   7.40%   7.40%       20%
0.85%..............................  7.39%   7.39%   7.40%   7.40%   7.40%       40%
1.25%..............................  7.39%   7.39%   7.40%   7.40%   7.40%       20%
1.25%..............................  7.39%   7.39%   7.40%   7.40%   7.40%       40%
3.00%..............................  7.39%   7.39%   7.40%   7.40%   7.40%       20%
3.00%..............................  6.86%   6.78%   6.66%   6.59%   6.54%       40%
</TABLE>
 
           PRE-TAX YIELD TO MATURITY OF THE CLASS II-B-3 CERTIFICATES
          AT AN ASSUMED PURCHASE PRICE OF 97.7500% OF THE CLASS II-B-3
         PRINCIPAL BALANCE PLUS ACCRUED INTEREST FROM THE CUT-OFF DATE
 
<TABLE>
<CAPTION>
DEFAULTED MORTGAGE
LOANS EXPRESSED AS A
PERCENTAGE OF THE
AGGREGATE PRINCIPAL
BALANCE OF THE GROUP II
LOANS AS OF THE CUT-OFF
DATE OVER THE 24-MONTH                       PERCENTAGE OF THE BPA              LOSS
PERIOD COMMENCING IN                 -------------------------------------    SEVERITY
NOVEMBER 1998                         0%     100%    250%    350%    500%    PERCENTAGE
- -----------------------------------  -----   -----   -----   -----   -----   ----------
<S>                                  <C>     <C>     <C>     <C>     <C>     <C>
0.00%..............................  7.28%   7.32%   7.35%   7.37%   7.39%        0%
0.85%..............................  7.28%   7.32%   7.35%   7.37%   7.39%       20%
0.85%..............................  7.28%   7.32%   7.35%   7.37%   7.39%       40%
1.25%..............................  7.28%   7.32%   7.35%   7.37%   7.39%       20%
1.25%..............................  7.28%   7.31%   7.35%   7.37%   7.39%       40%
3.00%..............................  7.28%   7.31%   7.35%   7.37%   7.39%       20%
3.00%..............................  4.12%   4.12%   3.49%   2.89%   2.26%       40%
</TABLE>
 
                                      S-73
<PAGE>
          PRE-TAX YIELD TO MATURITY OF THE CLASS III-B-3 CERTIFICATES
         AT AN ASSUMED PURCHASE PRICE OF 98.6250% OF THE CLASS III-B-3
         PRINCIPAL BALANCE PLUS ACCRUED INTEREST FROM THE CUT-OFF DATE
 
<TABLE>
<CAPTION>
DEFAULTED MORTGAGE
LOANS EXPRESSED AS A
PERCENTAGE OF THE
AGGREGATE PRINCIPAL
BALANCE OF THE GROUP III
LOANS AS OF THE CUT-OFF
DATE OVER THE 24-MONTH                       PERCENTAGE OF THE BPA              LOSS
PERIOD COMMENCING IN                 -------------------------------------    SEVERITY
NOVEMBER 1998                         0%     100%    235%    350%    500%    PERCENTAGE
- -----------------------------------  -----   -----   -----   -----   -----   ----------
<S>                                  <C>     <C>     <C>     <C>     <C>     <C>
0.00%..............................  7.00%   7.00%   7.01%   7.02%   7.02%        0%
0.35%..............................  7.00%   7.00%   7.01%   7.02%   7.02%       20%
0.35%..............................  7.00%   7.00%   7.01%   7.02%   7.02%       30%
0.75%..............................  7.00%   7.00%   7.01%   7.02%   7.02%       20%
0.75%..............................  7.00%   7.00%   7.01%   7.02%   7.02%       30%
1.50%..............................  7.00%   7.00%   7.01%   7.02%   7.02%       20%
1.50%..............................  7.00%   7.00%   7.01%   7.02%   7.02%       30%
</TABLE>
 
    The pre-tax yields to maturity set forth in the preceding tables were
calculated by determining the monthly discount rates which, when applied to the
assumed streams of cash flows to be paid on each Class of Senior Subordinate
Certificates, would cause the discounted present value of such assumed stream of
cash flows to equal the assumed offering prices (including accrued interest) of
each Class of the Senior Subordinate Certificates set forth above. In all cases
monthly rates are then converted to the corporate bond equivalent yields shown
above. Implicit in the use of any discounted present value or internal rate of
return calculation such as these is the assumption that intermediate cash flows
are invested at the discount rate or internal rate of return. Thus these
calculations do not take into account the different interest rates at which
investors may be able to reinvest funds received by them as distributed on the
Senior Subordinate Certificates. Consequently, these yields to maturity do not
purport to reflect the return on any investment in the Senior Subordinate
Certificates when such reinvestment rates are considered.
 
    The characteristics of the Mortgage Loans will not correspond exactly to
those assumed in preparing the tables above. The yield to maturity of each Class
of the Senior Subordinate Certificates therefore will differ even if all the
Mortgage Loans prepay monthly at the related assumed prepayment rate. In
addition, it is not likely that the Mortgage Loans will prepay at the same
percentage of the applicable BPA, and the timing of changes in the rate of
prepayments may affect significantly the yield to maturity received by a holder
of a Class of Senior Subordinate Certificates. There are no historical
prepayment data available for the Mortgage Pool, and comparable data are not
available because the Mortgage Loans do not constitute a representative sample
of mortgage loans generally. In addition, historical data available with respect
to mortgage loans underlying mortgage pass-through certificates issued by GNMA,
FNMA or FHLMC may not be comparable to prepayments expected to be experienced by
the Mortgage Pool, because the Mortgage Loans may have characteristics which
differ from mortgage loans underlying certificates issued by GNMA, FNMA and
FHLMC.
 
    The Company makes no representation that the Mortgage Loans will prepay in
the manner or at any of the rates assumed above. Each investor must make its own
decision as to the appropriate prepayment assumptions to be used in deciding
whether or not to purchase any of the Senior Subordinate Certificates. Since the
rate of principal payments (including Principal Prepayments) with respect to,
and repurchases of, the Mortgage Loans will significantly affect the yield to
maturity on each Class of the Senior Subordinate Certificates, prospective
investors are urged to consult their investment advisors as to both the
anticipated rate of future principal payments (including Principal Prepayments)
on the Mortgage Loans and the suitability of the Senior Subordinate Certificates
to their investment objectives.
 
                                      S-74
<PAGE>
ADDITIONAL YIELD CONSIDERATIONS APPLICABLE SOLELY TO THE CLASS R CERTIFICATES
 
    The Class R Certificateholders' after-tax rate of return on their
Certificates will reflect their pre-tax rate of return, reduced by the taxes
required to be paid with respect to such Certificates. Holders of Class R
Certificates may have tax liabilities with respect to their Certificates during
the early years of the REMIC's term that substantially exceed any distributions
payable thereon during any such period. In addition, holders of Class R
Certificates may have tax liabilities with respect to their Certificates the
present value of which substantially exceeds the present value of distributions
payable thereon and of any tax benefits that may arise with respect thereto.
Accordingly, the after-tax rate of return on the Class R Certificates may be
negative or may otherwise be significantly adversely affected. The timing and
amount of taxable income attributable to the Class R Certificates will depend
on, among other things, the timing and amounts of prepayments and losses
experienced with respect to the Mortgage Pool.
 
    The Class R Certificateholders should consult their own tax advisors as to
the effect of taxes and the receipt of any payments made to such holders in
connection with the purchase of the Class R Certificates on after-tax rates of
return on the Class R Certificates. See "Certain Federal Income Tax
Consequences" herein and in the Prospectus.
 
ADDITIONAL INFORMATION
 
    The Company intends to file with the Securities and Exchange Commission
certain additional yield tables and other computational materials with respect
to one or more Classes of the Offered Certificates on a Current Report on Form
8-K. Such tables and materials were prepared by the Underwriter at the request
of certain prospective investors, based on assumptions provided by, and
satisfying the special requirements of, such prospective investors. Such tables
and materials are preliminary in nature, and the information contained therein
is subject to, and superseded by, the information in this Supplement.
 
                              CREDIT ENHANCEMENTS
 
SUBORDINATION
 
    The Senior Certificates of a Certificate Group are entitled to receive
distributions of interest (except with respect to the related Class P
Certificates, which are not entitled to interest) and principal (except with
respect to the related Class X Certificates, which are not entitled to
principal) before distributions of interest or principal to the Class B
Certificates of the related Certificate Group. No Class B Certificates of a
Certificate Group will receive distributions of interest or principal on any
Distribution Date until the Class or Classes in the related Certificate Group
senior to such Class have received all distributions of interest and principal
due on or before such Distribution Date. See "Description of the Certificates--
Priority of Distributions" herein.
 
    Losses on Mortgage Loans in a Loan Group will be allocated, in each case
until the applicable Class or Component Principal Balances of the Classes or
Components of the related Certificate Group have been reduced to zero, first, to
the Junior Subordinate Certificates in the related Subordinate Group; second, to
the Class I-B-3 Certificates, Class II-B-3 Certificates or Class III-B-3
Certificates, as applicable; third, to the Class I-B-2 Certificates, Class
II-B-2 Certificates or Class III-B-2 Certificates, as applicable; fourth, to the
Class I-B-1 Certificates, Class II-B-1 Certificates or Class III-B-1
Certificates, as applicable; and fifth, to the outstanding Classes of Senior
Certificates in the related Certificate Group by Pro Rata Allocation; PROVIDED,
HOWEVER, that only a certain specified amount of Special Hazard Losses, Fraud
Losses and Bankruptcy Losses in a Loan Group will be allocated solely to the
Class B Certificates in the related Certificate Group, following which such
losses will be allocated among all outstanding Classes of Certificates in the
related Certificate Group by Pro Rata Allocation; PROVIDED, FURTHER, that in the
event any loss is incurred with respect to a Class P Mortgage Loan, the
applicable Class P Fraction of such loss will first be allocated to the related
Class P Certificates and the remainder of such loss will be allocated as
described above; PROVIDED, FURTHER, that all losses that would otherwise be
allocable to the Class II-A-1 Certificates on
 
                                      S-75
<PAGE>
any Distribution Date will be allocated to the Class II-A-9 Certificates, until
the Class II-A-9 Principal Balance has been reduced to zero.
 
SHIFTING OF INTERESTS
 
    The Senior Certificates of a Certificate Group entitled to principal, other
than the Lockout Certificates (unless the Credit Support Depletion Date has
occurred), will receive 100% of Principal Prepayments received with respect to
the Mortgage Loans in the related Loan Group until the fifth anniversary of the
first Distribution Date. During the next four years, such Senior Certificates,
other than the Lockout Certificates (unless the Credit Support Depletion Date
has occurred) will receive a disproportionately large, but decreasing, share of
Principal Prepayments received with respect to the Mortgage Loans in the related
Loan Group. This will result in an acceleration of the amortization of such
Senior Certificates, other than the Lockout Certificates, subject to the
priorities described in "Description of the Certificates-- Distributions of
Principal" herein, enhancing the likelihood that holders of such Classes of
Certificates will be paid the full amount of principal to which they are
entitled.
 
    Although the Lockout Certificates are Senior Certificates, the Class II-A-8
and Class II-A-9 Certificates will generally not be entitled to receive
principal distributions (other than the Lockout Liquidation Amount) until the
Distribution Date in December 2002 and thereafter will not be entitled to
receive the disproportionate allocation of Principal Prepayments in Loan Group
II that the other Senior Certificates in Certificate Group II are entitled to
receive.
 
    See "Description of the Certificates--Distributions of Principal" herein.
 
                    CERTAIN FEDERAL INCOME TAX CONSEQUENCES
 
    For federal income tax purposes, the Company will cause an election to be
made to treat the Trust as a REMIC. The certificates issued by the Trust, other
than the Class R Certificates, will be designated as REMIC regular interests. As
REMIC regular interests, such Certificates will generally be treated as
representing ownership of debt for federal income tax purposes.
Certificateholders will be required to include in income all interest and
original issue discount ("OID") on such Certificates in accordance with the
accrual method of accounting regardless of the Certificateholders' usual methods
of accounting. For federal income tax purposes the Class R Certificates will be
the residual interest in the Trust.
 
    The Class II-A-4, Class II-A-5, Class II-A-6, Class III-PT, Class X and
Class P Certificates will, and the Class II-A-7, Class II-A-8, Class II-A-9 and
Senior Subordinate Certificates may, be treated as having been issued with OID
for federal income tax purposes. The prepayment assumption that will be used in
determining the rate of accrual of market discount and premium, if any, for
federal income tax purposes is 100% of the BPA for Loan Group I, 250% of the BPA
for Loan Group II and 235% of the BPA for Loan Group III as described herein
under "Yield and Prepayment Considerations". No representation is made that the
Mortgage Loans will prepay at any given percentage of the BPA.
 
    In certain circumstances OID Regulations (as defined in "Certain Federal
Income Tax Consequences" in the Prospectus) permit the holder of a debt
instrument to recognize original issue discount under a method that differs from
that used by the issuer. Accordingly, it is possible that the holder of a
Certificate may be able to select a method for recognizing original issue
discount that differs from that used by the Company in preparing reports to the
Certificateholders and the IRS.
 
    If actual prepayments differ sufficiently from the prepayment assumption,
the calculation of OID for certain Classes of Offered Certificates might produce
a negative number for certain accrual periods. In such event, Certificateholders
will not be entitled to a deduction for such amount, but will be required to
carry such amount forward as an offset to OID, if any, accruing in future
accrual periods.
 
    Purchasers of the Floater Certificates and Inverse Floater Certificates
should be aware that Section 1272(a)(6) of the Code and the OID Regulations do
not adequately address certain issues relevant to, or
 
                                      S-76
<PAGE>
applicable to, prepayable securities bearing a variable rate of interest such as
the Floater Certificates and Inverse Floater Certificates. In the absence of
other authority, the REMIC Administrator intends to be guided by certain
principles of the OID Regulations applicable to variable rate debt instruments
in determining whether such Certificates should be treated as issued with
original issue discount and in adapting the provisions of Section 1272(a)(6) of
the Code to such Certificates for the purpose of preparing reports furnished to
Certificateholders and the IRS. Because of the uncertainties concerning the
application of Section 1272(a)(6) of the Code to such Certificates and because
the rules relating to debt instruments having a variable rate of interest are
limited in their application in ways that could preclude their application to
such Certificates even in the absence of Section 1272(a)(6) of the Code, the IRS
could assert that the Floater Certificates and Inverse Floater Certificates
should be governed by some other method not yet set forth in regulations.
Prospective purchasers of the Floater Certificates and Inverse Floater
Certificates are advised to consult their tax advisors concerning the tax
treatment of such Certificates.
 
    The REMIC Administrator intends to report all income with respect to the
Floater Certificates and Inverse Floater Certificates as original issue discount
for each period, computing such original issue discount (i) by assuming that the
value of the applicable index will remain constant for purposes of determining
the original yield to maturity of each such class of Certificates and projecting
future distributions on such Certificates, thereby treating such Certificates as
fixed rate instruments to which the original issue discount computation rules
described in the Prospectus can be applied, and (ii) by accounting for any
positive or negative variation in the actual value of the applicable index in
any period from its assumed value as a current adjustment to original issue
discount with respect to such period. The use of the foregoing method of
calculating the accrual of OID may result in the calculated accrual being
negative for some periods. As described in the second preceding paragraph such
negative accruals will not be currently deductible but must be carried forward
for deduction against positive accruals of OID in future periods. See "Certain
Federal Income Tax Consequences--Taxation of Owners of REMIC Regular
Certificates-- Original Issue Discount" in the Prospectus.
 
    Certain Classes of Certificates may be treated for federal income tax
purposes as having been issued at a premium. Whether any holder of a Certificate
will be treated as holding a Certificate with amortizable bond premium will
depend on such Certificateholder's purchase price and the distributions
remaining to be made on such Certificate at the time of its acquisition by such
Certificateholder. Holders of such Classes of Certificates should consult their
own tax advisors regarding the possibility of making an election to amortize any
such premium. See "Certain Federal Income Tax Consequences-- Taxation of Owners
of REMIC Regular Certificates-- Original Issue Discount" and "--Market Discount
and Premium" in the Prospectus.
 
    The Offered Certificates will generally be treated as "qualifying real
property loans" for mutual savings banks and domestic building and loan
associations, "loans secured by an interest in real property" for domestic
building and loan associations, and "real estate assets" for real estate
investment trusts ("REITs") in the same proportion that the assets in the REMICs
would be so treated. In addition interest on the Offered Certificates will
generally be treated as "interest on obligations secured by mortgages on real
property" for REITs to the extent that such Offered Certificates are treated as
"real estate assets". Recently enacted legislation repealed the provisions of
Section 593(d) of the Internal Revenue Code allowing the reserve method of
accounting for bad debts, effective for taxable years beginning after December
31, 1995. See "Certain Federal Income Tax Consequences" in the Prospectus.
 
NEW WITHHOLDING REGULATIONS
 
    The Treasury Department has issued new regulations (the "New Regulations")
which make certain modifications to the withholding, backup withholding and
information reporting rules described above. The New Regulations attempt to
unify certification requirements and modify reliance standards. The new
Regulations will generally be effective for payments made after December 31,
1998, subject to certain transition rules. Prospective investors are urged to
consult their own tax advisors regarding the New Regulations.
 
                                      S-77
<PAGE>
SPECIAL TAX CONSIDERATIONS APPLICABLE TO THE RESIDUAL CERTIFICATES
 
    The Internal Revenue Service has issued regulations under the provisions of
the Code related to REMICs (the "REMIC Regulations") that significantly affect
holders of the Class R Certificates. The REMIC Regulations impose restrictions
on the transfer or acquisition of certain residual interests, including the
Class R Certificates. In addition, the REMIC Regulations contain restrictions
that apply to the transfer of "noneconomic" residual interests to United States
persons. Pursuant to the Pooling Agreement, the Class R Certificates may not be
transferred to non-United States persons.
 
    The Small Business Job Protection Act of 1996 has eliminated the special
rule permitting Section 593 institutions ("thrift institutions") to use net
operating losses and other allowable deductions to offset their excess inclusion
income from REMIC residual certificates that have "significant value" within the
meaning of the REMIC Regulations, effective for taxable years beginning after
December 31, 1995, except with respect to residual certificates continuously
held by a thrift institution since November 1, 1995.
 
    In addition, the Small Business Job Protection Act of 1996 provides three
rules for determining the effect on excess inclusions on the alternative minimum
taxable income of a residual holder. First, alternative minimum taxable income
for such residual holder is determined without regard to the special rule that
taxable income cannot be less than excess inclusions. Second, a residual
holder's alternative minimum taxable income for a tax year cannot be less than
excess inclusions for the year. Third, the amount of any alternative minimum tax
net operating loss deductions must be computed without regard to any excess
inclusions. These rules are effective for tax years beginning after December 31,
1986, unless a residual holder elects to have such rules apply only to tax years
beginning after August 20, 1996.
 
    The REMIC Regulations provide that a transfer to a United States person of
"noneconomic" residual interests will be disregarded for all federal income tax
purposes, and that the purported transferor of "noneconomic" residual interests
will continue to remain liable for any taxes due with respect to the income on
such residual interests, unless "no significant purpose of the transfer was to
impede the assessment or collection of tax". Based on the REMIC Regulations, the
Class R Certificates may constitute noneconomic residual interests during some
or all of their terms for purposes of the REMIC Regulations and, accordingly,
unless no significant purpose of a transfer is to impede the assessment or
collection of tax, transfers of the Class R Certificates may be disregarded and
purported transferors may remain liable for any taxes due with respect to the
income on the Class R Certificates. All transfers of the Class R Certificates
will be subject to certain restrictions under the terms of the Pooling Agreement
that are intended to reduce the possibility of any such transfer being
disregarded to the extent that the Class R Certificates constitute noneconomic
residual interests. See "Certain Federal Income Tax Consequences-- Taxation of
Owners of REMIC Residual Certificates--Noneconomic REMIC Residual Certificates"
in the Prospectus.
 
    The Class R Certificateholders may be required to report an amount of
taxable income with respect to the earlier accrual periods of the REMIC's term
that significantly exceeds the amount of cash distributions received by such
Class R Certificateholders from the REMIC with respect to such periods.
Consequently, the Class R Certificateholders should have other sources of funds
sufficient to pay any federal income taxes due in the earlier years of the REMIC
as a result of their ownership of such Class R Certificates. In addition, the
required inclusion of this amount of taxable income during the REMIC's earlier
accrual periods and the deferral of corresponding tax losses or deductions until
later accrual periods or until the ultimate sale or disposition of a Class R
Certificate (or possibly later under the "wash sale" rules of Section 1091 of
the Code) may cause the Class R Certificateholders' after-tax rate of return to
be zero or negative even if the Class R Certificateholders' pre-tax rate of
return is positive. That is, on a present value basis, the Class R
Certificateholders' resulting tax liabilities could substantially exceed the sum
of any tax benefits and the amount of any cash distributions on such Class R
Certificates over their life.
 
    As discussed above, the rules for accrual of original issue discount with
respect to certain Classes of Certificates are subject to significant complexity
and uncertainty. Because original issue discount on the
 
                                      S-78
<PAGE>
Certificates will be deducted by the related REMIC in determining its taxable
income, any changes required by the Internal Revenue Service in the application
of those rules to the Certificates may significantly affect the timing of
original issue discount deductions to the related REMIC and therefore the amount
of the related REMIC's taxable income allocable to holders of the Class R
Certificates.
 
    Purchasers of the Class R Certificates are strongly advised to consult their
own tax advisors as to the economic and tax consequences of investment in such
Certificates.
 
    For further information regarding the federal income tax consequences of
investing in the Class R Certificates, see "Certain Yield and Prepayment
Considerations-- Additional Yield Considerations Applicable Solely to the Class
R Certificates" herein and "Certain Federal Income Tax Consequences-- Taxation
of Owners of REMIC Residual Certificates" in the Prospectus.
 
    An individual, trust or estate that holds (whether directly or indirectly
through certain pass-through entities) a Class R Certificate may have
significant additional gross income with respect to, but may be subject to
limitations on the deductibility of, servicing and trustee's fees and other
administrative expenses properly allocable to the related REMIC in computing
such Certificateholder's regular tax liability and will not be able to deduct
such fees or expenses to any extent in computing such Certificateholder's
alternative minimum tax liability. Such expenses will be allocated for federal
income tax information reporting purposes entirely to the Class R Certificates.
However, it is possible that the IRS may require all or some portion of such
fees and expenses to be allocated to the Class R Certificates. See "Certain
Federal Income Tax Consequences--Pass-Through of Servicing Fees" and "--Taxation
of Owners of REMIC Residual Certificates" in the Prospectus.
 
    The Company will be designated as the "tax matters persons" with respect to
the Trust as defined in the REMIC Regulations (defined below), and in connection
therewith will be required to hold not less than 0.01% of the Class R
Certificates.
 
    For further information regarding the federal income tax consequences of
investing in the Certificates, see "Certain Federal Income Tax Consequences" in
the Prospectus.
 
                        CERTAIN LEGAL INVESTMENT ASPECTS
 
    As of the date of their issuance, the Offered Certificates, other than the
Class I-B-2, Class II-B-2, Class III-B-2, Class I-B-3, Class II-B-3 and Class
III-B-3 Certificates, will constitute "mortgage related securities" for purposes
of the Secondary Mortgage Market Enhancement Act of 1984 ("SMMEA"), and as such
will be legal investments for persons, trusts, corporations, partnerships,
associations, business trusts and business entities (including depository
institutions, life insurance companies, and pension funds) created pursuant to
or existing under the laws of the United States or of any state whose authorized
investments are subject to state regulation to the same extent that, under
applicable law, obligations issued by or guaranteed as to principal and interest
by the United States or any agency or instrumentality thereof constitute legal
investments for such entities. Under SMMEA, if a state enacted legislation prior
to October 4, 1991 specifically limiting the legal investment authority of any
of such entities with respect to "mortgage related securities", the Offered
Certificates, other than the Class I-B-2, Class I-B-3, Class II-B-2, Class
II-B-3, Class III-B-2 and Class III-B-3 Certificates, will constitute legal
investments for entities subject to such legislation only to the extent provided
therein. Certain states have enacted such legislation. Investors should consult
their own legal advisors in determining whether and to what extent the Offered
Certificates, constitute legal investments for such investors.
 
    SMMEA also amended the legal investment authority of federally-chartered
depository institutions as follows: federal savings and loan associations and
federal savings banks may invest in, sell or otherwise deal with the Offered
Certificates, other than the Class I-B-2, Class I-B-3, Class II-B-2, Class
II-B-3, Class III-B-2 and Class III-B-3 Certificates, without limitation as to
the percentage of their assets represented thereby, federal credit unions may
invest in the Offered Certificates, other than the Class I-B-2, Class I-
 
                                      S-79
<PAGE>
B-3, Class II-B-2, Class II-B-3, Class III-B-2 and Class III-B-3 Certificates,
and national banks may purchase the Offered Certificates, other than the Class
I-B-2, Class I-B-3, Class II-B-2, Class II-B-3, Class III-B-2 and Class III-B-3
Certificates, for their own accounts without regard to the limitations generally
applicable to investment securities set forth in 12 U.S.C. 24 (Seventh), in each
case subject to such regulations as the applicable federal regulatory authority
may prescribe.
 
    Institutions whose investment activities are subject to review by certain
regulatory authorities hereafter may be or may become subject to restrictions on
investment in the Offered Certificates, and such restrictions may be
retroactively imposed. The Federal Financial Institutions Examination Council,
the Federal Deposit Insurance Corporation, the Office of the Comptroller of the
Currency, the Board of Governors of the Federal Reserve System, the Office of
Thrift Supervision and the National Credit Union Administration have adopted
guidelines, and have proposed policies, regarding the suitability of investments
in various types of derivative mortgage-backed securities, including securities
such as the Offered Certificates. In addition, several states have adopted or
are considering regulations that would prohibit regulated institutions subject
to their jurisdiction from holding mortgage-backed securities such as the
Offered Certificates, including such securities previously purchased. Investors
should consult their own legal advisors in determining whether and to what
extent the Offered Certificates constitute legal investments for such investors.
 
    There may be other restrictions on the ability of certain investors,
including depository institutions, either to purchase the Offered Certificates
or to purchase the Offered Certificates representing more than a specified
percentage of the investor's assets. Investors should consult their own legal
advisors in determining whether and to what extent the Offered Certificates
constitute legal investments for such investors.
 
                              ERISA CONSIDERATIONS
 
    Any fiduciary of an employee benefit plan or other benefit plan or
arrangement which is subject to the Employee Retirement Income Security Act of
1974, as amended ("ERISA"), or Section 4975 of the Internal Revenue Code of
1986, as amended (the "CODE") (each, a "PLAN"), or other person that proposes to
use "plan assets" of any Plan to acquire any Offered Certificates should consult
with its counsel with respect to the potential consequences under ERISA and
Section 4975 of the Code of the acquisition and ownership of such Certificates
by, on behalf of or with "plan assets" of any Plan. See "ERISA Considerations"
in the Prospectus.
 
UNDERWRITER'S PTE
 
    Donaldson, Lufkin & Jenrette Securities Corporation (the "UNDERWRITER") is
the recipient of a final prohibited transaction exemption (the "UNDERWRITER'S
PTE") which may afford protection from violations under Sections 406 and 407 of
ERISA and Section 4975 of the Code for Plans that acquire Offered Certificates
(other than the Class II-A-9 and Senior Subordinate Certificates). It is not
clear whether exemptive relief is available under the Underwriter's PTE for
Plans that acquire the Class R Certificates. Plans (or persons using "plan
assets" of any Plan) that acquire Offered Certificates (other than the Class
II-A-9 and Senior Subordinate Certificates) may be eligible for exemptive relief
under the Underwriter's PTE if:
 
        (a) The Class of such Certificates acquired by the Plan is not
    subordinated to other Classes of Certificates with respect to the right to
    receive payment in the event of defaults or delinquencies on the underlying
    Mortgage Loans;
 
        (b) The Plan is an "accredited investor" (as defined in Rule 501(a)(1)
    of Regulation D under the Securities Act of 1933, as amended (the "ACT"));
 
                                      S-80
<PAGE>
        (c) The acquisition of such Certificates by the Plan is on terms
    (including the price paid for the Certificates) that are at least as
    favorable to the Plan as they would be in an arm's length transaction with
    an unrelated party;
 
        (d) The sum of all payments made to and retained by the Underwriter in
    connection with the distribution of such Certificates represents not more
    than reasonable compensation for underwriting such Certificates; the sum of
    all payments made to and retained by the Company pursuant to the sale of the
    Mortgage Loans to the Trust represents not more than the fair market value
    of the Mortgage Loans; and the sum of all payments made to and retained by
    the Company or any other servicer represents not more than reasonable
    compensation for their services under the Pooling Agreement and
    reimbursement of their reasonable expenses in connection therewith;
 
        (e) The Certificates acquired by the Plan have received a rating from
    S&P, DCR, Moody's or Fitch that is in the three highest generic rating
    categories; and
 
        (f) The Trustee is not an affiliate of any other member of the
    Restricted Group (as defined below).
 
    In addition, the Underwriter's PTE will not provide exemptive relief for
certain transactions prohibited by Section 406(b)(1) of ERISA or Section
4975(c)(1)(E) of the Code that may result from an investment of "plan assets" of
any Plan in such Certificates if:
 
        (g) The Plan's investment in any Class of such Certificates exceeds 25%
    of the outstanding Certificates of that Class at the time of acquisition;
 
        (h) 25% or more of the Plan assets with respect to which the investing
    fiduciary has discretionary authority or renders investment advice are
    invested in certificates evidencing interests in trusts sponsored or
    containing assets sold or serviced by the Company;
 
        (i) The Plan is sponsored by the Company, the Underwriter, the Trustee,
    any servicer, the obligor under any credit support mechanism, or any
    mortgagor with respect to Mortgage Loans constituting more than 5% of the
    aggregate unamortized principal balance of the Mortgage Loans on the Closing
    Date (a "Major Obligor") or their affiliates (collectively, the "Restricted
    Group");
 
        (j) The Plan fiduciary responsible for the decision to invest or any of
    its affiliates is a Major Obligor; or
 
        (k) In connection with an acquisition of Certificates in the initial
    issuance, less than 50% of each Class of Certificates in which Plans have
    invested and less than 50% of the aggregate interests in the Trust are
    acquired by persons independent of members of the Restricted Group.
 
    Whether the conditions of the Underwriter's PTE will be satisfied with
respect to Offered Certificates of a particular Class (other than the Class
II-A-9 and Senior Subordinate Certificates, for which the Underwriter's PTE will
not afford exemptive relief) will depend upon the facts and circumstances
existing at the time the Plan acquires (or "plan assets" of the Plan are used to
acquire) Certificates of that Class. Any Plan fiduciary or other person that
proposes to use "plan assets" of any Plan to acquire such Offered Certificates
in reliance upon the Underwriter's PTE should determine whether such acquisition
will satisfy all applicable conditions and consult with its counsel regarding
other factors that may affect the applicability of the Underwriter's PTE.
Purchasers using insurance company general account assets to effect the purchase
of the Class II-A-9 or Senior Subordinate Certificates should consider the
availability of exemptive relief under Sections I and III of PTCE 95-60. See
"ERISA Considerations--Other Exemptions" in the Prospectus and "--Restrictions
on the Class II-A-9, Senior Subordinate and Residual Certificates" below.
 
                                      S-81
<PAGE>
PROHIBITED TRANSACTION CLASS EXEMPTIONS
 
    To qualify for exemption under PTCE 83-1 (see "ERISA
Considerations--Prohibited Transaction Class Exemption 83-1" in the Prospectus),
a Certificate (i) must entitle its holder to more than nominal pass-through
payments of both principal and interest from the Mortgage Loans, (ii) must not
be subordinated to other Classes of Certificates with respect to the right to
receive payments in the event of defaults or delinquencies on the underlying
Mortgage Loans and (iii) must not be issued by a Trust which holds cooperative
apartment Mortgage Loans. See "ERISA Considerations--Prohibited Transaction
Class Exemption 83-1" in the Prospectus. Because the Trust will hold cooperative
apartment Mortgage Loans, PTCE 83-1 will not afford exemptive relief to Plans
(or persons using "plan assets" of any Plan) that acquire Offered Certificates
from the prohibited transaction rules of ERISA or Section 4975 of the Code.
 
RESTRICTIONS ON THE CLASS II-A-9, SENIOR SUBORDINATE AND RESIDUAL CERTIFICATES
 
    Because the Class II-A-9 and Senior Subordinate Certificates will not
qualify for exemptive relief under the Underwriter's PTE or PTCE 83-1, because
it is not clear whether the Residual Certificates may qualify for exemptive
relief under the Underwriter's PTE, and because the Class R Certificates will
not qualify for exemptive relief under PTCE 83-1, purchases of such Certificates
by, on behalf of or with "plan assets" of any Plan are not to be registered
unless the transferee (i) provides an opinion of counsel satisfactory to the
Trustee and the Company that the purchase of any such Certificate by, on behalf
of or with "plan assets" of such Plan is permissible under applicable law, will
not constitute or result in a non-exempt prohibited transaction under ERISA or
Section 4975 of the Code, and will not subject the Certificate Administrator,
either Master Servicer, the Company or the Trustee to any obligation in addition
to those undertaken in the Pooling Agreement or (ii) represents that it is an
insurance company using assets of its general account to effect such purchase in
reliance upon the availability of exemptive relief under Sections I and III of
PTCE 95-60.
 
    In addition, so long as the Class II-A-9 Certificates are Book-Entry
Certificates, any purchaser of a Class II-A-9 Certificate will be deemed to have
represented by such purchase that either (i) such purchaser is not a Plan and is
not purchasing such Certificates on behalf of, or with "plan assets" of, any
Plan or (ii) the purchase of any such Certificate by, on behalf of or with "plan
assets" of any Plan is permissible under applicable law, will not result in any
non-exempt prohibited transaction under ERISA or Section 4975 of the Code, and
will not subject the Certificate Administrator, either Master Servicer, the
Company or the Trustee to any obligation in addition to those undertaken in the
Pooling Agreement. See "ERISA Considerations" in the Prospectus.
 
                             METHOD OF DISTRIBUTION
 
    Subject to the terms and conditions set forth in the Underwriting Agreement,
the Company has agreed to sell to the Underwriter, and the Underwriter has
agreed to purchase, all of the Offered Certificates, other than the 0.01%
Percentage Interest of the Class R Certificates to be retained by the Company.
The aggregate proceeds (excluding accrued interest) to the Company from the sale
of the Offered Certificates, before deducting expenses estimated to be $620,000,
will be approximately 101.87816% of the initial aggregate Certificate Principal
Balance of the Offered Certificates. Under the terms and conditions of the
Underwriting Agreement, the Underwriter is committed to take and pay for all of
such Offered Certificates, if any are taken. Distribution of such Offered
Certificates will be made by the Underwriter from time to time in negotiated
transactions or otherwise at varying prices to be determined at the time of
sale. The difference between the purchase price for the Offered Certificates
paid to the Company and the proceeds from the sale of such Certificates realized
by the Underwriter will constitute underwriting discounts and commissions.
 
                                      S-82
<PAGE>
    The Company has agreed to indemnify the Underwriter against certain civil
liabilities, including liabilities under the Act.
 
                                 LEGAL MATTERS
 
    Certain legal matters will be passed upon for the Company by Thomas G.
Lehmann, General Counsel, Vice President and Secretary of the Company, and by
its special counsel, Orrick, Herrington & Sutcliffe LLP, San Francisco,
California. Brown & Wood LLP, New York, New York, will pass upon certain legal
matters on behalf of the Underwriter.
 
                              CERTIFICATE RATINGS
 
    It is a condition to the issuance of the Offered Certificates that they
receive ratings from Standard & Poor's, a division of The McGraw-Hill Companies,
Inc. ("S&P"), Fitch Investors Service, L.P. ("Fitch") and Duff & Phelps Credit
Rating Co. ("DCR") as indicated:
 
<TABLE>
<CAPTION>
                                                                          RATING AGENCY
                                                                 -------------------------------
                             CLASS                                  S&P        DCR       FITCH
- ---------------------------------------------------------------  ---------  ---------  ---------
<S>                                                              <C>        <C>        <C>
I-A-1..........................................................  AAA                   AAA
II-A-1.........................................................  AAA        AAA
II-A-2.........................................................  AAA        AAA
II-A-3.........................................................  AAA        AAA
II-A-4.........................................................  AAA        AAA
II-A-5.........................................................  AAA        AAA
II-A-6.........................................................  AAA        AAA
II-A-7.........................................................  AAA        AAA
II-A-8.........................................................  AAA        AAA
II-A-9.........................................................  AAA        AAA
II-A-10........................................................  AAA        AAA
III-PT.........................................................  AAA        AAA
I-X-1..........................................................  AAAr                  AAA
I-X-2..........................................................  AAAr                  AAA
II-X...........................................................  AAAr       AAA
III-X..........................................................  AAAr       AAA
I-P............................................................  AAAr                  AAA
II-P...........................................................  AAAr       AAA
III-P..........................................................  AAAr       AAA
I-B-1..........................................................                        AA
I-B-2..........................................................                        A
I-B-3..........................................................                        BBB
II-B-1.........................................................             AA
II-B-2.........................................................             A
II-B-3.........................................................             BBB
III-B-1........................................................             AA
III-B-2........................................................             A
III-B-3........................................................             BBB
R..............................................................  AAA        AAA
</TABLE>
 
    A security rating is not a recommendation to buy, sell or hold securities
and may be subject to revision or withdrawal at any time by the assigning Rating
Agency. Each security rating should be evaluated independently of any other
security rating.
 
    The ratings by DCR assigned to this issue do not constitute a recommendation
to purchase or sell these securities. Rather, they are an indication of the
likelihood of the payment of principal and interest as
 
                                      S-83
<PAGE>
set forth in the transaction documentation. The ratings do not address the
effect on the Certificates' yield attributable to prepayments or recoveries on
the underlying Mortgage Loans. Further, the ratings on the Class II-X and Class
III-X Certificates do not address whether investors will recoup their initial
investment. Additionally, the ratings on the Class II-P and Class III-P
Certificates address only the return of the applicable Class Principal Balance,
and the rating on the Class R Certificates addresses only the return of the
Class R Principal Balance and interest thereon at the stated rate.
 
    The ratings on the Offered Certificates address the likelihood of the
receipt by Certificateholders of all distributions with respect to the
underlying Mortgage Loans to which they are entitled. The ratings do not
represent any assessment of the likelihood that the rate of Principal
Prepayments by Mortgagors might differ from those originally anticipated. As a
result of such differences in the rate of Principal Prepayments,
Certificateholders might suffer a lower than anticipated yield to maturity. See
"Risk Factors" and "Yield and Prepayment Considerations" herein.
 
    The Depositor has not requested a rating on the Offered Certificates by any
rating agency other than S&P, DCR and Fitch. However, there can be no assurance
as to whether any other rating agency will rate the Offered Certificates, or, if
it does, what rating would be assigned by any such other rating agency. A rating
on the Offered Certificates by another rating agency, if assigned at all, may be
lower than the rating assigned to the Offered Certificates by S&P, DCR or Fitch.
 
                                      S-84
<PAGE>
                                                                      APPENDIX A
 
                        PLANNED PRINCIPAL BALANCE TABLE
 
<TABLE>
<CAPTION>
                                                                                                       CLASS
DISTRIBUTION DATE                                                                                      II-A-1
- ------------------------------------------------------------------------------------------------  ----------------
<S>                                                                                               <C>
Initial Balance.................................................................................  $  85,246,108.00
December 25, 1997...............................................................................     85,246,108.00
January 25, 1998................................................................................     85,246,108.00
February 25, 1998...............................................................................     85,246,108.00
March 25, 1998..................................................................................     85,246,108.00
April 25, 1998..................................................................................     85,246,108.00
May 25, 1998....................................................................................     85,246,108.00
June 25, 1998...................................................................................     85,246,108.00
July 25, 1998...................................................................................     85,246,108.00
August 25, 1998.................................................................................     85,246,108.00
September 25, 1998..............................................................................     85,246,108.00
October 25, 1998................................................................................     84,547,846.80
November 25, 1998...............................................................................     83,812,774.97
December 25, 1998...............................................................................     83,041,080.87
January 25, 1999................................................................................     82,232,965.39
February 25, 1999...............................................................................     81,388,641.78
March 25, 1999..................................................................................     80,508,335.67
April 25, 1999..................................................................................     79,592,284.87
May 25, 1999....................................................................................     78,640,739.36
June 25, 1999...................................................................................     77,653,961.13
July 25, 1999...................................................................................     76,632,224.09
August 25, 1999.................................................................................     75,575,850.97
September 25, 1999..............................................................................     74,485,232.40
October 25, 1999................................................................................     73,360,781.22
November 25, 1999...............................................................................     72,202,999.22
December 25, 1999...............................................................................     71,012,458.27
January 25, 2000................................................................................     69,789,670.89
February 25, 2000...............................................................................     68,535,385.86
March 25, 2000..................................................................................     67,252,574.86
April 25, 2000..................................................................................     65,951,607.93
May 25, 2000....................................................................................     64,647,609.71
June 25, 2000...................................................................................     63,347,199.42
July 25, 2000...................................................................................     62,050,363.30
August 25, 2000.................................................................................     60,757,087.61
September 25, 2000..............................................................................     59,467,358.67
October 25, 2000................................................................................     58,181,162.83
November 25, 2000...............................................................................     56,898,486.49
December 25, 2000...............................................................................     55,619,316.08
January 25, 2001................................................................................     54,343,638.09
February 25, 2001...............................................................................     53,071,439.05
March 25, 2001..................................................................................     51,802,705.51
April 25, 2001..................................................................................     50,537,424.08
May 25, 2001....................................................................................     49,275,581.42
June 25, 2001...................................................................................     48,017,164.21
July 25, 2001...................................................................................     46,762,159.18
</TABLE>
 
                                      S-85
<PAGE>
                        Planned Principal Balance Table
 
<TABLE>
<CAPTION>
                                                                                                       CLASS
DISTRIBUTION DATE                                                                                      II-A-1
- ------------------------------------------------------------------------------------------------  ----------------
<S>                                                                                               <C>
August 25, 2001.................................................................................  $  45,510,553.10
September 25, 2001..............................................................................     44,262,332.80
October 25, 2001................................................................................     43,017,485.12
November 25, 2001...............................................................................     41,775,996.95
December 25, 2001...............................................................................     40,537,855.25
January 25, 2002................................................................................     39,303,046.97
February 25, 2002...............................................................................     38,071,559.14
March 25, 2002..................................................................................     36,843,378.83
April 25, 2002..................................................................................     35,618,493.11
May 25, 2002....................................................................................     34,396,889.14
June 25, 2002...................................................................................     33,178,554.09
July 25, 2002...................................................................................     31,963,475.19
August 25, 2002.................................................................................     30,751,639.68
September 25, 2002..............................................................................     29,543,034.86
October 25, 2002................................................................................     28,337,648.08
November 25, 2002...............................................................................     27,135,466.71
December 25, 2002...............................................................................     26,088,304.51
January 25, 2003................................................................................     25,044,522.65
February 25, 2003...............................................................................     24,004,110.27
March 25, 2003..................................................................................     22,967,056.54
April 25, 2003..................................................................................     21,933,350.69
May 25, 2003....................................................................................     20,902,982.00
June 25, 2003...................................................................................     19,875,939.78
July 25, 2003...................................................................................     18,852,213.41
August 25, 2003.................................................................................     17,831,792.28
September 25, 2003..............................................................................     16,814,665.87
October 25, 2003................................................................................     15,800,823.68
November 25, 2003...............................................................................     14,790,255.26
December 25, 2003...............................................................................     13,809,779.55
January 25, 2004................................................................................     12,832,431.09
February 25, 2004...............................................................................     11,858,199.26
March 25, 2004..................................................................................     10,887,073.49
April 25, 2004..................................................................................      9,919,043.24
May 25, 2004....................................................................................      8,954,098.05
June 25, 2004...................................................................................      7,992,227.46
July 25, 2004...................................................................................      7,033,421.07
August 25, 2004.................................................................................      6,077,668.52
September 25, 2004..............................................................................      5,124,959.50
October 25, 2004................................................................................      4,175,283.74
November 25, 2004...............................................................................      3,228,631.00
December 25, 2004...............................................................................      2,474,134.03
January 25, 2005................................................................................      1,742,087.34
February 25, 2005...............................................................................      1,031,955.42
March 25, 2005..................................................................................        343,214.43
April 25, 2005 and thereafter...................................................................              0.00
</TABLE>
 
                                      S-86
<PAGE>
                                                                      APPENDIX B
 
                       TARGETED PRINCIPAL BALANCE TABLES
 
<TABLE>
<CAPTION>
                                                                  CLASS             CLASS             CLASS
DISTRIBUTION DATE                                                 II-A-2            II-A-3           II-A-10
- -----------------------------------------------------------  ----------------  ----------------  ----------------
<S>                                                          <C>               <C>               <C>
Initial Balance............................................  $  72,411,210.00  $  65,563,181.00  $  10,086,644.00
December 25, 1997..........................................     72,142,886.50     65,298,128.77     10,049,267.42
January 25, 1998...........................................     71,812,046.65     64,974,392.96     10,003,182.51
February 25, 1998..........................................     71,418,791.52     64,592,067.84      9,948,403.36
March 25, 1998.............................................     70,963,329.54     64,151,348.35      9,884,959.00
April 25, 1998.............................................     70,445,897.49     63,652,455.99      9,812,882.41
May 25, 1998...............................................     69,866,812.20     63,095,687.28      9,732,217.73
June 25, 1998..............................................     69,226,470.54     62,481,413.80      9,643,020.24
July 25, 1998..............................................     68,525,349.30     61,810,082.03      9,545,356.35
August 25, 1998............................................     67,764,004.81     61,082,213.02      9,439,303.56
September 25, 1998.........................................     66,943,072.45     60,298,401.91      9,324,950.38
October 25, 1998...........................................     66,368,826.33     59,745,758.93      9,244,959.78
November 25, 1998..........................................     65,752,703.24     59,153,775.62      9,159,135.85
December 25, 1998..........................................     65,095,484.65     58,523,184.08      9,067,587.46
January 25, 1999...........................................     64,398,021.84     57,854,781.82      8,970,433.18
February 25, 1999..........................................     63,661,234.59     57,149,430.58      8,867,801.13
March 25, 1999.............................................     62,886,109.71     56,408,054.93      8,759,828.78
April 25, 1999.............................................     62,073,699.40     55,631,640.74      8,646,662.69
May 25, 1999...............................................     61,225,119.45     54,821,233.49      8,528,458.28
June 25, 1999..............................................     60,341,547.31     53,977,936.43      8,405,379.58
July 25, 1999..............................................     59,424,219.94     53,102,908.63      8,277,598.89
August 25, 1999............................................     58,474,476.45     52,197,404.92      8,145,302.74
September 25, 1999.........................................     57,493,776.72     51,262,793.29      8,008,694.48
October 25, 1999...........................................     56,483,641.22     50,300,498.58      7,867,985.92
November 25, 1999..........................................     55,445,727.79     49,312,074.37      7,723,407.98
December 25, 1999..........................................     54,381,802.47     48,299,175.68      7,575,206.68
January 25, 2000...........................................     53,293,580.03     47,263,409.47      7,423,620.86
February 25, 2000..........................................     52,183,075.27     46,206,663.93      7,268,931.19
March 25, 2000.............................................     51,054,942.11     45,133,301.27      7,111,785.94
April 25, 2000.............................................     49,922,488.56     44,055,796.28      6,954,038.88
May 25, 2000...............................................     48,804,210.22     42,991,486.77      6,798,266.38
June 25, 2000..............................................     47,707,908.44     41,947,685.41      6,645,555.13
July 25, 2000..............................................     46,633,268.72     40,924,096.85      6,495,861.35
August 25, 2000............................................     45,579,980.90     39,920,429.77      6,349,141.81
September 25, 2000.........................................     44,547,739.08     38,936,396.88      6,205,353.91
October 25, 2000...........................................     43,536,241.59     37,971,714.82      6,064,455.63
November 25, 2000..........................................     42,545,190.92     37,026,104.13      5,926,405.52
December 25, 2000..........................................     41,574,293.64     36,099,289.19      5,791,162.71
January 25, 2001...........................................     40,623,260.39     35,190,998.19      5,658,686.90
February 25, 2001..........................................     39,691,805.80     34,300,963.03      5,528,938.33
March 25, 2001.............................................     38,779,648.42     33,428,919.31      5,401,877.80
April 25, 2001.............................................     37,886,510.71     32,574,606.27      5,277,466.65
May 25, 2001...............................................     37,012,118.93     31,737,766.74      5,155,666.74
June 25, 2001..............................................     36,156,203.15     30,918,147.09      5,036,440.48
July 25, 2001..............................................     35,318,497.16     30,115,497.17      4,919,750.79
</TABLE>
 
                                      S-87
<PAGE>
                       TARGETED PRINCIPAL BALANCE TABLES
 
<TABLE>
<CAPTION>
                                                                  CLASS             CLASS             CLASS
DISTRIBUTION DATE                                                 II-A-2            II-A-3           II-A-10
- -----------------------------------------------------------  ----------------  ----------------  ----------------
<S>                                                          <C>               <C>               <C>
August 25, 2001............................................  $  34,498,738.41  $  29,329,570.29  $   4,805,561.08
September 25, 2001.........................................     33,696,668.01     28,560,123.15      4,693,835.31
October 25, 2001...........................................     32,912,030.62     27,806,915.81      4,584,537.89
November 25, 2001..........................................     32,144,574.44     27,069,711.63      4,477,633.77
December 25, 2001..........................................     31,394,051.17     26,348,277.22      4,373,088.34
January 25, 2002...........................................     30,660,215.93     25,642,382.43      4,270,867.49
February 25, 2002..........................................     29,942,827.22     24,951,800.27      4,170,937.60
March 25, 2002.............................................     29,241,646.89     24,276,306.88      4,073,265.48
April 25, 2002.............................................     28,556,440.11     23,615,681.49      3,977,818.43
May 25, 2002...............................................     27,886,975.28     22,969,706.39      3,884,564.17
June 25, 2002..............................................     27,233,024.00     22,338,166.84      3,793,470.90
July 25, 2002..............................................     26,594,361.06     21,720,851.10      3,704,507.25
August 25, 2002............................................     25,970,764.37     21,117,550.34      3,617,642.28
September 25, 2002.........................................     25,362,014.90     20,528,058.60      3,532,845.47
October 25, 2002...........................................     24,767,896.67     19,952,172.80      3,450,086.75
November 25, 2002..........................................     24,188,196.71     19,389,692.62      3,369,336.45
December 25, 2002..........................................     23,733,391.68     18,944,181.62      3,305,983.60
January 25, 2003...........................................     23,291,792.29     18,510,938.23      3,244,470.26
February 25, 2003..........................................     22,863,196.12     18,089,772.00      3,184,768.21
March 25, 2003.............................................     22,447,403.52     17,680,495.15      3,126,849.67
April 25, 2003.............................................     22,044,217.66     17,282,922.48      3,070,687.20
May 25, 2003...............................................     21,653,444.42     16,896,871.38      3,016,253.77
June 25, 2003..............................................     21,274,892.41     16,522,161.74      2,963,522.72
July 25, 2003..............................................     20,908,372.92     16,158,616.00      2,912,467.75
August 25, 2003............................................     20,553,699.84     15,806,059.02      2,863,062.96
September 25, 2003.........................................     20,210,689.68     15,464,318.12      2,815,282.77
October 25, 2003...........................................     19,879,161.53     15,133,223.00      2,769,101.98
November 25, 2003..........................................     19,558,936.96     14,812,605.73      2,724,495.75
December 25, 2003..........................................     19,284,100.73     14,534,417.71      2,686,211.97
January 25, 2004...........................................     19,019,732.02     14,265,922.39      2,649,386.27
February 25, 2004..........................................     18,765,663.46     14,006,962.19      2,613,995.36
March 25, 2004.............................................     18,521,730.07     13,757,381.74      2,580,016.24
April 25, 2004.............................................     18,287,769.20     13,517,027.87      2,547,426.26
May 25, 2004...............................................     18,063,620.51     13,285,749.53      2,516,203.08
June 25, 2004..............................................     17,849,125.92     13,063,397.86      2,486,324.69
July 25, 2004..............................................     17,644,129.62     12,849,826.03      2,457,769.37
August 25, 2004............................................     17,448,477.97     12,644,889.34      2,430,515.74
September 25, 2004.........................................     17,262,019.56     12,448,445.08      2,404,542.69
October 25, 2004...........................................     17,084,605.09     12,260,352.60      2,379,829.44
November 25, 2004..........................................     16,916,087.41     12,080,473.19      2,356,355.48
December 25, 2004..........................................     16,758,521.60     11,910,732.61      2,334,407.08
January 25, 2005...........................................     16,599,692.48     11,739,679.24      2,312,282.71
February 25, 2005..........................................     16,439,702.90     11,567,408.74      2,289,996.68
March 25, 2005.............................................     16,278,652.53     11,394,013.79      2,267,562.89
April 25, 2005.............................................     15,974,589.98     11,086,424.06      2,225,207.98
May 25, 2005...............................................     15,528,401.08     10,645,469.20      2,163,055.33
June 25, 2005..............................................     15,090,133.34     10,211,807.54      2,102,006.07
</TABLE>
 
                                      S-88
<PAGE>
                       TARGETED PRINCIPAL BALANCE TABLES
 
<TABLE>
<CAPTION>
                                                                  CLASS             CLASS             CLASS
DISTRIBUTION DATE                                                 II-A-2            II-A-3           II-A-10
- -----------------------------------------------------------  ----------------  ----------------  ----------------
<S>                                                          <C>               <C>               <C>
July 25, 2005..............................................  $  14,659,664.51  $   9,785,323.75  $   2,042,043.17
August 25, 2005............................................     14,236,874.17      9,365,904.11      1,983,149.87
September 25, 2005.........................................     13,821,643.58      8,953,436.58      1,925,309.61
October 25, 2005...........................................     13,413,855.75      8,547,810.68      1,868,506.10
November 25, 2005..........................................     13,013,395.40      8,148,917.55      1,812,723.29
December 25, 2005..........................................     12,695,983.68      7,827,739.73      1,768,508.88
January 25, 2006...........................................     12,384,030.09      7,511,540.71      1,725,054.76
February 25, 2006..........................................     12,077,448.56      7,200,238.99      1,682,348.96
March 25, 2006.............................................     11,776,154.29      6,893,754.27      1,640,379.66
April 25, 2006.............................................     11,480,063.74      6,592,007.45      1,599,135.22
May 25, 2006...............................................     11,189,094.65      6,294,920.56      1,558,604.18
June 25, 2006..............................................     10,903,165.97      6,002,416.82      1,518,775.25
July 25, 2006..............................................     10,622,197.88      5,714,420.58      1,479,637.32
August 25, 2006............................................     10,346,111.75      5,430,857.29      1,441,179.43
September 25, 2006.........................................     10,074,830.14      5,151,653.51      1,403,390.79
October 25, 2006...........................................      9,808,276.76      4,876,736.90      1,366,260.78
November 25, 2006..........................................      9,546,376.48      4,606,036.16      1,329,778.93
December 25, 2006..........................................      9,354,466.72      4,400,799.76      1,303,046.53
January 25, 2007...........................................      9,165,274.91      4,197,963.46      1,276,692.73
February 25, 2007..........................................      8,978,763.54      3,997,491.24      1,250,712.30
March 25, 2007.............................................      8,794,895.61      3,799,347.55      1,225,100.11
April 25, 2007.............................................      8,613,634.64      3,603,497.32      1,199,851.05
May 25, 2007...............................................      8,434,944.64      3,409,905.93      1,174,960.12
June 25, 2007..............................................      8,258,790.10      3,218,539.22      1,150,422.37
July 25, 2007..............................................      8,085,136.02      3,029,363.48      1,126,232.92
August 25, 2007............................................      7,913,947.85      2,842,345.43      1,102,386.97
September 25, 2007.........................................      7,745,191.52      2,657,452.25      1,078,879.77
October 25, 2007...........................................      7,578,833.43      2,474,651.52      1,055,706.63
November 25, 2007..........................................      7,414,840.44      2,293,911.27      1,032,862.95
December 25, 2007..........................................      7,253,179.85      2,115,199.94      1,010,344.16
January 25, 2008...........................................      7,093,819.41      1,938,486.37        988,145.77
February 25, 2008..........................................      6,936,727.32      1,763,739.83        966,263.36
March 25, 2008.............................................      6,781,872.19      1,590,929.97        944,692.55
April 25, 2008.............................................      6,629,223.10      1,420,026.86        923,429.03
May 25, 2008...............................................      6,478,749.50      1,251,000.92        902,468.55
June 25, 2008..............................................      6,330,421.30      1,083,823.01        881,806.92
July 25, 2008..............................................      6,184,208.80        918,464.32        861,440.00
August 25, 2008............................................      6,040,082.71        754,896.43        841,363.71
September 25, 2008.........................................      5,898,014.13        593,091.32        821,574.02
October 25, 2008...........................................      5,757,974.56        433,021.28        802,066.97
November 25, 2008..........................................      5,619,935.91        274,659.00        782,838.64
December 25, 2008..........................................      5,483,870.45        117,977.50        763,885.16
January 25, 2009...........................................      5,349,750.82              0.00        745,202.74
February 25, 2009..........................................      5,217,550.07              0.00        726,787.61
March 25, 2009.............................................      5,087,241.57              0.00        708,636.06
April 25, 2009.............................................      4,958,799.10              0.00        690,744.45
May 25, 2009...............................................      4,832,196.78              0.00        673,109.16
</TABLE>
 
                                      S-89
<PAGE>
                       TARGETED PRINCIPAL BALANCE TABLES
 
<TABLE>
<CAPTION>
                                                                  CLASS             CLASS             CLASS
DISTRIBUTION DATE                                                 II-A-2            II-A-3           II-A-10
- -----------------------------------------------------------  ----------------  ----------------  ----------------
<S>                                                          <C>               <C>               <C>
June 25, 2009..............................................  $   4,707,409.06  $           0.00  $     655,726.64
July 25, 2009..............................................      4,584,410.77              0.00        638,593.38
August 25, 2009............................................      4,463,177.09              0.00        621,705.93
September 25, 2009.........................................      4,343,683.50              0.00        605,060.86
October 25, 2009...........................................      4,225,905.85              0.00        588,654.82
November 25, 2009..........................................      4,109,820.30              0.00        572,484.49
December 25, 2009..........................................      3,995,403.36              0.00        556,546.58
January 25, 2010...........................................      3,882,631.84              0.00        540,837.88
February 25, 2010..........................................      3,771,482.86              0.00        525,355.19
March 25, 2010.............................................      3,661,933.88              0.00        510,095.38
April 25, 2010.............................................      3,553,962.64              0.00        495,055.34
May 25, 2010...............................................      3,447,547.22              0.00        480,232.02
June 25, 2010..............................................      3,342,665.95              0.00        465,622.40
July 25, 2010..............................................      3,239,297.51              0.00        451,223.52
August 25, 2010............................................      3,137,420.83              0.00        437,032.43
September 25, 2010.........................................      3,037,015.15              0.00        423,046.25
October 25, 2010...........................................      2,938,059.98              0.00        409,262.12
November 25, 2010..........................................      2,840,535.13              0.00        395,677.23
December 25, 2010..........................................      2,744,420.68              0.00        382,288.80
January 25, 2011...........................................      2,649,696.96              0.00        369,094.09
February 25, 2011..........................................      2,556,344.60              0.00        356,090.42
March 25, 2011.............................................      2,464,344.48              0.00        343,275.10
April 25, 2011.............................................      2,373,677.74              0.00        330,645.52
May 25, 2011...............................................      2,284,325.79              0.00        318,199.09
June 25, 2011..............................................      2,196,270.28              0.00        305,933.25
July 25, 2011..............................................      2,109,493.13              0.00        293,845.47
August 25, 2011............................................      2,023,976.48              0.00        281,933.28
September 25, 2011.........................................      1,939,702.74              0.00        270,194.23
October 25, 2011...........................................      1,856,654.55              0.00        258,625.89
November 25, 2011..........................................      1,774,814.79              0.00        247,225.88
December 25, 2011..........................................      1,694,166.58              0.00        235,991.85
January 25, 2012...........................................      1,614,693.26              0.00        224,921.47
February 25, 2012..........................................      1,536,378.41              0.00        214,012.47
March 25, 2012.............................................      1,459,205.83              0.00        203,262.58
April 25, 2012.............................................      1,383,159.53              0.00        192,669.59
May 25, 2012...............................................      1,308,223.77              0.00        182,231.28
June 25, 2012..............................................      1,234,382.99              0.00        171,945.50
July 25, 2012..............................................      1,161,621.87              0.00        161,810.12
August 25, 2012............................................      1,089,925.28              0.00        151,823.02
September 25, 2012.........................................      1,019,278.33              0.00        141,982.13
October 25, 2012...........................................        949,666.29              0.00        132,285.40
November 25, 2012..........................................        881,074.67              0.00        122,730.81
December 25, 2012..........................................        813,489.16              0.00        113,316.37
January 25, 2013...........................................        746,895.66              0.00        104,040.11
February 25, 2013..........................................        681,280.23              0.00         94,900.10
March 25, 2013.............................................        616,629.17              0.00         85,894.42
April 25, 2013.............................................        552,928.92              0.00         77,021.19
</TABLE>
 
                                      S-90
<PAGE>
                       TARGETED PRINCIPAL BALANCE TABLES
 
<TABLE>
<CAPTION>
                                                                  CLASS             CLASS             CLASS
DISTRIBUTION DATE                                                 II-A-2            II-A-3           II-A-10
- -----------------------------------------------------------  ----------------  ----------------  ----------------
<S>                                                          <C>               <C>               <C>
May 25, 2013...............................................  $     490,166.16  $           0.00  $      68,278.54
June 25, 2013..............................................        428,327.70              0.00         59,664.64
July 25, 2013..............................................        367,400.56              0.00         51,177.69
August 25, 2013............................................        307,371.94              0.00         42,815.90
September 25, 2013.........................................        248,229.21              0.00         34,577.51
October 25, 2013...........................................        189,959.90              0.00         26,460.79
November 25, 2013..........................................        132,551.73              0.00         18,464.02
December 25, 2013..........................................         75,992.58              0.00         10,585.52
January 25, 2014...........................................         20,270.51              0.00          2,823.62
February 25, 2014 and thereafter...........................              0.00              0.00              0.00
</TABLE>
 
                                      S-91
<PAGE>
                                                                     APPENDIX C+
 
             PERCENT OF INITIAL CLASS PRINCIPAL BALANCE OUTSTANDING
           AT VARIOUS PERCENTAGES OF THE BASIC PREPAYMENT ASSUMPTION
<TABLE>
<CAPTION>
                                                          CLASS I-A-1
<S>                                  <C>        <C>        <C>        <C>        <C>
                                     -----------------------------------------------------
 
<CAPTION>
DISTRIBUTION DATE                       0%         50%       100%       150%       200%
- -----------------------------------  -----------------------------------------------------
<S>                                  <C>        <C>        <C>        <C>        <C>
Initial Percentage.................        100%       100%       100%       100%       100%
November 25, 1998..................         99         93         87         81         75
November 25, 1999..................         98         84         71         59         48
November 25, 2000..................         97         76         58         43         30
November 25, 2001..................         96         69         47         31         18
November 25, 2002..................         95         62         38         21         10
November 25, 2003..................         94         56         31         15          5
November 25, 2004..................         93         50         25         10          2
November 25, 2005..................         91         46         20          7          1
November 25, 2006..................         90         41         17          5          *
November 25, 2007..................         88         37         14          4          *
November 25, 2008..................         86         33         11          3          *
November 25, 2009..................         84         30          9          2          *
November 25, 2010..................         82         27          8          2          *
November 25, 2011..................         79         24          6          1          *
November 25, 2012..................         77         21          5          1          *
November 25, 2013..................         74         19          4          1          *
November 25, 2014..................         71         17          3          *          *
November 25, 2015..................         68         15          3          *          *
November 25, 2016..................         64         13          2          *          *
November 25, 2017..................         60         11          2          *          *
November 25, 2018..................         56          9          1          *          *
November 25, 2019..................         51          8          1          *          *
November 25, 2020..................         47          7          1          *          *
November 25, 2021..................         41          5          1          *          *
November 25, 2022..................         36          4          *          *          *
November 25, 2023..................         29          3          *          *          *
November 25, 2024..................         23          2          *          *          *
November 25, 2025..................         15          1          *          *          *
November 25, 2026..................          7          1          *          *          *
November 25, 2027..................          *          *          *          *          *
Weighted Average Life (Years)
 (1)...............................       20.5        9.2        5.2        3.4        2.5
 
<CAPTION>
                                                        CLASS II-A-1
<S>                                  <C>     <C>        <C>        <C>        <C>
                                     --------------------------------------------------
DISTRIBUTION DATE                      0%      100%       250%       350%       500%
- -----------------------------------  --------------------------------------------------
<S>                                  <C>     <C>        <C>        <C>        <C>
Initial Percentage.................     100%       100%       100%       100%       100   %
November 25, 1998..................      99         98         98         98         98
November 25, 1999..................      96         85         85         85         85
November 25, 2000..................      92         67         67         67         67
November 25, 2001..................      88         49         49         49         34
November 25, 2002..................      84         32         32         32          0
November 25, 2003..................      80         17         17         17          0
November 25, 2004..................      76          4          4          4          0
November 25, 2005..................      71          0          0          0          0
November 25, 2006..................      66          0          0          0          0
November 25, 2007..................      61          0          0          0          0
November 25, 2008..................      56          0          0          0          0
November 25, 2009..................      49          0          0          0          0
November 25, 2010..................      43          0          0          0          0
November 25, 2011..................      36          0          0          0          0
November 25, 2012..................      28          0          0          0          0
November 25, 2013..................      20          0          0          0          0
November 25, 2014..................      10          0          0          0          0
November 25, 2015..................       1          0          0          0          0
November 25, 2016..................       0          0          0          0          0
November 25, 2017..................       0          0          0          0          0
November 25, 2018..................       0          0          0          0          0
November 25, 2019..................       0          0          0          0          0
November 25, 2020..................       0          0          0          0          0
November 25, 2021..................       0          0          0          0          0
November 25, 2022..................       0          0          0          0          0
November 25, 2023..................       0          0          0          0          0
November 25, 2024..................       0          0          0          0          0
November 25, 2025..................       0          0          0          0          0
November 25, 2026..................       0          0          0          0          0
November 25, 2027..................       0          0          0          0          0
Weighted Average Life (Years)
 (1)...............................    11.1        4.1        4.1        4.1        3.4
 
<CAPTION>
                                                        CLASS II-A-2
                                     --------------------------------------------------
DISTRIBUTION DATE                      0%      100%       250%       350%       500%
- -----------------------------------  --------------------------------------------------
Initial Percentage.................     100%       100%       100%       100%       100%
November 25, 1998..................      98         95         91         91         90
November 25, 1999..................      97         91         77         72         55
November 25, 2000..................      96         86         59         44         16
November 25, 2001..................      96         82         44         23          0
November 25, 2002..................      95         78         33          9          0
November 25, 2003..................      94         75         27          2          0
November 25, 2004..................      93         72         23          *          0
November 25, 2005..................      92         65         18          0          0
November 25, 2006..................      91         57         13          0          0
November 25, 2007..................      90         49         10          0          0
November 25, 2008..................      88         42          8          0          0
November 25, 2009..................      87         35          6          0          0
November 25, 2010..................      85         29          4          0          0
November 25, 2011..................      84         22          2          0          0
November 25, 2012..................      82         16          1          0          0
November 25, 2013..................      80         10          *          0          0
November 25, 2014..................      78          4          0          0          0
November 25, 2015..................      76          0          0          0          0
November 25, 2016..................      68          0          0          0          0
November 25, 2017..................      60          0          0          0          0
November 25, 2018..................      50          0          0          0          0
November 25, 2019..................      40          0          0          0          0
November 25, 2020..................      28          0          0          0          0
November 25, 2021..................      16          0          0          0          0
November 25, 2022..................       3          0          0          0          0
November 25, 2023..................       0          0          0          0          0
November 25, 2024..................       0          0          0          0          0
November 25, 2025..................       0          0          0          0          0
November 25, 2026..................       0          0          0          0          0
November 25, 2027..................       0          0          0          0          0
Weighted Average Life (Years)
 (1)...............................    19.2        9.6        4.7        2.9        2.1
 
<CAPTION>
                                                        CLASS II-A-3
                                     --------------------------------------------------
DISTRIBUTION DATE                      0%      100%       250%       350%       500%
- -----------------------------------  --------------------------------------------------
Initial Percentage.................     100%       100%       100%       100%       100%
November 25, 1998..................      97         94         90        100         96
November 25, 1999..................      96         90         75         76         58
November 25, 2000..................      95         84         56         47         17
November 25, 2001..................      93         79         41         24          0
November 25, 2002..................      92         74         30          9          0
November 25, 2003..................      90         70         23          2          0
November 25, 2004..................      88         66         18          *          0
November 25, 2005..................      86         58         12          0          0
November 25, 2006..................      84         48          7          0          0
November 25, 2007..................      82         39          3          0          0
November 25, 2008..................      80         31          *          0          0
November 25, 2009..................      77         23          0          0          0
November 25, 2010..................      75         14          0          0          0
November 25, 2011..................      72          6          0          0          0
November 25, 2012..................      69          0          0          0          0
November 25, 2013..................      66          0          0          0          0
November 25, 2014..................      62          0          0          0          0
November 25, 2015..................      58          0          0          0          0
November 25, 2016..................      48          0          0          0          0
November 25, 2017..................      37          0          0          0          0
November 25, 2018..................      25          0          0          0          0
November 25, 2019..................      12          0          0          0          0
November 25, 2020..................       0          0          0          0          0
November 25, 2021..................       0          0          0          0          0
November 25, 2022..................       0          0          0          0          0
November 25, 2023..................       0          0          0          0          0
November 25, 2024..................       0          0          0          0          0
November 25, 2025..................       0          0          0          0          0
November 25, 2026..................       0          0          0          0          0
November 25, 2027..................       0          0          0          0          0
Weighted Average Life (Years)
 (1)...............................    16.4        8.3        4.1        3.1        2.2
</TABLE>
 
- ----------------------------------
 +  This table has been prepared based on the assumptions described herein under
    "Yield and Prepayment Considerations--General" (including the assumptions
    regarding the characteristics and performance of the Mortgage Loans which
    differ from the actual characteristics and performance thereof) and should
    be read in conjunction therewith.
 
 *  Indicates an amount above zero and less than 0.5% of original principal
    balance outstanding.
 
(1) The weighted average life of any Class of Certificates is determined by (i)
    multiplying the amount of each assumed principal distribution on such Class
    of Certificates by the number of years from the date of issuance of the
    Certificates to the related Distribution Date, (ii) summing the results, and
    (iii) dividing the sum by the total amount of principal distributed on such
    Class of Certificates.
 
                                      S-92
<PAGE>
             PERCENT OF INITIAL CLASS PRINCIPAL BALANCE OUTSTANDING
           AT VARIOUS PERCENTAGES OF THE BASIC PREPAYMENT ASSUMPTION
<TABLE>
<CAPTION>
                                                         CLASS II-A-4
<S>                                  <C>        <C>        <C>        <C>        <C>
                                     -----------------------------------------------------
 
<CAPTION>
DISTRIBUTION DATE                       0%        100%       250%       350%       500%
- -----------------------------------  -----------------------------------------------------
<S>                                  <C>        <C>        <C>        <C>        <C>
Initial Percentage.................        100%       100%       100%       100%       100%
November 25, 1998..................        107        107         91         49          0
November 25, 1999..................        115        115         77          0          0
November 25, 2000..................        123        123         59          0          0
November 25, 2001..................        132        132         44          0          0
November 25, 2002..................        142        142         33          0          0
November 25, 2003..................        152        152         27          0          0
November 25, 2004..................        163        163         23          0          0
November 25, 2005..................        175        175         18          0          0
November 25, 2006..................        187        187         13          0          0
November 25, 2007..................        201        201         10          0          0
November 25, 2008..................        215        215          8          0          0
November 25, 2009..................        231        231          6          0          0
November 25, 2010..................        248        248          4          0          0
November 25, 2011..................        266        266          2          0          0
November 25, 2012..................        285        285          1          0          0
November 25, 2013..................        305        305          *          0          0
November 25, 2014..................        328        328          0          0          0
November 25, 2015..................        351        326          0          0          0
November 25, 2016..................        377        284          0          0          0
November 25, 2017..................        404        245          0          0          0
November 25, 2018..................        433        207          0          0          0
November 25, 2019..................        464        171          0          0          0
November 25, 2020..................        498        137          0          0          0
November 25, 2021..................        534        105          0          0          0
November 25, 2022..................        573         74          0          0          0
November 25, 2023..................        493         45          0          0          0
November 25, 2024..................        367         17          0          0          0
November 25, 2025..................        230          0          0          0          0
November 25, 2026..................         82          0          0          0          0
November 25, 2027..................          0          0          0          0          0
Weighted Average Life (Years)
 (1)...............................       27.5       22.3        4.7        1.0        0.6
 
<CAPTION>
                                                        CLASS II-A-5
<S>                                  <C>     <C>        <C>        <C>        <C>
                                     --------------------------------------------------
DISTRIBUTION DATE                      0%      100%       250%       350%       500%
- -----------------------------------  --------------------------------------------------
<S>                                  <C>     <C>        <C>        <C>        <C>
Initial Percentage.................     100%       100%       100%       100%       100   %
November 25, 1998..................     107        107         94          9          0
November 25, 1999..................     115        115         85          0          0
November 25, 2000..................     123        123         73          0          0
November 25, 2001..................     132        132         64          0          0
November 25, 2002..................     142        142         57          0          0
November 25, 2003..................     152        152         55          0          0
November 25, 2004..................     163        163         54          0          0
November 25, 2005..................     175        175         53          0          0
November 25, 2006..................     187        187         52          0          0
November 25, 2007..................     201        201         52          0          0
November 25, 2008..................     215        215         54          0          0
November 25, 2009..................     231        231         41          0          0
November 25, 2010..................     248        248         28          0          0
November 25, 2011..................     266        266         18          0          0
November 25, 2012..................     285        274          9          0          0
November 25, 2013..................     305        245          1          0          0
November 25, 2014..................     328        218          0          0          0
November 25, 2015..................     351        192          0          0          0
November 25, 2016..................     377        167          0          0          0
November 25, 2017..................     404        144          0          0          0
November 25, 2018..................     433        122          0          0          0
November 25, 2019..................     464        101          0          0          0
November 25, 2020..................     482         81          0          0          0
November 25, 2021..................     423         62          0          0          0
November 25, 2022..................     359         43          0          0          0
November 25, 2023..................     290         26          0          0          0
November 25, 2024..................     216         10          0          0          0
November 25, 2025..................     135          0          0          0          0
November 25, 2026..................      48          0          0          0          0
November 25, 2027..................       0          0          0          0          0
Weighted Average Life (Years)
 (1)...............................    26.5       20.6        8.5        0.7        0.5
 
<CAPTION>
                                                        CLASS II-A-6
                                     --------------------------------------------------
DISTRIBUTION DATE                      0%      100%       250%       350%       500%
- -----------------------------------  --------------------------------------------------
Initial Percentage.................     100%       100%       100%       100%       100%
November 25, 1998..................     107        107         91         26          0
November 25, 1999..................     115        115         77          0          0
November 25, 2000..................     123        123         59          0          0
November 25, 2001..................     132        132         44          0          0
November 25, 2002..................     142        142         33          0          0
November 25, 2003..................     152        152         27          0          0
November 25, 2004..................     163        163         23          0          0
November 25, 2005..................     175        175         18          0          0
November 25, 2006..................     187        187         13          0          0
November 25, 2007..................     201        201         10          0          0
November 25, 2008..................     215        215          8          0          0
November 25, 2009..................     231        231          6          0          0
November 25, 2010..................     248        248          4          0          0
November 25, 2011..................     266        266          2          0          0
November 25, 2012..................     285        285          1          0          0
November 25, 2013..................     305        305          *          0          0
November 25, 2014..................     328        328          0          0          0
November 25, 2015..................     351        351          0          0          0
November 25, 2016..................     377        377          0          0          0
November 25, 2017..................     404        380          0          0          0
November 25, 2018..................     433        321          0          0          0
November 25, 2019..................     464        266          0          0          0
November 25, 2020..................     498        213          0          0          0
November 25, 2021..................     534        163          0          0          0
November 25, 2022..................     573        115          0          0          0
November 25, 2023..................     614         70          0          0          0
November 25, 2024..................     570         27          0          0          0
November 25, 2025..................     357          0          0          0          0
November 25, 2026..................     128          0          0          0          0
November 25, 2027..................       0          0          0          0          0
Weighted Average Life (Years)
 (1)...............................    28.2       23.5        4.7        0.8        0.5
 
<CAPTION>
                                                        CLASS II-A-7
                                     --------------------------------------------------
DISTRIBUTION DATE                      0%      100%       250%       350%       500%
- -----------------------------------  --------------------------------------------------
Initial Percentage.................     100%       100%       100%       100%       100%
November 25, 1998..................     100        100        100        100        100
November 25, 1999..................     100        100        100        100        100
November 25, 2000..................     100        100        100        100        100
November 25, 2001..................     100        100        100        100        100
November 25, 2002..................     100        100        100        100          0
November 25, 2003..................     100        100        100        100          0
November 25, 2004..................     100        100        100        100          0
November 25, 2005..................     100        100        100         40          0
November 25, 2006..................     100        100        100          1          0
November 25, 2007..................     100        100        100          1          0
November 25, 2008..................     100        100        100          1          0
November 25, 2009..................     100        100        100          1          0
November 25, 2010..................     100        100        100          *          0
November 25, 2011..................     100        100        100          *          0
November 25, 2012..................     100        100        100          *          0
November 25, 2013..................     100        100        100          *          0
November 25, 2014..................     100        100         85          *          0
November 25, 2015..................     100        100         69          *          0
November 25, 2016..................     100        100         55          *          0
November 25, 2017..................     100        100         44          *          0
November 25, 2018..................     100        100         35          *          0
November 25, 2019..................     100        100         27          *          0
November 25, 2020..................     100        100         21          *          0
November 25, 2021..................     100        100         16          *          0
November 25, 2022..................     100        100         12          *          0
November 25, 2023..................     100        100          8          *          0
November 25, 2024..................     100        100          5          *          0
November 25, 2025..................     100         83          3          *          0
November 25, 2026..................     100         38          1          *          0
November 25, 2027..................       0          0          0          0          0
Weighted Average Life (Years)
 (1)...............................    29.8       28.8       20.4        8.1        4.9
</TABLE>
 
- ----------------------------------
 *  Indicates an amount above zero and less than 0.5% of original principal
    balance outstanding.
 
(1) The weighted average life of any Class of Certificates is determined by (i)
    multiplying the amount of each assumed principal distribution on such Class
    of Certificates by the number of years from the date of issuance of the
    Certificates to the related Distribution Date, (ii) summing the results, and
    (iii) dividing the sum by the total amount of principal distributed on such
    Class of Certificates.
 
                                      S-93
<PAGE>
             PERCENT OF INITIAL CLASS PRINCIPAL BALANCE OUTSTANDING
           AT VARIOUS PERCENTAGES OF THE BASIC PREPAYMENT ASSUMPTION
<TABLE>
<CAPTION>
                                                     CLASS II-A-8, II-A-9
<S>                                  <C>        <C>        <C>        <C>        <C>
                                     -----------------------------------------------------
 
<CAPTION>
DISTRIBUTION DATE                       0%        100%       250%       350%       500%
- -----------------------------------  -----------------------------------------------------
<S>                                  <C>        <C>        <C>        <C>        <C>
Initial Percentage.................        100%       100%       100%       100%       100%
November 25, 1998..................        100        100        100        100        100
November 25, 1999..................        100        100        100        100        100
November 25, 2000..................        100        100        100        100        100
November 25, 2001..................        100        100        100        100        100
November 25, 2002..................        100        100        100        100         99
November 25, 2003..................         99         97         94         92         63
November 25, 2004..................         97         93         87         83         39
November 25, 2005..................         96         88         77         71         25
November 25, 2006..................         94         83         67         57         16
November 25, 2007..................         92         76         56         44         11
November 25, 2008..................         90         70         46         34          8
November 25, 2009..................         88         64         38         26          5
November 25, 2010..................         86         59         32         20          3
November 25, 2011..................         83         54         26         16          2
November 25, 2012..................         80         49         22         12          2
November 25, 2013..................         77         44         18          9          1
November 25, 2014..................         74         40         14          7          1
November 25, 2015..................         71         36         12          5          *
November 25, 2016..................         67         32          9          4          *
November 25, 2017..................         63         28          7          3          *
November 25, 2018..................         58         24          6          2          *
November 25, 2019..................         54         21          5          2          *
November 25, 2020..................         49         18          4          1          *
November 25, 2021..................         43         15          3          1          *
November 25, 2022..................         37         12          2          1          *
November 25, 2023..................         30          9          1          *          *
November 25, 2024..................         23          7          1          *          *
November 25, 2025..................         16          4          1          *          *
November 25, 2026..................          8          2          *          *          *
November 25, 2027..................          0          0          0          0          0
Weighted Average Life (Years)
 (1)...............................       21.3       15.8       11.8       10.4        7.3
 
<CAPTION>
                                                       CLASS II-A-10
<S>                                  <C>     <C>        <C>        <C>        <C>
                                     --------------------------------------------------
DISTRIBUTION DATE                      0%      100%       250%       350%       500%
- -----------------------------------  --------------------------------------------------
<S>                                  <C>     <C>        <C>        <C>        <C>
Initial Percentage.................     100%       100%       100%       100%       100   %
November 25, 1998..................      98         95         91         91         87
November 25, 1999..................      98         92         77         70         53
November 25, 2000..................      97         88         59         42         16
November 25, 2001..................      97         84         44         22          0
November 25, 2002..................      96         80         33          8          0
November 25, 2003..................      96         77         27          2          0
November 25, 2004..................      95         75         23          *          0
November 25, 2005..................      94         68         18          0          0
November 25, 2006..................      94         61         13          0          0
November 25, 2007..................      93         54         10          0          0
November 25, 2008..................      92         48          8          0          0
November 25, 2009..................      91         41          6          0          0
November 25, 2010..................      90         35          4          0          0
November 25, 2011..................      89         30          2          0          0
November 25, 2012..................      88         24          1          0          0
November 25, 2013..................      87         19          *          0          0
November 25, 2014..................      86         14          0          0          0
November 25, 2015..................      85          9          0          0          0
November 25, 2016..................      78          4          0          0          0
November 25, 2017..................      70          0          0          0          0
November 25, 2018..................      62          0          0          0          0
November 25, 2019..................      53          0          0          0          0
November 25, 2020..................      43          0          0          0          0
November 25, 2021..................      32          0          0          0          0
November 25, 2022..................      21          0          0          0          0
November 25, 2023..................       8          0          0          0          0
November 25, 2024..................       0          0          0          0          0
November 25, 2025..................       0          0          0          0          0
November 25, 2026..................       0          0          0          0          0
November 25, 2027..................       0          0          0          0          0
Weighted Average Life (Years)
 (1)...............................    20.9       10.5        4.7        2.9        2.1
 
<CAPTION>
                                                        CLASS III-PT
                                     --------------------------------------------------
DISTRIBUTION DATE                      0%      100%       235%       350%       500%
- -----------------------------------  --------------------------------------------------
Initial Percentage.................     100%       100%       100%       100%       100%
November 25, 1998..................      96         94         92         89         86
November 25, 1999..................      92         86         79         72         64
November 25, 2000..................      88         77         64         54         42
November 25, 2001..................      83         68         52         40         27
November 25, 2002..................      78         60         41         29         17
November 25, 2003..................      73         53         33         21         10
November 25, 2004..................      67         45         26         15          6
November 25, 2005..................      60         38         20         10          4
November 25, 2006..................      53         32         15          7          2
November 25, 2007..................      46         26         11          5          1
November 25, 2008..................      38         20          8          3          1
November 25, 2009..................      30         15          5          2          *
November 25, 2010..................      20         10          3          1          *
November 25, 2011..................      11          5          1          *          *
November 25, 2012..................       *          *          *          *          *
November 25, 2013..................       0          0          0          0          0
November 25, 2014..................       0          0          0          0          0
November 25, 2015..................       0          0          0          0          0
November 25, 2016..................       0          0          0          0          0
November 25, 2017..................       0          0          0          0          0
November 25, 2018..................       0          0          0          0          0
November 25, 2019..................       0          0          0          0          0
November 25, 2020..................       0          0          0          0          0
November 25, 2021..................       0          0          0          0          0
November 25, 2022..................       0          0          0          0          0
November 25, 2023..................       0          0          0          0          0
November 25, 2024..................       0          0          0          0          0
November 25, 2025..................       0          0          0          0          0
November 25, 2026..................       0          0          0          0          0
November 25, 2027..................       0          0          0          0          0
Weighted Average Life (Years)
 (1)...............................     8.9        6.8        5.0        4.0        3.2
</TABLE>
 
- ----------------------------------
 *  Indicates an amount above zero and less than 0.5% of original principal
    balance outstanding.
 
(1) The weighted average life of any Class of Certificates is determined by (i)
    multiplying the amount of each assumed principal distribution on such Class
    of Certificates by the number of years from the date of issuance of the
    Certificates to the related Distribution Date, (ii) summing the results, and
    (iii) dividing the sum by the total amount of principal distributed on such
    Class of Certificates.
 
                                      S-94
<PAGE>
             PERCENT OF INITIAL CLASS PRINCIPAL BALANCE OUTSTANDING
           AT VARIOUS PERCENTAGES OF THE BASIC PREPAYMENT ASSUMPTION
<TABLE>
<CAPTION>
                                                           CLASS I-P
<S>                                  <C>        <C>        <C>        <C>        <C>
                                     -----------------------------------------------------
 
<CAPTION>
DISTRIBUTION DATE                       0%         50%       100%       150%       200%
- -----------------------------------  -----------------------------------------------------
<S>                                  <C>        <C>        <C>        <C>        <C>
Initial Percentage.................        100%       100%       100%       100%       100%
November 25, 1998..................         99         93         87         81         75
November 25, 1999..................         98         84         72         61         50
November 25, 2000..................         96         77         60         46         34
November 25, 2001..................         95         69         50         34         23
November 25, 2002..................         93         63         41         26         15
November 25, 2003..................         92         57         34         19         10
November 25, 2004..................         90         51         28         14          7
November 25, 2005..................         88         46         23         11          5
November 25, 2006..................         86         42         19          8          3
November 25, 2007..................         84         37         15          6          2
November 25, 2008..................         81         33         13          4          1
November 25, 2009..................         79         30         10          3          1
November 25, 2010..................         77         27          8          2          1
November 25, 2011..................         74         24          7          2          *
November 25, 2012..................         72         21          6          1          *
November 25, 2013..................         69         19          4          1          *
November 25, 2014..................         66         16          4          1          *
November 25, 2015..................         63         14          3          *          *
November 25, 2016..................         59         12          2          *          *
November 25, 2017..................         55         11          2          *          *
November 25, 2018..................         51          9          1          *          *
November 25, 2019..................         47          8          1          *          *
November 25, 2020..................         42          6          1          *          *
November 25, 2021..................         37          5          1          *          *
November 25, 2022..................         32          4          *          *          *
November 25, 2023..................         26          3          *          *          *
November 25, 2024..................         20          2          *          *          *
November 25, 2025..................         13          1          *          *          *
November 25, 2026..................          6          1          *          *          *
November 25, 2027..................          *          *          *          *          *
Weighted Average Life (Years)
 (1)...............................       19.4        9.2        5.5        3.7        2.8
 
<CAPTION>
                                                         CLASS II-P
<S>                                  <C>     <C>        <C>        <C>        <C>
                                     --------------------------------------------------
DISTRIBUTION DATE                      0%      100%       250%       350%       500%
- -----------------------------------  --------------------------------------------------
<S>                                  <C>     <C>        <C>        <C>        <C>
Initial Percentage.................     100%       100%       100%       100%       100   %
November 25, 1998..................      99         97         94         92         90
November 25, 1999..................      98         92         84         78         70
November 25, 2000..................      97         86         70         61         49
November 25, 2001..................      95         79         59         48         34
November 25, 2002..................      94         74         50         37         23
November 25, 2003..................      93         68         41         29         16
November 25, 2004..................      91         63         35         23         11
November 25, 2005..................      89         58         29         17          8
November 25, 2006..................      88         54         24         14          5
November 25, 2007..................      86         49         20         10          4
November 25, 2008..................      84         45         17          8          2
November 25, 2009..................      81         41         14          6          2
November 25, 2010..................      79         38         11          5          1
November 25, 2011..................      76         34          9          4          1
November 25, 2012..................      74         31          8          3          1
November 25, 2013..................      71         28          6          2          *
November 25, 2014..................      68         25          5          2          *
November 25, 2015..................      64         22          4          1          *
November 25, 2016..................      61         20          3          1          *
November 25, 2017..................      57         18          3          1          *
November 25, 2018..................      53         15          2          *          *
November 25, 2019..................      48         13          2          *          *
November 25, 2020..................      43         11          1          *          *
November 25, 2021..................      38          9          1          *          *
November 25, 2022..................      32          7          1          *          *
November 25, 2023..................      27          6          *          *          *
November 25, 2024..................      20          4          *          *          *
November 25, 2025..................      13          3          *          *          *
November 25, 2026..................       6          1          *          *          *
November 25, 2027..................       0          0          0          0          0
Weighted Average Life (Years)
 (1)...............................    19.8       11.5        6.5        5.0        3.7
 
<CAPTION>
                                                        CLASS III-P
                                     --------------------------------------------------
DISTRIBUTION DATE                      0%      100%       235%       350%       500%
- -----------------------------------  --------------------------------------------------
Initial Percentage.................     100%       100%       100%       100%       100%
November 25, 1998..................      96         94         92         90         87
November 25, 1999..................      92         86         79         73         66
November 25, 2000..................      87         77         65         55         44
November 25, 2001..................      82         68         52         41         29
November 25, 2002..................      76         60         42         30         19
November 25, 2003..................      71         52         33         22         12
November 25, 2004..................      65         45         26         16          8
November 25, 2005..................      58         38         20         11          5
November 25, 2006..................      51         31         15          8          3
November 25, 2007..................      44         25         11          5          2
November 25, 2008..................      36         19          8          3          1
November 25, 2009..................      27         14          5          2          1
November 25, 2010..................      18          9          3          1          *
November 25, 2011..................       8          4          1          *          *
November 25, 2012..................       0          0          0          0          0
November 25, 2013..................       0          0          0          0          0
November 25, 2014..................       0          0          0          0          0
November 25, 2015..................       0          0          0          0          0
November 25, 2016..................       0          0          0          0          0
November 25, 2017..................       0          0          0          0          0
November 25, 2018..................       0          0          0          0          0
November 25, 2019..................       0          0          0          0          0
November 25, 2020..................       0          0          0          0          0
November 25, 2021..................       0          0          0          0          0
November 25, 2022..................       0          0          0          0          0
November 25, 2023..................       0          0          0          0          0
November 25, 2024..................       0          0          0          0          0
November 25, 2025..................       0          0          0          0          0
November 25, 2026..................       0          0          0          0          0
November 25, 2027..................       0          0          0          0          0
Weighted Average Life (Years)
 (1)...............................     8.6        6.8        5.1        4.1        3.3
</TABLE>
 
- ----------------------------------
 *  Indicates an amount above zero and less than 0.5% of original principal
    balance outstanding.
 
(1) The weighted average life of any Class of Certificates is determined by (i)
    multiplying the amount of each assumed principal distribution on such Class
    of Certificates by the number of years from the date of issuance of the
    Certificates to the related Distribution Date, (ii) summing the results, and
    (iii) dividing the sum by the total amount of principal distributed on such
    Class of Certificates.
 
                                      S-95
<PAGE>
             PERCENT OF INITIAL CLASS PRINCIPAL BALANCE OUTSTANDING
           AT VARIOUS PERCENTAGES OF THE BASIC PREPAYMENT ASSUMPTION
<TABLE>
<CAPTION>
                                                   CLASS I-B-1, I-B-2, I-B-3
<S>                                  <C>        <C>        <C>        <C>        <C>
                                     -----------------------------------------------------
 
<CAPTION>
DISTRIBUTION DATE                       0%         50%       100%       150%       200%
- -----------------------------------  -----------------------------------------------------
<S>                                  <C>        <C>        <C>        <C>        <C>
Initial Percentage.................        100%       100%       100%       100%       100%
November 25, 1998..................         99         99         99         99         99
November 25, 1999..................         98         98         98         98         98
November 25, 2000..................         97         97         97         97         97
November 25, 2001..................         96         96         96         96         96
November 25, 2002..................         95         95         95         95         95
November 25, 2003..................         94         92         89         87         84
November 25, 2004..................         93         87         82         77         71
November 25, 2005..................         91         82         73         64         55
November 25, 2006..................         90         75         62         50         40
November 25, 2007..................         88         68         51         38         27
November 25, 2008..................         86         61         42         28         18
November 25, 2009..................         84         55         35         21         12
November 25, 2010..................         82         49         28         15          8
November 25, 2011..................         79         44         23         11          5
November 25, 2012..................         77         39         19          8          3
November 25, 2013..................         74         35         15          6          2
November 25, 2014..................         71         31         12          4          1
November 25, 2015..................         68         27         10          3          1
November 25, 2016..................         64         23          8          2          1
November 25, 2017..................         60         20          6          2          *
November 25, 2018..................         56         17          5          1          *
November 25, 2019..................         51         15          4          1          *
November 25, 2020..................         47         12          3          1          *
November 25, 2021..................         41         10          2          *          *
November 25, 2022..................         36          8          2          *          *
November 25, 2023..................         29          6          1          *          *
November 25, 2024..................         23          4          1          *          *
November 25, 2025..................         15          3          *          *          *
November 25, 2026..................          7          1          *          *          *
November 25, 2027..................          *          *          *          *          *
Weighted Average Life (Years)
 (1)...............................       20.5       14.0       11.1        9.6        8.7
 
<CAPTION>
                                                CLASS II-B-1, II-B-2, II-B-3
<S>                                  <C>     <C>        <C>        <C>        <C>
                                     --------------------------------------------------
DISTRIBUTION DATE                      0%      100%       250%       350%       500%
- -----------------------------------  --------------------------------------------------
<S>                                  <C>     <C>        <C>        <C>        <C>
Initial Percentage.................     100%       100%       100%       100%       100   %
November 25, 1998..................      99         99         99         99         99
November 25, 1999..................      98         98         98         98         98
November 25, 2000..................      97         97         97         97         97
November 25, 2001..................      96         96         96         96         96
November 25, 2002..................      95         95         95         95         95
November 25, 2003..................      94         92         89         87         84
November 25, 2004..................      92         88         82         78         72
November 25, 2005..................      91         84         74         67         57
November 25, 2006..................      89         78         63         55         42
November 25, 2007..................      87         72         53         42         29
November 25, 2008..................      86         66         44         33         20
November 25, 2009..................      84         61         37         25         14
November 25, 2010..................      81         56         30         19          9
November 25, 2011..................      79         51         25         15          6
November 25, 2012..................      76         46         20         11          4
November 25, 2013..................      74         42         17          9          3
November 25, 2014..................      70         38         14          7          2
November 25, 2015..................      67         34         11          5          1
November 25, 2016..................      64         30          9          4          1
November 25, 2017..................      60         27          7          3          1
November 25, 2018..................      56         23          6          2          *
November 25, 2019..................      51         20          4          1          *
November 25, 2020..................      46         17          3          1          *
November 25, 2021..................      41         14          3          1          *
November 25, 2022..................      35         11          2          *          *
November 25, 2023..................      29          9          1          *          *
November 25, 2024..................      22          6          1          *          *
November 25, 2025..................      15          4          *          *          *
November 25, 2026..................       7          2          *          *          *
November 25, 2027..................       0          0          0          0          0
Weighted Average Life (Years)
 (1)...............................    20.4       15.1       11.3       10.0        8.8
 
<CAPTION>
                                              CLASS III-B-1, III-B-2, III-B-3
                                     --------------------------------------------------
DISTRIBUTION DATE                      0%      100%       235%       350%       500%
- -----------------------------------  --------------------------------------------------
Initial Percentage.................     100%       100%       100%       100%       100%
November 25, 1998..................      96         96         96         96         96
November 25, 1999..................      92         92         92         92         92
November 25, 2000..................      88         88         88         88         88
November 25, 2001..................      83         83         83         83         83
November 25, 2002..................      78         78         78         78         78
November 25, 2003..................      73         71         69         68         65
November 25, 2004..................      67         64         60         57         52
November 25, 2005..................      60         56         50         44         38
November 25, 2006..................      53         47         39         33         25
November 25, 2007..................      46         38         29         22         15
November 25, 2008..................      38         30         20         15          9
November 25, 2009..................      30         22         14          9          5
November 25, 2010..................      20         14          8          5          2
November 25, 2011..................      11          7          4          2          1
November 25, 2012..................       0          0          0          0          0
November 25, 2013..................       0          0          0          0          0
November 25, 2014..................       0          0          0          0          0
November 25, 2015..................       0          0          0          0          0
November 25, 2016..................       0          0          0          0          0
November 25, 2017..................       0          0          0          0          0
November 25, 2018..................       0          0          0          0          0
November 25, 2019..................       0          0          0          0          0
November 25, 2020..................       0          0          0          0          0
November 25, 2021..................       0          0          0          0          0
November 25, 2022..................       0          0          0          0          0
November 25, 2023..................       0          0          0          0          0
November 25, 2024..................       0          0          0          0          0
November 25, 2025..................       0          0          0          0          0
November 25, 2026..................       0          0          0          0          0
November 25, 2027..................       0          0          0          0          0
Weighted Average Life (Years)
 (1)...............................     8.9        8.4        7.8        7.4        7.0
 
<CAPTION>
                                                          CLASS R
                                     --------------------------------------------------
DISTRIBUTION DATE                      0%      100%       250%       350%       500%
- -----------------------------------  --------------------------------------------------
Initial Percentage.................     100%       100%       100%       100%       100%
November 25, 1998..................       0          0          0          0          0
November 25, 1999..................       0          0          0          0          0
November 25, 2000..................       0          0          0          0          0
November 25, 2001..................       0          0          0          0          0
November 25, 2002..................       0          0          0          0          0
November 25, 2003..................       0          0          0          0          0
November 25, 2004..................       0          0          0          0          0
November 25, 2005..................       0          0          0          0          0
November 25, 2006..................       0          0          0          0          0
November 25, 2007..................       0          0          0          0          0
November 25, 2008..................       0          0          0          0          0
November 25, 2009..................       0          0          0          0          0
November 25, 2010..................       0          0          0          0          0
November 25, 2011..................       0          0          0          0          0
November 25, 2012..................       0          0          0          0          0
November 25, 2013..................       0          0          0          0          0
November 25, 2014..................       0          0          0          0          0
November 25, 2015..................       0          0          0          0          0
November 25, 2016..................       0          0          0          0          0
November 25, 2017..................       0          0          0          0          0
November 25, 2018..................       0          0          0          0          0
November 25, 2019..................       0          0          0          0          0
November 25, 2020..................       0          0          0          0          0
November 25, 2021..................       0          0          0          0          0
November 25, 2022..................       0          0          0          0          0
November 25, 2023..................       0          0          0          0          0
November 25, 2024..................       0          0          0          0          0
November 25, 2025..................       0          0          0          0          0
November 25, 2026..................       0          0          0          0          0
November 25, 2027..................       0          0          0          0          0
Weighted Average Life (Years)
 (1)...............................     0.1        0.1        0.1        0.1        0.1
</TABLE>
 
- ----------------------------------
 *  Indicates an amount above zero and less than 0.5% of original principal
    balance outstanding.
 
(1) The weighted average life of any Class of Certificates is determined by (i)
    multiplying the amount of each assumed principal distribution on such Class
    of Certificates by the number of years from the date of issuance of the
    Certificates to the related Distribution Date, (ii) summing the results, and
    (iii) dividing the sum by the total amount of principal distributed on such
    Class of Certificates.
 
                                      S-96
<PAGE>
                                                                      APPENDIX D
 
                          PERCENTAGE REDUCTION FACTOR
 
<TABLE>
<CAPTION>
DISTRIBUTION DATE
- ---------------------------------------------------------------------------------------------
<S>                                                                                            <C>
December 25, 1997............................................................................         0.1835505662%
January 25, 1998.............................................................................         0.2258713456
February 25, 1998............................................................................         0.2684079682
March 25, 1998...............................................................................         0.3111281460
April 25, 1998...............................................................................         0.3540676609
May 25, 1998.................................................................................         0.3972278059
June 25, 1998................................................................................         0.4406099283
July 25, 1998................................................................................         0.4842154289
August 25, 1998..............................................................................         0.5280457607
September 25, 1998...........................................................................         0.5721024286
October 25, 1998.............................................................................         0.6163578227
November 25, 1998............................................................................         0.6608006069
December 25, 1998............................................................................         0.7054758859
January 25, 1999.............................................................................         0.7503852604
February 25, 1999............................................................................         0.7955303810
March 25, 1999...............................................................................         0.8409129480
April 25, 1999...............................................................................         0.8865347099
May 25, 1999.................................................................................         0.9323974634
June 25, 1999................................................................................         0.9785030523
July 25, 1999................................................................................         1.0248533672
August 25, 1999..............................................................................         1.0714042536
September 25, 1999...........................................................................         1.1180866198
October 25, 1999.............................................................................         1.1648871316
November 25, 1999............................................................................         1.2117058860
December 25, 1999............................................................................         1.2584644794
January 25, 2000.............................................................................         1.3052489064
February 25, 2000............................................................................         1.3517574736
March 25, 2000...............................................................................         1.3950250600
April 25, 2000...............................................................................         1.4249576247
May 25, 2000.................................................................................         1.4346443378
June 25, 2000................................................................................         1.4352715844
July 25, 2000................................................................................         1.4359040847
August 25, 2000..............................................................................         1.4365418909
September 25, 2000...........................................................................         1.4371850559
October 25, 2000.............................................................................         1.4378336332
November 25, 2000............................................................................         1.4384876770
December 25, 2000............................................................................         1.4391472421
January 25, 2001.............................................................................         1.4398123841
February 25, 2001............................................................................         1.4404831592
March 25, 2001...............................................................................         1.4411596243
April 25, 2001...............................................................................         1.4418418372
May 25, 2001.................................................................................         1.4425298562
June 25, 2001................................................................................         1.4432237405
July 25, 2001................................................................................         1.4439235499
August 25, 2001..............................................................................         1.4446293450
September 25, 2001...........................................................................         1.4453411874
</TABLE>
 
                                      S-97
<PAGE>
                          PERCENTAGE REDUCTION FACTOR
 
<TABLE>
<CAPTION>
DISTRIBUTION DATE
- ---------------------------------------------------------------------------------------------
<S>                                                                                            <C>
October 25, 2001.............................................................................         1.4460591392%
November 25, 2001............................................................................         1.4467832634
December 25, 2001............................................................................         1.4475136239
January 25, 2002.............................................................................         1.4482502853
February 25, 2002............................................................................         1.4489933131
March 25, 2002...............................................................................         1.4497427737
April 25, 2002...............................................................................         1.4504987342
May 25, 2002.................................................................................         1.4512612628
June 25, 2002................................................................................         1.4520304284
July 25, 2002................................................................................         1.4528063010
August 25, 2002..............................................................................         1.4535889515
September 25, 2002...........................................................................         1.4543784515
October 25, 2002.............................................................................         1.4551748738
November 25, 2002............................................................................         1.4559782921
December 25, 2002............................................................................         1.4567887811
January 25, 2003.............................................................................         1.4576064165
February 25, 2003............................................................................         1.4584312751
March 25, 2003...............................................................................         1.4592634345
April 25, 2003...............................................................................         1.4601029737
May 25, 2003.................................................................................         1.4609499725
June 25, 2003................................................................................         1.4618045119
July 25, 2003................................................................................         1.4626666740
August 25, 2003..............................................................................         1.4635365420
September 25, 2003...........................................................................         1.4644142004
October 25, 2003.............................................................................         1.4652997347
November 25, 2003............................................................................         1.4661932317
December 25, 2003............................................................................         1.4670947792
January 25, 2004.............................................................................         1.4680044666
February 25, 2004............................................................................         1.4689223842
March 25, 2004...............................................................................         1.4698486239
April 25, 2004...............................................................................         1.4707832786
May 25, 2004.................................................................................         1.4717264427
June 25, 2004................................................................................         1.4726782119
July 25, 2004................................................................................         1.4736386833
August 25, 2004..............................................................................         1.4746079553
September 25, 2004...........................................................................         1.4755861279
October 25, 2004.............................................................................         1.4765733024
November 25, 2004............................................................................         1.4775695816
December 25, 2004............................................................................         1.4785750698
January 25, 2005.............................................................................         1.4795898728
February 25, 2005............................................................................         1.4806140981
March 25, 2005...............................................................................         1.4816478547
April 25, 2005...............................................................................         1.4826912530
May 25, 2005.................................................................................         1.4837444054
June 25, 2005................................................................................         1.4848074258
July 25, 2005................................................................................         1.4858804298
August 25, 2005..............................................................................         1.4869635347
</TABLE>
 
                                      S-98
<PAGE>
                          PERCENTAGE REDUCTION FACTOR
 
<TABLE>
<CAPTION>
DISTRIBUTION DATE
- ---------------------------------------------------------------------------------------------
<S>                                                                                            <C>
September 25, 2005...........................................................................         1.4880568596%
October 25, 2005.............................................................................         1.4891605256
November 25, 2005............................................................................         1.4902746552
December 25, 2005............................................................................         1.4913993733
January 25, 2006.............................................................................         1.4925348063
February 25, 2006............................................................................         1.4936810826
March 25, 2006...............................................................................         1.4948383329
April 25, 2006...............................................................................         1.4960066895
May 25, 2006.................................................................................         1.4971862871
June 25, 2006................................................................................         1.4983772622
July 25, 2006................................................................................         1.4995797537
August 25, 2006..............................................................................         1.5007939026
September 25, 2006...........................................................................         1.5020198520
October 25, 2006.............................................................................         1.5032577474
November 25, 2006............................................................................         1.5045077366
December 25, 2006............................................................................         1.5057699699
January 25, 2007.............................................................................         1.5070445996
February 25, 2007............................................................................         1.5083317809
March 25, 2007...............................................................................         1.5096316713
April 25, 2007...............................................................................         1.5109444309
May 25, 2007.................................................................................         1.5122702224
June 25, 2007................................................................................         1.5136092111
July 25, 2007................................................................................         1.5149615651
August 25, 2007..............................................................................         1.5163274553
September 25, 2007...........................................................................         1.5177070554
October 25, 2007.............................................................................         1.5191005420
November 25, 2007............................................................................         1.5205080946
December 25, 2007............................................................................         1.5219298958
January 25, 2008.............................................................................         1.5233661312
February 25, 2008............................................................................         1.5248169896
March 25, 2008...............................................................................         1.5262826629
April 25, 2008...............................................................................         1.5277633465
May 25, 2008.................................................................................         1.5292592389
June 25, 2008................................................................................         1.5307705422
July 25, 2008................................................................................         1.5322974620
August 25, 2008..............................................................................         1.5338402073
September 25, 2008...........................................................................         1.5353989909
October 25, 2008.............................................................................         1.5369740293
November 25, 2008............................................................................         1.5385655427
December 25, 2008............................................................................         1.5401737555
January 25, 2009.............................................................................         1.5417988957
February 25, 2009............................................................................         1.5434411956
March 25, 2009...............................................................................         1.5451008917
April 25, 2009...............................................................................         1.5467782245
May 25, 2009.................................................................................         1.5484734393
June 25, 2009................................................................................         1.5501867853
July 25, 2009................................................................................         1.5519185166
</TABLE>
 
                                      S-99
<PAGE>
                          PERCENTAGE REDUCTION FACTOR
 
<TABLE>
<CAPTION>
DISTRIBUTION DATE
- ---------------------------------------------------------------------------------------------
<S>                                                                                            <C>
August 25, 2009..............................................................................         1.5536688921%
September 25, 2009...........................................................................         1.5554381750
October 25, 2009.............................................................................         1.5572266338
November 25, 2009............................................................................         1.5590345417
December 25, 2009............................................................................         1.5608621773
January 25, 2010.............................................................................         1.5627098241
February 25, 2010............................................................................         1.5645777712
March 25, 2010...............................................................................         1.5664663131
April 25, 2010...............................................................................         1.5683757499
May 25, 2010.................................................................................         1.5703063875
June 25, 2010................................................................................         1.5722585374
July 25, 2010................................................................................         1.5742325176
August 25, 2010..............................................................................         1.5762286519
September 25, 2010...........................................................................         1.5782472705
October 25, 2010.............................................................................         1.5802887102
November 25, 2010............................................................................         1.5823533142
December 25, 2010............................................................................         1.5844414329
January 25, 2011.............................................................................         1.5865534231
February 25, 2011............................................................................         1.5886896493
March 25, 2011...............................................................................         1.5908504830
April 25, 2011...............................................................................         1.5930363033
May 25, 2011.................................................................................         1.5952474970
June 25, 2011................................................................................         1.5974844586
July 25, 2011................................................................................         1.5997475911
August 25, 2011..............................................................................         1.6020373055
September 25, 2011...........................................................................         1.6043540215
October 25, 2011.............................................................................         1.6066981673
November 25, 2011............................................................................         1.6090701802
December 25, 2011............................................................................         1.6114705070
January 25, 2012.............................................................................         1.6138996034
February 25, 2012............................................................................         1.6163579352
March 25, 2012...............................................................................         1.6188459782
April 25, 2012...............................................................................         1.6213642181
May 25, 2012.................................................................................         1.6239131514
June 25, 2012................................................................................         1.6264932854
July 25, 2012................................................................................         1.6291051382
August 25, 2012..............................................................................         1.6317492397
September 25, 2012...........................................................................         1.6344261311
October 25, 2012.............................................................................         1.6371363661
November 25, 2012............................................................................         1.6398805105
December 25, 2012............................................................................         1.6426591427
January 25, 2013.............................................................................         1.6454728544
February 25, 2013............................................................................         1.6483222508
March 25, 2013...............................................................................         1.6512079508
April 25, 2013...............................................................................         1.6541305876
May 25, 2013.................................................................................         1.6570908091
June 25, 2013................................................................................         1.6600892781
</TABLE>
 
                                     S-100
<PAGE>
                          PERCENTAGE REDUCTION FACTOR
 
<TABLE>
<CAPTION>
DISTRIBUTION DATE
- ---------------------------------------------------------------------------------------------
<S>                                                                                            <C>
July 25, 2013................................................................................         1.6631266731%
August 25, 2013..............................................................................         1.6662036886
September 25, 2013...........................................................................         1.6693210355
October 25, 2013.............................................................................         1.6724794416
November 25, 2013............................................................................         1.6756796522
December 25, 2013............................................................................         1.6789224305
January 25, 2014.............................................................................         1.6822085584
February 25, 2014............................................................................         1.6855388368
March 25, 2014...............................................................................         1.6889140862
April 25, 2014...............................................................................         1.6923351475
May 25, 2014.................................................................................         1.6958028825
June 25, 2014................................................................................         1.6993181746
July 25, 2014................................................................................         1.7028819294
August 25, 2014..............................................................................         1.7064950755
September 25, 2014...........................................................................         1.7101585651
October 25, 2014.............................................................................         1.7138733750
November 25, 2014............................................................................         1.7176405071
December 25, 2014............................................................................         1.7214609897
January 25, 2015.............................................................................         1.7253358775
February 25, 2015............................................................................         1.7292662535
March 25, 2015...............................................................................         1.7332532291
April 25, 2015...............................................................................         1.7372979456
May 25, 2015.................................................................................         1.7414015749
June 25, 2015................................................................................         1.7455653206
July 25, 2015................................................................................         1.7497904193
August 25, 2015..............................................................................         1.7540781413
September 25, 2015...........................................................................         1.7584297922
October 25, 2015.............................................................................         1.7628467138
November 25, 2015............................................................................         1.7673302857
December 25, 2015............................................................................         1.7718819263
January 25, 2016.............................................................................         1.7765030944
February 25, 2016............................................................................         1.7811952904
March 25, 2016...............................................................................         1.7859600583
April 25, 2016...............................................................................         1.7907989866
May 25, 2016.................................................................................         1.7957137105
June 25, 2016................................................................................         1.8007059135
July 25, 2016................................................................................         1.8057773288
August 25, 2016..............................................................................         1.8109297418
September 25, 2016...........................................................................         1.8161649914
October 25, 2016.............................................................................         1.8214849727
November 25, 2016............................................................................         1.8268916386
December 25, 2016............................................................................         1.8323870023
January 25, 2017.............................................................................         1.8379731395
February 25, 2017............................................................................         1.8436521912
March 25, 2017...............................................................................         1.8494263657
April 25, 2017...............................................................................         1.8552979419
May 25, 2017.................................................................................         1.8612692716
</TABLE>
 
                                     S-101
<PAGE>
                          PERCENTAGE REDUCTION FACTOR
 
<TABLE>
<CAPTION>
DISTRIBUTION DATE
- ---------------------------------------------------------------------------------------------
<S>                                                                                            <C>
June 25, 2017................................................................................         1.8673427828%
July 25, 2017................................................................................         1.8735209826
August 25, 2017..............................................................................         1.8798064608
September 25, 2017...........................................................................         1.8853215566
October 25, 2017.............................................................................         1.8918138750
November 25, 2017............................................................................         1.8984213661
December 25, 2017............................................................................         1.9051469716
January 25, 2018.............................................................................         1.9119937336
February 25, 2018............................................................................         1.9189647997
March 25, 2018...............................................................................         1.9260634270
April 25, 2018...............................................................................         1.9332929872
May 25, 2018.................................................................................         1.9406569715
June 25, 2018................................................................................         1.9481589961
July 25, 2018................................................................................         1.9558028080
August 25, 2018..............................................................................         1.9635922904
September 25, 2018...........................................................................         1.9715314695
October 25, 2018.............................................................................         1.9796245210
November 25, 2018............................................................................         1.9878757770
December 25, 2018............................................................................         1.9962897336
January 25, 2019.............................................................................         2.0048710583
February 25, 2019............................................................................         2.0136245989
March 25, 2019...............................................................................         2.0225553916
April 25, 2019...............................................................................         2.0316686707
May 25, 2019.................................................................................         2.0409698786
June 25, 2019................................................................................         2.0504646755
July 25, 2019................................................................................         2.0601589513
August 25, 2019..............................................................................         2.0700588366
September 25, 2019...........................................................................         2.0801707157
October 25, 2019.............................................................................         2.0905012395
November 25, 2019............................................................................         2.1010573399
December 25, 2019............................................................................         2.1118462445
January 25, 2020.............................................................................         2.1228754925
February 25, 2020............................................................................         2.1341529521
March 25, 2020...............................................................................         2.1456868381
April 25, 2020...............................................................................         2.1574857317
May 25, 2020.................................................................................         2.1695586009
June 25, 2020................................................................................         2.1819148224
July 25, 2020................................................................................         2.1945642055
August 25, 2020..............................................................................         2.2075170171
September 25, 2020...........................................................................         2.2207840089
October 25, 2020.............................................................................         2.2343764461
November 25, 2020............................................................................         2.2483061386
December 25, 2020............................................................................         2.2625854745
January 25, 2021.............................................................................         2.2772274553
February 25, 2021............................................................................         2.2922457352
March 25, 2021...............................................................................         2.3076546619
April 25, 2021...............................................................................         2.3234693216
</TABLE>
 
                                     S-102
<PAGE>
                          PERCENTAGE REDUCTION FACTOR
 
<TABLE>
<CAPTION>
DISTRIBUTION DATE
- ---------------------------------------------------------------------------------------------
<S>                                                                                            <C>
May 25, 2021.................................................................................         2.3397055869%
June 25, 2021................................................................................         2.3545952418
July 25, 2021................................................................................         2.3716755605
August 25, 2021..............................................................................         2.3892283019
September 25, 2021...........................................................................         2.4050368023
October 25, 2021.............................................................................         2.4235286172
November 25, 2021............................................................................         2.4425517981
December 25, 2021............................................................................         2.4621291402
January 25, 2022.............................................................................         2.4822847609
February 25, 2022............................................................................         2.5030441972
March 25, 2022...............................................................................         2.5244345118
April 25, 2022...............................................................................         2.5448228893
May 25, 2022.................................................................................         2.5675091025
June 25, 2022................................................................................         2.5909152004
July 25, 2022................................................................................         2.6150754546
August 25, 2022..............................................................................         2.6400263463
September 25, 2022...........................................................................         2.6644829479
October 25, 2022.............................................................................         2.6892813125
November 25, 2022............................................................................         2.7167365036
December 25, 2022............................................................................         2.7451484507
January 25, 2023.............................................................................         2.7745673854
February 25, 2023............................................................................         2.8050471181
March 25, 2023...............................................................................         2.8366453614
April 25, 2023...............................................................................         2.8694240917
May 25, 2023.................................................................................         2.9017158674
June 25, 2023................................................................................         2.9369915232
July 25, 2023................................................................................         2.9736593257
August 25, 2023..............................................................................         3.0118024784
September 25, 2023...........................................................................         3.0495733030
October 25, 2023.............................................................................         3.0908611843
November 25, 2023............................................................................         3.1339121525
December 25, 2023............................................................................         3.1788405809
January 25, 2024.............................................................................         3.2257709531
February 25, 2024............................................................................         3.2748390061
March 25, 2024...............................................................................         3.3261930303
April 25, 2024...............................................................................         3.3799953560
May 25, 2024.................................................................................         3.4364240550
June 25, 2024................................................................................         3.4956748958
July 25, 2024................................................................................         3.5561194060
August 25, 2024..............................................................................         3.6215846781
September 25, 2024...........................................................................         3.6905818300
October 25, 2024.............................................................................         3.7613740322
November 25, 2024............................................................................         3.8382253935
December 25, 2024............................................................................         3.9195784835
January 25, 2025.............................................................................         4.0037545304
February 25, 2025............................................................................         4.0952453907
March 25, 2025...............................................................................         4.1926002397
</TABLE>
 
                                     S-103
<PAGE>
                          PERCENTAGE REDUCTION FACTOR
 
<TABLE>
<CAPTION>
DISTRIBUTION DATE
- ---------------------------------------------------------------------------------------------
<S>                                                                                            <C>
April 25, 2025...............................................................................         4.2963991195%
May 25, 2025.................................................................................         4.4073011802
June 25, 2025................................................................................         4.5260586412
July 25, 2025................................................................................         4.6535338194
August 25, 2025..............................................................................         4.7907200367
September 25, 2025...........................................................................         4.9359924205
October 25, 2025.............................................................................         5.0960053233
November 25, 2025............................................................................         5.2697568038
December 25, 2025............................................................................         5.4590911908
January 25, 2026.............................................................................         5.6661983963
February 25, 2026............................................................................         5.8873864641
March 25, 2026...............................................................................         6.1377737884
April 25, 2026...............................................................................         6.4124926581
May 25, 2026.................................................................................         6.7168915415
June 25, 2026................................................................................         7.0634185271
July 25, 2026................................................................................         7.4549998377
August 25, 2026..............................................................................         7.9010224782
September 25, 2026...........................................................................         8.4070620856
October 25, 2026.............................................................................         9.0013577321
November 25, 2026............................................................................         9.6998800179
December 25, 2026............................................................................        10.5109470786
January 25, 2027.............................................................................        11.5019761410
February 25, 2027............................................................................        12.7031763756
March 25, 2027...............................................................................        14.1857317433
April 25, 2027...............................................................................        16.1333511217
May 25, 2027.................................................................................        18.7847108452
June 25, 2027................................................................................        22.5170981794
July 25, 2027................................................................................        28.2028891461
August 25, 2027..............................................................................        37.7914625528
September 25, 2027...........................................................................        54.6371202105
October 25, 2027.............................................................................        74.2963944276
November 25, 2027............................................................................       100.0000000000
</TABLE>
 
                                     S-104
<PAGE>
                               TABLE OF CONTENTS
 
<TABLE>
<CAPTION>
CAPTION                                                                     PAGE
- --------------------------------------------------------------------------  ----
<S>                                                                         <C>
Summary of Prospectus.....................................................    3
Risk Factors..............................................................   10
The Mortgage Pools........................................................   11
Use of Proceeds...........................................................   16
Yield Considerations......................................................   16
Maturity, Average Life and Prepayment Assumptions.........................   18
The Company...............................................................   19
Description of Certificates...............................................   22
Primary Insurance, FHA Mortgage Insurance, VA Mortgage Guaranty, Hazard
 Insurance; Claims Thereunder.............................................   44
Description of Credit Enhancements........................................   48
Certain Legal Aspects of the Mortgage Loans...............................   57
ERISA Considerations......................................................   64
Certain Federal Income Tax Consequences...................................   67
Methods of Distribution...................................................   84
Transferability of Certificates...........................................   85
Legal Matters.............................................................   85
Financial Information.....................................................   85
Additional Information....................................................   85
Glossary..................................................................   86
</TABLE>
 
    UNTIL 90 DAYS AFTER THE DATE OF EACH SUPPLEMENT TO THIS PROSPECTUS, ALL
DEALERS EFFECTING TRANSACTIONS IN THE REGISTERED SECURITIES COVERED BY SUCH
SUPPLEMENT, WHETHER OR NOT PARTICIPATING IN THE DISTRIBUTION THEREOF, MAY BE
REQUIRED TO DELIVER SUCH SUPPLEMENT AND THIS PROSPECTUS. THIS IS IN ADDITION TO
THE OBLIGATION OF DEALERS TO DELIVER A SUPPLEMENT AND PROSPECTUS WHEN ACTING AS
UNDERWRITERS OF SECURITIES COVERED BY SUCH SUPPLEMENT AND WITH RESPECT TO THEIR
UNSOLD ALLOTMENTS OR SUBSCRIPTIONS.
 
    NO PERSON HAS BEEN AUTHORIZED TO GIVE ANY INFORMATION OR TO MAKE ANY
REPRESENTATION OTHER THAN THOSE CONTAINED IN THIS PROSPECTUS AND EACH SUPPLEMENT
TO THIS PROSPECTUS AND, IF GIVEN OR MADE, SUCH INFORMATION OR REPRESENTATION
MUST NOT BE RELIED UPON. THIS PROSPECTUS DOES NOT CONSTITUTE AN OFFER TO SELL OR
A SOLICITATION OF AN OFFER TO BUY ANY SECURITIES OTHER THAN THE CERTIFICATES
OFFERED HEREBY, NOR AN OFFER OF THE CERTIFICATES TO ANY PERSON IN ANY STATE OR
OTHER JURISDICTION IN WHICH SUCH OFFER WOULD BE UNLAWFUL. THE DELIVERY OF THIS
PROSPECTUS AT ANY TIME DOES NOT IMPLY THAT INFORMATION HEREIN IS CORRECT AS OF
ANY TIME SUBSEQUENT TO ITS DATE; HOWEVER, IF ANY MATERIAL CHANGE OCCURS WHILE
THIS PROSPECTUS IS REQUIRED BY LAW TO BE DELIVERED, THIS PROSPECTUS WILL BE
AMENDED OR SUPPLEMENTED ACCORDINGLY.
 
               INCORPORATION OF CERTAIN INFORMATION BY REFERENCE
 
    There are incorporated herein by reference all documents and reports filed
or caused to be filed by the Company with respect to a Series pursuant to
Section 13(a), Section 13(c), Section 14 or Section 15(d) of the Securities
Exchange Act of 1934, prior to the termination of an offering of Certificates
evidencing interests therein. Upon request, the Company will provide or cause to
be provided without charge to each person to whom this Prospectus is delivered
in connection with the offering of one or more Classes of Certificates, a list
identifying all filings with respect to a Series pursuant to Section 13(a),
Section 13(c), Section 14 or Section 15(d) of the Securities Exchange Act of
1934, since the Company's last fiscal year covered by its annual report on Form
10-K, if any, and a copy of any or all documents or reports incorporated herein
by reference, in each case to the extent such documents or reports relate to one
or more such Classes of such Certificates, other than the exhibits to such
documents (unless such exhibits are specifically incorporated by reference in
such documents). Requests to the Company should be directed to: PNC Mortgage
Securities Corp., 75 North Fairway Dr., Vernon Hills, IL 60061, telephone number
(847) 549-6500, Attn: Legal Department.
 
                                       2
<PAGE>
                             SUMMARY OF PROSPECTUS
 
    THE FOLLOWING IS A SUMMARY OF CERTAIN PERTINENT INFORMATION AND IS QUALIFIED
IN ITS ENTIRETY BY REFERENCE TO THE DETAILED INFORMATION APPEARING ELSEWHERE IN
THIS PROSPECTUS, AND BY REFERENCE TO INFORMATION WITH RESPECT TO EACH MORTGAGE
POOL AND SERIES OF CERTIFICATES CONTAINED IN THE SUPPLEMENT TO THIS PROSPECTUS
TO BE PREPARED IN CONNECTION WITH SUCH SERIES.
 
<TABLE>
<S>                           <C>
Title of Certificates.......  Mortgage Pass-Through Certificates, issuable in
                              Series and in one or more Classes of each Series
                              (the "Certificates").
 
Depositor...................  PNC Mortgage Securities Corp. (the "Company"), an
                              indirect subsidiary of PNC Bank Corp.
 
Description of
  Certificates..............  Each Certificate will represent an undivided
                              interest in one of a number of trusts to be
                              created by the Company from time to time. The
                              property of each trust fund (a "Trust Fund") will
                              consist either of a pool (a "Mortgage Pool") of
                              mortgage loans secured by one-to four-family
                              residential properties or multi-family residential
                              properties (the "Mortgage Loans") which Mortgage
                              Loans, if so specified in the related Prospectus
                              Supplement, may include leaseholds in the
                              underlying real property or cooperative apartment
                              loans ("Cooperative Loans"), and related property
                              and interests, conveyed to such Trust Fund by the
                              Company, or of certificates which in turn
                              represent ownership of a Mortgage Pool and related
                              property and interests. Unless otherwise specified
                              in the applicable Prospectus Supplement, each
                              Certificate will represent an interest in all the
                              principal and in interest up to a specified rate
                              on the Mortgage Loans in such Mortgage Pool. If so
                              specified in the Prospectus Supplement applicable
                              to any Series, Certificates may be issued in
                              several Classes, which may pay interest at
                              different rates, may represent different
                              allocations of the right to receive principal and
                              interest, and certain of which may be subordinated
                              to others. Any such Class of Certificates may
                              provide for payments of principal only or interest
                              only or for disproportionate payments of principal
                              and interest. See "Description of Certificates".
                              The related Prospectus Supplement or Current
                              Report on Form 8-K described below will set forth
                              the actual undivided interest in a Mortgage Pool,
                              or entitlement to principal and/or interest,
                              represented by each Certificate (and, if
                              applicable, describe the manner in which such
                              undivided interest may change from time to time).
 
                              The Certificates will be offered in fully
                              registered form only. If specified in the
                              applicable Prospectus Supplement, one or more
                              Classes of Certificates for any Series may be
                              transferable only on the books of The Depository
                              Trust Company or another depository identified in
                              such Prospectus Supplement. The Certificates of a
                              particular Series or Class may or may not be rated
                              by one or more nationally recognized rating
                              organizations. Neither the Certificates, the
                              underlying Mortgage Loans nor certificates will be
                              guaranteed by the Company, PNC Bank Corp. or any
                              other affiliate of the Company and, unless
                              otherwise specified in the applicable Prospectus
                              Supplement, neither the Certificates, the
                              underlying Mortgage Loans nor certificates will be
                              insured or
</TABLE>
 
                                       3
<PAGE>
 
<TABLE>
<S>                           <C>
                              guaranteed by any governmental agency. Additional
                              information about the Mortgage Pool relating to a
                              Series of Certificates may be set forth in a
                              Current Report on Form 8-K that will be filed with
                              the Securities and Exchange Commission within 15
                              days after the issuance of such Certificates. If
                              so indicated in the applicable Prospectus
                              Supplement, a Series of Certificates may include
                              one or more Classes of Certificates (which may be
                              sold in one or more private offerings or may be
                              offered pursuant to this Prospectus) representing
                              subordinated interests in the Mortgage Pool,
                              undivided interests in a portion of the interest
                              paid on the Mortgage Loans in the related Mortgage
                              Pool or such other interests as may be described
                              therein.
 
Sellers.....................  Mortgage Loans will be purchased from qualified
                              originators or entities that have purchased or
                              otherwise acquired the Mortgage Loans from
                              qualified originators ("Sellers"), as described
                              herein.
 
Servicing and
  Administration............  Generally with respect to each Series, the
                              Company, another entity set forth in the related
                              Prospectus Supplement (who will generally be a
                              Seller) (a "Servicing Entity") or the Company
                              together with such Servicing Entity will be
                              responsible for the servicing and administration
                              of the Mortgage Loans (in such capacity, each of
                              the Company and/or such Servicing Entity, a
                              "Master Servicer") and the Sellers will perform
                              certain servicing functions with respect to the
                              Mortgage Loans (in such capacity,
                              "Seller/Servicers"). In the event that both the
                              Company and a Servicing Entity are acting as
                              Master Servicers with respect to a single Series,
                              (i) each of the Company and such Servicing Entity
                              will act as Master Servicer only for a specific
                              group or groups of Mortgage Loans in the related
                              Mortgage Pool (a "Mortgage Loan Servicing Group")
                              as set forth in the related Prospectus
                              Supplement,(ii) the duties, liabilities and
                              obligations of each of the Company and such
                              Servicing Entity shall relate only to its
                              respective Mortgage Loan Servicing Group, and
                              (iii) the Company, unless otherwise specified in
                              the related Prospectus Supplement, will calculate
                              amounts distributable to the Certificateholders,
                              prepare tax returns on behalf of the Trust Fund
                              and provide certain other services specified in
                              the Pooling Agreement (in such capacity, the
                              "Certificate Administrator"). Unless otherwise
                              specified in the related Prospectus Supplement, in
                              the event that a Servicing Entity is the only
                              Master Servicer with respect to any Series, such
                              Serving Entity will be the Certificate
                              Administrator with respect to such Series. If so
                              specified in the applicable Prospectus Supplement,
                              however, (i) the servicing of the Mortgage Loans
                              will be performed by the Seller which sold the
                              Mortgage Loans to the Company for inclusion in the
                              Trust Fund, or by a qualified servicer selected by
                              the Company (either entity acting in such
                              capacity, the "Servicer"), (ii) there will not be
                              a Master Servicer and (iii) the Company will act
                              as the Certificate Administrator.
 
Interest....................  Except as otherwise specified in the applicable
                              Prospectus Supplement, interest payments will be
                              passed through on the
</TABLE>
 
                                       4
<PAGE>
 
<TABLE>
<S>                           <C>
                              25th day (or if such day is not a business day,
                              the business day immediately following such 25th
                              day) of each month or such other date as specified
                              in the applicable Prospectus Supplement (the
                              "Distribution Date") at the interest rate (the
                              "Remittance Rate") applicable to each Class of
                              Certificates, commencing with the month following
                              the month of initial issuance of such
                              Certificates. See "Maturity, Average Life and
                              Prepayment Assumptions", "Yield Considerations"
                              and "Description of Certificates".
 
Principal (including
  Principal Prepayments)....  Except as otherwise specified in the applicable
                              Prospectus Supplement, principal payments will be
                              passed through on each Distribution Date,
                              commencing with the month following the month of
                              initial issuance of each Series of Certificates.
                              See "Maturity, Average Life and Prepayment
                              Assumptions", "Yield Considerations" and
                              "Description of Certificates".
 
Advances....................  With respect to Series of Certificates as to which
                              the Company and/or a Servicing Entity will act as
                              Master Servicer and except as otherwise specified
                              in the applicable Prospectus Supplement, the
                              Company or such Servicing Entity, as applicable,
                              will be obligated to make advances of its own
                              funds in order to cover deficiencies in amounts
                              distributable to Certificateholders resulting from
                              Mortgagor delinquencies only (and, in the event
                              that both the Company and a Servicing Entity are
                              Master Servicers, only to the extent that such
                              delinquencies arise from its respective Mortgage
                              Loan Servicing Group), to the extent the Company
                              or such Servicing Entity, as applicable,
                              determines such advances are recoverable from
                              future payments or collections on the Mortgage
                              Loans or, if applicable, in its respective
                              Mortgage Loan Servicing Group, amounts available
                              as a result of any subordination feature or from
                              applicable credit enhancements. Similarly, with
                              respect to Series of Certificates as to which
                              there will be no Master Servicer and the servicing
                              of the Mortgage Loans will be performed by the
                              Servicer, the Servicer, except as otherwise
                              specified in the applicable prospectus supplement,
                              will be obligated to make advances of its own
                              funds in order to cover deficiencies in amounts
                              distributable to Certificateholders only to the
                              extent the Servicer determines such advances are
                              recoverable from future payments or collections on
                              the Mortgage Loans, amounts available as a result
                              of any subordination in right of payment of one or
                              more Classes of Certificates to such rights of
                              holders of other Classes of Certificates or from
                              applicable credit enhancements. See "Description
                              of Certificates--Advances".
 
The Mortgage Loans..........  Each Mortgage Pool will have an aggregate
                              principal balance of at least $5,000,000 and will
                              consist of one or more of the following types of
                              Mortgage Loans with various original terms:
</TABLE>
 
<TABLE>
<S>                           <C>   <C>
                               (1)  fixed-rate, fully amortizing Mortgage Loans
                                    providing for level monthly payments of
                                    principal and interest;
</TABLE>
 
                                       5
<PAGE>
 
<TABLE>
<S>                           <C>   <C>
                               (2)  adjustable-rate Mortgage Loans ("ARMs" or
                                    "ARM Loans"), which may include graduated
                                    payment Mortgage Loans and other Mortgage
                                    Loans providing for negative amortization;
 
                               (3)  Mortgage Loans, with either fixed or
                                    adjustable rates, that do not provide for
                                    level monthly payments of principal and
                                    interest and/or do not provide for
                                    amortization in full by their maturity
                                    dates;
 
                               (4)  fixed-rate Mortgage Loans that do not
                                    provide for amortization in full by their
                                    maturity dates and which may at the end of
                                    their terms be converted by the Mortgagors
                                    to fully-amortizing ARM Loans, provided that
                                    certain conditions are met; and
 
                               (5)  any other type of Mortgage Loan, as
                                    described in the applicable Prospectus
                                    Supplement.
</TABLE>
 
<TABLE>
<S>                           <C>
                              If provided for in the applicable Prospectus
                              Supplement, a Mortgage Pool may contain Mortgage
                              Loans subject to buy- down plans ("Buydown
                              Loans"). See "The Mortgage Pools".
 
Primary Insurance
  Policies..................  To the extent specified in the applicable
                              Prospectus Supplement, each Mortgage Loan having a
                              loan-to-value ratio at origination and at the
                              applicable Cut-Off Date (as defined herein) above
                              80% (or another specified level) will be covered
                              by a primary mortgage insurance policy (a "Primary
                              Insurance Policy") insuring against default by the
                              Mortgagor with respect to all or a specified
                              portion of the principal amount thereof, until the
                              principal balance of such Mortgage Loan is reduced
                              below 80% of the then current appraised value of
                              the Mortgaged Property or the principal balance of
                              the Mortgage Loan at origination, as applicable.
                              See "The Mortgage Pools" and "Primary Mortgage
                              Insurance, FHA Mortgage Insurance, VA Mortgage
                              Guaranty, Hazard Insurance; Claims Thereunder".
 
Credit Enhancements.........  The Company, the Servicing Entity or the Servicer,
                              as applicable, may obtain for certain Mortgage
                              Pools (or, if applicable, the related Mortgage
                              Loan Servicing Group in such Mortgage Pool) a
                              mortgage pool insurance policy (a "Mortgage Pool
                              Insurance Policy"), limited in scope, covering
                              defaults on the Mortgage Loans in such Mortgage
                              Pool or, if applicable, the related Mortgage Loan
                              Servicing Group in such Mortgage Pool that are not
                              covered as to their entire outstanding principal
                              balance by insurance coverage provided by the
                              Federal Housing Authority or guarantees issued by
                              the Department of Veterans Affairs.
 
                              The Company, the Servicing Entity or the Servicer,
                              as applicable, may also obtain for certain
                              Mortgage Pools (or, if applicable, the related
                              Mortgage Loan Servicing Group in such Mortgage
                              Pool) a fraud bond (a "Fraud Bond"), limited in
                              scope, insuring Certificateholders against losses
                              on any Mortgage Loan (or, if applicable, any
                              Mortgage Loan in the
</TABLE>
 
                                       6
<PAGE>
 
<TABLE>
<S>                           <C>
                              related Mortgage Loan Servicing Group) which
                              result in an exclusion from, denial of, or defense
                              to coverage under a Primary Insurance Policy or,
                              if applicable, a Mortgage Pool Insurance Policy,
                              because of circumstances involving fraudulent
                              conduct or negligence by the Seller, a Seller/
                              Servicer, the Servicer or the related mortgagor
                              (the "Mortgagor").
 
                              In addition, the Company, the Servicing Entity or
                              the Servicer, as applicable, may obtain for
                              certain Mortgage Pools (or, if applicable, the
                              related Mortgage Loan Servicing Group in such
                              Mortgage Pool) a bankruptcy bond (a "Bankruptcy
                              Bond"), limited in scope, insuring against losses
                              resulting from the bankruptcy of a Mortgagor under
                              a Mortgage Loan contained in a Mortgage Pool (or,
                              if applicable, a Mortgage Loan in the related
                              Mortgage Loan Servicing Group).
 
                              All of the Mortgage Loans (other than Cooperative
                              Loans and Mortgage Loans secured by condominium
                              apartments) will be covered by standard hazard
                              insurance policies insuring against losses due to
                              various causes, including fire, lightning and
                              windstorm. For some Series of Certificates,
                              certain other physical risks which are not
                              otherwise insured against (including earthquakes
                              in some geographical regions, mud flows and
                              floods) will be covered by a special hazard
                              insurance policy (a "Special Hazard Insurance
                              Policy") to be obtained with respect to the
                              Mortgage Pool.
 
                              In lieu of obtaining one or more of the credit
                              enhancements described above, the Seller, the
                              Company, the Servicing Entity or the Servicer, as
                              applicable, may establish a reserve fund (a
                              "Reserve Fund") and/or obtain a letter of credit
                              (a "Letter of Credit"), either of which would
                              provide coverage substantially similar to the
                              credit enhancement or enhancements it replaces.
                              Any losses not covered by any of these credit
                              enhancements will not be insured against and will
                              therefore be borne by Certificateholders for such
                              Series. See "The Mortgage Pools" and "Description
                              of Credit Enhancements".
 
                              In addition to the credit enhancements described
                              above, the Company, the Servicing Entity or the
                              Servicer, as applicable, may obtain or provide for
                              other credit enhancements for a Series of
                              Certificates which provide for coverage of certain
                              risks of default or losses, such as, but not
                              limited to, certificate insurance policies issued
                              by insurers acceptable to each rating agency
                              rating the Certificates, insuring to holders of
                              the Certificates the payment of amounts due in
                              accordance with the terms of the Certificates, or
                              other arrangements acceptable to each rating
                              agency rating the Certificates. Coverage of
                              certain risks of default or loss may also be
                              provided to a particular Class or Classes of
                              Certificates by the subordination in right of
                              payment of one or more Classes of Certificates of
                              the same Series to the right of holders of such
                              Class or Classes of Certificates to receive
                              payments.
</TABLE>
 
                                       7
<PAGE>
 
<TABLE>
<S>                           <C>
                              The Prospectus Supplement for each Series will
                              indicate whether such Series or the Mortgage Loans
                              contained therein are covered by various credit
                              enhancements, indicating the nature, amount and
                              extent of such coverage.
 
Private Certificates and
  Agency Certificates.......  If specified in the related Prospectus Supplement,
                              a Trust Fund may include private mortgage
                              pass-through certificates ("Private Certificates")
                              or certificates issued by the Federal Home Loan
                              Mortgage Corporation ("FHLMC"), the Federal
                              National Mortgage Association ("FNMA") or the
                              Government National Mortgage Association ("GNMA")
                              (collectively, "Agency Certificates"). Any Private
                              Certificates or Agency Certificates will be
                              described in the related Prospectus Supplement.
 
Tax Status..................  For Federal income tax purposes, the
                              Certificateholders of a Series will be considered
                              to own "regular interests" or "residual interests"
                              in a REMIC. Holders of Certificates designated in
                              the applicable Prospectus Supplement as "regular
                              interests" will be treated as holders of debt of
                              the REMIC for federal income tax purposes. Such
                              Certificateholders must include in income interest
                              due and original issue discount on their
                              Certificates using the accrual method of
                              accounting, regardless of their usual methods of
                              accounting. Holders of Certificates designated in
                              the applicable Prospectus Supplement as "residual
                              interests" will be taxable on their allocable
                              share of the taxable income of the REMIC
                              regardless of the cash distributable on such
                              interests. See "Certain Federal Income Tax
                              Consequences--Taxation of Owners of REMIC Residual
                              Certificates".
 
                              With certain exceptions described herein,
                              Certificates held by a "domestic building and loan
                              association" will be considered to represent
                              "loans secured by an interest in real property"
                              within the meaning of Section 7701(a)(19)(C)(v) of
                              the Internal Revenue Code of 1986, as amended (the
                              "Code").
 
                              See "Certain Federal Income Tax Consequences".
 
Optional Termination........  For each Series of Certificates, any of the
                              Company, the Master Servicers, the Servicing
                              Entity or the Servicer, as set forth in the
                              applicable Prospectus Supplement, will have the
                              option to repurchase the related Mortgage Loans
                              (or, if applicable, the related Mortgage Loan
                              Servicing Group) or certificates, as the case may
                              be, and thereby effect the early retirement of
                              such Series at any time after the principal
                              balances of the Mortgage Loans or certificates
                              aggregate less than the percentage specified in
                              the related Prospectus Supplement of the aggregate
                              principal balance of the Mortgage Loans in such
                              Mortgage Pool or the certificates as of the first
                              day of the month in which such Certificates were
                              issued or such other day as may be specified in
                              the applicable Prospectus Supplement (the "Cut-Off
                              Date"). The amount distributable to
                              Certificateholders in connection with any such
                              repurchase will also be set forth in the
                              applicable Prospectus Supplement.
</TABLE>
 
                                       8
<PAGE>
 
<TABLE>
<S>                           <C>
Optional Redemption.........  If so specified in the Prospectus Supplement for a
                              Series, the related Trust Fund will enter into a
                              redemption agreement pursuant to which the
                              counterparty to the agreement will have the right
                              to cause a redemption of the outstanding
                              Certificates of such Series, beginning on the
                              Distribution Date and subject to payment of the
                              redemption price and other conditions specified in
                              the Prospectus Supplement. See "Risk Factors",
                              "Yield Considerations", "Maturity, Average Life
                              and Prepayment Assumptions", and "Description of
                              the Certificates-Redemption Agreement" herein.
 
Put Option..................  If so specified in the Prospectus Supplement for a
                              Series, each Certificateholder of such Series, of
                              a Class of such Series or of a group for such
                              Series will have the option to require the entity
                              named in such Prospectus Supplement to purchase
                              such Certificates in full on the date, at the
                              purchase price and on the terms specified in such
                              Prospectus Supplement.
 
Investment Considerations...  Potential investors should be aware that (a) any
                              decline in the value of a property securing a
                              Mortgage Loan in a Mortgage Pool may result in a
                              loss to Certificateholders if the related
                              Mortgagor defaults and the loss is not covered by
                              the credit enhancements provided for such Mortgage
                              Loan or Mortgage Pool and (b) any hazard loss not
                              covered by the standard hazard insurance policy or
                              any applicable Special Hazard Insurance Policy or
                              comparable credit enhancement covering a defaulted
                              Mortgage Loan may result in a loss to
                              Certificateholders.
 
                              Prepayments of Mortgage Loans, or early
                              liquidations of Mortgage Loans by foreclosure or
                              otherwise (whether or not a loss is incurred) may,
                              in certain circumstances, increase or, in certain
                              circumstances, decrease Certificateholders' yield
                              on the Certificates. See "Yield Considerations"
                              and "Maturity, Average Life and Prepayment
                              Assumptions".
 
                              There is no assurance that a secondary market will
                              exist for any Series of the Certificates.
 
                              See "Risk Factors" herein.
 
ERISA Limitations...........  A fiduciary of any employee benefit plan subject
                              to the Employee Retirement Income Security Act of
                              1974, as amended ("ERISA"), or Section 4975 of the
                              Code (and any person which proposes to cause any
                              such plan to acquire Certificates) should
                              carefully review with its own legal advisors
                              whether the purchase or holding of Certificates
                              could give rise to a transaction prohibited or
                              otherwise impermissible under ERISA or the Code.
                              See "ERISA Considerations".
</TABLE>
 
                                       9
<PAGE>
                                  RISK FACTORS
 
    Investors should consider, among other things, the following factors in
connection with the purchase of the Certificates:
 
    LIMITED LIQUIDITY.  There can be no assurance that a secondary market for
the Certificates of any Series will develop or, if it does develop, that it will
provide Certificateholders with liquidity of investment or that it will continue
for the life of the Certificates of any Series. The Prospectus Supplement for
any Series of Certificates may indicate that an underwriter specified therein
intends to establish a secondary market in such Certificates. However, no
underwriter will be obligated to do so and offerings may be effected hereunder
without participation by any underwriter. The Certificates will not be listed on
any securities exchange.
 
    LIMITED OBLIGATIONS.  The Certificates will not represent an interest in or
obligation of the Company, PNC Bank Corp., a Servicing Entity, a Servicer or any
of their respective affiliates. The obligations of the Company, a Servicing
Entity or a Servicer, as applicable, with respect to the Certificates or the
Mortgage Loans will be limited to any representations and warranties made by the
Company in, as well as any servicing and/or administrative obligations under,
the Pooling Agreement (as defined herein) for each Series of Certificates.
Unless otherwise specified in the applicable Prospectus Supplement, these
obligations, for Series of Certificates as to which the Company and/or a
Servicing Entity will act as Master Servicer, will consist primarily of the
obligation under certain circumstances of the Company or Servicing Entity, as
applicable, to repurchase Mortgage Loans as to which there has been a breach of
representations and warranties which materially and adversely affects the
interests of the Certificateholders in a Mortgage Loan or to cure such breach.
In addition, unless otherwise specified in the applicable Prospectus Supplement,
the Company or Servicing Entity, as Master Servicer, will have a limited
obligation to make certain advances (to the extent not previously advanced by
the Seller/Servicers) in the event of delinquencies on the related Mortgage
Loans, but only to the extent deemed recoverable. Except as so described in the
related Prospectus Supplement, neither the Certificates, the underlying Mortgage
Loans nor Certificateholders will be guaranteed or insured by any governmental
agency or instrumentality, or by the Company or any of its affiliates. Proceeds
of the assets included in the related Trust Fund for each Series of Certificates
(including the Mortgage Loans and any form of credit enhancement) will be the
sole source of payments on the Certificates, and there will be no recourse to
the Company or any other entity in the event that such proceeds are insufficient
or otherwise unavailable to make all payments provided for under the
Certificates.
 
    LIMITATIONS, REDUCTION AND SUBSTITUTION OF CREDIT ENHANCEMENT.  With respect
to each Series of Certificates, credit enhancement may be provided in limited
amounts to cover certain types of losses on the underlying Mortgage Loans.
Credit enhancement will be provided in one or more of the forms referred to
herein, including, but not limited to: subordination of other Classes of
Certificates of the same Series; a Letter of Credit; a Mortgage Pool Insurance
Policy; a Special Hazard Insurance Policy; a Fraud Bond; a Bankruptcy Bond; a
Reserve Fund; and any combination thereof. See "Description of Credit
Enhancements" herein. Regardless of the form of credit enhancement provided, the
amount of coverage will be limited in amount and in most cases will be subject
to periodic reduction in accordance with a schedule or formula. Furthermore,
such credit enhancements may provide only very limited coverage as to certain
types of losses, and may provide no coverage as to certain other types of
losses. All or a portion of the credit enhancement for any series of
Certificates will generally be permitted to be reduced, terminated or
substituted for, if each applicable rating agency indicates that the then
current rating thereof will not be adversely affected. See "Description of
Credit Enhancements".
 
    RISKS OF THE MORTGAGE LOANS.  An investment in securities such as the
Certificates which generally represent interests in mortgage loans may be
affected by, among other things, a decline in real estate values and changes in
the related Mortgagors' financial condition. No assurance can be given that the
values of the Mortgaged Properties (as defined herein) have remained or will
remain at their levels on the dates of origination of the related Mortgage
Loans. If the residential real estate market should experience an overall
decline in property values such that the outstanding balances of the Mortgage
Loans, and any secondary financing on the Mortgaged Properties, in a particular
Mortgage Pool become equal to or greater than the value of the Mortgaged
Properties, the actual rates of delinquencies, foreclosures and losses could be
higher than those now generally experienced in the
 
                                       10
<PAGE>
mortgage lending industry. In addition, in the case of the Mortgage Loans that
are subject to negative amortization, the principal balances of such Mortgage
Loans could be increased to amounts equal to or in excess of the values of the
underlying Mortgaged Properties, thereby increasing the likelihood of default.
To the extent that such losses are not covered by the applicable credit
enhancement, holders of Certificates of the Series evidencing interests in the
related Mortgage Pool will bear all risk of loss resulting from default by
Mortgagors and will have to look primarily to the value of the Mortgaged
Properties for recovery of the outstanding principal and unpaid interest on the
defaulted Mortgage Loans. Certain of the types of loans which may be included in
the Mortgage Pools may involve additional uncertainties not present in
traditional types of loans. For example, certain of the Mortgage Loans may
provide for escalating or variable payments by the Mortgagor, as to which the
Mortgagor is generally qualified on the basis of the initial payment amount. In
some instances the Mortgagors' income may not be sufficient to enable them to
continue to make their loan payments as such payments increase and thus the
likelihood of default will increase. In addition to the foregoing, certain
geographic regions of the United States from time to time will experience weaker
regional economic conditions and housing markets and, consequently, will
experience higher rates of loss and delinquency on mortgage loans generally. The
Mortgage Loans underlying certain Series of Certificates may be concentrated in
these regions, and such concentration may present risk considerations in
addition to those generally present for similar mortgage-backed securities
without such concentration.
 
    YIELD AND PREPAYMENT CONSIDERATIONS.  The yield to maturity of the
Certificates of each Series will depend on the rate of principal payment
(including prepayments, liquidations due to defaults and repurchases) on the
Mortgage Loans and the price paid by Certificateholders. Such yield to maturity
may be adversely affected by a higher or lower than anticipated rate of
prepayments on the related Mortgage Loans. The yield to maturity on Certificates
entitling the holders thereof primarily or exclusively to payments of interest
on the Mortgage Loans will be extremely sensitive to the rate of prepayments on
the related Mortgage Loans and, if applicable, to the occurrence of a redemption
or other call feature of the Certificates or the Mortgage Loans. In addition,
the yield on certain other types of Classes of Certificates may be relatively
more sensitive to the rate of prepayment on the related Mortgage Loans than
other Classes of Certificates. Prepayments are influenced by a number of
factors, including prevailing mortgage market interest rates, local and regional
economic conditions and homeowner mobility. See "Yield Considerations" and
"Maturity, Average Life and Prepayment Assumptions".
 
    REDEMPTION OF CERTIFICATES OR UNDERLYING MORTGAGE LOANS.  If the
Certificates of a Series or the underlying Mortgage Loans are subject to
redemption or other call feature, the average life and yield of each Class of
such Series will also be affected by the occurrence of such a redemption as
described under "Yield Considerations", "Maturity, Average Life and Prepayment
Assumptions" and "The Mortgage Pools--General" herein.
 
                              THE MORTGAGE POOLS*
 
GENERAL
 
    Unless otherwise indicated in the applicable Prospectus Supplement, each
Mortgage Pool will consist entirely of either fixed- or adjustable-rate mortgage
loans (the "Mortgage Loans") evidenced by promissory notes (the "Mortgage
Notes") secured by first mortgages, deeds of trust or security deeds (the
"Mortgages") on one- to four-family residential properties or multi-family
residential properties (the "Mortgaged Properties"). The types of Mortgaged
Properties securing the Mortgage Loans in each Mortgage Pool may include (a)
owner occupied, (i) attached or detached single-family residences, including
residences in planned unit developments, (ii) two- to four-family primary
residences and (iii) condominiums or other attached dwelling units, (b)
second/vacation homes and nonowner occupied residences, and (c) leasehold in the
underlying Mortgaged Property and such
 
- --------------
* Whenever in this Prospectus the terms "Mortgage Pool", "Certificates" and
"Trust Fund" are used, those terms apply, unless the context indicates
otherwise, to one specific Mortgage Pool, to the Series of Certificates
representing undivided interests in the related Trust Fund and to the related
Trust Fund, respectively. Similarly, the term "Remittance Rate" will refer to
the rate of interest borne by the Certificates of one specific Series (or borne
by one Class of Certificates of one specific Series).
 
                                       11
<PAGE>
other types of homes or dwellings as are set forth in the related Prospectus
Supplement. In the case of leasehold interests, the term of the leasehold will
exceed the scheduled maturity of the Mortgage Loan by at least five years,
unless otherwise specified in the related Prospectus Supplement. If specified in
the applicable Prospectus Supplement, a Mortgage Pool may contain cooperative
apartment loans ("Cooperative Loans") evidenced by promissory notes
("Cooperative Notes") secured by security interests in shares issued by private
cooperative housing corporations (each, a "Cooperative") and in the related
proprietary leases or occupancy agreements granting exclusive rights to occupy
specific dwelling units in the related buildings. As used herein, unless the
context indicates otherwise, "Mortgage Loans" includes Cooperative Loans,
"Mortgaged Properties" includes shares in the related Cooperative and the
related proprietary leases or occupancy agreements securing Cooperative Notes,
"Mortgage Notes" includes Cooperative Notes and "Mortgages" includes a security
agreement with respect to a Cooperative Note.
 
    The Mortgage Loans to be purchased by the Company for inclusion in a
Mortgage Pool will be screened and underwritten in accordance with the standards
set forth herein under "The Company-- Mortgage Purchase Program" and "--Credit,
Appraisal and Underwriting Standards". The Mortgage Loans in each Mortgage Pool
will be originated by or purchased from lending institutions which meet the
requirements set forth under "The Company--Mortgage Purchase Program" (such
institutions, "Sellers"). Generally, with respect to each Series, the Company,
another entity set forth in the related Prospectus Supplement (who will
generally be a Seller) (a "Servicing Entity) or the Company together with such
Servicing Entity will be responsible for the servicing and administration of the
Mortgage Loans (in such capacity, each of the Company and/or such Servicing
Entity, a "Master Servicer") and the Sellers will perform certain servicing
functions with respect to the Mortgage Loans (in such capacity,
"Seller/Servicers"), which term includes related servicing corporations, agents
and replacement servicers designated by the Company. In the event that both the
Company and a Servicing Entity are acting as Master Servicers with respect to a
single Series, (i) each of the Company and such Servicing Entity will act as
Master Servicer only for a specific group or groups of Mortgage Loans in the
related Mortgage Pool (a "Mortgage Loan Servicing Group") as set forth in the
related Prospectus Supplement,(ii) the duties, obligations and liabilities of
each the Company and such Servicing Entity shall relate only to its respective
Mortgage Loan Servicing Group, and (iii) the Company, unless otherwise specified
in the related Prospectus Supplement, will calculate amounts distributable to
the Certificateholders, prepare tax returns on behalf of the Trust Fund and
provide certain other services specified in the Pooling Agreement (in such
capacity, the "Certificate Administrator"). Unless otherwise specified in the
related Prospectus Supplement, in the event that a Servicing Entity is the only
Master Servicer with respect to any Series, such Servicing Entity will be the
Certificate Administrator with respect to such Series. If so specified in the
applicable Prospectus Supplement, however, (i) the servicing of the Mortgage
Loans will be performed by the Seller which sold the Mortgage Loans to the
Company for inclusion in the Trust Fund, or by a qualified servicer selected by
the Company (either entity acting in such capacity, the "Servicer"), (ii) there
will not be a Master Servicer and (iii) the Company will act as the Certificate
Administrator. The Servicer and the Certificate Administrator may perform their
respective servicing and administrative responsibilities through agents or
independent contractors, but shall not thereby be released from any of their
obligations under the Pooling Agreement. See "Description of
Certificates--Servicing". The applicable Prospectus Supplement will set forth
information respecting the number and principal amount of Mortgage Loans which
were originated for the purpose of (a) purchasing and (b) refinancing the
related Mortgaged Properties.
 
    To the extent specified in the applicable Prospectus Supplement, Mortgage
Loans with loan-to-value ratios and/or principal balances exceeding certain
limits will be covered partially by Primary Insurance Policies. A Mortgage Pool
may include Mortgage Loans insured by the Federal Housing Administration ("FHA")
or guaranteed by the Department of Veterans Affairs ("VA"), which loans will be
covered by FHA insurance policies ("FHA Insurance Policies") and VA guaranties
("VA Guaranties"), respectively. Mortgage Loans guaranteed by the VA ("VA
Loans") may also be covered by supplemental Primary Insurance Policies. In
addition, if specified in the applicable Prospectus Supplement, the Company or a
Servicing Entity, as applicable, as Master Servicer, the Seller or the Servicer,
as applicable, may obtain or establish one or more credit enhancements for a
Mortgage Pool. Any such credit enhancement will be described in the applicable
Prospectus Supplement. Such credit
 
                                       12
<PAGE>
enhancements may be limited to one or more Classes of Certificates and may
include, but will not necessarily be limited to, any of the following: a
Mortgage Pool Insurance Policy, a Special Hazard Insurance Policy, a Fraud Bond,
a Bankruptcy Bond, a Letter of Credit, a Reserve Fund, a certificate insurance
policy, or any combination of the foregoing. Coverage of certain risks of
default or loss may also be provided to a particular Class or Classes of
Certificates by the subordination in right of payment of one or more Classes of
Certificates of the same Series to the right of holders of such Class or Classes
of Certificates to receive payments. See "Description of Credit Enhancements".
 
    Unless otherwise specified in the related Prospectus Supplement for any
Series of Certificates, all Mortgage Loans will be of one or more of the
following types of Mortgage Loans of varying terms at origination:
 
        (1) fully amortizing Mortgage Loans, each providing for interest (the
    "Mortgage Interest Rate") at a fixed rate and level monthly payments of
    principal and interest over the term of such Mortgage Loan;
 
        (2) Mortgage Loans, each with an adjustable Mortgage Interest Rate,
    which may include graduated payment Mortgage Loans and other Mortgage Loans
    providing for negative amortization;
 
        (3) Mortgage Loans with either fixed or adjustable Mortgage Interest
    Rates, that do not provide for level monthly payments of principal and
    interest and/or do not provide for amortization in full by their maturity
    dates;
 
        (4) fixed-rate Mortgage Loans that do not provide for amortization in
    full by their maturity dates and which may at the end of their terms be
    converted by the Mortgagors to fully amortizing adjustable-rate Mortgage
    Loans, provided that certain conditions are met; and
 
        (5) any other type of Mortgage Loan described in the applicable
    Prospectus Supplement.
 
    If so specified in the related Prospectus Supplement for any Series of
Certificates, a Mortgage Pool may contain Buydown Loans which include provisions
whereby the Seller or a third party partially subsidizes the monthly payments of
the Mortgagor during the initial portion of the term of the Buydown Loan, the
difference to be made up from a fund (the "Buydown Fund") contributed by the
Seller or a third party at the time of origination of the Mortgage Loan. A
Buydown Fund will be in an amount equal either to the discounted value or full
aggregate amount of future payment subsidies. The applicable Prospectus
Supplement or Current Report on Form 8-K will contain information with respect
to any Buydown Loans, including information on the interest rate initially
payable by the Mortgagor, annual increases in the interest rate, the length of
the buydown period and the Buydown Fund. The underlying assumption of buydown
plans is that the income of the Mortgagor will increase during the buydown
period as a result of normal increases in compensation and of inflation, so that
the Mortgagor will be able to meet the full mortgage payments at the end of the
buydown period. To the extent that this assumption as to increased income is not
correct, the possibility of defaults on Buydown Loans is increased.
 
    The aggregate principal balances of the Mortgage Loans in each Mortgage Pool
on the date specified in the related Prospectus Supplement as the Cut-Off Date
will be at least $5,000,000. Unless otherwise specified in the Prospectus
Supplement of a particular Series, each Mortgage Loan at origination will have
an outstanding principal balance of not less than $30,000 nor more than
$1,000,000. With respect to each Mortgage Pool, unless otherwise specified in
the related Prospectus Supplement, all principal and interest payments on the
Mortgage Loans due prior to the Cut-Off Date will have been made.
 
    For each Mortgage Pool, the related Prospectus Supplement will generally
contain specific information as of the Cut-Off Date regarding (i) the aggregate
principal balance of the Mortgage Loans; (ii) the range of Mortgage Interest
Rates or initial Mortgage Interest Rates borne by the Mortgage Loans; (iii) the
month and year in which the first monthly payments occur, and the latest
maturity of the Mortgage Loans; (iv) the largest and smallest principal balances
of the Mortgage Loans at origination; (v) the aggregate principal balance of all
Mortgage Loans having loan-to-value ratios at origination exceeding 80%; (vi)
the types of dwellings constituting the Mortgaged Properties securing the
Mortgage Loans; (vii) the percentage of the Mortgage Loans (by principal
balance) of
 
                                       13
<PAGE>
nonowner occupied and of second and vacation properties; (viii) the geographic
distribution of the Mortgage Loans, prepared on a state-by-state basis for
states containing 5% or more of the Mortgage Pool; and (ix) the number and
aggregate principal balance of Buydown Loans.
 
    Specific information with respect to the Mortgage Loans in a particular
Mortgage Pool and the applicable credit enhancements which is not included in
the related Prospectus Supplement will generally be included in a Current Report
on Form 8-K which will be available to purchasers of the Certificates at or
before the time of initial issuance of the related Series of Certificates, and
which will be filed with the Securities and Exchange Commission (the
"Commission") within 15 days thereafter.
 
    The Company and/or a Servicing Entity, as applicable, as Master Servicer,
has entered or will enter into a contract with each related Seller/Servicer to
perform, as an independent contractor, certain servicing functions for such
Master Servicer subject to its supervision and may enter into a contract with an
independent entity to perform administration functions for the Mortgage Pools
(or, if applicable, the Mortgage Loan Servicing Group), subject to such Master
Servicer's supervision. Unless otherwise specified in the applicable Prospectus
Supplement, such Master Servicer will reserve the right to remove any related
Seller/Servicer of any Mortgage Loan at any time if such Master Servicer
considers such removal to be in the best interests of Certificateholders. In
such event, such Master Servicer would continue to be responsible for servicing
such Mortgage Loan and may designate a replacement Seller/Servicer (which may
include the Company or the related Servicing Entity, as applicable, or an
affiliate of the Company or Servicing Entity, as applicable). Each Master
Servicer may perform its administrative and servicing responsibilities through
agents or independent contractors, but shall not thereby be released from any of
its responsibilities under the Pooling Agreement. Each Master Servicer will
receive a fee (the "Master Servicing Fee") for its services. In the event that
both the Company and a Servicing Entity are acting as Master Servicers for a
Series, unless otherwise specified in the related Prospectus Supplement, the
Master Servicing Fee for each of the Company and such Servicing Entity will only
relate to its respective Mortgage Loan Servicing Group. The Seller/Servicers
will perform certain servicing functions for the Company pursuant to servicing
contracts (the "Servicing Contracts") with a Master Servicer and will receive a
fee for acting as the primary servicer of the related Mortgage Loans (the
"Servicing Fee"). The fees to a Master Servicer and the Seller/Servicers will be
paid from the difference between the Mortgage Interest Rates on each Mortgage
Loan (or Mortgage Loan Servicing Group, if applicable) and the Remittance Rate
with respect to such Mortgage Loan.
 
    If so specified in the applicable Prospectus Supplement, there will be no
Master Servicer for a particular Series of Certificates. In such event, (i) the
servicing of the Mortgage Loans will be performed by the Servicer specified in
the applicable Prospectus Supplement, (ii) there will not be a Master Servicer,
and (iii) the Certificate Administrator will calculate amounts distributable to
the Certificateholders, prepare tax returns on behalf of the Trust Fund and
provide certain other administrative services specified in the Pooling
Agreement. The Servicer and the Certificate Administrator may perform their
respective servicing and administrative responsibilities through agents or
independent contractors, but shall not thereby be released from any of their
respective responsibilities under the Pooling Agreement. With respect to such
Series of Certificates, the Servicer will receive the Servicing Fee and, with
respect to each such Series and each Series in which both the Company and a
Servicing Entity are acting as Master Servicers, the Certificate Administrator
will receive a fee for its services (the "Certificate Administrator Fee"), each
of which will be paid from the difference between the Mortgage Interest Rate on
each Mortgage Loan and the Remittance Rate with respect to such Mortgage Loan.
 
    Unless otherwise specified in the applicable Prospectus Supplement, the
Certificates of each Series will represent undivided interests in a Trust Fund
consisting of the Mortgage Loans included in the Mortgage Pool for that Series
and related property. Certain Series will be enhanced by mortgage loan insurance
or other forms of credit enhancement, in each case as more fully described
herein under the captions "Description of Certificates" and "Description of
Credit Enhancements" and/or in the related Prospectus Supplement. When each
Series of Certificates is issued, the Company will cause the Mortgage Loans in
the Mortgage Pool for that Series to be assigned to an independent bank
 
                                       14
<PAGE>
or trust company as trustee (the "Trustee") for the benefit of the holders of
Certificates of that Series, and the Master Servicer or the Servicer will be
responsible for servicing the Mortgage Loans pursuant to a separate pooling and
servicing agreement ("Pooling Agreement") for the Series.
 
    The Company's assignment of the Mortgage Loans to the Trustee will be
without recourse, and the Company's obligations with respect to the Mortgage
Loans will, unless otherwise indicated in the Prospectus Supplement for a Series
of Certificates, be limited to any representations and warranties made by it in,
as well as its contractual obligations under, the Pooling Agreement for each
Series. These obligations consist primarily of the obligation to administer and,
if applicable, service the Mortgage Loans. With respect to Series of
Certificates as to which the Company and/or a Servicing Entity will act as
Master Servicer and unless otherwise stated in the Prospectus Supplement for
such Series, in the event of delinquencies in payments on the Mortgage Loans in
any Mortgage Pool (or the related Mortgage Loan Servicing Group for such Series
if both the Company and a Servicing Entity are acting as Master Servicers), to
advance cash ("Advances") in the amounts described herein under "Description of
Certificates--Advances", to the extent such Advances are not made by the Seller/
Servicers and, if the Company and a Servicing Entity are acting as Master
Servicers for such Series, to the extent that such Advances relate to a Mortgage
Loan in their respective Mortgage Loan Servicing Group. Any such Advances by a
Master Servicer will be limited to amounts which, in the judgment of such Master
Servicer, ultimately will be reimbursable with respect to such Mortgage Pool (or
the related Mortgage Loan Servicing Group for such Series if both the Company
and a Servicing Entity are acting as Master Servicers) from Mortgagor payments
or under any applicable Mortgage Pool Insurance Policy, any applicable Special
Hazard Insurance Policy, any Primary Insurance Policy, FHA Insurance Policy or
VA Guaranty issued with respect to a Mortgage Loan, any applicable Letter of
Credit, Reserve Fund or any other applicable policy of insurance, any
subordination feature described herein or the proceeds of liquidation of a
Mortgage Loan. See "Description of Credit Enhancements". Unless otherwise
specified in the applicable Prospectus Supplement, each Seller/Servicer will be
obligated, in the event of delinquencies on the Mortgage Loans serviced by it in
any Mortgage Pool, to make Advances limited to amounts which, in its judgment,
after consultation with the Master Servicer (or the related Master Servicer if
both the Company and a Servicing Entity are acting as Master Servicers),
ultimately will be reimbursable from the sources stated above. If so specified
in the applicable Prospectus Supplement, neither a Master Servicer nor any
Seller/Servicers will be obligated to make Advances with respect to Mortgage
Loans delinquent longer than the time period specified in such Prospectus
Supplement. See "Description of Certificates--Advances" and "Description of
Credit Enhancements". A Master Servicer is obligated to remit to
Certificateholders of a Series all amounts relating to the Mortgage Loans (or
the related Mortgage Loan Servicing Group for such Series if both the Company
and a Servicing Entity are acting as Master Servicers) to the extent such
amounts have been collected or advanced by the Seller/Servicers or advanced by
such Master Servicer and are due Certificateholders pursuant to the terms of the
Pooling Agreement for such Series. With respect to Series of Certificates as to
which there will be no Master Servicer and the servicing of the Mortgage Loans
will be performed by the Servicer, unless otherwise stated in the applicable
Prospectus Supplement, the Servicer will be obligated to make Advances in the
amounts described herein under "Description of Certificates--Advances", limited
to amounts which, in the judgment of the Servicer, ultimately will be
reimbursable with respect to such Mortgage Pool from any of the sources stated
above.
 
CONVERSION OF MORTGAGE LOANS
 
    The Prospectus Supplement for certain Series of Certificates representing
undivided interests in a Trust Fund consisting of adjustable-rate Mortgage Loans
may provide that some or all of the Mortgage Loans in the related Mortgage Pool
may have a conversion feature. Unless otherwise specified in the related
Prospectus Supplement, each such Mortgage Loan may be converted at the
Mortgagor's option at any time during a specified initial period to a fixed-rate
Mortgage Loan, subject to the Seller/Servicer's or the Servicer's determination
that the Mortgagor has met certain payment history requirements and the payment
of a conversion fee ("Conversion Fee") to the Seller/Servicer or the Servicer,
as applicable. Unless otherwise specified in the applicable Prospectus
Supplement, upon any such conversion, the Company or the Servicing Entity, as
applicable, as Master Servicer, or the Seller with respect to Series of
Certificates as to which there will be no Master Servicer, will repurchase the
Mortgage Loan from the Mortgage Pool at its then outstanding principal balance,
plus
 
                                       15
<PAGE>
interest at the Mortgage Interest Rate on such Mortgage Loan to the date of
repurchase. The amounts distributable to Certificateholders of different
Classes, if applicable, upon such repurchase, and the portion of the Conversion
Fee to be passed through to Certificateholders, if any, will be set forth in the
Prospectus Supplement for each such Series of Certificates.
 
                                USE OF PROCEEDS
 
    All of the net proceeds to be received from the sale of each Series of the
Certificates will be used by the Company to purchase the Mortgage Loans related
to that Series or to return to the Company the amounts previously used to effect
such purchases, the costs of carrying the Mortgage Loans until sale of the
Certificates and other expenses connected with pooling the Mortgage Loans and
issuing the Certificates, or for general corporate purposes. The Company expects
to issue Certificates in Series from time to time as part of its continuing
program of acquiring Mortgage Loans and selling Certificates. See "The
Company--Mortgage Purchase Program".
 
                              YIELD CONSIDERATIONS
 
GENERAL
 
    The yield to maturity on any Certificate will depend on the purchase price
paid by the Certificateholder, the effective interest rate of the Certificate
and the weighted average life of the Mortgage Loans underlying the Certificate.
See "Maturity, Average Life and Prepayment Assumptions" for a discussion of
weighted average life. Any prepayment of a Mortgage Loan, liquidation of a
Mortgage Loan (by foreclosure proceedings or by virtue of the purchase of a
Mortgage Loan in advance of its stated maturity or otherwise) or, if applicable,
the occurrence of a redemption or other call feature of the Certificates of a
Series or the underlying Mortgage Loans will have the effect of passing through
to Certificateholders amounts of principal which would otherwise be passed
through in amortized increments over the remaining term of such Mortgage Loan.
The effect of such prepayments on the yield to maturity to Certificateholders
depends on several factors. For example, if the Certificates are purchased above
par (I.E., for more than 100% of the outstanding principal balance of the
Mortgage Loans they represent), such prepayments will tend to decrease the yield
to maturity. If the Certificates were purchased at a discount (I.E., for less
than 100% of such outstanding principal balance), such prepayments will tend to
increase the yield to maturity. See "Certain Legal Aspects of the Mortgage
Loans--Enforceability of Certain Provisions" for a description of certain
provisions of each Mortgage Loan and statutory, regulatory and judicial
developments that may affect the prepayment experience and maturity assumptions
on the Mortgage Loans. See also "Description of Certificates--Termination" for a
description of the repurchase of the Mortgage Loans in any Mortgage Pool when
the aggregate outstanding principal balance thereof is less than a specified
percentage of the aggregate outstanding principal balance of the Mortgage Loans
in such Mortgage Pool on the related Cut-Off Date.
 
    The timing of changes in the rate of principal payments on or repurchases of
the Mortgage Loans (including, if applicable, the occurrence of a redemption or
other call feature of the Certificates of a Series or the underlying Mortgage
Loans) may significantly affect an investor's actual yield to maturity, even if
the average rate of principal payments experienced over time is consistent with
an investor's expectation. In general, the earlier a prepayment of principal on
the underlying Mortgage Loans or a repurchase thereof (including, if applicable,
the occurrence of a redemption or other call feature of the Certificates of a
Series or the underlying Mortgage Loans), the greater will be the effect on an
investor's yield to maturity. As a result, the effect on an investor's yield to
maturity of principal payments and repurchases occurring at a rate higher (or
lower) than the rate anticipated by the investor during the period immediately
following the issuance of a Series of Certificates would not be fully offset by
a subsequent like reduction (or increase) in the rate of principal payments.
 
EFFECTIVE INTEREST RATE
 
    Unless otherwise specified in the applicable Prospectus Supplement, each
monthly interest payment on a Mortgage Loan is calculated as 1/12 of the
applicable Mortgage Interest Rate multiplied by the unpaid principal balance
outstanding on the first day of the month after application of principal
payments made on such date. Unless otherwise specified in the applicable
Prospectus Supplement, the Remittance Rate for each Class of Certificates will
be calculated on the basis of the "Pass-Through
 
                                       16
<PAGE>
Rate" for the related Mortgage Loans. With respect to a Series of Certificates
as to which the Company will act as Master Servicer, the "Pass-Through Rate" for
any Mortgage Loan will equal the related Mortgage Interest Rate less the sum of
the Servicing Fee and the Master Servicing Fee for such Mortgage Loan. With
respect to a Series of Certificates as to which the Company will not act as
Master Servicer, the "Pass-Through Rate" for any Mortgage Loan will equal the
related Mortgage Interest Rate less the sum of the Servicing Fee and the
Certificate Administrator Fee for such Mortgage Loan.
 
    As described in the applicable Prospectus Supplement, in certain events, if
the amounts available for distribution in respect of interest are not sufficient
to cover the total of all accrued and unpaid interest at the Pass-Through Rate,
the available amount will be distributed to the Certificateholders pro rata in
accordance with their respective interests or in an order of priority described
in the applicable Prospectus Supplement.
 
    For the sale of Certificates under this Prospectus, the Company may
establish one or more Mortgage Pools having a variable, as opposed to a fixed,
Pass-Through Rate. A Mortgage Pool with a variable Pass-Through Rate may be
composed of Mortgage Loans that have adjustable Mortgage Interest Rates, or of
Mortgage Loans with fixed Mortgage Interest Rates if the amount to be passed
through is determined on a Mortgage Loan-by-Mortgage Loan basis as the Mortgage
Interest Rate minus specified fees for servicing and administrative
compensation, which may include any of the Servicing Fee, the Master Servicing
Fee and the Certificate Administrator Fee, for each such Mortgage Loan, as set
forth in the Prospectus Supplement, or as otherwise determined as described in
the applicable Prospectus Supplement. Because the Mortgage Interest Rates may
vary in such a Mortgage Pool, and the servicing and administrative compensation
generally will be fixed, the Pass-Through Rate will be affected by
disproportionate principal prepayments among Mortgage Loans bearing different
Mortgage Interest Rates and, consequently, the yield to maturity
Certificateholders will be affected. The characteristics of any such
variable-rate Mortgage Pools will be described in the applicable Prospectus
Supplement. Although Mortgage Interest Rates in a fixed Pass-Through Rate
Mortgage Pool may vary from Mortgage Loan to Mortgage Loan, disproportionate
principal prepayments among the Mortgage Loans bearing different Mortgage
Interest Rates will not affect the return to Certificateholders.
 
    For any Series of Certificates, the effective yield to maturity to
Certificateholders generally will be slightly lower than the yield to maturity
otherwise produced by the applicable Pass-Through Rate because, while interest
will accrue on each Mortgage Loan from the first day of each month, the
distribution of such interest to Certificateholders at the applicable
Pass-Through Rate generally will be made on a later day, which, unless otherwise
specified in the applicable Prospectus Supplement, will be the 25th day (or, if
such day is not a business day, the next succeeding business day) of the month
following the month of accrual.
 
    When a prepayment in full (a "Payoff") is made by a Mortgagor on a Mortgage
Loan during a month, the Mortgagor is charged interest on the days in the month
actually elapsed up to the date of the Payoff at the daily interest rate
(determined by dividing the Mortgage Interest Rate by 365, or 360 in the case of
Payoffs received on a date on which the monthly payment for such Mortgage Loan
is due (a "Due Date")) which is applied to the principal amount of the Mortgage
Loan so prepaid. Similarly, when a Mortgage Loan is liquidated under a Mortgage
Pool Insurance Policy during a month, the pool insurer will pay interest on the
Mortgage Loan only to the date the claim is paid. Also, when a partial principal
prepayment (a "Curtailment") is made on a Mortgage Loan together with the
scheduled Monthly Payment for a month on or after the related Due Date, the
Mortgagor does not pay interest on the prepaid amount, and therefore
Certificateholders will not receive any interest on such prepaid amount.
 
    Unless otherwise specified in the applicable Prospectus Supplement, to the
extent that Compensating Interest (as defined below) is not paid, the effect of
a Payoff or such a liquidation will be to reduce slightly the amount of interest
passed through on the next Distribution Date, because interest on the principal
amount of the Mortgage Loan so prepaid was paid only to the date of such Payoff
or liquidation and not to the end of the month of prepayment. Unless otherwise
specified in the applicable Prospectus Supplement, the following will apply:
Payoffs received during the period from the first day of a calendar month
through the 14th day of such month will be passed through, without Compensating
Interest and without interest accrued from the first day of such month to the
date of
 
                                       17
<PAGE>
the Payoff, on the Distribution Date in such month, and Payoffs received during
the period from the 15th day of a calendar month through the last day of such
month will be passed through, with Compensating Interest and with interest at
the applicable Pass-Through Rate attributable to interest paid through the date
of the Payoff by the Mortgagors on the Distribution Date in the following month.
Proceeds of Mortgage Loans liquidated under a Mortgage Pool Insurance Policy
during a month will be passed through, with Compensating Interest and interest
at the applicable Pass-Through Rate attributable to interest paid by the pool
insurer under an applicable Mortgage Pool Insurance Policy, on the Distribution
Date in the following month.
 
    Unless otherwise specified in the applicable Prospectus Supplement, the
following will apply: "Compensating Interest" will consist of a full month's
payment of interest at the applicable Pass-Through Rate on a Mortgage Loan for
which a Payoff is made or which is liquidated, less the interest at the
applicable Pass-Through Rate attributable to interest paid by the Mortgagor or
by the pool insurer under an applicable Mortgage Pool Insurance Policy through
the date of Payoff. Compensating Interest on liquidated Mortgage Loans will be
passed through to Certificateholders, together with any interest at the
applicable Pass-Through Rate attributable to interest paid by the pool insurer
under any applicable Mortgage Pool Insurance Policy to the date of liquidation
on the Distribution Date of the month following liquidation. Compensating
Interest on Payoffs will be paid on a Distribution Date only with respect to
Payoffs received during the period from the 15th day of the preceding calendar
month through the last day of such preceding month. The applicable Pooling and
Servicing Agreement will specify any limitations on the extent of or source of
funds available for payments of Compensating Interest.
 
               MATURITY, AVERAGE LIFE AND PREPAYMENT ASSUMPTIONS
 
    The Mortgage Loans at origination will have varying maturities as more fully
described in the applicable Prospectus Supplement. The Company expects that most
such Mortgage Loans will have maturities at origination of either 10 to 15 years
or 20 to 30 years and that such Mortgage Loans may be prepaid in full or in part
at any time, generally without penalty. The prepayment experience or, if
applicable, the occurrence of a redemption or other call feature of the
Certificates of a Series or the underlying Mortgage Loans will affect the lives
of the Certificates. The Company anticipates that a substantial number of
Mortgage Loans will be paid in full prior to their scheduled maturity.
 
    A number of factors, including homeowner mobility, economic conditions,
enforceability of "due-on-sale" clauses, assumability of the Mortgage Loans,
mortgage market interest rates and the general availability of mortgage funds
affect prepayment experience. Generally, each Mortgage executed in connection
with a fixed-rate Mortgage Loan, except for FHA-insured or VA-guaranteed
Mortgage Loans, will contain "due-on-sale" provisions permitting the holder of
the Mortgage Note to accelerate the maturity of the Mortgage Loan upon
conveyance by the Mortgagor of the underlying Mortgaged Property. With respect
to Series of Certificates as to which the Company will act as Master Servicer,
the Master Servicer will agree that it or the applicable Seller/Servicer will
enforce any "due-on-sale" clause contained in any such Mortgage to the extent it
has knowledge of the conveyance or proposed conveyance of the underlying
Mortgaged Property and reasonably believes that it is entitled to do so under
applicable law; provided, however, that neither the Master Servicer nor the
Seller/Servicer will take any action in relation to the enforcement of any
"due-on-sale" provision which would impair or threaten to impair any recovery
under any related Primary Insurance Policy or Mortgage Pool Insurance Policy.
With respect to Series of Certificates as to which the Company will not act as
Master Servicer, the Servicer will agree to enforce any "due-on-sale" clause in
the instances and to the extent described in the preceding sentence. However, a
Mortgage Pool may contain fixed-rate Mortgage Loans which will allow a
subsequent owner of a Mortgaged Property, if credit underwriting standards are
met, to assume such fixed-rate Mortgage Loan without enforcement of any
"due-on-sale" clause. With respect to Mortgage Loans bearing adjustable Mortgage
Interest Rates, unless otherwise specified in the related Prospectus Supplement,
the related Mortgages will generally provide that such Mortgage Loans are
assumable by creditworthy subsequent owners without enforcement of any "due-
on-sale" clause. An assumption of a Mortgage Loan may have the effect of
increasing the life of such Mortgage Loan.
 
    "Weighted average life" refers to the average amount of time that will
elapse from the date of issuance of a Certificate until each dollar of principal
will be repaid to the Certificateholders. The
 
                                       18
<PAGE>
weighted average life of the Certificates will be influenced by the rate at
which principal on the Mortgage Loans in the Mortgage Pool is paid, which may be
in the form of (i) scheduled amortization or (ii) Curtailments and Payoffs
(collectively "Principal Prepayments"). Based upon published information, the
rate of prepayments on fixed- and adjustable-rate conventional one-to
four-family mortgage loans has fluctuated significantly in recent years. The
Company believes such fluctuation is due to a number of factors, including those
discussed above, and that such factors will also affect the prepayment
experience on the Mortgage Loans in any Mortgage Pool. Accordingly, the Company
cannot predict what future prepayment experience will be or what the resulting
weighted average life might be. However, principal prepayments on mortgage loans
are commonly measured relative to a prepayment standard or model. The model used
in this Prospectus and in each Prospectus Supplement, unless otherwise indicated
therein (the "Basic Prepayment Assumption" or "BPA"), represents an assumed rate
of prepayment each month relative to the then outstanding principal balance of a
pool of new Mortgage Loans. The BPA assumes prepayment rates of 0.2% per annum
of the then outstanding principal balance of such Mortgage Loans in the first
month of the life of the Mortgage Loans and an additional 0.2% per annum in each
month thereafter until the 30th month. Beginning in the 30th month and in each
month thereafter during the life of the Mortgage Loans, such prepayment model
assumes a constant prepayment rate of 6.0% per annum. Varying prepayment
assumptions are often expressed as percentages of the BPA (E.G., at 150% of the
BPA, assumed prepayments during the first month of a pool would be 0.3% per
annum, each month thereafter the rate of prepayments would increase by 0.3% per
annum, and in the 30th and succeeding months the rate would be 9% per annum).
The Prospectus Supplement or Current Report on Form 8-K for each Series of
Certificates may contain a table setting forth the projected weighted average
life of each Class of Certificates of such Series and the percentage of the
original principal amounts or notional principal amounts of each such Class that
would be outstanding on specified Distribution Dates for such Series, based on
the assumptions set forth with respect to the BPA deemed appropriate by the
Company and specified therein.
 
REDEMPTION OF CERTIFICATES OR UNDERLYING MORTGAGE LOANS
 
    If so specified in the Prospectus Supplement for a Series, the Certificates
of such Series or the underlying Mortgage Loans may be subject to redemption at
the direction of the holder of certain redemption rights, beginning on the
Distribution Date and subject to payment of the redemption price and other
conditions specified in the related Prospectus Supplement. A redemption would
result in the concurrent retirement of all outstanding Certificates of the
Series and would decrease the average lives of such Certificates, perhaps
significantly. The earlier after the Closing Date that a redemption occurs, the
greater would be such effect. In general, a redemption is most likely to occur
if prevailing interest rates have declined. The holder of the redemption right
may also be a Holder of one or more Classes of the related Series, which may
affect such holder's decision whether to direct a redemption. The effect of a
redemption of the Certificates or underlying Mortgage Loans on interest payments
on the Classes of Certificates of a Series will be described in the related
Prospectus Supplement. See "Description of the Certificates-Redemption
Agreement" and "The Mortgage Pools--General".
 
                                  THE COMPANY
 
    The Company, a Delaware corporation, is a wholly-owned indirect subsidiary
of PNC Bank Corp., a bank holding company. The Company was organized for the
purpose of providing mortgage lending institutions, including affiliated
institutions, with greater financing and lending flexibility by purchasing
mortgage loans from such institutions and issuing mortgage-backed securities.
The Company's principal executive offices are located at 75 North Fairway Drive,
Vernon Hills, Illinois 60061, telephone (847) 549-6500.
 
MORTGAGE PURCHASE PROGRAM
 
    Set forth below is a description of the principal aspects of the Company's
purchase program for Mortgage Loans eligible for inclusion in a Mortgage Pool.
The Company will represent and warrant to the Trustee that each Mortgage Pool
will consist of Mortgage Loans purchased from one or more institutions
("Sellers") which are (i) state-chartered or federally-chartered savings and
loan associations, banks or similar financial institutions whose deposits or
accounts are insured by the Federal Deposit Insurance Corporation ("FDIC") or,
if specified in the applicable Prospectus
 
                                       19
<PAGE>
Supplement or Current Report on Form 8-K, substantially similar deposit
insurance approved by any applicable rating agency, (ii) approved as mortgagees
by the FHA ("FHA-Approved Mortgagees"), (iii) approved by the Federal National
Mortgage Association ("FNMA") as mortgagees ("FNMA-Approved Mortgagees") or by
the Federal Home Loan Mortgage Corporation ("FHLMC") as mortgagees
("FHLMC-Approved Mortgagees"), or any successor entity to either, (iv) assignees
of FHA-Approved Mortgagees, FNMA-Approved Mortgagees or FHLMC-Approved
Mortgagees, (v) the FDIC or the Resolution Trust Corporation, (vi) entities
which have purchased Mortgage Loans from institutions described in clauses
(i)-(v) above or (vii) such other entities as may be described in the applicable
Prospectus Supplement. The institutions described in clauses (i)-(v) of the
preceding sentence will collectively be referred to herein as "Lenders". The
Company has approved (or will approve) individual institutions as eligible
Lenders by applying certain criteria, including the Lender's depth of mortgage
origination experience, servicing experience and financial stability. In
general, each Lender must have experience in originating and servicing
conventional residential mortgages and must have a net worth acceptable to the
Company. Each Lender is required to use the services of qualified underwriters,
appraisers and attorneys. Other factors evaluated by the Company in approving
Lenders include delinquency and foreclosure ratio performances.
 
LOAN STANDARDS
 
    The Mortgage Loans to be included in each Mortgage Pool will be loans with
fixed or adjustable rates of interest secured by first mortgages, deeds of trust
or security deeds on residential properties with original principal balances
which did not exceed 95% of the value of the Mortgaged Properties, unless such
loans are FHA-insured or VA-guaranteed. Generally, each Mortgage Loan having a
loan-to-value ratio at origination and as of the Cut-Off Date in excess of 80%
or which is secured by a second or vacation home will be covered by a Primary
Insurance Policy, FHA Insurance Policy or VA Guaranty insuring against default
all or a specified portion of the principal amount thereof. See "Primary
Insurance, FHA Mortgage Insurance, VA Mortgage Guaranty, Hazard Insurance;
Claims Thereunder". Each mortgage insurer must be a Qualified Insurer (defined
herein to mean a mortgage guaranty insurance company which is duly qualified as
such under the laws of each state in which the Mortgaged Properties are located,
duly authorized and licensed in such states to transact a mortgage guaranty
insurance business and to write the insurance provided by the Primary Insurance
Policy or the Mortgage Pool Insurance Policy, as the case may be, and which is
approved as an insurer by FHLMC, FNMA or any successor entity to either, and by
the Company).
 
    The Mortgage Loans to be included in each Mortgage Pool will be "one- to
four-family" mortgage loans, which means permanent loans (as opposed to
construction or land development loans) secured by Mortgages on non-farm
properties, including attached or detached single-family or second/vacation
homes, two-to four-family primary residences and condominiums or other attached
dwelling units, including individual condominiums, row houses, townhouses and
other separate dwelling units even when located in buildings containing five or
more such units. Each Mortgage Loan must be secured by an owner occupied primary
residence or second/vacation home, or by a nonowner occupied residence. The
Mortgaged Property may not be a mobile home.
 
CREDIT, APPRAISAL AND UNDERWRITING STANDARDS
 
    The Mortgage Loans to be included in each Mortgage Pool will be subject to
the various credit, appraisal and underwriting standards described herein. The
Company's credit, appraisal and underwriting standards with respect to certain
Mortgage Loans will generally conform to those published in the Company's
Selling Guide (together with the Company's Servicing Guide, the "Guide", as
modified from time to time). The credit, appraisal and underwriting standards as
set forth in the Guide are continuously revised based on opportunities and
prevailing conditions in the residential mortgage market and the market for the
Company's mortgage pass-through certificates. The Mortgage Loans may be
underwritten by the Company or by designated third parties.
 
    In addition, the Company may purchase Mortgage Loans which do not conform to
the underwriting standards set forth in the Guide. Such Mortgage Loans may be
purchased in negotiated transactions from Sellers who will represent that the
Mortgage Loans have been originated in accordance with credit, appraisal and
underwriting standards agreed to by the Company. The Company will generally
review only a limited portion of the Mortgage Loans in any delivery of such
 
                                       20
<PAGE>
Mortgage Loans for conformity with the applicable credit, appraisal and
underwriting standards. Certain other Mortgage Loans will be purchased from
Sellers who will represent that the Mortgage Loans were originated pursuant to
credit, appraisal and underwriting standards determined by a mortgage insurance
company acceptable to the Company. The Company will accept a certification from
such insurance company as to a Mortgage Loan's insurability in a mortgage pool
as of the date of certification as evidence that such Mortgage Loan conforms to
applicable underwriting standards. Such certifications will likely have been
issued before the purchase of the Mortgage Loans by the Company. The Company
will perform only random quality assurance reviews on Mortgage Loans delivered
with such certifications.
 
    The credit, appraisal and underwriting standards utilized in negotiated
transactions and the credit, appraisal and underwriting standards of insurance
companies issuing certificates may vary substantially from the credit, appraisal
and underwriting standards set forth in the Guide. All of the credit, appraisal
and underwriting standards will provide an underwriter with sufficient
information to evaluate the borrower's repayment ability and the adequacy of the
Mortgaged Property as collateral. Due to the variety of underwriting standards
and review procedures that may be applicable to the Mortgage Loans included in
any Mortgage Pool, the related Prospectus Supplement will not distinguish among
the various credit, appraisal and underwriting standards applicable to the
Mortgage Loans nor describe any review for compliance with applicable credit,
appraisal and underwriting standards performed by the Company. Moreover, there
can be no assurance that every Mortgage Loan was originated in conformity with
the applicable credit, appraisal and underwriting standards in all material
respects, or that the quality or performance of Mortgage Loans underwritten
pursuant to varying standards as described above will be equivalent under all
circumstances.
 
    The Company's underwriting standards are intended to evaluate the
prospective Mortgagor's credit standing and repayment ability, and the value and
adequacy of the proposed Mortgaged Property as collateral. In the loan
application process, prospective Mortgagors will be required to provide
information regarding such factors as their assets, liabilities, income, credit
history, employment history and other related items. Each prospective Mortgagor
will also provide an authorization to apply for a credit report which summarizes
the Mortgagor's credit history. With respect to establishing the prospective
Mortgagor's ability to make timely payments, the Company will require evidence
regarding the Mortgagor's employment and income, and of the amount of deposits
made to financial institutions where the Mortgagor maintains demand or savings
accounts. In some instances, Mortgage Loans which were originated under a
Limited Documentation Origination Program may be sold to the Company. For a
mortgage loan originated under a Limited Documentation Origination Program to
qualify for purchase by the Company, the prospective mortgagor must have a good
credit history and be financially capable of making a larger cash down payment,
in a purchase, or be willing to finance less of the appraised value, in a
refinancing, than would otherwise be required by the Company. Currently, the
Company's underwriting standards provide that only mortgage loans with certain
loan-to-value ratios will qualify for purchase. If the mortgage loan qualifies,
the Company waives some of its documentation requirements and eliminates
verification of income and employment for the prospective mortgagor.
 
    The Company's underwriting standards generally follow guidelines acceptable
to FNMA and FHLMC. In determining the adequacy of the property as collateral, an
independent appraisal is made of each property considered for financing. The
appraiser is required to inspect the property and verify that it is in good
condition and that construction, if new, has been completed. The appraisal is
based on the appraiser's judgment of values, giving appropriate weight to both
the market value of comparable homes and the cost of replacing the property.
 
    Certain states where the Mortgaged Properties may be located are
"anti-deficiency" states where, in general, lenders providing credit on one- to
four-family properties must look solely to the property for repayment in the
event of foreclosure. See "Certain Legal Aspects of the Mortgage
Loans--Anti-Deficiency Legislation and Other Limitations on Lenders." The
Company's underwriting standards in all states (including anti-deficiency
states) require that the underwriting officers be satisfied that the value of
the property being financed, as indicated by the independent appraisal,
currently supports and is anticipated to support in the future the outstanding
loan balance, and provides sufficient value to mitigate the effects of adverse
shifts in real estate values.
 
                                       21
<PAGE>
SELLER WARRANTIES AND INDEMNIFICATION OF THE COMPANY
 
    With respect to Series of Certificates as to which the Company will be the
only Master Servicer or with respect to each Series as to which the Company and
a Servicing Entity will act as Master Servicers, each Seller generally will make
representations and warranties with respect to Mortgage Loans or the Mortgage
Loans in the Company's Mortgage Loan Servicing Group, respectively, sold by it
to the Company for inclusion in the Trust Fund which the Company deems
sufficient to permit it to make its representations and warranties in respect of
such Mortgage Loans to the Trustee and the Certificateholders under the Pooling
Agreement. See "Description of Certificates--Representations and Warranties"
below. Each Seller will also make certain other representations and warranties
regarding Mortgage Loans sold by it. Upon the breach of any representation or
warranty made by a Seller that materially and adversely affects the interests of
the Certificateholder in a Mortgage Loan (other than those breaches which have
been cured), the Company may require the Seller to repurchase the related
Mortgage Loan. In addition, each Seller will agree to indemnify the Company
against any loss or liability incurred by the Company on account of any breach
of any representation or warranty made by the Seller, any failure to disclose
any matter that makes any such representation and warranty misleading, or any
inaccuracy in information furnished by the Seller to the Company, including any
information set forth in this Prospectus or in any Prospectus Supplement. See
"Description of Certificates--Assignment of Mortgage Loans" and
"--Representations and Warranties".
 
    With respect to Series of Certificates as to which there will be no Master
Servicer, the Seller which sold the Mortgage Loans to the Company for inclusion
in the Trust Fund will make representations and warranties to the Company with
respect to such Mortgage Loans, and the Company will assign such representations
and warranties to the Trustee and the Certificateholders under the Pooling
Agreement. With respect to each Series of Certificates as to which a Servicing
Entity will be a Master Servicer, such Servicing Entity which sold the Mortgage
Loans or the Mortgage Loan Servicing Group, as applicable, to the Company for
inclusion in the Trust Fund will make representations and warranties to the
Company with respect to such Mortgage Loans or Mortgage Loans in the related
Mortgage Loan Servicing Group, as applicable, and the Company will assign such
representations and warranties to the Trustee and the Certificateholders under
the Pooling Agreement. Upon the breach of any representation or warranty made by
such Seller or Servicing Entity that materially and adversely affects the
interests of the Certificateholder in a Mortgage Loan (other than those breaches
which have been cured), the Seller or Servicing Entity will be required to
repurchase the related Mortgage Loan. See "Description of
Certificates--Assignment of Mortgage Loans" and "--Representations and
Warranties".
 
RELATIONSHIPS WITH AFFILIATES
 
    PNC Mortgage Corp. of America, an affiliate of the Company, may be a Seller,
a Seller/Servicer or a Servicer. Two of the Company's directors are also
directors of PNC Mortgage Corp. of America.
 
                          DESCRIPTION OF CERTIFICATES
 
    Each Series of Certificates will be issued pursuant to a separate Pooling
Agreement. With respect to Series of Certificates as to which there will be a
Master Servicer, the Pooling Agreement will be between the Company, as Depositor
and, if applicable, as Master Servicer, the Servicing Entity, if applicable, as
Master Servicer, and the Trustee named in the Prospectus Supplement, and the
Mortgage Loans will be serviced by Seller/Servicers pursuant to selling and
servicing contracts ("Selling and Servicing Contracts") between the Company or
the Servicing Entity, as applicable, and such Seller/Servicers, or will be
serviced by servicers pursuant to servicing arrangements approved by the Company
or the Servicing Entity, as applicable. With respect to Series of Certificates
as to which there will be no Master Servicer, the Pooling Agreement will be
among the Company, as Depositor and Certificate Administrator, the Servicer and
the Trustee named in the Prospectus Supplement. A form of Pooling Agreement and
a form of the Selling and Servicing Contract are filed as exhibits to the
Registration Statement of which this Prospectus is a part. The following
discussion summarizes certain provisions expected to be contained in each
Pooling Agreement which governs the Trust Funds consisting principally of one-
to-four family residential properties. The applicable Prospectus Supplement will
describe material features of the related Pooling Agreement, which may differ
from
 
                                       22
<PAGE>
the features described below. The following summary and the summary contained in
a Prospectus Supplement do not purport to be complete and are subject to, and
are qualified in their entirety by reference to, all of the provisions of the
Pooling Agreement for each particular Series and of the applicable Selling and
Servicing Contracts or similar contracts.
 
GENERAL
 
    The Certificates of each Series will represent undivided interests in the
Trust Fund created pursuant to the Pooling Agreement for such Series. The Trust
Fund for each Series will consist, to the extent provided in the Pooling
Agreement, of (i) such Mortgage Loans as from time to time are subject to the
Pooling Agreement (exclusive of any related Retained Yield (described below),
except as otherwise specified in the related Prospectus Supplement), (ii) such
assets as from time to time are held in the Certificate Account (described
below) and the Custodial Accounts for P&I (described below) related to such
Mortgage Loans (exclusive of any Retained Yield, except as otherwise specified
in the related Prospectus Supplement), (iii) property acquired by foreclosure of
Mortgage Loans or deed in lieu of foreclosure, (iv) any combination, as
specified in the related Prospectus Supplement, of a Letter of Credit, Mortgage
Pool Insurance Policy, Special Hazard Insurance Policy, Bankruptcy Bond, Fraud
Bond, Reserve Fund or other type of credit enhancement as described under
"Description of Credit Enhancements", (v) the Private Certificates and Agency
Certificates, if any, described in the applicable Prospectus Supplement, and
(vi) such other assets or rights as are described in the applicable Prospectus
Supplement. If so specified in the applicable Prospectus Supplement,
Certificates of a given Series may be issued in several Classes, which may pay
interest at different rates, may represent different allocations of the right to
receive principal and interest, and certain of which may be subordinated to
others. Any such Class of Certificates may also provide for payments of
principal only or interest only or for disproportionate payments of principal
and interest. Subordinated Classes of a given Series of Certificates may or may
not be offered by the same Prospectus Supplement as the senior Classes of such
Series.
 
    The Certificates will be freely transferable and exchangeable for
Certificates of the same Series and Class at the office set forth in such
Certificates, provided, however, that certain Classes of Certificates may be
subject to transfer restrictions set forth in such Certificates and described in
the applicable Prospectus Supplement. A reasonable service charge may be imposed
for any registration of exchange or transfer of Certificates, and the Company
may require payment of a sum sufficient to cover any tax or other governmental
charge. If specified in the applicable Prospectus Supplement, one or more
Classes of Certificates for any Series may be transferable only on the books of
The Depository Trust Company or another depository identified in such Prospectus
Supplement.
 
    Unless otherwise indicated in the applicable Prospectus Supplement,
beginning with the month following the month in which the Cut-Off Date occurs
for a Series of Certificates, distributions of principal and interest (or, where
applicable, principal only or interest only) on each Class of Certificates will
be made either by the Trustee, the Master Servicer or the Certificate
Administrator, as applicable, acting on behalf of the Trustee or a paying agent
appointed by the Trustee (the "Paying Agent") on the 25th day (or if such 25th
day is not a business day, the business day immediately following such 25th day)
of each calendar month (the "Distribution Date") to the persons in whose names
the Certificates are registered at the close of business on the last business
day of the month preceding the month in which the Distribution Date occurs (the
"Record Date"). Distributions for each Series will be made by wire transfer in
immediately available funds for the account of, or by check mailed to, each
Certificateholder of record; provided, however, that, unless otherwise specified
in the related Prospectus Supplement, the final distribution in retirement of
the Certificates for each Class of a Series will be made only upon presentation
and surrender of the Certificates at the office or agency of the Company or the
Trustee specified in the notice to Certificateholders of such final
distribution.
 
ASSIGNMENT OF MORTGAGE LOANS
 
    The Company will cause the Mortgage Loans to be assigned to the Trustee,
together with all principal and interest on the Mortgage Loans other than
principal and interest due on or before the Cut-Off Date. The Company or a
Servicing Entity, as applicable, will expressly reserve its or a Seller's rights
in and to any Retained Yield, which accordingly will not constitute part of the
Trust Fund. In
 
                                       23
<PAGE>
addition, the applicable Prospectus Supplement may specify that the Seller will
retain the right to a specified portion of either principal or interest, or
both. The Trustee will, concurrently with such assignment, authenticate and
deliver the Certificates or cause the Certificates to be authenticated and
delivered to the Company or its designated agent in exchange for the Trust Fund.
Each Mortgage Loan will be identified in a schedule appearing as an exhibit to
the Pooling Agreement for the related Series. Unless otherwise specified in the
related Prospectus Supplement, such schedule will include information as of the
close of business on the Cut-Off Date as to the principal balance of each
Mortgage Loan, the Mortgage Interest Rate and the maturity of each Mortgage
Note, the Seller/ Servicer's or the Servicer's Servicing Fee, whether a Primary
Insurance Policy has been obtained for each Mortgage Loan and the then-current
scheduled monthly payment of principal and interest for each Mortgage Loan.
 
    In addition, the Company, a Servicing Entity or a Servicer, as the case may
be, will, as to each Mortgage Loan, deliver or cause to be delivered to the
Trustee the Mortgage Note, an assignment to the Trustee of the Mortgage in a
form for recording or filing as may be appropriate in the state where the
Mortgaged Property is located, the original recorded Mortgage with evidence of
recording or filing indicated thereon, a copy of the title insurance policy or
other evidence of title and evidence of any Primary Insurance Policy, FHA
Insurance Policy or VA Guaranty for such Mortgage Loan, if applicable; or, in
the case of each Cooperative Loan, the related Cooperative Note, the original
security agreement, the proprietary lease or occupancy agreement, the related
stock certificate and related blank stock powers, and a copy of the original
filed financing statement together with assignments thereof from the applicable
Seller to the Trustee in a form sufficient for filing. In certain instances
where original documents respecting a Mortgage Loan may not be available prior
to execution of the Pooling Agreement, the Company, such Servicing Entity or
such Servicer will deliver such documents to the Trustee within 270 days
thereafter unless, as set forth in the Pooling Agreement, the county recorder
has not yet returned such Mortgage Loan. Notwithstanding the foregoing, a Trust
Fund may include Mortgage Loans where the original Mortgage Note is not
delivered to the Trustee if the Company delivers to the Trustee or the custodian
a copy or a duplicate original of the Mortgage Note, together with an affidavit
certifying that the original thereof has been lost or destroyed. With respect to
such Mortgage Loans, the Trustee (or its nominee) may not be able to enforce the
Mortgage Note against the related borrower. The Company, such Servicing Entity
or such Servicer will agree to repurchase or substitute for such a Mortgage Loan
in certain circumstances (see "Description of Certificates--Representations and
Warranties").
 
    In instances where, due to a delay on the part of the title insurer, a copy
of the title insurance policy for a particular Mortgage Loan cannot be delivered
to the Trustee prior to or concurrently with the execution of the Pooling
Agreement, the Company will provide a copy of such title insurance policy to the
Trustee within 90 days after the Company's receipt of the original recorded
Mortgage, any intervening recorded assignments or other documents necessary to
issue such title insurance policy.
 
    The Trustee will review the mortgage documents within 45 days of receipt
thereof to ascertain that all required documents have been properly executed and
received. The Trustee will hold such documents for each Series in trust for the
benefit of Certificateholders of such Series. With respect to Series of
Certificates as to which the Company and/or a Servicing Entity will act as
Master Servicer, if any document is found by the Trustee not to have been
properly executed or received or to be unrelated to the Mortgage Loans (or the
related Mortgage Loan Servicing Group for such Series if both the Company and a
Servicing Entity are acting as Master Servicers) identified in the Pooling
Agreement, the Trustee will notify the Company or such Servicing Entity, as
applicable. If the Company or such Servicing Entity, as applicable, cannot cure
such defect, the Company or such Servicing Entity, as applicable, will
substitute a new mortgage loan meeting the conditions set forth in the Pooling
Agreement (see "--Substitution of Mortgage Loans" below) or repurchase the
related Mortgage Loan from the Trustee at a price equal to 100% of the
outstanding principal balance of such Mortgage Loan, plus accrued interest
thereon at the applicable Pass-Through Rate through the last day of the month of
such repurchase. With respect to Series of Certificates as to which there will
be no Master Servicer, if a defect of the type described in the preceding
sentence is discovered by the Trustee and cannot be cured by the Seller, the
Seller will substitute a new mortgage loan or repurchase the related Mortgage
Loan from the Trustee upon the terms described in the preceding sentence. The
purchase price of any Mortgage Loan so repurchased will be passed through to
Certificateholders as
 
                                       24
<PAGE>
liquidation proceeds in accordance with the procedures specified under
"--Distributions on Certificates". This substitution or repurchase obligation
constitutes the sole remedy available to the Certificateholders or the Trustee
for such a defect in a constituent document.
 
    An assignment of each Mortgage Loan to the Trustee will be recorded or filed
except in states where, in the written opinion of counsel admitted to practice
in such state acceptable to the Company and the Trustee, such filing or
recording is not required to protect the Trustee's interest in the Mortgage Loan
against sale, further assignment, satisfaction or discharge by the Seller, the
Seller/ Servicers, the Servicer, the Company, the Servicing Entity or the Master
Servicer.
 
    Buydown Funds provided by the Sellers or other parties for any Buydown Loans
included in a Mortgage Pool may be deposited on the date of settlement of the
sale of the Certificates to the original purchasers thereof (the "Closing Date")
into either (a) a separate account (the "Buydown Fund Account") maintained (i)
with the Trustee or another financial institution approved by the Company or
Servicing Entity, as applicable, as Master Servicer, (ii) within FDIC insured
accounts (or other insured accounts acceptable to the rating agency or agencies)
held and monitored by a Servicer or (iii) in a separate non-trust account
without FDIC or other insurance in an institution having the highest unsecured
long-term debt rating by the rating agency or agencies (or such other
institution acceptable to the rating agency or agencies) or (b) held in a
Custodial Account for P&I or a Custodial Account for Reserves and monitored by a
Servicer. Since Buydown Funds may be funded at either the par values of future
payment subsidies or funded in an amount less than the par values of future
payment subsidies and determined by discounting such par values in accordance
with interest accruing on such values, Buydown Fund Accounts may be
non-interest-bearing or may bear interest. In no event will the amount held in
any Buydown Fund Account exceed the level of deposit insurance covering such
account. Accordingly, more than one such account may be established.
 
SUBSTITUTION OF MORTGAGE LOANS
 
    With respect to Series of Certificates as to which the Company and/or a
Servicing Entity will act as Master Servicer, the Company or the Servicing
Entity, as applicable, may substitute an eligible mortgage loan for a defective
Mortgage Loan (or, if applicable, a Mortgage Loan in its related Mortgage Loan
Servicing Group) in lieu of repurchasing such defective Mortgage Loan or the
related Mortgaged Property (a) within three months after the Closing Date for
the related Series of Certificates, and (b) within two years after such Closing
Date, if the related Mortgage Loan is a "defective obligation" within the
meaning of Section 860G(a)(4)(A)(ii) of the Code. Any mortgage loan, to be
eligible for substitution, must fit within the general description of the
Mortgage Loans set forth herein and in the related Prospectus Supplement. With
respect to Series of Certificates as to which there will be no Master Servicer,
the Seller or the Servicer, as specified in the related Prospectus Supplement,
may substitute an eligible mortgage loan for a defective Mortgage Loan in lieu
of repurchasing such defective Mortgage Loan or the related Mortgaged Property
in the circumstances and to the extent described in the two preceding sentences.
See "The Mortgage Pools".
 
REPRESENTATIONS AND WARRANTIES
 
    Unless otherwise stated in the applicable Prospectus Supplement, in the
Pooling Agreement for each Series of Certificates as to which the Company will
act as a Master Servicer, the Company will represent and warrant to the Trustee
with respect to (a) all Mortgage Loans if it is the only Master Servicer and (b)
the Mortgage Loans in its Mortgage Loan Servicing Group if both the Company and
a Servicing Entity are acting as Master Servicers, among other things, that (i)
the information set forth in the schedule of Mortgage Loans is true and correct
in all material respects; (ii) except in the case of Cooperative Loans, a
lender's title policy (or other satisfactory evidence of title) was issued on
the date of the origination of each Mortgage Loan and each such policy or other
evidence of title is valid and remains in full force and effect; (iii) if a
Primary Insurance Policy, FHA Insurance Policy or VA Guaranty is required with
respect to such Mortgage Loan, such policy or guaranty is valid and remains in
full force and effect as of the Closing Date; (iv) as of the Closing Date, the
Company had good title to the Mortgage Loans and the Mortgage Notes are subject
to no offsets, defenses or counterclaims, except to the extent that the buydown
agreement for a Buydown Loan forgives certain indebtedness of a Mortgagor; (v)
except in the case of Cooperative Loans, as of the Closing Date, each Mortgage
is a valid first lien on an unencumbered estate in fee simple or leasehold
interest in the Mortgaged
 
                                       25
<PAGE>
Property (subject only to (a) liens for current real property taxes and special
assessments, (b) covenants, conditions and restrictions, rights of way,
easements and other matters of public record as of the date of recording of such
Mortgage, such exceptions appearing of record being acceptable to mortgage
lending institutions generally or specifically reflected in the mortgage
originator's appraisal, (c) exceptions set forth in the title insurance policy
covering such Mortgaged Property and (d) other matters to which like properties
are commonly subject which do not materially interfere with the benefits of the
security intended to be provided by the Mortgage); (vi) as of the Closing Date,
each Mortgaged Property is free of damage and is in good repair, except for
ordinary wear and tear; (vii) as of the time each Mortgage Loan was originated,
the Mortgage Loan complies with all applicable state and federal laws, including
usury, equal credit opportunity, disclosure and recording laws; (viii) as of the
Closing Date, there are no delinquent tax or assessment liens against any
Mortgaged Property; and (ix) unless otherwise specified in the related
Prospectus Supplement, each Mortgage Loan was originated and will be serviced by
(a) an institution which is a member of the Federal Reserve System or the
deposits of which are insured by the FDIC, (b) an institution which is a member
of the Federal Home Loan Bank System, (c) an institution which is a FHA-Approved
Mortgagee, (d) an institution which is a FNMA-Approved Mortgagee, or (e) an
institution which is a FHLMC-Approved Mortgagee. The applicable Prospectus
Supplement and Pooling Agreement may set forth additional representations and
warranties of the Company. In addition, with respect to any Mortgage Loan as to
which the Company delivers to the Trustee or the custodian an affidavit
certifying that the original Mortgage Note has been lost or destroyed, if such
Mortgage Loan subsequently is in default and the enforcement thereof or of the
related Mortgage is materially adversely affected by the absence of the original
Mortgage Note, the Company will be obligated to repurchase or substitute for
such Mortgage Loan in the manner described below. However, the Company will not
be required to repurchase or substitute for any Mortgage Loan as described above
if the circumstances giving rise to such requirement also constitute fraud in
the origination of the related Mortgage Loan.
 
    If the Mortgage Loans include Cooperative Loans, representations and
warranties with respect to title insurance or hazard insurance will not be
given. Generally, a Cooperative itself is responsible for the maintenance of
hazard insurance for property owned by such Cooperative, and the borrowers
(tenant-stockholders) of such Cooperative do not maintain hazard insurance on
their individual dwelling units. Title insurance is not obtained for Cooperative
Loans because such loans are not secured by real property. See "Certain Legal
Aspects of the Mortgage Loans--Cooperative Loans".
 
    With respect to Series of Certificates as to which the Company will not act
as a Master Servicer, the Seller or the Servicing Entity, as applicable, which
sold the Mortgage Loans to the Company for inclusion in the Trust Fund will make
representations and warranties to the Company with respect to such Mortgage
Loans substantially similar to those indicated in the second preceding
paragraph, and the Company will assign such representations and warranties to
the Trustee and the Certificateholders under the Pooling Agreement. The
applicable Prospectus Supplement and Pooling Agreement may set forth additional
representations and warranties of the Seller, the Servicing Entity and/or the
Company.
 
    In the event of the discovery by the Company, the Servicing Entity or the
Servicer of a breach of any representation or warranty which materially and
adversely affects the interest of the Certificateholders in the related Mortgage
Loan, or the receipt of notice of such a breach from the Trustee, the Company,
the Servicing Entity or the Seller, as the case may be, will cure the breach,
substitute a new mortgage loan for such Mortgage Loan or repurchase such
Mortgage Loan, or any Mortgaged Property acquired with respect thereto, on the
terms set forth above under "--Assignment of Mortgage Loans". The proceeds of
any such repurchase will be passed through to Certificateholders as liquidation
proceeds. This substitution or repurchase obligation constitutes the sole remedy
available to the Certificateholders or the Trustee for any such breach.
 
    Under the Pooling Agreement, the Company or a Servicing Entity, as Master
Servicer, or the Servicer with respect to Series of Certificates for which there
will be no Master Servicer, will have the right, but not the obligation, to
purchase any Mortgage Loan (or, if applicable, Mortgage Loan in the Company's or
Servicing Entity's Mortgage Loan Servicing Group), subject to the limitations
set forth in the Pooling Agreement, from the applicable Mortgage Pool in the
event that such Mortgage Loan
 
                                       26
<PAGE>
becomes 90 days or more delinquent; provided, that the aggregate purchase price
of the Mortgage Loans so repurchased (as set forth in the Pooling Agreement)
shall not exceed one-half of one percent (0.50%) of the aggregate Principal
Balance of all Mortgage Loans as of the Cut-Off Date.
 
SERVICING
 
    With respect to Series of Certificates as to which the Company and/or a
Servicing Entity will act as Master Servicer, pursuant to the Pooling Agreement
the Company or Servicing Entity, as applicable, as Master Servicer, will be
responsible for servicing and administering the Mortgage Loans, or the Mortgage
Loans in its respective Mortgage Loan Servicing Group, as applicable, but will
be permitted to contract with the Seller/Servicer from whom each Mortgage Loan
was purchased, or another eligible servicing institution, to perform such
functions under the supervision of the Master Servicer as more fully described
below.
 
    In the contract pursuant to which each Seller/Servicer will perform its
servicing duties, which contract will generally be the Selling and Servicing
Contract, each Seller/Servicer will agree, subject to the general supervision of
the Company or Servicing Entity, as applicable, as Master Servicer, or its
respective agent, to perform diligently all services and duties customary to the
servicing of mortgage loans. Such Master Servicer or its agent will monitor each
Seller/Servicer's performance and, unless otherwise specified in the applicable
Prospectus Supplement, such Master Servicer will have the right to remove and
substitute a replacement Seller/Servicer at any time if it considers such
removal to be in the best interest of Certificateholders. The duties performed
by the Seller/Servicers include collection and remittance of principal and
interest payments, administration of mortgage escrow accounts, collection of
insurance claims and, if necessary, foreclosure. In the event a Selling and
Servicing Contract is terminated by the Company or Servicing Entity, as
applicable, as Master Servicer, for any reason, such Master Servicer may procure
a substitute Seller/Servicer, which may be an affiliate of such Master Servicer.
During the period necessary to effect the execution and implementation of a
contract with such substitute Seller/Servicer, all duties and responsibilities
of the Seller/Servicer under the terminated Selling and Servicing Contract will
be performed by such Master Servicer. In such event, such Master Servicer will
be entitled to retain the same Servicing Fee as was paid to the Seller/Servicer
under such terminated Selling and Servicing Contract.
 
    With respect to Series of Certificates as to which there will be no Master
Servicer, pursuant to the Pooling Agreement the servicing of the Mortgage Loans
will be performed by the Servicer, and the Company (as Certificate
Administrator) will calculate amounts distributable to the Certificateholders,
prepare tax returns on behalf of the Trust Fund and provide certain other
administrative services specified in the Pooling Agreement. With respect to a
Series as to which the Company and the Servicing Entity will act as Master
Servicers, unless otherwise specified in the applicable Prospectus Supplement,
the Company will also act as the Certificate Administrator. Unless otherwise
specified in the related Prospectus Supplement, with respect to a Series as to
which a Servicing Entity is the only Master Servicer, such Servicing Entity
shall act as the Certificate Administrator. The Servicer will generally perform
the same services and duties as a Seller/Servicer under a Selling and Servicing
Agreement, as well as certain services of a Master Servicer described herein.
The Trustee or its agent will monitor the Servicer's performance and, unless
otherwise specified in the applicable Prospectus Supplement, the Trustee will
have the right to remove and substitute a replacement servicer, which may be the
Company or an affiliate of the Company, to assume the servicing obligations of
the Servicer at any time if it considers such removal to be in the best
interests of Certificateholders. During the period necessary to effect the
execution and implementation of a contract with such substitute servicer,
certain duties and responsibilities of the Servicer under the Pooling Agreement
will be performed by the Trustee. In such event, the Trustee will be entitled to
retain the same Servicing Fee as was to be paid the Servicer under the Pooling
Agreement. The obligation of the Trustee or a replacement servicer to perform
the servicing duties of the Servicer will not, however, require such party to
cure any defect with respect to any Mortgage Loan, or substitute a new mortgage
loan for or repurchase a Mortgage Loan as to which there has been a breach of a
representation or warranty made by the Seller or to cure any breach of a
servicing covenant made by the former Servicer.
 
    With respect to Series of Certificates as to which the Company and/or a
Servicing Entity will act as Master Servicer, each Seller/Servicer will retain
as its Servicing Fee a portion of the interest payable
 
                                       27
<PAGE>
on each Mortgage Loan serviced by it. The Servicing Fee will be established by
the Company or a Servicing Entity, as applicable, either as a fixed rate or as a
rate calculated as the difference between interest at the Mortgage Interest Rate
and interest at the rate required to be passed through to the Company or
Servicing Entity, as applicable, as Master Servicer (the "Net Rate"). Unless
otherwise set forth in the applicable Prospectus Supplement, the Servicing Fee
will be no less than 0.25% per annum for each individual Mortgage Loan serviced.
In addition, unless otherwise set forth in the Prospectus Supplement, the
Seller/Servicer will retain late charges, assumption fees and similar charges to
the extent collected from Mortgagors. The Company expects that such fees and
charges will be negligible in amount. Unless otherwise provided in the
applicable Prospectus Supplement, each of the Company and Servicing Entity, as
applicable, as Master Servicer, will retain as its Master Servicing Fee an
amount which will be calculated as a per annum percentage for each Mortgage Loan
plus an amount calculated to reimburse the Company or Servicing Entity, as
applicable, as Master Servicer, for the expenses required to be borne by it,
which, unless otherwise set forth in the applicable Prospectus Supplement, will
include the Trustee's fees and premiums on or other expenses relating to any
Mortgage Pool Insurance Policy and/or other credit enhancements.
 
    With respect to Series of Certificates as to which there will be no Master
Servicer, the Servicer will receive a Servicing Fee, as established in the
applicable Pooling Agreement, which, unless otherwise indicated in the
applicable Prospectus Supplement, will be no less than 0.25% per annum for each
individual Mortgage Loan serviced and with respect to each such Series and each
Series as to which both the Company and a Servicing Entity are acting as Master
Servicers, the Certificate Administrator will retain as its Certificate
Administrator Fee an amount which will be calculated as a per annum percentage
for each Mortgage Loan plus an amount calculated to reimburse the Certificate
Administrator for payment by it of the Trustee's fees.
 
RETAINED YIELD
 
    For certain Series, the Company, a Servicing Entity or a Seller may retain a
portion of the interest payable on each Mortgage Loan (the "Retained Yield").
The Retained Yield will either be set as a fixed rate or will be calculated by
subtracting the Master Servicing Fee and the Remittance Rate from the Net Rate
or, if applicable, by subtracting the Servicing Fee, the Certificate
Administrator Fee and the Remittance Rate from interest at the Mortgage Interest
Rate. Unless otherwise specified in the applicable Prospectus Supplement, any
such Retained Yield and any earnings from reinvestments thereof will not be part
of the Trust Fund. The Company, the Servicing Entity or the Seller, as the case
may be, may at its option transfer to a third party all or a portion of the
Retained Yield for a Series of Certificates.
 
PAYMENTS ON MORTGAGE LOANS; CUSTODIAL ACCOUNTS FOR P&I,
    INVESTMENT ACCOUNT, CERTIFICATE ACCOUNT AND RESERVE
  ACCOUNT
 
    With respect to Series of Certificates as to which the Company and/or a
Servicing Entity will act as Master Servicer, pursuant to the Servicing Contract
each Seller/Servicer will agree to establish and maintain for the Master
Servicer (or for the related Master Servicer if both the Company and a Servicing
Entity are acting as Master Servicers for such Series) a special custodial
account for principal and interest (the "Custodial Account for P&I"), into which
it will deposit on a daily basis (unless otherwise specified in the applicable
Prospectus Supplement) the following payments and collections received
subsequent to the Cut-Off Date (other than payments due on or before the Cut-Off
Date) with respect to the Mortgage Loans serviced by it:
 
        (i) All payments on account of principal and interest, including
    Principal Prepayments;
 
        (ii) All net proceeds received in connection with the liquidation of
    defaulted Mortgage Loans, by foreclosure or otherwise (hereinafter referred
    to as "Liquidation Proceeds"), or under
 
                                       28
<PAGE>
any applicable credit enhancements or title, hazard or other insurance policy
covering any Mortgage Loan, other than proceeds to be applied to the restoration
or repair of the related Mortgaged Property (hereinafter referred to as
"Insurance Proceeds");
 
       (iii) Any Advances of such Seller/Servicer's funds (such Advances to be
    deposited prior to the Withdrawal Date, as defined below); and
 
       (iv) All proceeds of any Mortgage Loans or property acquired in respect
    thereof repurchased as required for defects in documentation, breach of
    representations or warranties, or otherwise.
 
    Each Seller/Servicer has the option of either (i) depositing gross interest
collections in the Custodial Account for P&I, subject to withdrawal of its
related Servicing Fees, or (ii) deducting its Servicing Fees from gross interest
collections prior to deposit in such account.
 
    On the Withdrawal Date or, with the Master Servicer's approval (or the
related Master Servicer if both the Company and a Servicing Entity are acting as
Master Servicers), on a daily basis, each Seller/ Servicer may withdraw the
following amounts from its Custodial Account for P&I:
 
        (i) Amounts received on particular Mortgage Loans as late payments of
    principal or interest and respecting which the Seller/Servicer has made an
    unreimbursed Advance;
 
        (ii) Amounts to reimburse the Seller/Servicer for Advances the Master
    Servicer (or the related Master Servicer if both the Company and a Servicing
    Entity are acting as Master Servicers) has determined to be otherwise
    nonrecoverable; and
 
       (iii) Amounts in respect of Servicing Fees previously deposited.
 
    The Company and/or the Servicing Entity, as applicable, will require that
deposits in each Custodial Account for P&I be held (a) in a trust account in the
corporate trust department of the Trustee or another financial institution
approved by the Company or Servicing Entity, as applicable, as Master Servicer,
such that the rights of the Company or Servicing Entity, as applicable, as
Master Servicer, the Trustee and the Certificateholders will be fully protected
against the claims of any creditors of the Servicer and of any creditors or
depositors of the institution in which such account is maintained, (b) in FDIC
insured accounts (or other accounts with comparable insurance coverage
acceptable to the rating agency or agencies) created maintained and monitored by
a Servicer or (c) in a separate non-trust account without FDIC or other
insurance in an institution having an unsecured long-term debt rating of at
least one of the two highest unsecured long-term debt ratings of the rating
agency or agencies (or such other institution acceptable to the rating agency or
agencies). If a Custodial Account for P&I is insured by the FDIC and at any time
the amount in such account exceeds the limits of insurance on such account, the
Seller/Servicer shall be required to withdraw such excess from such account and
remit it to the Company or Servicing Entity, as applicable, for deposit in the
Investment Account described below.
 
    With respect to Series of Certificates as to which the Company and/or the
Servicing Entity, as applicable, will act as Master Servicer and unless
otherwise specified in the related Prospectus Supplement, not later than the
20th day of each month (or the preceding business day if such 20th day is not a
business day) (the "Withdrawal Date"), the Company or Servicing Entity, as
applicable, will withdraw or direct the withdrawal from any funds in the
Custodial Account for P&I maintained by each related Seller/Servicer an amount
representing:
 
        (i) Scheduled installments of principal and interest on the Mortgage
    Loans received or advanced by such Seller/Servicer which were due on the
    first day of the current month, net of Servicing Fees due the
    Seller/Servicer and less any amounts to be withdrawn later by the Company or
    Servicing Entity, as applicable, from any applicable Buydown Fund Account;
 
        (ii) Proceeds of liquidations of Mortgage Loans received by the
    Seller/Servicer in the immediately preceding calendar month, with interest
    to the date of liquidation, net of Servicing Fees due such Seller/Servicer
    and less any amounts to be withdrawn later by the Company or Servicing
    Entity, as applicable, from any applicable Buydown Fund Account;
 
       (iii) Principal due to Payoffs received during the period from the 15th
    of the immediately preceding calendar month through the 14th of such
    calendar month; in each case with interest at
 
                                       29
<PAGE>
    the applicable Pass-Through Rate attributable to interest paid by the
    Mortgagor through the date of the Payoff (provided, however, that in the
    case of Payoffs received between the first day and the 14th day of any
    month, interest accrued from the first day of such month to the date of such
    Payoff will not be paid to the Certificateholders), less any amounts to be
    withdrawn later by the Company or Servicing Entity, as applicable, from any
    applicable Buydown Fund Account; and
 
       (iv) Curtailments received by such Seller/Servicer on such Mortgage Loans
    in the immediately preceding calendar month.
 
    All amounts withdrawn from the Custodial Accounts for P&I, together with any
Insurance Proceeds or Liquidation Proceeds (including any amounts paid in
respect of repurchase obligations on defective Mortgage Loans or otherwise) not
otherwise applied by Seller/Servicers and amounts withdrawn from any Buydown
Fund Account, if applicable, shall be immediately deposited into the Investment
Account (or if both the Company and a Servicing Entity are acting as Master
Servicers, the related Investment Account).
 
    Under the Pooling Agreement for each Series of Certificates as to which the
Company will act as Master Servicer, the Master Servicer or the related
Seller/Servicer is permitted to make the following withdrawals from the Buydown
Fund Account or Custodial Account for P&I, as applicable:
 
        (i) To deposit in the Investment Account the amount necessary in order
    to supplement payments received on Buydown Loans;
 
        (ii) In the event of a Payoff of any Buydown Loan, to apply the
    remaining related Buydown Funds to reduce the required amount of such Payoff
    (or, if the Mortgagor has made a Payoff equal in amount to the total unpaid
    principal balance, to refund such remaining Buydown Funds to the person
    entitled to receive such Buydown Funds);
 
       (iii) In the event of foreclosure or liquidation of any Buydown Loan, to
    deposit the remaining related Buydown Funds in the Investment Account; and
 
       (iv) To clear and terminate the portion of any account representing
    Buydown Funds.
 
    Unless otherwise specified in the applicable Prospectus Supplement, the
Company or Servicing Entity, as applicable, as Master Servicer, may invest funds
withdrawn from the Custodial Accounts for P&I each month and remitted to the
related Master Servicer, as well as any Insurance Proceeds, Liquidation Proceeds
and Buydown Funds, for its own account and at its own risk, for the period from
the Withdrawal Date to the next Distribution Date, or for such longer or shorter
period as may be specified in the applicable Prospectus Supplement (in each
case, the "Investment Period"). Notwithstanding the foregoing, in the event that
both the Company and a Servicing Entity are acting as Master Servicers with
respect to any Series, each of the Company and such Servicing Entity may only
invest funds described in the preceding sentence to the extent that such funds
relate to Mortgage Loans in its respective Mortgage Loan Servicing Group.
Investment of such funds shall be made through an account in the name of the
Company or Servicing Entity, as applicable, as Master Servicer, and the Trustee
(an "Investment Account") (or, if both the Company and a Servicing Entity are
acting as Master Servicers, to the extent that such funds relate to Mortgage
Loans in its respective Mortgage Loan Servicing Group), which shall be
maintained in the trust department of a bank acceptable to any applicable rating
agency or agencies for the Series of Certificates. The Investment Account may be
a commingled account with other similar accounts maintained by the Company or
Servicing Entity, as applicable, as Master Servicer, and invested for its own
account; provided, that the maintenance of such a commingled account has been
approved by any applicable rating agency or agencies for the Series of
Certificates. Unless otherwise specified in the applicable Prospectus
Supplement, the investment of funds in the Investment Account shall be limited
to the investments described below.
 
    On the last day of the Investment Period, the Company or Servicing Entity,
as applicable, as Master Servicer, will withdraw from the Investment Account
(or, if both the Company and a Servicing Entity are acting as Master Servicers,
the related Investment Account) all funds due to be distributed to
Certificateholders, and shall deposit such funds, together with any Advances
required to be made by it, in the Certificate Account described below.
 
                                       30
<PAGE>
    Unless otherwise specified in the applicable Prospectus Supplement, the
investment of funds in an Investment Account shall be limited to one or more of
the following investments ("Eligible Investments") which shall in no event
mature later than the next Distribution Date:
 
        (i) Obligations of, or guaranteed as to principal and interest by, the
    United States or any agency or instrumentality thereof, when such
    obligations are backed by the full faith and credit of the United States;
 
        (ii) Repurchase agreements on obligations of, or guaranteed as to
    principal and interest by, the United States or any agency or
    instrumentality thereof, when such obligations are backed by the full faith
    and credit of the United States; provided that the unsecured obligations of
    the party agreeing to repurchase such obligations are at the time assigned
    such ratings as may be required by the applicable rating agency or agencies
    for the Series of Certificates at the date of acquisition thereof;
 
       (iii) Federal funds, certificates of deposit, time deposits and bankers'
    acceptances of any bank or trust company incorporated under the laws of the
    United States or any state thereof; provided that the debt obligations of
    such bank or trust company (or, in the case of the principal bank in a bank
    holding company system, debt obligations of the bank holding company) have
    been assigned such ratings as may be required by the applicable rating
    agency or rating agencies for the Series of Certificates at the date of
    acquisition thereof;
 
       (iv) Obligations of, or guaranteed by, any state of the United States or
    the District of Columbia receiving the highest long-term debt ratings
    available for such securities by the applicable rating agency or rating
    agencies for the Series of Certificates;
 
        (v) Commercial paper of any corporation incorporated under the laws of
    the United States or any state thereof which on the date of acquisition has
    been assigned such ratings as may be required by the applicable rating
    agency or rating agencies for the Series of Certificates; or
 
       (vi) Securities (other than stripped bonds or stripped coupons) bearing
    interest or sold at a discount that are issued by any corporation
    incorporated under the laws of the United States or any state thereof and
    rated by each applicable rating agency or rating agencies for the Series of
    Certificates in its highest long-term unsecured rating category; provided,
    however, that securities issued by any such corporation will not be
    investments to the extent that investment therein would cause the
    outstanding principal amount of securities issued by such corporation that
    are then held as part of the Investment Account or the Certificate Account
    to exceed 20% of the aggregate principal amount of all Eligible Investments
    then held in the Investment Account and the Certificate Account;
 
       (vii) Units of taxable money market funds or mutual funds, which funds
    have been rated by each applicable rating agency or rating agencies for the
    Series of Certificates in its highest rating category or which have been
    designated in writing by each such rating agency or rating agencies as
    Eligible Investments with respect to this definition; or
 
      (viii) such other investments bearing interest or sold at a discount the
    investment in which will not, as evidenced by a letter from each applicable
    rating agency or rating agencies for the Series of Certificates, result in
    the downgrading or withdrawal of the rating or ratings assigned to the
    Certificates by such rating agency or rating agencies.
 
    Not later than the Distribution Date for a Series of Certificates as to
which the Company and/or a Servicing Entity will act as Master Servicer, the
Company or Servicing Entity, as applicable, will withdraw from the Investment
Account (or, if both the Company and a Servicing Entity are acting as Master
Servicers, the related Investment Account) all amounts required to be
distributed on such Distribution Date and deposit such amounts into a separate
non-interest-bearing trust account (the "Certificate Account") in the corporate
trust department of the Trustee or another depository institution acceptable to
the applicable rating agency or rating agencies.
 
    Under the Pooling Agreement for each Series of Certificates as to which the
Company and/or a Servicing Entity will act as Master Servicer, the Company or
Servicing Entity, as applicable, will be authorized to make the following
withdrawals from the Certificate Account (provided, however, that if
 
                                       31
<PAGE>
both the Company and a Servicing Entity are acting as Master Servicers, each of
the Company's and Servicing Entity's right to any such withdrawals will be
limited to proceeds received in respect of Mortgage Loans in its respective
Mortgage Loan Servicing Group):
 
        (i) To reimburse the Company or Servicing Entity, as applicable, as
    Master Servicer, or the applicable Servicer for Advances made pursuant to
    the Pooling Agreement or a Selling and Servicing Contract, the Company's or
    Servicing Entity's right to reimburse itself or such Servicer pursuant to
    this paragraph (i) being limited to amounts received on particular Mortgage
    Loans (including, for this purpose, Insurance Proceeds and Liquidation
    Proceeds) which represent late recoveries of principal and/or interest
    respecting which any such Advance was made;
 
        (ii) To reimburse the Company or Servicing Entity, as applicable, as
    Master Servicer, or the applicable Servicer for amounts expended by or for
    the account of the Company or Servicing Entity, as applicable, as Master
    Servicer, pursuant to the Pooling Agreement or amounts expended by such
    Servicer pursuant to the Selling and Servicing Contracts in connection with
    the restoration of property damaged by an Uninsured Cause (as defined in the
    Pooling Agreement) or in connection with the liquidation of a Mortgage Loan;
 
       (iii) To pay to the Company or Servicing Entity, as applicable, as Master
    Servicer, the Master Servicing Fee, net of Compensating Interest reduced by
    Payoff Earnings and Payoff Interest (each as defined herein or in the
    Pooling Agreement), as to which no prior withdrawals from funds deposited by
    the Master Servicer have been made;
 
       (iv) To reimburse the Company or Servicing Entity, as applicable, as
    Master Servicer, or the applicable Servicer for advances which the Company
    or Servicing Entity, as applicable, has determined to be Nonrecoverable
    Advances;
 
        (v) To pay to the Company or Servicing Entity, as applicable, as Master
    Servicer, reinvestment earnings deposited or earned in the Certificate
    Account (net of reinvestment losses) to which the Company or Servicing
    Entity, as applicable, is entitled and to reimburse the Company or Servicing
    Entity, as applicable, for expenses incurred by and reimbursable to the
    Company or Servicing Entity, as applicable, pursuant to the Pooling
    Agreement;
 
       (vi) To deposit amounts in the Investment Account representing amounts in
    the Certificate Account not required to be on deposit therein at the time of
    such withdrawal; and,
 
    after making or providing for the above withdrawals,
 
       (vii) To clear and terminate the Certificate Account upon liquidation of
    all Mortgage Loans or other termination of the Trust Fund.
 
    Each of the Company and Servicing Entity, as applicable, may also establish
with the Trustee for a Series of Certificates as to which it is acting as a
Master Servicer a Reserve Account if required to assure timely distributions of
principal and interest, as a condition to obtaining a specified rating for such
Certificates or to provide for the expenses of the Trust Fund. Any such Reserve
Account so established will be described in the applicable Prospectus
Supplement.
 
    With respect to Series of Certificates as to which there will be no Master
Servicer, unless otherwise specified in the applicable Prospectus Supplement,
the Custodial Account for P&I, the Buydown Fund Account and the Reserve Account
will be established by the Servicer, and the required and permitted deposits
into and withdrawals from such accounts set forth above will be made by the
Servicer. The Servicer shall deposit any required Advances in the Custodial
Account for P&I on the Withdrawal Date. The withdrawal of funds and their
deposit into the Investment Account on the Withdrawal Date, as described above,
will also be effected by the Servicer. The Investment Account described above
will be established by the Certificate Administrator and the Trustee, and
investments of amounts therein in Eligible Investments will be directed by the
Certificate Administrator for its own account and at its own risk. The
Certificate Administrator will make the required withdrawal from the Investment
Account on the last day of the Investment Period for deposit in the Certificate
Account, as described above. Authorized withdrawals from the Certificate Account
for the purposes described above will be made by the Certificate Administrator.
Other than as set forth in this
 
                                       32
<PAGE>
paragraph, unless the context otherwise requires, references above to "Master
Servicer" or "Seller/ Servicer", and to "Master Servicing Fee" shall refer
instead to "Servicer" and "Servicing Fee", respectively.
 
DISTRIBUTIONS ON CERTIFICATES
 
    For each Series, on each Distribution Date commencing in the month following
the month in which the Cut-Off Date occurs (or such other time as may be set
forth in the applicable Prospectus Supplement), the Trustee, the Master Servicer
(if there will be only one Master Servicer) or the Certificate Administrator, as
applicable, acting on behalf of the Trustee or the Paying Agent will withdraw
from the Certificate Account and distribute to Certificateholders of record on
the applicable Record Date, and to holders of residual interests, if any, who
are entitled to receive such distributions pursuant to the terms of the
applicable Pooling Agreement, to the extent of their entitlement thereto, an
amount in the aggregate equal to the sum of:
 
        (i) All scheduled payments of principal and interest at the Pass-Through
    Rate either collected from the Mortgagors on the Mortgage Loans prior to the
    related Determination Date (as defined below) or advanced by the Company or
    Servicing Entity, as applicable, the Servicer or the Seller/Servicers;
 
        (ii) Scheduled amounts of Buydown Funds respecting Buydown Loans (not
    withdrawn and remitted by the Servicer or the related Seller/Servicer, as
    applicable);
 
       (iii) All Curtailments received on the Mortgage Loans in the month prior
    to the month in which the Distribution Date occurs (the "Distribution
    Period");
 
       (iv) All Insurance Proceeds or Liquidation Proceeds received during the
    Distribution Period, together with interest at the applicable Pass-Through
    Rate to the extent described herein under "Yield Considerations--Effective
    Interest Rate"; and
 
        (v) All Payoffs received during the period from the 15th day of the
    immediately preceding calendar month through the 14th day of such calendar
    month; in each case together with interest at the applicable Pass-Through
    Rate to the extent described under "Yield Considerations-- Effective
    Interest Rate" herein;
 
    less the sum of:
 
        (a) Previously unreimbursed Advances made by the Company or Servicing
    Entity, as applicable, as Master Servicer, the Seller/Servicers or the
    Servicer on Mortgage Loans which are considered by the Master Servicer or
    the Servicer, as the case may be, as of the Distribution Date to be
    nonrecoverable;
 
        (b) Amounts expended by the Seller/Servicers, the Company or Servicing
    Entity, as applicable, as Master Servicer or the Servicer in connection with
    the preservation or restoration of property securing Mortgage Loans which
    have been liquidated and related liquidation expenses; and
 
        (c) Amounts representing other expenses of the Master Servicer, the
    Seller/Servicers or the Servicer, reimbursable pursuant to the Pooling
    Agreement;
 
PROVIDED, HOWEVER, that in the event that both the Company and a Servicing
Entity are acting as Master Servicers for any Series, any amounts retained on
behalf of any of the Company, such Servicing Entity or a related Seller/Servicer
pursuant to clauses (a), (b) and (c) above shall be limited to amounts received
in respect of any Mortgage Loans in its related Mortgage Loan Servicing Group.
 
    In addition, if the Master Servicer with respect to Series of Certificates
as to which the Company and/or a Servicing Entity will act as Master Servicer,
or the Servicer with respect to Series of Certificates as to which there will be
no Master Servicer, is obligated to do so under the applicable Pooling
Agreement, such Master Servicer or the Servicer, as the case may be, shall
include with any such distribution an Advance equal to principal payments and
interest payments (adjusted to the applicable Pass-Through Rate or Rates) due on
the first day of the month in which the Distribution Date occurs and not
received as of the close of business on the Withdrawal Date, subject to such
 
                                       33
<PAGE>
Master Servicer's or Servicer's determination that such payments are recoverable
from future payments or collections on the Mortgage Loans, any subordination
feature or Insurance Proceeds or Liquidation Proceeds. See "--Advances" below.
 
    The method of allocating the amount withdrawn from the Certificate Account
on each Distribution Date to principal and interest (or, where applicable, to
principal only or interest only) on a particular Series of Certificates will be
described in the applicable Prospectus Supplement. Distributions of interest on
each Class of Certificates will be made prior to distributions of principal
thereon. Each Class of Certificates may have a different Remittance Rate, and
each Remittance Rate may be fixed, variable or adjustable. The applicable
Prospectus Supplement will specify the Remittance Rate for each Class, or in the
case of a variable or adjustable Remittance Rate, the initial Remittance Rate
and the method for determining the Remittance Rate.
 
    On each Distribution Date for a Series of Certificates, the Trustee, the
Master Servicer (if there will be only one Master Servicer) or the Certificate
Administrator, as applicable, on behalf of the Trustee or the Paying Agent, as
the case may be, will distribute to each holder of record on the Record Date, an
amount equal to the Percentage Interest (as defined below) represented by the
Certificate held by such holder multiplied by the sum of the Class Principal
Distribution Amount (as defined below) for such Class and, if such Class is
entitled to payments of interest on such Distribution Date, one month's interest
at the applicable Remittance Rate on the principal balance or notional principal
balance of such Class specified in the applicable Prospectus Supplement, less
(unless otherwise specified in the related Prospectus Supplement) such Class's
pro rata share of the sum of (i) the shortfalls in collections of interest on
Payoffs with respect to which distribution is to be made on such Distribution
Date, if any, (ii) the amount of any deferred interest added to the principal
balance of the Mortgage Loans and/or the outstanding balance of the Certificates
on the related Due Date, (iii) one month's interest at the applicable
Pass-Through Rate on the amount of any Curtailments received on the Mortgage
Loans in the month preceding the month of the distribution and (iv) any other
interest shortfalls (including, without limitation, shortfalls arising out of
application of the Soldiers' and Sailors' Relief Act or similar legislation or
regulations as in effect from time to time) allocable to Certificateholders
which are not covered by advances or applicable credit enhancements, in each
case in such amount as is allocated to such Class on the basis set forth in the
related Prospectus Supplement. The "Percentage Interest" represented by a
Certificate of a particular Class will be equal to the percentage obtained by
dividing the initial principal balance or notional amount of such Certificate by
the aggregate initial amount or notional amount of all the Certificates of such
Class. The "Class Principal Distribution Amount" for a Class of Certificates for
any Distribution Date will be the portion, if any, of the Principal Distribution
Amount (as defined in the related Prospectus Supplement) allocable to such Class
for such Distribution Date, as described in the related Prospectus Supplement.
 
    In the case of a Series of Certificates which includes two or more Classes
of Certificates, the timing, sequential order, priority of payment or amount of
distributions in respect of principal, and any schedule or formula or other
provisions applicable to the determination thereof with respect to each such
Class shall be as provided in the related Prospectus Supplement. Distributions
in respect of principal of any Class of Certificates will be made on a pro rata
basis among all of the Certificates of such Class.
 
    With respect to Series of Certificates as to which there will be only one
Master Servicer and except as otherwise provided in the applicable Pooling
Agreement, not later than the tenth day preceding each Distribution Date (the
"Determination Date"), such Master Servicer will furnish to the Trustee (and to
any Certificateholder upon request) a statement setting forth the aggregate
amount to be distributed on such Distribution Date to each Class of
Certificates, on account of principal and/or interest, stated separately. With
respect to Series of Certificates as to which there will be no Master Servicer,
or as to which both the Company and a Servicing Entity will act as Master
Servicers, the Certificate Administrator will provide the statements described
in the preceding sentence.
 
REPORTS TO CERTIFICATEHOLDERS
 
    For each Series of Certificates, with each distribution to
Certificateholders from the Certificate Account, the Trustee, or the Master
Servicer (if there will be only one Master Servicer) or Certificate
 
                                       34
<PAGE>
Administrator, as applicable, on behalf of the Trustee, will forward to each
Certificateholder a statement or statements with respect to the related Trust
Funds setting forth the information specifically described in the related
Pooling Agreement, which generally will include the following with respect to
such Series of Certificates:
 
        (i) the beginning principal balance or notional principal balance
    representing the ending balance from the prior statement;
 
        (ii) the amount, if any, of such distribution principal;
 
       (iii) the amount, if any, of such distribution allocable to interest on
    the Mortgage Loans accrued at the applicable Pass-Through Rate on the
    beginning principal balance or notional principal balance, and, with respect
    to a Series of Certificates where one or more Classes of such Series are
    subordinated in right of payment to one or more other Classes of such
    Series, the amount, if any, of any shortfall in the amount of interest and
    principal distributed;
 
       (iv) the total amount distributed;
 
        (v) the ending principal balance or notional principal balance after the
    application in (ii) above; and
 
       (vi) the then applicable Pass-Through Rate or weighted average
    Pass-Through Rate, calculated as of the close of business on the related
    Determination Date.
 
    Upon request, a Certificateholder may receive a monthly report which sets
forth (i) the amount of the distribution for such month allocable to Principal
Prepayments, miscellaneous post-liquidation collections and Conversion Fees,
(ii) Mortgage Loan delinquencies, indicating the number and aggregate principal
amount of Mortgage Loans delinquent one, two and three months, as well as the
book value of any Mortgaged Property acquired through foreclosure, deed in lieu
of foreclosure or other exercise of rights respecting the Trustee's security
interest in the Mortgage Loans, (iii) the amount of remaining coverage under any
applicable credit enhancements, stated separately, as of the close of business
on the applicable Determination Date and (iv) the sum of the Master Servicing
Fee and the aggregate Servicing Fees for the month.
 
    In addition, by the date required by applicable tax law of each year, the
Master Servicer with respect to Series of Certificates as to which there will be
only one Master Servicer, or the Certificate Administrator with respect to
Series of Certificates as to which there will be no Master Servicer or as to
which both the Company and a Servicing Entity will act as Master Servicers, will
furnish a report to each Certificateholder of record at any time during the
preceding calendar year as to the aggregate of amounts reported pursuant to (ii)
in the second preceding paragraph above, plus information with respect to the
amount of servicing compensation for the related Mortgage Pool, the value of any
property acquired by the Trustee through abandonment or foreclosure, deferred
interest added to the principal balance or the notional principal balance of
each Class of Certificates, as applicable, and such other customary information
as the Master Servicer or Certificate Administrator, as applicable, determines
to be necessary to enable Certificateholders to prepare their tax returns for
such calendar year or, in the event such person was a Certificateholder of
record during a portion of such calendar year, for the applicable portion of
such a year.
 
ADVANCES
 
    With respect to Series of Certificates as to which the Company and/or a
Servicing Entity will act as Master Servicer and unless otherwise stated in the
applicable Prospectus Supplement, the Company or Servicing Entity, as
applicable, will be obligated under the Pooling Agreement to make Advances (to
the extent not previously advanced by the Seller/Servicers as described below).
In the event that both the Company and a Servicing Entity are acting as Master
Servicers for any Series, unless otherwise specified in the applicable
Prospectus Supplement, each of the Company's and such Servicing Entity's
obligation to make Advances shall be limited to Mortgage Loans in its respective
Mortgage Loans Servicing Group. Such Advances shall be in amounts sufficient to
cover any deficiency between the funds scheduled to be received on the Mortgage
Loans during the Distribution Period, and amounts withdrawn from the Custodial
Accounts for P&I on each Withdrawal Date during the Distribution Period and from
any Buydown Fund Account; provided, however, that the
 
                                       35
<PAGE>
Company or Servicing Entity, as applicable, will be obligated to make such
Advances only to the extent any such Advance, in the judgment of the Company or
Servicing Entity, as applicable, made on the Determination Date, will be
reimbursable from any applicable credit enhancements, from Mortgagor payments or
from Liquidation Proceeds or Insurance Proceeds of the related Mortgage Loans.
In connection with certain credit enhancements, the Company or Servicing Entity,
as applicable, may make other advances, such as to pay insurance premiums, real
estate property taxes, protection and preservation taxes, sales expenses and
foreclosure costs including court costs and reasonable attorneys' fees in
connection with a Mortgage Pool Insurance Policy, which shall also constitute
"Advances". If an Advance made by a Master Servicer later proves unrecoverable,
such Master Servicer will be reimbursed from funds in the Certificate Account.
Notwithstanding the foregoing, if both the Company and a Servicing Entity are
acting as Master Servicers for any Series, such right of reimbursement shall be
limited to amounts received in respect of Mortgage Loans in its respective
Mortgage Loan Servicing Group.
 
    With respect to Series of Certificates as to which the Company and/or a
Servicing Entity will act as Master Servicer and unless otherwise stated in the
applicable Prospectus Supplement, each Seller/ Servicer will be obligated to
advance on the Withdrawal Date its own funds or funds from the Custodial Account
for P&I maintained by it equal to the amount of any deficiency between the
amount in such Custodial Account for P&I on the Withdrawal Date and the amount
due to be remitted to the Company or Servicing Entity, as applicable, on such
date. Each Seller/Servicer will advance only funds which the Master Servicer
anticipates will be ultimately reimbursable from the sources discussed above. To
the extent the Seller/Servicers make such Advances, the Company or Servicing
Entity, as applicable, will be relieved of its obligation, if any, to make
Advances with respect to the Mortgage Loans respecting which such amounts were
advanced. If an Advance made by any Seller/Servicer later proves to be
unrecoverable, the Company or Servicing Entity, as applicable, will cause such
Seller/ Servicer to be reimbursed from funds in the Certificate Account.
Notwithstanding the foregoing, if both the Company and a Servicing Entity are
acting as Master Servicers, such right of reimbursement shall be limited to
amounts received in respect of Mortgage Loans in its respective Mortgage Loan
Servicing Group.
 
    With respect to Series of Certificates as to which there will be no Master
Servicer and unless otherwise stated in the applicable Prospectus Supplement,
the Servicer will be obligated under the Pooling Agreement to advance on the
Withdrawal Date its own funds or funds from the Custodial Account for P&I equal
to the amount of any deficiency between the amount in such Custodial Account for
P&I on the Withdrawal Date and the amount due to be remitted to the Certificate
Administrator on such date. The Servicer will be obligated to make such Advances
only to the extent any such Advance, in the judgment of the Servicer made on the
related Determination Date, will be reimbursable from any applicable credit
enhancements, from Mortgagor payments or from Liquidation Proceeds or Insurance
Proceeds of the related Mortgage Loans. In connection with certain credit
enhancements, the Servicer may make other advances, such as to pay insurance
premiums, real estate property taxes, protection and preservation taxes, sales
expenses and foreclosure costs including court costs and reasonable attorneys'
fees in connection with a Mortgage Pool Insurance Policy, which shall also
constitute "Advances". If an Advance made by the Servicer later proves to be
unrecoverable, the Servicer will be reimbursed from funds in the Certificate
Account.
 
COLLECTION AND OTHER SERVICING PROCEDURES
 
    With respect to Series of Certificates as to which the Company and/or a
Servicing Entity will act as Master Servicer, under the Selling and Servicing
Contract each Seller/Servicer agrees to make reasonable efforts to collect all
payments called for under the Mortgage Notes and will, consistent with the
Selling and Servicing Contract, the Pooling Agreement for any Series and any
applicable credit enhancements, follow such collection procedures as it follows
or would follow with respect to mortgage loans held for its own account which
are comparable to the Mortgage Loans. With respect to Series of Certificates as
to which there will be no Master Servicer and the servicing of the Mortgage
Loans will be performed by the Servicer, the Pooling Agreement will require the
Servicer to make the same efforts to collect payments on the Mortgage Notes and
follow the same collection procedures as would be required of the Servicer if it
were a Seller/Servicer under a Selling and Servicing Contract.
 
                                       36
<PAGE>
Consistent with the above, each Seller/Servicer with respect to Series of
Certificates as to which the Company and/or a Servicing Entity will act as
Master Servicer, or the Servicer with respect to Series of Certificates as to
which there will be no Master Servicer, may, in its discretion, (i) waive any
prepayment charge, assumption fee, late payment charge or any other charge in
connection with a Principal Prepayment on a Mortgage Loan and (ii) only upon
receiving authorization from the insurer on any applicable Mortgage Pool
Insurance Policy or Primary Insurance Policy, and with respect to each
Seller/Servicer, from the Master Servicer, arrange with a Mortgagor a schedule
for the liquidation of delinquencies running for no more than 180 days after the
first delinquent due date for payment on any Mortgage Note. Such authorization
shall be given by the Company or Servicing Entity, as applicable, as Master
Servicer, or the Servicer only upon determining that the coverage of such
Mortgage Loan by any applicable credit enhancement will not be affected. In the
event of any such arrangement, the Company's or Servicing Entity's, as
applicable, obligation to make Advances on the related Mortgage Loan, if any,
shall continue during the scheduled period to the extent such Advances are not
made by the Seller/Servicers.
 
    With respect to Series of Certificates as to which the Company and/or a
Servicing Entity will act as Master Servicer, the Selling and Servicing Contract
with each Seller/Servicer requires that such Seller/Servicer enforce
"due-on-sale" clauses, where applicable, with respect to the Mortgage Loans on
the same basis as with loans in its own portfolio, provided that such clause is
not to be enforced if it is unenforceable under applicable law or the terms of
the related Mortgage Note or if the coverage of any related credit enhancement
would be adversely affected by such enforcement. Subject to the above, if a
Mortgaged Property has been or is about to be conveyed by the Mortgagor, the
Seller/ Servicer or the Company or Servicing Entity, as applicable, will be
authorized to take or enter into an assumption agreement, pursuant to which the
Mortgagor remains liable under the Mortgage Note, from or with the person to
whom such Mortgaged Property has been or is about to be conveyed. Any fees
collected by a Seller/Servicer for entering into an assumption agreement will be
retained by it as additional servicing compensation. With respect to Series of
Certificates as to which there will be no Master Servicer and the servicing of
the Mortgage Loans will be performed by the Servicer, the Pooling Agreement will
require the Servicer to enforce any "due-on-sale" clause in the instances and to
the extent described in the first sentence of this paragraph, and the Servicer
will be authorized to take or enter into an assumption agreement and retain any
fees collected for entering into an assumption agreement as additional servicing
compensation to the same extent as a Seller/Servicer will be so authorized under
a Selling and Servicing Contract.
 
    With respect to Series of Certificates as to which the Company and/or a
Servicing Entity will act as Master Servicer, the Company or Servicing Entity,
as applicable, may, or upon receiving authorization from the Company or
Servicing Entity, as applicable, as Master Servicer, a Seller/ Servicer may, in
connection with any such conveyance and only upon assurance that the related
Mortgage Loan will continue to be covered by any applicable credit enhancement,
release the original Mortgagor from liability upon the Mortgage Note and
substitute the new Mortgagor as liable thereon. If required by law or the terms
of the related Mortgage Note, the Company or Servicing Entity, as applicable,
may allow such release and substitution without the consent of the provider of
any applicable credit enhancement. In connection with any such assumption or
substitution, the Mortgage Interest Rate borne by the related Mortgage Note may
not be changed. With respect to Series of Certificates as to which there will be
no Master Servicer and the servicing of the Mortgage Loans will be performed by
the Servicer, the Servicer may in connection with any such conveyance release
the original Mortgager from liability upon the Mortgage Note and substitute a
new Mortgagor as liable thereon in the instances and to the extent described
above in this paragraph with respect to the Company or Servicing Entity, as
applicable, as Master Servicer.
 
    With respect to Series of Certificates as to which the Company and/or a
Servicing Entity will act as Master Servicer, under each Selling and Servicing
Contract the Seller/Servicer is required to establish and maintain a Custodial
Account for Reserves into which Mortgagors deposit amounts sufficient to pay
taxes, assessments, hazard insurance premiums or comparable items to the extent
it is consistent with such Seller/Servicer's normal practices to collect
payments from Mortgagors to cover tax and insurance expenses. Withdrawals from
the Custodial Account for Reserves maintained for Mortgagors may be made to
effect timely payment of taxes, assessments and hazard insurance premiums or
comparable items, to reimburse the Seller/Servicer out of related assessments
for
 
                                       37
<PAGE>
maintaining hazard insurance, to refund to Mortgagors amounts determined to be
overages, to pay interest to Mortgagors on balances in the Custodial Account for
Reserves, if required, to repair or otherwise protect the Mortgaged Property and
to clear and terminate the Custodial Account for Reserves. Each Seller/Servicer
is solely responsible for administration of the Custodial Account for Reserves
and is expected to make Advances to such account when a deficiency exists
therein. With respect to Series of Certificates as to which there will be no
Master Servicer and the servicing of the Mortgage Loans will be performed by the
Servicer, the Servicer will be required to establish and maintain a Custodial
Account for Reserves and to make Advances to such account, and will be
authorized to make withdrawals from the Custodial Account for Reserves, in the
instances and to the extent a Seller/Servicer would be so required and
authorized under a Selling and Servicing Contract.
 
SERVICING COMPENSATION AND PAYMENT OF EXPENSES
 
    With respect to Series of Certificates as to which the Company and/or a
Servicing Entity will act as Master Servicer, the Seller/Servicers' primary
compensation for their servicing activities will come from the payment to them
or the retention by them, of an amount equal to the Servicing Fee for each
Mortgage Loan. The Company's or Servicing Entity's, as applicable, primary
compensation for supervising the mortgage servicing and advancing certain
expenses of a Mortgage Pool will come from the payment to it, of an amount equal
to the Master Servicing Fee with respect to each Mortgage Loan (or a Mortgage
Loan in its respective Mortgage Loan Servicing Group) in such Mortgage Pool. The
Master Servicing Fee and the Servicing Fee with respect to each payment of
interest received on a Mortgage Loan will equal one-twelfth of the annual Master
Servicing Fee or Servicing Fee annual percentage, as applicable, set forth in
the Pooling Agreement multiplied by the outstanding principal balance of such
Mortgage Loan during the month for which such amount is computed. In addition to
the Servicing Fee and Master Servicing Fee, the Company, a Servicing Entity or a
Seller may retain as its Retained Yield the right to a portion of the interest
payable on each Mortgage Loan calculated by subtracting the applicable
Pass-Through Rate and related Servicing Fee and Master Servicing Fee from the
applicable Mortgage Interest Rate.
 
    With respect to Series of Certificates as to which there will be no Master
Servicer and the servicing of the Mortgage Loans will be performed by the
Servicer, the Servicer's primary compensation for its servicing activities will
come from the payment to it or its retention, with respect to each interest
payment on a Mortgage Loan, of an amount equal to the Servicing Fee for such
Mortgage Loan. The Servicing Fee with respect to each payment of interest
received on a Mortgage Loan will equal one-twelfth of the Servicing Fee annual
percentage set forth in the Pooling Agreement multiplied by the outstanding
principal balance of such Mortgage Loan during the month for which such amount
is computed. In addition to the Servicing Fee, the Company or a Seller may
retain as its Retained Yield the right to a portion of the interest payable on
each Mortgage Loan calculated by subtracting the related Servicing Fee, the
Certificate Administrator Fee and the Remittance Rate from the applicable
Mortgage Interest Rate.
 
    With respect to Series of Certificates as to which there will be no Master
Servicer and the servicing of the Mortgage Loans will be performed by the
Servicer or with respect to each Series as to which both the Company and a
Servicing Entity will act as Master Servicers, the Certificate Administrator's
compensation for its administrative services will come from the payment to it,
with respect to each interest payment on a Mortgage Loan, of an amount equal to
the Certificate Administrator Fee for such Mortgage Loan. The Certificate
Administrator Fee with respect to each payment of interest received on a
Mortgage Loan will equal one-twelfth of the annual Certificate Administrator Fee
annual percentage set forth in the Pooling Agreement multiplied by the
outstanding principal balance of such Mortgage Loan during the month for which
such amount is computed, subject to any minimum fee as will be set forth in the
applicable Prospectus Supplement.
 
    As principal payments are made on each Mortgage Loan, the outstanding
principal balance of the Mortgage Loans will decline, and thus compensation to
the Seller/Servicers and the related Master Servicer, or to the Servicer and the
Certificate Administrator with respect to Series of Certificates for which there
will be no Master Servicer or both the Company and a Servicing Entity will act
as Master Servicers, and any Retained Yield will decrease as the Mortgage Loans
amortize (subject to any minimum levels of such compensation set forth in the
applicable Prospectus Supplement). Principal Prepayments and liquidations of
Mortgage Loans prior to maturity will also cause servicing
 
                                       38
<PAGE>
compensation to the Seller/Servicers and the Company and/or Servicing Entity, as
applicable, as Master Servicer, or to the Servicer and the Certificate
Administrator, as applicable, and any Retained Yield to decrease (subject to any
minimum levels of such compensation set forth in the applicable Prospectus
Supplement).
 
    In addition to their primary compensation, the Seller/Servicers or the
Servicer, as applicable, will retain all prepayment fees, assumption fees and
late payment charges, to the extent collected from Mortgagors. The
Seller/Servicers' or the Servicer's income from such charges will depend upon
their origination and servicing policies.
 
    With respect to Series of Certificates as to which the Company and/or a
Servicing Entity will act as Master Servicer, the Company or Servicing Entity,
as applicable, will pay all expenses incurred in connection with its activities
as Master Servicer (subject to limited reimbursement as described below), which,
unless otherwise specified in the applicable Prospectus Supplement, will include
payment of the fees and disbursements of the Trustee, payment of premiums of any
Mortgage Pool Insurance Policy, Special Hazard Insurance Policy, certificate
insurance policy, Fraud Bond or Bankruptcy Bond or the costs of obtaining or
maintaining any Letter of Credit or Reserve Fund and payment of expenses
incurred in connection with distributions and reports to Certificateholders of
each Series.
 
    With respect to Series of Certificates as to which there will be no Master
Servicer and the servicing of the Mortgage Loans will be performed by the
Servicer, the Servicer will pay certain expenses incurred in connection with its
activities as Servicer (subject to limited reimbursement as described below),
which, unless otherwise specified in the applicable Prospectus Supplement, will
include payment of premiums of any Mortgage Pool Insurance Policy, Special
Hazard Insurance Policy, certificate insurance policy, Fraud Bond or Bankruptcy
Bond or the costs of maintaining any Letter of Credit or Reserve Fund. The
Certificate Administrator will pay the fees and disbursements of the Trustee.
 
    As set forth in the preceding section, each Master Servicer and the
Seller/Servicers, or the Servicer, as applicable, are entitled to reimbursement
for certain expenses incurred by them in connection with the liquidation of
related defaulted Mortgage Loans. Certificateholders of such Series will suffer
no loss by reason of such expenses to the extent claims are paid under any
applicable credit enhancements. In the event, however, that claims are not paid
under such policies or alternative coverages, or if coverage has been exhausted,
Certificateholders of such Series will suffer a loss to the extent that the
proceeds of liquidation of a defaulted Mortgage Loan, after reimbursement of
each such Master Servicer's and the Seller/Servicer's expenses, or the
Servicer's expenses, as applicable, are less than the principal balance of such
Mortgage Loan. In addition, each Master Servicer and the Seller/Servicers, or
the Servicer, as applicable, are entitled to reimbursement of expenditures
incurred by them in connection with the restoration of a related damaged
Mortgaged Property, such right of reimbursement being prior to the rights of
Certificateholders to receive any related Insurance Proceeds or Liquidation
Proceeds.
 
EVIDENCE AS TO COMPLIANCE
 
    Except as may be specified in the applicable Prospectus Supplement, each
Pooling Agreement will provide that on or before April 30 of each year,
beginning on the first April 30 that is at least six months after the Cut-Off
Date, one or more firms of independent public accountants will furnish
statements to the Trustee to the effect that, in connection with such firm's
examination of the financial statements of the Company and/or Servicing Entity,
as Master Servicer, or the Servicer, as applicable, as of the previous December
31, nothing came to such firm's attention that indicated that the Company or
Servicing Entity, as applicable, as Master Servicer, or the Servicer, as
applicable, was not in compliance with specified sections of the Pooling
Agreement, except for (i) such exceptions as such firm believes to be immaterial
and (ii) such other exceptions as are set forth in such statement.
 
    Except as may be provided in the applicable Prospectus Supplement, each
Pooling Agreement will also provide for delivery to the Trustee of an annual
statement signed by an officer of the Company and/or Servicing Entity, as Master
Servicer, or the Servicer, as applicable, to the effect that, based on a review
of the Company's and/or Servicing Entity's, as Master Servicer, or the
Servicer's activities during the preceding calendar year, to the best of such
officer's knowledge the Company and/or
 
                                       39
<PAGE>
Servicing Entity, as Master Servicer, or the Servicer, as applicable, has
fulfilled its obligations under the Pooling Agreement throughout the preceding
year or, if there has been a default in the fulfillment of any such obligations,
specifying each such default and the nature and status thereof.
 
CERTAIN MATTERS REGARDING THE MASTER SERVICER, THE
  SERVICER, THE CERTIFICATE ADMINISTRATOR AND THE COMPANY
 
    Except as may otherwise be specified in the applicable Prospectus
Supplement, the Pooling Agreement for each Series will provide that neither the
Company nor a Servicing Entity, as applicable, may resign from its obligations
and duties thereunder as Master Servicer or, if applicable, Certificate
Administrator, or that the Servicer, where applicable, may not resign from its
obligations and duties thereunder, except upon determination that its duties
thereunder are no longer permissible under applicable law. No such resignation
will become effective until the Trustee or a successor has assumed the Company's
or Servicing Entity's, as applicable, master servicing obligations and duties,
or, where applicable, the Servicer's obligations and duties, under such Pooling
Agreement.
 
    The Pooling Agreement for each Series will provide that neither the Company
nor any Master Servicer, or that, where applicable, neither the Servicer nor the
Certificate Administrator, nor any director, officer, employee or agent of the
Company, any Master Servicer, the Servicer and the Certificate Administrator
(where applicable) (the "Indemnified Parties") will be under any liability to
the Trust Fund or the Certificateholders or the Trustee, any Seller/Servicer or
others for any action taken by any Indemnified Party, any Seller/Servicer or the
Trustee in good faith pursuant to the Pooling Agreement, or for errors in
judgment; provided, however, that neither the Company, the Master Servicer, the
Servicer nor the Certificate Administrator nor any such person will be protected
against any liability which would otherwise be imposed by reason of willful
misfeasance, bad faith or gross negligence in the performance of duties or by
reason of reckless disregard of obligations and duties thereunder. The Pooling
Agreement relating to each such Series will further provide that any Indemnified
Party is entitled to indemnification by the Trust Fund and will be held harmless
against any loss, liability or expense incurred in connection with any legal
action relating to the Pooling Agreement or the Certificates, other than any
loss, liability or expense related to any specific Mortgage Loan or Mortgage
Loans (except any such loss, liability or expense otherwise reimbursable
pursuant to the Pooling Agreement) and any loss, liability or expense incurred
by reason of willful misfeasance, bad faith or gross negligence in the
performance of duties thereunder or by reason of reckless disregard of
obligations and duties thereunder. In addition, the Pooling Agreement for each
such Series will provide that neither the Company nor any Master Servicer or,
where applicable, neither the Servicer nor the Certificate Administrator, is
under any obligation to appear in, prosecute or defend any legal action which is
not incidental to its responsibilities under the Pooling Agreement and which in
its opinion may involve it in any expense or liability. The Company or, where
applicable, a Master Servicer or the Servicer or the Certificate Administrator,
may, however, in its discretion, undertake any such action which it may deem
necessary or desirable with respect to the Pooling Agreement and the rights and
duties of the parties thereto and the interests of the Certificateholders
thereunder. In such event, the legal expenses and costs of such action and any
liability resulting therefrom will be expenses, costs and liabilities of the
Trust Fund, and the Company or, where applicable, a Master Servicer, the
Servicer or the Certificate Administrator, will be entitled to be reimbursed
therefor and to charge the Certificate Account.
 
    Any person into which a Master Servicer, the Servicer or the Certificate
Administrator may be merged, converted or consolidated, or any person resulting
from any merger, conversion or consolidation to which such Master Servicer, the
Servicer or the Certificate Administrator is a party, or any person succeeding
to the business of such Master Servicer, the Servicer or the Certificate
Administrator, will be the successor of such Master Servicer, the Servicer or
the Certificate Administrator, respectively, under the Pooling Agreement.
 
EVENTS OF DEFAULT
 
    With respect to Series of Certificates as to which the Company and/or a
Servicing Entity will act as Master Servicer, Events of Default under the
Pooling Agreement for each such Series (but, in the event that both the Company
and a Servicing Entity are acting as Master Servicers for a Series, such Event
of Default shall apply only to the defaulting Master Servicer), unless otherwise
specified in the
 
                                       40
<PAGE>
applicable Prospectus Supplement, will include, without limitation, (i) any
failure by the Company or Servicing Entity, as applicable, as Master Servicer,
to make a required deposit to the Certificate Account or, if the Company or
Servicing Entity, as applicable, as Master Servicer, is the Paying Agent, to
distribute to Certificateholders of any Class any required payment which
continues unremedied for ten days after the giving of written notice of such
failure to the Company or Servicing Entity, as applicable, as Master Servicer,
by the Trustee, or to the Company or Servicing Entity, as applicable, as Master
Servicer, and the Trustee by the holders of Certificates for that Series
evidencing interests aggregating not less than 25% of the Trust Fund, as
determined in the manner set forth in such Pooling Agreement; (ii) any failure
on the part of the Company or Servicing Entity, as applicable, as Master
Servicer, duly to observe or perform in any material respects any other of the
covenants or agreements on the part of the Company or Servicing Entity, as
applicable, as Master Servicer, contained in the Certificates for that Series or
in such Pooling Agreement which continues unremedied for 60 days after the
giving of written notice of such failure to the Company or Servicing Entity, as
applicable, as Master Servicer, by the Trustee, or to the Company or Servicing
Entity, as applicable, as Master Servicer, and the Trustee by the holders of
Certificates for that Series evidencing interests aggregating not less than 25%
of the Trust Fund, as determined in the manner set forth in such Pooling
Agreement; (iii) certain events of insolvency, readjustment of debt, marshalling
of assets and liabilities or similar proceedings and certain actions by the
Company or Servicing Entity, as applicable, as Master Servicer, indicating
insolvency, reorganization or inability to pay its obligations and (iv) any
failure of the Company or Servicing Entity, as applicable, to make any Advance
(other than a Nonrecoverable Advance) which continues unremedied at the opening
of business on the Distribution Date in respect of which such Advance was to
have been made. With respect to Series of Certificates as to which there will be
no Master Servicer, the Events of Default under the Pooling Agreement for each
such Series, unless otherwise specified in the applicable Prospectus Supplement,
will be the same failures by or conditions of the Servicer as will constitute
Events of Default by a Master Servicer under the Pooling Agreement for each
Series of Certificates for which the Company and/or a Servicing Entity will act
as Master Servicer, except that an Event of Default created by a failure of a
Master Servicer to make a required deposit to the Certificate Account referred
to in clause (i) of the immediately prior sentence will instead be the failure
of the Servicer to make a required deposit to the Investment Account on the
Withdrawal Date. Notwithstanding the foregoing, if an Event of Default described
in clause (iv) above occurs, the Trustee will, upon written notice to the
Company or Servicing Entity, as applicable, immediately suspend all of the
rights and obligations of the Company or Servicing Entity, as applicable,
thereafter arising under the Pooling Agreement and the Trustee will act to carry
out the duties of the Master Servicer, including the obligation to make any
Advance the nonpayment of which was an Event of Default described in clause (iv)
above. The Trustee will permit the Company or Servicing Entity, as applicable,
to resume its rights and obligations as Master Servicer under the Pooling
Agreement if the Company or Servicing Entity, as applicable, within two Business
Days following its suspension, remits to the Trustee the amount of any Advance
the nonpayment of which was an Event of Default described in clause (iv) above.
If an Event of Default as described in clause (iv) above occurs more than two
times in any twelve month period, the Trustee will not be obligated to permit
the Company or Servicing Entity, as applicable, to resume its rights and
obligations as Master Servicer under the Pooling Agreement.
 
RIGHTS UPON EVENT OF DEFAULT
 
    As long as an Event of Default under the Pooling Agreement for any Series
remains unremedied, the Trustee or holders of Certificates for that Series
evidencing interests aggregating not less than 25% of the Trust Fund, as
determined in the manner set forth in such Pooling Agreement, may terminate all
of the rights and obligations of the defaulting Master Servicer, the Servicer or
the Certificate Administrator, as applicable, under such Pooling Agreement and
in and to the Trust Fund, whereupon the Trustee will succeed to all the
responsibilities, duties and liabilities of the Master Servicer, the Servicer or
the Certificate Administrator, as applicable, under such Pooling Agreement and
will be entitled to similar compensation arrangements and limitations on
liability. In the event that the Trustee is unwilling or unable so to act, it
may appoint or petition a court of competent jurisdiction for the appointment of
a housing and home finance institution with a net worth of at least $10,000,000
to act as successor to the defaulting Master Servicer, the Servicer or the
Certificate Administrator, as applicable, under such Pooling Agreement. Pending
any such appointment, the
 
                                       41
<PAGE>
Trustee is obligated to act in such capacity. In the event the Trustee acts as
successor to such Master Servicer or the Servicer, the Trustee will be obligated
to make Advances unless it is prohibited by law from doing so. The Trustee and
such successor may agree upon the compensation to be paid, which in no event may
be greater than the compensation to the Company or Servicing Entity, as
applicable, as initial Master Servicer, or with respect to a Series of
Certificates as to which there will be no Master Servicer, to the Servicer named
in the applicable Prospectus Supplement or the Certificate Administrator, as
applicable, under such Pooling Agreement. Subject to certain limitations,
holders of Certificates for a Series evidencing interests aggregating not less
than 25% of the Trust Fund, as determined in the manner set forth in the Pooling
Agreement for that Series, may direct the action of the Trustee in pursuing
remedies and exercising powers under such Pooling Agreement.
 
    No Certificateholder of any Series will have any right under the applicable
Pooling Agreement to institute any proceeding with respect to such Pooling
Agreement unless such Certificateholder previously has given to the Trustee
written notice of default and unless the holders of Certificates for that Series
evidencing interests aggregating not less than 25% of the Trust Fund, as
determined in the manner set forth in such Pooling Agreement, have made written
request upon the Trustee to institute such proceeding in its own name as Trustee
thereunder and have offered to the Trustee reasonable indemnity and the Trustee
for 60 days has neglected or refused to institute any such proceeding. However,
the Trustee is under no obligation to exercise any of the trusts or powers
vested in it by the Pooling Agreement for any Series or to make any
investigation of matters arising thereunder or to institute, conduct or defend
any litigation thereunder or in relation thereto at the request, order or
direction of any of the Certificateholders, unless such Certificateholders have
offered to the Trustee reasonable security or indemnity against the costs,
expenses and liabilities which may be incurred therein or thereby.
 
AMENDMENT
 
    The Pooling Agreement for each Series may be amended by the Company and/or a
Servicing Entity and the Trustee, with respect to Series of Certificates as to
which the Company and/or a Servicing Entity will act as Master Servicer (and in
the case where both the Company and a Servicing Entity are acting as Master
Servicers, the Certificate Administrator), and by the Company, the Servicer, the
Certificate Administrator and the Trustee with respect to Series of Certificates
as to which there will be no Master Servicer, without the consent of any of the
Certificateholders covered by such Pooling Agreement, (i) to cure any ambiguity,
(ii) to correct or supplement any provision therein which may be inconsistent
with any other provision therein, (iii) to comply with any requirements imposed
by the Internal Revenue Code of 1986, as amended (the "Code") or any regulations
thereunder, including provisions to such extent as shall be necessary to
maintain the qualification of the Trust Fund as a REMIC or to avoid or minimize
the risk of imposition of any tax on the related Trust Fund, and (iv) to correct
the description of any property at any time included in the Trust Fund, or to
assure conveyance to the Trustee of any property included in the Trust Fund. The
Pooling Agreement for each Series may also be amended by the Company and the
Trustee, with respect to Series of Certificates as to which the Company will act
as Master Servicer, and by the Company, the Servicer, the Certificate
Administrator and the Trustee with respect to Series of Certificates as to which
the Company will not act as Master Servicer, with the consent of the holders of
Certificates for that Series evidencing interests aggregating not less than 66%
of the Trust Fund, as determined in the manner set forth in such Pooling
Agreement, for the purpose of adding any provisions to or changing in any manner
or eliminating any of the provisions of such Pooling Agreement or of modifying
in any manner the rights of the holders of Certificates of that Series;
provided, however, that no such amendment may (i) reduce in any manner the
amount of, or delay the timing of, payments received on Mortgage Loans which are
required to be distributed in respect of any Certificate without the consent of
the holder of such Certificate, or (ii) reduce the aforesaid percentage of
Certificates, the holders of which are required to consent to any such amendment
without the consent of the holders of all Certificates of such Series then
outstanding.
 
    The Prospectus Supplement for a particular Series may describe other or
different provisions concerning conditions to the amendment of the related
Pooling Agreement.
 
                                       42
<PAGE>
LIST OF CERTIFICATEHOLDERS
 
    With respect to Series of Certificates as to which the Company will act as a
Master Servicer or with respect to a Series where a Servicing Entity is the only
Master Servicer, upon written request of the Trustee, the Company or Servicing
Entity as applicable, will provide to the Trustee within 30 days after the
receipt of such request a list of the names and addresses of all
Certificateholders of record of a particular Series or Class as of the most
recent Record Date for payment of distributions to Certificateholders of that
Series or Class. Upon written request of three or more Certificateholders of
record of such a Series of Certificates, for purposes of communicating with
other Certificateholders with respect to their rights under the Pooling
Agreement for such Series, the Trustee will afford such Certificateholders
access during business hours to the most recent list of Certificateholders of
that Series held by the Trustee. If such list is as of a date more than 90 days
prior to the date of receipt of such Certificateholders' request, the Trustee
shall promptly request from the Master Servicer a current list and will afford
such requesting Certificateholders access to such list promptly upon receipt.
With respect to Series of Certificates as to which there will be no Master
Servicer, the Company, as Certificate Administrator, will provide the list of
names and addresses of the Certificateholders described above in the same manner
as so described.
 
TERMINATION
 
    The obligations created by the Pooling Agreement for each Series will
terminate upon the occurrence of both (i) the later of the maturity or other
liquidation of the last Mortgage Loan subject thereto and the disposition of all
property acquired upon foreclosure of any Mortgage Loan and (ii) the payment to
Certificateholders of each Class, if any, of that Series of all amounts held on
behalf of such Certificateholders and required to be paid to them pursuant to
such Pooling Agreement. The Pooling Agreement for each Series will permit, but
not require, the Company to repurchase from the Trust Fund for such Series all
remaining Mortgage Loans at a price equal to the unpaid principal amount thereof
or the Trust Fund's adjusted basis in the Mortgage Loans, as described in the
related Prospectus Supplement, in either case together with interest at the
applicable Mortgage Interest Rates (which will generally be passed through to
Certificateholders at the applicable Pass-Through Rates). The exercise of such
right will effect early retirement of the Certificates of such Series, but the
Company's right so to repurchase is subject to the aggregate principal balances
of the Mortgage Loans at the time of repurchase being less than the percentage
specified in the related Prospectus Supplement of the aggregate principal amount
of the Mortgage Loans underlying the Certificates of such Series as of the
Cut-Off Date. In no event, however, will the trust created by any Pooling
Agreement continue beyond the expiration of 21 years from the death of the
survivor of the issue of the person named in such Pooling Agreement. For each
Series, the Trustee will give written notice of termination of the Pooling
Agreement to each Certificateholder, and the final distribution will be made
only upon surrender and cancellation of the Certificates at an office or agency
specified in the notice of termination.
 
REDEMPTION AGREEMENT
 
    If so specified in the Prospectus Supplement for a Series, the related Trust
Fund will enter into a redemption agreement pursuant to which the counterparty
to the agreement will have the right to cause a redemption of the outstanding
Certificates of such Series, beginning on the Distribution Date and subject to
payment of the redemption price and other conditions specified in the Prospectus
Supplement. In general, the redemption price will equal the aggregate
outstanding principal balance of all Certificates of such Series(other than such
Certificates with a notional principal balance), plus any interest described in
the Prospectus Supplement. Payment of the redemption price will be in lieu of
any distribution of principal and interest that would otherwise be made on that
Distribution Date. Upon a redemption, the holder of the redemption right will
receive the assets of the Trust Fund and each Certificateholder will receive the
outstanding principal balance of its Certificate(other than a holder of
Certificates with a notional principal balance), plus any interest specified in
the Prospectus Supplement. See "Yield, Prepayment and Maturity Considerations"
for a discussion of the effects of such a redemption of an investor's yield to
maturity. In the case of a Trust Fund for which a REMIC election or elections
have been made, the transaction by which the Certificates are retired and the
related redemption is conducted will constitute a "qualified liquidation" under
Section 860F of the Code.
 
                                       43
<PAGE>
PUT OPTION
 
    If so specified in the Prospectus Supplement for a Series, each
Certificateholder of such Series, of a Class of such Series or of a group for
such Series will have the option to require the entity named in such Prospectus
Supplement to purchase such Certificates in full on the date, at the purchase
price and on the terms specified in such Prospectus Supplement.
 
THE TRUSTEE
 
    The Trustee under each Pooling Agreement will be named in the related
Prospectus Supplement. The bank or trust company serving as Trustee may have
normal banking relationships with the Company and/or its affiliates. The Trustee
will have combined capital and surplus of not less than $50 million.
 
    The Trustee under each Pooling Agreement may resign at any time, in which
event the Company will be obligated to appoint a successor Trustee. The Company
may also remove the Trustee if the Trustee ceases to be eligible to continue as
such under the applicable Pooling Agreement or if the capital and surplus of the
Trustee is reduced below $50 million. Upon becoming aware of such circumstances,
the Company will be obligated to appoint a successor Trustee for the related
Series. The Trustee may also be removed at any time by holders of Certificates
of a Series evidencing more than 50% of the aggregate undivided interests in the
related Trust Fund. Any resignation or removal of the Trustee and appointment of
a successor Trustee will not become effective until acceptance of the
appointment by the successor Trustee.
 
             PRIMARY INSURANCE, FHA MORTGAGE INSURANCE, VA MORTGAGE
                 GUARANTY, HAZARD INSURANCE; CLAIMS THEREUNDER
 
    As set forth below, a Mortgage Loan may be required to be covered by a
hazard insurance policy and either an FHA Insurance Policy, a VA Guaranty or a
Primary Insurance Policy. The following is only a brief description of such
coverage and does not purport to describe all of the characteristics of each
type of insurance. Such insurance is subject to underwriting and approval of
individual Mortgage Loans by the respective insurers and guarantors. In some
cases, however, the issuer of the insurance or guaranty may delegate
underwriting authority to the originator of the Mortgage Loan. The descriptions
of any insurance coverage in this Prospectus or any Prospectus Supplement do not
purport to be complete and are qualified in their entirety by reference to such
forms of policies, and to such statutes or regulations as may be applicable.
 
PRIMARY INSURANCE
 
    Unless otherwise specified in the applicable Prospectus Supplement, each
Mortgage Loan with a loan-to-value ratio at origination and at the Cut-Off Date
greater than 80% will be covered by a Primary Insurance Policy providing
insurance coverage against default on such Mortgage Loan, in general, of up to
25% of the principal balance of such Mortgage Loan with maintenance requirements
in certain cases for the remaining term of such Mortgage Loan, but at least
until the loan-to-value ratio drops to 80%. Conversely, Mortgage Loans with
lower loan-to-value ratios (up to approximately 80%) may not be covered by any
Primary Insurance Policies. Applicable state laws may in some instances limit
the maximum coverage which may be obtained with respect to certain Mortgage
Loans. Any such policy will be issued by a Qualified Insurer.
 
    While the terms and conditions of the Primary Insurance Policies will
differ, each Primary Insurance Policy will in general provide substantially the
following coverage. The amount of the loss as calculated under a Primary
Insurance Policy covering a Mortgage Loan (herein referred to as the "Loss")
will generally consist of the unpaid principal balance of such Mortgage Loan and
accrued and unpaid interest thereon and reimbursement of certain expenses, less
(i) rents or other payments collected or received by the insured (other than the
proceeds of hazard insurance) that are derived from the related Mortgaged
Property, (ii) hazard insurance proceeds in excess of the amount required to
restore such Mortgaged Property and which have not been applied to the payment
of the Mortgage Loan, (iii) certain amounts expended by the insured but not
approved by the insurer, (iv) claim payments previously made on such Mortgage
Loan and (v) unpaid premiums and certain other amounts.
 
                                       44
<PAGE>
    The issuer of a Primary Insurance Policy will generally be required to pay
either: (i) the insured percentage of the Loss; (ii) the entire amount of the
Loss, after receipt by the insurer of good and merchantable title to, and
possession of, the Mortgaged Property; or (iii) at the option of the insurer
under certain Primary Insurance Policies, the sum of the delinquent monthly
payments plus any advances made by the insured, both to the date of the claim
payment and, thereafter, monthly payments in the amount that would have become
due under the Mortgage Loan if it had not been discharged plus any advances made
by the insured until the earlier of (a) the date the Mortgage Loan would have
been discharged in full if the default had not occurred or (b) an approved sale.
 
    As conditions precedent to the filing or payment of a claim under a Primary
Insurance Policy, in the event of default by the Mortgagor, the insured will
typically be required, among other things, to: (i) advance or discharge (a)
hazard insurance premiums and (b) as necessary and approved in advance by the
insurer, real estate taxes, protection and preservation expenses and foreclosure
and related costs; (ii) in the event of any physical loss or damage to the
Mortgaged Property, have the Mortgaged Property restored to at least its
condition at the effective date of the Primary Insurance Policy (ordinary wear
and tear excepted); and (iii) tender to the insurer good and merchantable title
to, and possession of, the Mortgaged Property. If any Advance to be made
(including expenses to be paid) by the Master Servicer as a condition for
coverage of a loss by a Primary Insurance Policy is not so made by the Master
Servicer because the such Advance has been determined to be nonrecoverable, then
such loss will be allocated to the Certificateholders. See "Description of
Certificates--Advances".
 
    For any Certificates offered hereunder as to which the Company and/or a
Servicing Entity will act as Master Servicer, the Company or Servicing Entity,
as applicable, will cause each Servicer to maintain, or with respect to a Series
of Certificates as to which there will be no Master Servicer, the Servicer will
maintain, in full force and effect and to the extent coverage is available a
Primary Insurance Policy with regard to each Mortgage Loan for which such
coverage is required under the standard described above, provided that such
Primary Insurance Policy was in place as of the Cut-Off Date and the Company or
Servicing Entity, as applicable, had knowledge of such Primary Insurance Policy.
With respect to Series of Certificates as to which the Company and/or a
Servicing Entity will act as Master Servicer, in the event that the Company or
Servicing Entity, as applicable learns that a Mortgage Loan had a loan-to-value
ratio at origination and as of the Cut-Off Date in excess of 80% and was not the
subject of a Primary Insurance Policy (and was not included in any exception to
such standard disclosed in the related Prospectus Supplement), then the Company
or Servicing Entity, as applicable is required to use its reasonable efforts to
obtain and maintain a Primary Insurance Policy to the extent that such a policy
is obtainable at a reasonable price. With respect to Series of Certificates as
to which there will be no Master Servicer, in the event the Servicer learns of
the lack of a Primary Insurance Policy described in the preceding sentence, the
Servicer shall notify the Trustee who shall require the Seller to obtain a
Primary Insurance Policy, repurchase the Mortgage Loan or substitute a mortgage
loan for the applicable Mortgage Loan. The Company or Servicing Entity, as
Master Servicer, or the Servicer, as applicable, will not cancel or refuse to
renew any such Primary Insurance Policy in effect at the time of the initial
issuance of a Series of Certificates that is required to be kept in force under
the applicable Pooling Agreement unless, in the event that such Series of
Certificates was rated at the time of issuance, the replacement Primary
Insurance Policy from such cancelled or non-renewed policy is maintained with an
insurer whose claims-paying ability is acceptable to the rating agency or
agencies that rated such Series of Certificates for mortgage pass-through
certificates having a rating equal to or better than the then-current ratings of
such series of Certificates.
 
    Evidence of each Primary Insurance Policy will be provided to the Trustee
simultaneously with the transfer to the Trustee of the related Mortgage Loan.
With respect to Series of Certificates as to which the Company and/or a
Servicing Entity will act as Master Servicer, under the Selling and Servicing
Contract each Seller/Servicer, on behalf of itself, the Company, the related
Master Servicer, the Trustee and the Certificateholders, will be required to
present claims to the insurer under any Primary Insurance Policy and take such
reasonable steps as are necessary to permit recovery thereunder with respect to
defaulted Mortgage Loans. Amounts collected by a Seller/Servicer under such
Primary Insurance Policy shall be deposited in the Custodial Account for P&I
maintained by such Seller/Servicer on behalf of the Company, the Master
Servicer, the Trustee and the Certificateholders. The Company or Servicing
Entity, as applicable, will agree to cause each Seller/
 
                                       45
<PAGE>
Servicer not to cancel or refuse to renew any Primary Insurance Policy required
to be kept in force by the Pooling Agreement. With respect to Series of
Certificates as to which there will be no Master Servicer, under the Pooling
Agreement the Servicer will agree not to cancel or refuse to renew any Primary
Insurance Policy and will be required to present claims to the insurer under any
such Primary Insurance Policy, take steps to permit recovery under any such
Primary Insurance Policy and deposit amounts collected thereunder in the
Custodial Account for P&I to the same extent as a Seller/ Servicer will be so
required under a Selling and Servicing Contract.
 
    See "Description of Credit Enhancements--The Fraud Bond" for a discussion of
the possible effect of fraudulent conduct or negligence by the Seller, the
Seller/Servicer or the Mortgagor with respect to a Mortgage Loan on the coverage
of a Primary Insurance Policy.
 
FHA MORTGAGE INSURANCE
 
    The National Housing Act of 1934, as amended (the "Housing Act"), authorizes
various FHA mortgage insurance programs. Some of the Mortgage Loans may be
insured under either Section 203(b), Section 234 or Section 235 of the Housing
Act. Under Section 203(b), FHA insures mortgage loans of up to 30 years'
duration for the purchase of one- to four-family dwelling units. Mortgage loans
for the purchase of condominium units are insured by FHA under Section 234.
Loans insured under these programs must bear interest at a rate not exceeding
the maximum rate in effect at the time the loan is made, as established by the
United States Department of Housing and Urban Development ("HUD"), and may not
exceed specified percentages of the lesser of the appraised value of the
property and the sales price, less seller paid closing costs for the property,
up to certain specified maximums. In addition, FHA imposes initial investment
minimums and other requirements on mortgage loans insured under the Section
203(b) and Section 234 programs.
 
    Under Section 235, assistance payments are paid by HUD to the mortgagee on
behalf of eligible mortgagors for as long as the mortgagors continue to be
eligible for the payments. To be eligible, a mortgagor must be part of a family,
must have income within the limits prescribed by HUD at the time of initial
occupancy, must occupy the property and must meet requirements for
recertification at least annually.
 
    The regulations governing these programs provide that insurance benefits are
payable either (i) upon foreclosure (or other acquisition of possession) and
conveyance of the mortgaged premises to HUD or (ii) upon assignment of the
defaulted mortgage loan to HUD. The FHA insurance that may be provided under
these programs upon conveyance of the home to HUD is equal to 100% of the
outstanding principal balance of the mortgage loan, plus accrued interest, as
described below, and certain additional costs and expenses. When entitlement to
insurance benefits results from assignment of the mortgage loan to HUD, the
insurance payment is computed as of the date of the assignment and includes the
unpaid principal amount of the mortgage loan plus mortgage interest accrued and
unpaid to the assignment date.
 
    When entitlement to insurance benefits results from foreclosure (or other
acquisition of possession) and conveyance, the insurance payment is equal to the
unpaid principal amount of the mortgage loan, adjusted to reimburse the
mortgagee for certain tax, insurance and similar payments made by it and to
deduct certain amounts received or retained by the mortgagee after default, plus
reimbursement not to exceed two-thirds of the mortgagee's foreclosure costs.
 
VA MORTGAGE GUARANTY
 
    The Servicemen's Readjustment Act of 1944, as amended, permits a veteran
(or, in certain instances, his or her spouse) to obtain a mortgage loan guaranty
by the VA covering mortgage financing of the purchase of a one-to four-family
dwelling unit to be occupied as the veteran's home at an interest rate not
exceeding the maximum rate in effect at the time the loan is made, as
established by HUD. The program has no limit on the amount of a mortgage loan,
requires no down payment from the purchaser and permits the guaranty of mortgage
loans with terms limited by the estimated economic life of the property, up to
30 years. The maximum guaranty that may be issued by the VA under this program
is 50% of the original principal amount of the mortgage loan up to a certain
dollar limit established by the VA. The loan-to-value ratios allowed for
VA-guaranteed loans are set forth in the FNMA Seller's Guide. The liability on
the guaranty is reduced or increased pro rata with any
 
                                       46
<PAGE>
reduction or increase in the amount of indebtedness, but in no event will the
amount payable on the guaranty exceed the amount of the original guaranty.
Notwithstanding the dollar and percentage limitations of the guaranty, a
mortgagee will ordinarily suffer a monetary loss only where the difference
between the unsatisfied indebtedness and the proceeds of a foreclosure sale of
mortgaged premises is greater than the original guaranty as adjusted. The VA
may, at its option, and without regard to the guaranty, make full payment to a
mortgagee of the unsatisfied indebtedness on a mortgage upon its assignment to
the VA.
 
    Since there is no limit imposed by the VA on the principal amount of a
VA-guaranteed mortgage loan but there is a limit on the amount of the VA
guaranty, additional coverage under a Primary Insurance Policy may be required
by the Company for VA loans in excess of certain amounts. The amount of any such
additional coverage will be set forth in the related Prospectus Supplement.
 
HAZARD INSURANCE
 
    Unless otherwise specified in the applicable Prospectus Supplement, each
Seller/Servicer with respect to Series of Certificates as to which the Company
and/or a Servicing Entity will act as Master Servicer, or the Servicer with
respect to Series of Certificates as to which there will be no Master Servicer,
will cause to be maintained for each Mortgage Loan (other than Cooperative Loans
and Mortgage Loans secured by condominium apartments) that it services a hazard
insurance policy providing for no less than the coverage of the standard form of
fire insurance policy with extended coverage customary in the state in which the
Mortgaged Property is located. Such coverage will be in an amount not less than
the maximum insurable value of the Mortgaged Property or the original principal
balance of such Mortgage Loan, whichever is less. As set forth above, all
amounts collected by the Company or Servicing Entity, as applicable, as Master
Servicer, or a Seller/Servicer, or the Servicer, as applicable, under any hazard
policy (except for amounts to be applied to the restoration or repair of the
Mortgaged Property or released to the Mortgagor in accordance with the
Seller/Servicer's or the Servicer's normal servicing procedures) will be
deposited in the Custodial Account for P&I. In the event that the Company or
Servicing Entity, as applicable, as Master Servicer, or the Seller/ Servicer, or
the Servicer, as applicable, maintains a blanket policy insuring against hazard
losses on all of the Mortgage Loans, it shall conclusively be deemed to have
satisfied its obligation relating to the maintenance of hazard insurance. Such
blanket policy may contain a deductible clause, in which case the Company or
Servicing Entity, as applicable, as Master Servicer, or the Seller/Servicer, or
the Servicer, as applicable, will deposit in the Custodial Account for P&I or
the Certificate Account all sums which would have been deposited therein but for
such clause. The Company or Servicing Entity, as applicable, as Master Servicer,
and each of the Seller/Servicers with respect to Series of Certificates as to
which the Company and/or a Servicing Entity will act as Master Servicer, or the
Servicer with respect to Series of Certificates as to which there will be no
Master Servicer, are required to maintain a fidelity bond and errors and
omissions policy with respect to officers and employees which provide coverage
against losses which may be sustained as a result of an officer's or employee's
misappropriation of funds or errors and omissions in failing to maintain
insurance, subject to certain limitations as to amount of coverage, deductible
amounts, conditions, exclusions and exceptions in such form and amount as
specified in the Servicing Contract or the Pooling Agreement, as applicable.
 
    In general, the standard form of fire and extended coverage policy covers
physical damage to or destruction of the improvements on the property by fire,
lightning, explosion, smoke, windstorm and hail, and riot, strike and civil
commotion, subject to the conditions and exclusions particularized in each
policy. Although the policies relating to the Mortgage Loans will be
underwritten by different insurers under different state laws in accordance with
different applicable state forms and therefore will not contain identical terms
and conditions, the basic terms thereof are dictated by respective state laws,
and most such policies typically do not cover any physical damage resulting from
the following: war, revolution, governmental actions, floods and other
water-related causes, earth movement (including earthquakes, landslides and mud
flows), nuclear reactions, wet or dry rot, vermin, rodents, insects or domestic
animals, theft and, in certain cases, vandalism. The foregoing list is merely
indicative of certain kinds of uninsured risks and is not intended to be
all-inclusive. The Company or Servicing Entity, as applicable, may require
Mortgaged Properties in certain locations to be covered by policies of
earthquake insurance, to the extent it is reasonably available. When any
improvement to a Mortgaged Property is located in a designated flood area and in
a community which participates in the
 
                                       47
<PAGE>
National Flood Insurance Program at the time of origination of the related
Mortgage Loan, and flood insurance is required and available, the Pooling
Agreement requires the Company or Servicing Entity, as applicable, as Master
Servicer, through the Seller/Servicer responsible for servicing such Mortgage
Loan, or the Servicer, as applicable, to cause the Mortgagor to acquire and
maintain such insurance.
 
    The hazard insurance policies covering the Mortgaged Properties typically
contain a clause which, in effect, requires the insured at all times to carry
insurance of a specified percentage (generally 80% to 90%) of the full
replacement value of the improvements on the property in order to recover the
full amount of any partial loss. If the insured's coverage falls below this
specified percentage, such clause provides that the insurer's liability in the
event of partial loss does not exceed the larger of (i) the replacement cost of
the improvements less physical depreciation, and (ii) such proportion of the
loss, without deduction for depreciation, as the amount of insurance carried
bears to the specified percentage of the full replacement cost of such
improvements.
 
    Neither the Seller/Servicer with respect to Series of Certificates as to
which the Company and/or a Servicing Entity will act as Master Servicer, or the
Servicer with respect to Series of Certificates as to which there will be no
Master Servicer, will require that a hazard or flood insurance policy be
maintained for any Cooperative Loan or Mortgage Loan secured by a condominium
apartment. With respect to a Cooperative Loan, generally the Cooperative itself
is responsible for maintenance of hazard insurance for the property owned by the
Cooperative, and the tenant-stockholders of the Cooperative do not maintain
individual hazard insurance policies. To the extent, however, that a Cooperative
and the related borrower on a Cooperative Note do not maintain such insurance or
do not maintain adequate coverage or any insurance proceeds are not applied to
the restoration of the damaged property, damage to such borrower's cooperative
apartment or such Cooperative's building could significantly reduce the value of
the collateral securing such Cooperative Note. With respect to a Mortgage Loan
secured by a condominium apartment, the condominium owner's association for the
related building generally is responsible for maintenance of hazard insurance
for such building, and the condominium owners do not maintain individual hazard
insurance policies. To the extent that the owner of a Mortgage Loan secured by a
condominium apartment and the related condominium owner's association do not
maintain such insurance or do not maintain adequate coverage or any insurance
proceeds are not applied to the restoration of the damaged property, damage to
such borrower's condominium apartment or the related building could
significantly reduce the value of the Mortgaged Property.
 
    Since the amount of hazard insurance a Master Servicer or the
Seller/Servicers, or the Servicer, as applicable, will cause to be maintained on
the Mortgaged Properties declines as the principal balances owing on the related
Mortgage Loans decrease, and since residential properties have historically
appreciated in value over time, in the event of partial loss, hazard insurance
proceeds may be insufficient to restore fully the damaged property. See
"Description of Credit Enhancements--Special Hazard Insurance" for a description
of the limited protection afforded by the Special Hazard Insurance Policy,
Letter of Credit or Reserve Fund, if any is obtained, against losses occasioned
by certain hazards which are otherwise uninsured against, as well as against
losses caused by the application of the clause described in the preceding
paragraph.
 
    Any losses incurred with respect to Mortgage Loans due to uninsured risks
(including earthquakes, mudflows and floods) or insufficient hazard insurance
proceeds could affect distributions to the Certificateholders.
 
                       DESCRIPTION OF CREDIT ENHANCEMENTS
 
    To the extent provided in the applicable Prospectus Supplement, credit
enhancement for each Series of Certificates may be comprised of one or more of
the following components, each of which will have a dollar limit. Credit
enhancement components may include coverage with respect to losses that are (i)
attributable to the Mortgagor's failure to make any payment of principal or
interest as required under the Mortgage Note, but not including Special Hazard
Losses, Extraordinary Losses (as defined below) or other losses resulting from
damage to a Mortgaged Property, Bankruptcy Losses or Fraud Losses (any such
loss, a "Defaulted Mortgage Loss"); (ii) of a type generally covered by a
Special Hazard Insurance Policy (any such loss, a "Special Hazard Loss"); (iii)
attributable to certain actions which may be taken by a bankruptcy court in
connection with a Mortgage Loan, including a reduction
 
                                       48
<PAGE>
by a bankruptcy court of the principal balance of or the Mortgage Interest Rate
on a Mortgage Loan or an extension of its maturity (any such loss, a "Bankruptcy
Loss"); (iv) incurred on defaulted Mortgage Loans as to which there was
fraudulent conduct or negligence by either the Seller, the Seller/Servicer, the
Servicer or the Mortgagor in connection with such Mortgage Loans (any such loss,
a "Fraud Loss"); and (v) attributable to shortfalls in the payment of amounts
due to one or more Classes of Certificates. Losses occasioned by war, civil
insurrection, certain governmental actions, nuclear reaction, chemical
contamination, errors in design, faulty workmanship or materials or waste by the
Mortgagor ("Extraordinary Losses") will not be covered. To the extent that the
credit enhancement for any Series of Certificates is exhausted, the
Certificateholders will bear all further risks of loss not otherwise insured
against.
 
    As set forth below and in the applicable Prospectus Supplement, (i) coverage
with respect to Defaulted Mortgage Losses may be provided by one or more of a
Letter of Credit, Reserve Fund or a Mortgage Pool Insurance Policy, (ii)
coverage with respect to Special Hazard Losses may be provided by one or more of
a Letter of Credit, Reserve Fund or a Special Hazard Insurance Policy (any
instrument, to the extent providing such coverage, a "Special Hazard
Instrument"); (iii) coverage with respect to Bankruptcy Losses may be provided
by one or more of a Letter of Credit, Reserve Fund or Bankruptcy Bond (any
instrument, to the extent providing such coverage, a "Bankruptcy Instrument")
and (iv) coverage with respect to Fraud Losses may be provided by one or more of
a Letter of Credit, Reserve Fund or Fraud Bond (any instrument, to the extent
providing such coverage, a "Fraud Instrument"). In addition, if provided in the
applicable Prospectus Supplement, in lieu of or in addition to any or all of the
foregoing arrangements, credit enhancement may be in the form of subordination
of one or more Classes of Certificates to provide credit support to one or more
other Classes of Certificates.
 
    The amounts and types of credit enhancement arrangements as well as the
provider thereof, if applicable, with respect to each Series of Certificates
will be set forth in the related Prospectus Supplement. To the extent provided
in the applicable Prospectus Supplement and the Pooling Agreement, the credit
enhancement arrangements may be periodically modified, reduced and substituted
for based on the aggregate outstanding principal balance of the Mortgage Loans
covered thereby. If specified in the applicable Prospectus Supplement, credit
support for a Series of Certificates may cover one or more other series of
certificates issued by the Company or others.
 
    Unless otherwise specified in the applicable Prospectus Supplement, to the
extent permitted by any applicable rating agency and provided that the then
current ratings of the Certificates are maintained, coverage under any credit
enhancement may be cancelled or reduced.
 
    The descriptions of any credit enhancement instruments included in this
Prospectus or any Prospectus Supplement and the coverage thereunder do not
purport to be complete and are qualified in their entirety by reference to the
actual forms of governing documents, copies of which are available upon request.
 
MORTGAGE POOL INSURANCE
 
    A Mortgage Pool Insurance Policy may be obtained for a particular Series of
Certificates. Any such policy will be obtained by the Company or the Servicer,
as applicable, from a Qualified Insurer for the Mortgage Pool, covering loss by
reason of the default in payments on any Mortgage Loans included therein that
are not covered as to their entire outstanding principal balances by Primary
Insurance, FHA Insurance or VA Guarantees. Each Mortgage Pool Insurance Policy
will cover all or a portion of those Mortgage Loans in a Mortgage Pool in an
amount to be specified in the applicable Prospectus Supplement or in the related
Current Report on Form 8-K. The term "Mortgage Pool Insurance Policy" wherever
used in this Prospectus or any Supplement shall refer to one or more such
Mortgage Pool Insurance Policies as the context may require. The identity of the
insurer or insurers and certain financial information with respect to the
insurer or insurers for each Mortgage Pool will be contained in the applicable
Prospectus Supplement or in the related Current Report on Form 8-K. The Trustee
will be the named insured under any Mortgage Pool Insurance Policy. A Mortgage
Pool Insurance Policy is not a blanket policy against loss, since claims
thereunder may only be made respecting particular defaulted Mortgage Loans and
only upon the satisfaction of certain conditions precedent described below.
 
                                       49
<PAGE>
    Any Mortgage Pool Insurance Policy will provide that no claim may be validly
presented thereunder unless (i) hazard insurance on the property securing the
defaulted Mortgage Loan has been kept in force and real estate taxes and other
protection and preservation expenses have been paid, (ii) if there has been
physical loss or damage to the Mortgaged Property, it has been restored to its
condition (reasonable wear and tear excepted) at the Cut-Off Date, (iii) any
required Primary Insurance Policy is in effect for the defaulted Mortgage Loan
and a claim thereunder has been submitted and settled, and (iv) the insured has
acquired good and merchantable title to the Mortgaged Property free and clear of
liens except permitted encumbrances. Assuming the satisfaction of these
conditions, the insurer will have the option to either (i) purchase the property
securing the defaulted Mortgage Loan at a price equal to the principal balance
thereof, plus accrued and unpaid interest at the Mortgage Interest Rate to the
date of purchase, less the amount of any loss paid under a Primary Insurance
Policy, if any, or (ii) pay the difference between the proceeds received from an
approved sale of the property and the principal balance of the defaulted
Mortgage Loan, plus accrued and unpaid interest at the Mortgage Interest Rate to
the date of payment of the claim, less the amount of such loss paid under a
Primary Insurance Policy, if any. In each case, the insurer will reimburse the
Master Servicer and the Seller/Servicer, or the Servicer with respect to Series
of Certificates for which the Company will not act as Master Servicer, for
certain expenses incurred by them.
 
    An endorsement (an "Advance Claims Endorsement") may be issued to any
Mortgage Pool Insurance Policy which provides that the Insurer will make
advances of monthly principal and interest payments on Mortgage Loans as to
which the Seller/Servicer, or the Servicer with respect to Series of
Certificates for which the Company will not act as Master Servicer, has not
received a payment from the related Mortgagor and neither the Seller/Servicer
nor the Master Servicer, or the Servicer, as applicable, has advanced such
payment. The presence of such endorsement, if any, will be disclosed in the
Prospectus Supplement.
 
    An endorsement may also be issued to any Mortgage Pool Insurance Policy
which provides that the insurer will pay claims presented under the Mortgage
Pool Insurance Policy although claims made against the applicable Primary
Insurance Policy have not been settled due to the insolvency, bankruptcy,
receivership or assignment for the benefit of creditors of the issuer of the
Primary Insurance Policy. The presence of such endorsement, if any, will be
disclosed in the Prospectus Supplement.
 
    Unless otherwise specified in the applicable Prospectus Supplement, to the
extent permitted by any applicable rating agency and provided that the then
current ratings of the Certificates are maintained, coverage under any Mortgage
Pool Insurance Policy may be cancelled or reduced.
 
    The original amount of coverage under any Mortgage Pool Insurance Policy
will be reduced over the life of the Certificates by the aggregate dollar amount
of claims paid, less certain amounts realized by the insurer upon disposition of
foreclosed properties. The amount of claims paid includes certain expenses
incurred by the Company or a Servicing Entity, as applicable, as Master
Servicer, or the Servicer with respect to Series of Certificates for which there
will be no Master Servicer, as well as accrued interest on delinquent Mortgage
Loans to the date of payment of the claim. Accordingly, if aggregate net claims
paid under any Mortgage Pool Insurance Policy reach the original policy limit,
coverage thereunder will lapse and any further losses will be borne by
Certificateholders. In addition, in such event, the Company or a Servicing, as
applicable, as Master Servicer, or the Servicer, as applicable, will not be
obligated (unless sufficient recoveries from other sources are expected) to make
any further Advances, since such Advances would no longer be ultimately
recoverable under the Mortgage Pool Insurance Policy. See "Description of
Certificates--Advances".
 
    Since the property subject to a defaulted Mortgage Loan must be restored to
its original condition prior to claiming against the insurer, no Mortgage Pool
Insurance Policy will provide coverage against hazard losses. As set forth under
"Primary Insurance, FHA Mortgage Insurance, VA Mortgage Guaranty, Hazard
Insurance; Claims Thereunder", the hazard insurance policies covering the
Mortgage Loans typically exclude from coverage physical damage resulting from a
number of causes, and even when the damage is covered, may afford recoveries
which are significantly less than the full replacement of such losses. Further,
any Special Hazard Insurance Policy which may be obtained does not cover all
risks, and such coverage will be limited in amount. See "--Special Hazard
Insurance" below. Certain hazard risks will, as a result, be uninsured against
and will therefore be borne by Certificateholders.
 
                                       50
<PAGE>
    A Mortgage Pool Insurance Policy may include a provision permitting the
insurer to purchase defaulted Mortgage Loans from the Trust.
 
    See "--The Fraud Bond" below for a discussion of the possible effect of
fraudulent conduct or negligence by the Seller, the Seller/Servicer, the
Servicer or the Mortgagor with respect to a Mortgage Loan on the coverage of a
Mortgage Pool Insurance Policy.
 
SUBORDINATION
 
    If so specified in the applicable Prospectus Supplement, distributions with
respect to scheduled principal, Principal Prepayments, interest or any
combination thereof that otherwise would have been payable to one or more
Classes of Certificates of a Series (the "Subordinated Certificates") will
instead be payable to holders of one or more other Classes of such Series (the
"Senior Certificates") under the circumstances and to the extent specified in
the Prospectus Supplement. If specified in the applicable Prospectus Supplement,
delays in receipt of scheduled payments on the Mortgage Loans and losses on
defaulted Mortgage Loans will be borne first by the various Classes of
Subordinated Certificates and thereafter by the various Classes of Senior
Certificates, in each case under the circumstances and subject to the
limitations specified in the Prospectus Supplement. The aggregate distributions
in respect of delinquent payments on the Mortgage Loans over the lives of the
Certificates or at any time, the aggregate losses in respect of defaulted
Mortgage Loans which must be borne by the Subordinated Certificates by virtue of
subordination and the amount of the distributions otherwise distributable to the
Subordinated Certificateholders that will be distributable to Senior
Certificateholders on any Distribution Date may be limited as specified in the
applicable Prospectus Supplement. If the aggregate distribution with respect to
delinquent payments on the Mortgage Loans or aggregate losses in respect of such
Mortgage Loans were to exceed the total amounts payable and available for
distribution to holders of Subordinated Certificates or, if applicable, were to
exceed the specified maximum amount, holders of Senior Certificates could
experience losses on the Certificates.
    In addition to or in lieu of the foregoing, if so specified in the
applicable Prospectus Supplement, all or any portion of distributions otherwise
payable to holders of Subordinated Certificates on any Distribution Date may
instead be deposited into one or more reserve accounts (the "Reserve Account")
established by the Trustee. If so specified in the applicable Prospectus
Supplement, such deposits may be made on each Distribution Date, on each
Distribution Date for specified periods or until the balance in the Reserve
Account has reached a specified amount and, following payments from the Reserve
Account to holders of Senior Certificates or otherwise, thereafter to the extent
necessary to restore the balance in the Reserve Account to required levels, in
each case as specified in the Prospectus Supplement. If so specified in the
applicable Prospectus Supplement, amounts on deposit in the Reserve Account may
be released to the Company, a Servicing Entity, the Servicer or the Seller, as
applicable, or the holders of any Class of Certificates at the times and under
the circumstances specified in the Prospectus Supplement.
 
    If specified in the applicable Prospectus Supplement, various Classes of
Senior Certificates and Subordinated Certificates may themselves be subordinate
in their right to receive certain distributions to other Classes of Senior and
Subordinated Certificates, respectively, through a cross support mechanism or
otherwise.
 
    As between Classes of Senior Certificates and as between Classes of
Subordinated Certificates, distributions may be allocated among such classes (i)
in the order of their scheduled final distribution dates, (ii) in accordance
with a schedule or formula, (iii) in relation to the occurrence of events, or
(iv) otherwise, in each case as specified in the applicable Prospectus
Supplement. As between Classes of Subordinated Certificates, payments to holders
of Senior Certificates on account of delinquencies or losses and payments to any
Reserve Account will be allocated as specified in the Prospectus Supplement.
 
THE FRAUD BOND
 
    Some or all of the Primary Insurance Policies covering Mortgage Loans in any
Mortgage Pool may contain an exclusion from coverage for Fraud Losses. To
provide limited protection to Certificateholders against losses in the event
that coverage relating to a Mortgage Loan which otherwise would have been
available under a Primary Insurance Policy is not ultimately available by
 
                                       51
<PAGE>
reason of such an exclusion, if so specified in the applicable Prospectus
Supplement, a Fraud Instrument may be obtained or established by the Company or
the Servicer, as applicable, for the Mortgage Pool. The type, coverage amount
and term of any such Fraud Instrument will be disclosed in the applicable
Prospectus Supplement or in the related Current Report on Form 8-K, and the
coverage amount may be cancelled or reduced during the life of the Mortgage
Pool, provided that the then current ratings of the Certificates will not be
adversely affected thereby. The Company, a Servicing Entity or the Servicer, as
applicable, may also replace the initial Fraud Instrument with any other type of
Fraud Instrument, provided that the then current ratings of the Certificates
will not be adversely affected thereby. The identity of the issuer of any Fraud
Bond or the Letter of Credit providing such coverage and certain financial
information with respect to such issuer will be contained in the applicable
Prospectus Supplement or related Current Report on Form 8-K.
 
    In addition, the Company understands that, regardless of whether exclusion
language such as that described above is included in the insurance documents, it
is the policy of some or all issuers of Primary Insurance Policies and of
Mortgage Pool Insurance Policies to deny coverage in circumstances involving
fraudulent conduct or negligence by either the Seller, the Seller/Servicer, the
Servicer or the Mortgagor. It is unclear whether any such denial would be upheld
by a court. Neither the repurchase obligation of the Company or the Servicing
Entity, as applicable, with respect to Series of Certificates as to which the
Company and/or a Servicing Entity will act as Master Servicer, or the Seller
with respect to Series of Certificates as to which there will be no Master
Servicer, nor any of the Fraud Instruments described above would apply to any
such denial of coverage unless, as described above, such denial is based upon a
specific exclusion relating to fraudulent conduct or negligence which is
included in a Primary Insurance Policy.
 
THE BANKRUPTCY BOND
 
    The Prospectus Supplement for certain Series may specify that the Company
and/or a Servicing Entity, as Master Servicer, or the Servicer with respect to
Series of Certificates as to which there will be no Master Servicer, has
undertaken to pay to the Trustee for the benefit of Certificateholders any
portion of the principal balance of a Mortgage Loan which becomes unsecured
pursuant to a proceeding under Chapter 7, 11 or 13 of the Federal Bankruptcy
Code. If such obligation is undertaken, the Company and/or a Servicing Entity,
as Master Servicer, or the Servicer, as applicable, will also agree to pay to
the Trustee for the benefit of Certificateholders any shortfall in payment of
principal and interest resulting from the recasting of any originally scheduled
monthly principal and interest payment pursuant to a ruling under the Bankruptcy
Code. These payment obligations will be subject to the limitations specified in
the applicable Pooling Agreement. The Company and/or Servicing Entity, as Master
Servicer, or the Servicer, as applicable, will have the option, in lieu of
making such payments, to repurchase any Mortgage Loan affected by bankruptcy
court rulings. To insure the Company's or Servicing Entity's, as Master
Servicer, or the Servicer's obligation to make the payments described above, the
Company and/or a Servicing Entity, as Master Servicer, or the Servicer, as
applicable, will obtain or establish a Bankruptcy Instrument in an initial
amount specified in the Prospectus Supplement or in the related Current Report
on Form 8-K. The Prospectus Supplement or Current Report on Form 8-K may also
specify that, provided that the then current ratings of the Certificates are
maintained, coverage under any Bankruptcy Instrument may be cancelled or
reduced. The Master Servicer with respect to Series of Certificates as to which
the Company and/or a Servicing Entity will act as Master Servicer, or the
Servicer with respect to Series of Certificates as to which there will be no
Master Servicer, may also replace the initial method pursuant to which such
coverage is provided with either of the other two alternative methods, provided
that the then current ratings of the Certificates will not be adversely affected
thereby.
 
SPECIAL HAZARD INSURANCE
 
    A Special Hazard Insurance Instrument may be established or obtained by the
Company, Servicing Entity or the Servicer, as applicable, for certain Series.
Any Special Hazard Insurance Instrument will, subject to limitations described
below, protect the holders of the Certificates evidencing such Mortgage Pool
from (i) loss by reason of damage to properties subject to defaulted Mortgage
Loans covered thereby caused by certain hazards (including earthquakes in some
geographic areas, mud flows and floods) not insured against under customary
standard forms of fire and hazard insurance policies with extended coverage, and
(ii) loss on such loans caused by reason of
 
                                       52
<PAGE>
the application of the co-insurance clause typically contained in hazard
insurance policies. The Company and/or a Servicing Entity, as Master Servicer,
with respect to Series of Certificates as to which the Company and/or a
Servicing Entity will act as Master Servicer, or the Servicer with respect to
Series of Certificates as to which there will be no Master Servicer, may also
replace the initial method pursuant to which such coverage is provided with
either of the other two alternative methods, provided that the then current
ratings of the Certificates will not be adversely affected thereby. The
Prospectus Supplement or Current Report on Form 8-K may also specify that,
provided the then current ratings of the Certificates are maintained, coverage
under any Special Hazard Instrument may be cancelled or reduced. Any Special
Hazard Insurance Policy will be issued by an insurance company licensed to
transact a property and casualty insurance business in each state in which
Mortgaged Properties covered thereby are located. The identity of the issuer of
any Special Hazard Insurance Policy or the Letter of Credit providing such
coverage and certain financial information with respect to such issuer will be
contained in the related Prospectus Supplement. No Special Hazard Insurance
Instrument will cover Extraordinary Losses.
 
    Subject to the foregoing limitations, the terms of any Special Hazard
Insurance Instrument will provide generally that, where there has been damage to
property securing a defaulted Mortgage Loan covered by such instrument and such
damage is not fully covered by the hazard insurance policy maintained with
respect to such property, the Special Hazard Insurance Instrument will pay
either (i) the cost of repair of such property or (ii) the unpaid principal
balance of such Mortgage Loan at the time of an approved sale of such property,
plus accrued interest at the Mortgage Interest Rate to the date of claim
settlement and certain expenses incurred in respect of such property, less any
net proceeds upon the sale of such property. In either case, the amount paid
under any Special Hazard Insurance Instrument will be reduced by the proceeds,
if any, received under the hazard insurance policy maintained with respect to
such property. It is expected that the Mortgage Pool Insurer, if any, will
represent to the Company and/or a Servicing Entity, as Master Servicer, or the
Servicer, as applicable, that restoration of the property securing a Mortgage
Loan from the proceeds described under (i) above will satisfy the condition
under any related Mortgage Pool Insurance Policy that the property securing a
defaulted Mortgage Loan be restored before a claim under any such policy may be
validly presented in respect of such Mortgage Loan. The payment described under
(ii) above will render unnecessary presentation of a claim in respect of such
Mortgage Loan under any Mortgage Pool Insurance Policy. Therefore, so long as
any Mortgage Pool Insurance Policy for a Series of Certificates remains in
effect, the decision to pay the cost of repair rather than to pay the unpaid
principal balance of the related Mortgage Loan, plus accrued interest and
certain expenses, will not affect the amount of the total insurance proceeds
paid to the holders of the Certificates of that Series with respect to such
Mortgage Loan, but will affect the amount of special hazard insurance coverage
remaining under any Special Hazard Insurance Instrument and the coverage
remaining under any Mortgage Pool Insurance Policy obtained for that Series.
 
LETTER OF CREDIT
 
    If any component of credit enhancement as to any Series of Certificates is
to be provided by a letter of credit (the "Letter of Credit"), a bank or other
entity (the "Letter of Credit Bank") will deliver to the Trustee an irrevocable
Letter of Credit. The Letter of Credit Bank and certain information with respect
thereto, as well as the amount available under the Letter of Credit with respect
to each component of credit enhancement, will be specified in the applicable
Prospectus Supplement. The Letter of Credit will expire on the expiration date
set forth in the related Prospectus Supplement, unless earlier terminated or
extended in accordance with its terms.
 
    The Letter of Credit may also provide for the payment of Advances which the
Company or Servicing Entity, as applicable, as Master Servicer, with respect to
Series of Certificates as to which the Company will act as Master Servicer, or
the Servicer with respect to Series of Certificates as to which there will be no
Master Servicer, would be obligated to make with respect to delinquent monthly
payments.
 
RESERVE FUND
 
    If so specified in the related Prospectus Supplement, the Company, a
Servicing Entity, the Servicer or the Seller, as applicable, will deposit or
cause to be deposited in a Reserve Fund cash or
 
                                       53
<PAGE>
Eligible Investments in specified amounts, or any other instruments satisfactory
to the rating agency or agencies rating the Certificates offered pursuant to
such Prospectus Supplement, which will be applied and maintained in the manner
and under the conditions specified in such Prospectus Supplement. In the
alternative or in addition to such deposit, to the extent described in the
related Prospectus Supplement, a Reserve Fund may be funded through application
of all or a portion of amounts otherwise payable on one or more related Classes
of Certificates, from Retained Yield, or otherwise. Amounts in a Reserve Fund
may be used to provide one or more components of credit enhancement, or applied
to reimburse the Company or Servicing Entity, as applicable, as Master Servicer,
with respect to Series of Certificates as to which the Company and/or a
Servicing Entity will act as Master Servicer, or the Servicer with respect to
Series of Certificates as to which there will be no Master Servicer, for
outstanding Advances, or may be used for other purposes, in the manner and to
the extent specified in the related Prospectus Supplement. Unless otherwise
provided in the related Prospectus Supplement, any such Reserve Fund will not be
deemed to be part of the related Trust Fund.
 
    Amounts deposited in any Reserve Fund for a Series of Certificates will be
invested in Eligible Investments by, or at the direction of, and for the benefit
of the Company or Servicing Entity, as applicable, as Master Servicer, or the
Certificate Administrator, as applicable, or any other person named in the
related Prospectus Supplement. Unless otherwise specified in the applicable
Prospectus Supplement, any amounts remaining in the Reserve Fund upon the
termination of the Trust Fund will be returned to whomever deposited such
amounts in the Reserve Fund.
 
CERTIFICATE INSURANCE POLICIES
 
    If so specified in the related Prospectus Supplement, the Company or the
Servicer may obtain one or more certificate insurance policies, issued by
insurers acceptable to the rating agency or agencies rating the Certificates
offered pursuant to such Prospectus Supplement, insuring the holders of one or
more Classes of Certificates the payment of amounts due in accordance with the
terms of such Class or Classes of Certificates, subject to such limitations and
exceptions as are set forth in the applicable Prospectus Supplement.
 
MAINTENANCE OF CREDIT ENHANCEMENTS; CLAIMS THEREUNDER
    AND OTHER REALIZATION UPON DEFAULTED MORTGAGE LOANS
 
    For each Series of Certificates which will be covered by a Mortgage Pool
Insurance Policy, or a Letter of Credit established in lieu of such policy (such
coverage to be disclosed in the applicable Prospectus Supplement), the Company
and/or Servicing Entity, as Master Servicer, with respect to Series of
Certificates as to which the Company will act as Master Servicer, or the
Servicer with respect to Series of Certificates as to which there will be no
Master Servicer, will exercise its best reasonable efforts to keep such Mortgage
Pool Insurance Policy or Letter of Credit in full force and effect throughout
the term of the Pooling Agreement, unless coverage thereunder has been exhausted
through the payment of claims or until such instrument is replaced in accordance
with the terms of the Pooling Agreement. Unless otherwise specified in the
applicable Prospectus Supplement, the Company and/or Servicing Entity, as Master
Servicer, or the Servicer, as applicable, will agree to pay the premiums for any
Mortgage Pool Insurance Policy, and the fee for any Letter of Credit, on a
timely basis. In the event that the insurer under the Mortgage Pool Insurance
Policy ceases to be a Qualified Insurer (as defined in the Pooling Agreement),
or the Letter of Credit Bank ceases to be acceptable to the agency or agencies,
if any, rating the Series, the Company or Servicing Entity, as applicable, as
Master Servicer, or the Servicer, as applicable, will use its best reasonable
efforts to obtain from another Qualified Insurer or letter of credit issuer a
replacement policy or letter of credit comparable to the Mortgage Pool Insurance
Policy or Letter of Credit which it replaces, with total coverage equal to the
then outstanding coverage of the Mortgage Pool Insurance Policy or Letter of
Credit, provided that if the cost of the replacement policy or letter of credit
is greater than the cost of the Mortgage Pool Insurance Policy or Letter of
Credit being replaced, the coverage of the replacement policy or letter of
credit for a Series of Certificates may be reduced to a level such that its
premium rate or cost does not exceed 150% of the premium rate or cost of the
Mortgage Pool Insurance Policy or Letter of Credit for a Series which is rated
by one or more rating agencies, or 100% of the premium rate or cost for such
policy or letter of credit for a Series which is not so rated.
 
                                       54
<PAGE>
    In addition, the Company and/or Servicing Entity, as Master Servicer, or the
Servicer, as applicable, may substitute at any time a Mortgage Pool Insurance
Policy or Letter of Credit for an existing Mortgage Pool Insurance Policy or
Letter of Credit. In no event, however, may the Company and/or Servicing Entity,
as Master Servicer, or the Servicer, as applicable, provide a Letter of Credit
in lieu of a Mortgage Pool Insurance Policy, or vice-versa, or substitute one
such instrument for another, except under the circumstances detailed in the
preceding paragraph, if such action will impair the then current ratings, if
any, of the Certificates.
 
    Unless otherwise specified in the applicable Prospectus Supplement, each
Seller/Servicer with respect to Series of Certificates as to which the Company
and/or a Servicing Entity will act as Master Servicer, or the Servicer with
respect to Series of Certificates as to which there will be no Master Servicer,
will cause a Primary Insurance Policy to be maintained in full force and effect
with respect to each Mortgage Loan it services with a loan-to-value ratio in
excess of 80%; provided, however, that if the loan-to-value ratio of a Mortgage
Loan based on a subsequent appraisal of the Mortgaged Property is less than 80%,
such Primary Insurance Policy may be terminated, if so specified in the
applicable Prospectus Supplement. Each Seller/Servicer or the Servicer, as
applicable, will agree to pay the premium for each Primary Insurance Policy on a
timely basis in the event that the Mortgagor does not make such payments. See
"Primary Insurance, FHA Mortgage Insurance, VA Mortgage Guaranty, Hazard
Insurance; Claims Thereunder--Primary Insurance" herein.
 
    For each Series of Certificates which will be covered by a Special Hazard
Insurance Instrument (such coverage to be disclosed in the applicable Prospectus
Supplement), the Company and/or Servicing Entity, as Master Servicer with
respect to Series of Certificates as to which the Company and/or a Servicing
Entity will act as Master Servicer, or the Servicer with respect to Series of
Certificates as to which there will be no Master Servicer, will exercise its
best reasonable efforts to keep such Special Hazard Insurance Instrument in full
force and effect throughout the term of the Pooling Agreement, unless coverage
thereunder has been exhausted through the payment of claims or until such
Special Hazard Insurance Instrument has been replaced in accordance with the
terms of the Pooling Agreement. So long as any applicable rating on a Series of
Certificates will be maintained, the Company and/or Servicing Entity, as Master
Servicer, or the Servicer, as applicable, may at any time replace the initial
instrument providing special hazard coverage with either of the other two
alternative methods. Unless otherwise specified in the applicable Prospectus
Supplement, the Company or Servicing Entity, as Master Servicer, or the
Servicer, as applicable, will agree to pay the premium for any Special Hazard
Insurance Policy (or Letter of Credit obtained in lieu thereof) on a timely
basis. Unless otherwise specified in the applicable Prospectus Supplement, any
such policy will provide for a fixed premium rate on the declining balance of
the Mortgage Loans. In the event that any Special Hazard Insurance Policy is
cancelled or terminated for any reason other than the exhaustion of total policy
coverage, the Company, Servicing Entity or the Servicer, as applicable, is
obligated either to substitute a Letter of Credit or Reserve Fund or to exercise
its best reasonable efforts to obtain from another insurer a replacement policy
comparable to such Special Hazard Insurance Policy with a total coverage which
is equal to the then existing coverage of such Special Hazard Insurance Policy;
provided, however, that if the cost of any such replacement policy shall be
greater than the cost of the original Special Hazard Insurance Policy, the
amount of coverage of such replacement policy may be reduced to a level such
that the cost shall be equal to the cost of the original Special Hazard
Insurance Policy. As indicated above, in lieu of obtaining a replacement Special
Hazard Insurance Policy, the Company, Servicing Entity or the Servicer, as
applicable, may obtain a Letter of Credit or establish a Reserve Fund in
accordance with terms prescribed by any applicable rating agency so that any
rating obtained for the Certificates will not be impaired.
 
    For each Series of Certificates which will be covered by a Fraud Instrument
(such coverage to be disclosed in the applicable Prospectus Supplement), the
Company and/or a Servicing Entity, as Master Servicer, with respect to Series of
Certificates as to which the Company and/or a Servicing Entity will act as
Master Servicer, or the Servicer with respect to Series of Certificates as to
which there will be no Master Servicer, will exercise its best reasonable
efforts to maintain and keep any such Fraud Instrument in full force and effect
throughout the required term as set forth in the applicable Prospectus
Supplement, unless coverage thereunder has been exhausted through the payment of
claims. The Company, Servicing Entity or the Servicer, as applicable, will agree
to pay the premium for any Fraud Bond or Bankruptcy Bond on a timely basis.
 
                                       55
<PAGE>
    For each Series of Certificates or Class of Certificates which will be
covered by a certificate insurance policy or a Letter of Credit or Reserve Fund
(such coverage to be disclosed in the applicable Prospectus Supplement), the
Company and/or a Servicing Entity, as Master Servicer, with respect to Series of
Certificates as to which the Company will act as Master Servicer, or the
Servicer with respect to Series of Certificates as to which there will be no
Master Servicer, will exercise its best reasonable efforts to maintain and keep
any such certificate insurance policy, Letter of Credit or Reserve Fund in full
force and effect throughout the required term set forth in the applicable
Prospectus Supplement. Unless otherwise specified in the Prospectus Supplement,
the Company, Servicing Entity or the Servicer, as applicable, will agree to pay
the premium for any certificate insurance policy on a timely basis.
 
    The Company or Servicing Entity, as applicable, as Master Servicer, or the
Seller/Servicers, with respect to Series of Certificates as to which the Company
will act as Master Servicer, or the Servicer with respect to Series of
Certificates as to which there will be no Master Servicer, on behalf of the
Trustee and Certificateholders, will present claims to the issuer of any
applicable Primary Insurance Policy, FHA Insurance Policy, VA Guaranty, Mortgage
Pool Insurance Policy, Special Hazard Insurance Policy or Letter of Credit, or
under any Reserve Fund or other form of credit enhancement, and will take such
reasonable steps as are necessary to permit recovery under such insurance
policies or alternative coverages respecting defaulted Mortgage Loans. With
respect to any applicable Fraud Bond, Bankruptcy Bond or certificate insurance
policy, the Trustee will present claims to the issuer of such bond or policy on
behalf of the Certificateholders. As set forth above, all collections by the
Company or Servicing Entity, as applicable, as Master Servicer, or the
Seller/Servicer, or the Servicer, as applicable, under such policies or
alternative coverages that are not applied to the restoration of the related
Mortgaged Property are to be deposited in the applicable Custodial Account for
P&I, the Investment Account or the Certificate Account, subject to withdrawal as
heretofore described.
 
    If any property securing a defaulted Mortgage Loan is damaged and proceeds,
if any, from the related hazard insurance policy or any applicable Special
Hazard Insurance Policy (or Letter of Credit or Reserve Fund), as the case may
be, are insufficient to restore the damaged property to a condition sufficient
to permit recovery under any applicable Mortgage Pool Insurance Policy or
Primary Insurance Policy, the Company or Servicing Entity, as applicable, as
Master Servicer, with respect to Series of Certificates as to which the Company
and/or Servicing Entity will act as Master Servicer, or the Servicer with
respect to Series of Certificates as to which there will be no Master Servicer,
will not be required to expend its own funds to restore the damaged property
unless it determines (i) that such restoration will increase the proceeds to
Certificateholders upon liquidation of the Mortgage Loan after reimbursement of
the Company, Servicing Entity or the Servicer, as applicable, for its expenses
and (ii) that such expenses will be recoverable to it through Liquidation
Proceeds or Insurance Proceeds.
 
    If recovery under any Mortgage Pool Insurance Policy (or Letter of Credit
established in lieu of such policy), Primary Insurance Policy, FHA Insurance
Policy or VA Guaranty is not available because the Master Servicer, with respect
to Series of Certificates as to which the Company and/or a Servicing Entity will
act as Master Servicer, or the Servicer with respect to Series of Certificates
as to which there will be no Master Servicer, has been unable to make the
determinations described in the second preceding paragraph, or otherwise, the
Seller/Servicer or the Servicer, as applicable, is, nevertheless, obligated to
follow such normal practices and procedures as it deems necessary or advisable
to realize upon the defaulted Mortgage Loan. If the proceeds of any liquidation
of the property securing the defaulted Mortgage Loan are less than the principal
balance of the defaulted Mortgage Loan plus accrued and unpaid interest thereon
at the applicable Pass-Through Rate (after deduction of the Retained Yield, if
any, or a pro rata portion thereof as required by the applicable Pooling
Agreement), Certificateholders in the aggregate will realize a loss in the
amount of such difference plus the aggregate of expenses incurred by the Company
or Servicing Entity, as applicable, as Master Servicer, and the Seller/Servicer,
or the Servicer, as applicable, in connection with such proceedings and which
are reimbursable under the Pooling Agreement. In addition, and as set forth
above, in the event that the Company or Servicing Entity, as applicable, as
Master Servicer, or the Servicer, as applicable, has expended its own funds to
restore damaged property and such funds have not been reimbursed under any
Special Hazard Insurance Policy or Letter of Credit or Reserve Fund, it will be
entitled to receive from the Certificate Account, out of related Liquidation
Proceeds or Insurance Proceeds, an amount
 
                                       56
<PAGE>
equal to such expenses incurred by it, in which event the Certificateholders may
realize a loss up to the amount so charged. Since Insurance Proceeds cannot
exceed deficiency claims and certain expenses incurred by the Company or
Servicing Entity, as applicable, as Master Servicer, and the Seller/ Servicers,
or the Servicer, as applicable, no insurance payments will result in a recovery
to Certificateholders which exceeds the principal balance of the defaulted
Mortgage Loan together with accrued and unpaid interest thereon at the
applicable Pass-Through Rate. In addition, where property securing a defaulted
Mortgage Loan can be resold for an amount exceeding the principal balance of any
related Mortgage Note together with accrued interest and expenses, it may be
expected that, where retention of any such amount is legally permissible, the
insurer will exercise its right under any related Mortgage Pool Insurance Policy
to purchase such property and realize for itself any excess proceeds. In
addition, with respect to certain Series of Certificates, if so provided in the
applicable Prospectus Supplement, the Company or Servicing Entity, as
applicable, as Master Servicer, or the Servicer, as applicable, may have the
option to purchase from the Trust Fund any defaulted Mortgage Loan after a
specified period of delinquency. If a defaulted Mortgage Loan is not so removed
from the Trust Fund, then, upon the final liquidation thereof, if a loss is
realized which is not covered by any applicable form of credit enhancement or
other insurance, the Certificateholders will bear such loss. However, if a gain
results from the final liquidation of a defaulted Mortgage Loan which is not
required by law to be remitted to the related Mortgagor, the Company or
Servicing Entity, as applicable, as Master Servicer, or the Servicer, as
applicable, will be entitled to retain such gain as additional servicing
compensation unless the applicable Prospectus Supplement provides otherwise. See
"Description of Credit Enhancements".
 
                  CERTAIN LEGAL ASPECTS OF THE MORTGAGE LOANS
 
    The Mortgages (other than the security agreements with respect to the
Cooperative Loans) will be either deeds of trust or mortgages, depending upon
the prevailing practice in the state in which the Mortgaged Property is located.
A mortgage creates a lien upon the real property encumbered by the mortgage. It
is not prior to the lien for real estate taxes and assessments. Priority between
mortgages depends on their terms and generally on the order of filing with a
state or county office. There are two parties to a mortgage: the mortgagor, who
is usually the borrower and homeowner, and the mortgagee, who is the lender.
Under the mortgage instrument, the mortgagor delivers to the mortgagee a note or
bond and the mortgage. Although a deed of trust is similar to a mortgage, a deed
of trust formally has three parties; the borrower-homeowner, called the trustor
(similar to a mortgagor), a lender, called the beneficiary (similar to a
mortgagee), and a third-party grantee, called the trustee. Under a deed of
trust, the trustor grants the property, irrevocably until the debt is paid, in
trust, generally with a power of sale, to the trustee to secure payment of the
obligation. In some cases, a mortgage will also contain a power of sale. The
trustee's authority under a deed of trust and the mortgagee's authority under a
mortgage are governed by law, by the express provisions of the deed of trust or
mortgage and, in some cases, by the directions of the beneficiary. For purposes
of the following discussion, "mortgagor" shall, as appropriate, refer to a
mortgagor or trustor and "lender" shall refer to a mortgagee or beneficiary. A
Mortgage Pool may also contain Cooperative Loans which are described below under
"--Cooperative Loans".
 
COOPERATIVE LOANS
 
    If specified in the Prospectus Supplement relating to a Series of
Certificates, the Mortgage Loans may also include Cooperative Loans. Each
promissory note (a "Cooperative Note") evidencing a Cooperative Loan will be
secured by a security interest in shares issued by the related private
cooperative housing corporation (a "Cooperative") that owns the related
apartment building, which is a corporation entitled to be treated as a housing
cooperative under federal tax law, and in the related proprietary lease or
occupancy agreement granting exclusive rights to occupy a specific dwelling unit
in the Cooperative's building. The security agreement will create a lien upon or
grant a security interest in the cooperative shares and proprietary lease or
occupancy agreement, the priority of which will depend on the terms of the
particular security agreement as well as the order of recordation of the
agreement (or the filing of the financing statements related thereto) in the
appropriate recording office or the taking of possession of the cooperative
shares, depending on the law of the state in which the cooperative is located.
Such a lien or security interest is not, in general, prior to liens in favor of
the Cooperative for unpaid assessments or common charges.
 
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<PAGE>
    Unless otherwise specified in the related Prospectus Supplement, all
cooperative buildings relating to the Cooperative Loans are located in the
States of New York and New Jersey. Generally, each Cooperative owns in fee or
has a leasehold interest in all the real property and owns in fee or leases the
building and all separate dwelling units therein. The Cooperative is directly
responsible for property management and, in most cases, payment of real estate
taxes, other governmental impositions and hazard and liability insurance. If
there is an underlying mortgage (or mortgages) on the Cooperative's building or
underlying land, as is generally the case, or an underlying lease of the land,
as is the case in some instances, the Cooperative, as mortgagor or lessee, as
the case may be, is also responsible for fulfilling such mortgage or rental
obligations. An underlying mortgage loan is ordinarily obtained by the
Cooperative in connection with either the construction or purchase of the
Cooperative's building or the obtaining of capital by the Cooperative. The
interest of the occupant under proprietary leases or occupancy agreements as to
which that Cooperative is the landlord are generally subordinate to the interest
of the holder of an underlying mortgage and to the interest of the holder of a
land lease. If the Cooperative is unable to meet the payment obligations (i)
arising under an underlying mortgage, the mortgagee holding an underlying
mortgage could foreclose on that mortgage and terminate all subordinate
proprietary leases and occupancy agreements or (ii) arising under its land
lease, the holder of the landlord's interest under the land lease could
terminate it and all subordinate proprietary leases and occupancy agreements. In
addition, an underlying mortgage on a Cooperative may provide financing in the
form of a mortgage that does not fully amortize, with a significant portion of
principal being due in one final payment at maturity. The inability of the
Cooperative to refinance a mortgage and its consequent inability to make such
final payment could lead to foreclosure by the mortgagee. Similarly, a land
lease has an expiration date and the inability of the Cooperative to extend its
term or, in the alternative, to purchase the land, could lead to termination of
the Cooperative's interest in the property and termination of all proprietary
leases and occupancy agreements. In either event, a foreclosure by the holder of
an underlying mortgage or the termination of the underlying lease could
eliminate or significantly diminish the value of any collateral held by the
lender who financed the purchase by an individual tenant-stockholder of shares
of the Cooperative or, in the case of a Mortgage Pool, the collateral securing
any related Cooperative Loans.
 
    Each Cooperative is owned by shareholders (referred to as
tenant-stockholders) who, through ownership of stock or shares in the
Cooperative, receive proprietary leases or occupancy agreements which confer
exclusive rights to occupy specific dwellings. Generally, a tenant-stockholder
of a Cooperative must make a monthly maintenance payment to the Cooperative
pursuant to the proprietary lease, which maintenance payment represents such
tenant-stockholder's PRO RATA share of the Cooperative's payments for its
underlying mortgage, real property taxes, maintenance expenses and other capital
or ordinary expenses. An ownership interest in a Cooperative and accompanying
occupancy rights may be financed through a Cooperative Loan evidenced by a
Cooperative Note and secured by an assignment of and a security interest in the
occupancy agreement or proprietary lease and a security interest in the shares
of the related Cooperative. The lender generally takes possession of the share
certificate and a counterpart of the proprietary lease or occupancy agreement
and a financing statement covering the proprietary lease or occupancy agreement
and the Cooperative shares is filed in the appropriate state and local offices
to perfect the lender's interest in its collateral. Subject to the limitations
discussed below, upon default of the tenant-stockholder, the lender may sue for
judgment on the Cooperative Note, dispose of the collateral at a public or
private sale or otherwise proceed against the collateral or tenant-stockholder
as an individual as provided in the security agreement covering the assignment
of the proprietary lease or occupancy agreement and the pledge of Cooperative
shares. See "-- Foreclosure on Shares of Cooperatives" below.
 
TAX ASPECTS OF COOPERATIVE OWNERSHIP
 
    In general, a "tenant-stockholder" (as defined in Section 216(b)(2) of the
Code) of a corporation that qualifies as a "cooperative housing corporation"
within the meaning of Section 216(b)(1) of the Code is allowed a deduction under
Section 216(a) of the Code for amounts paid or accrued within his or her taxable
year to the corporation representing his or her proportionate share of certain
interest expenses and certain real estate taxes allowable as deductions to the
corporation under Sections 163 and 164 of the Code. In order for a corporation
to qualify under Section 216(b)(1) of the Code for the taxable year to which
such interest and tax deductions relate, such section requires, among other
 
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<PAGE>
things, that at least 80% of the gross income of the corporation be derived from
its tenant-stockholders. By virtue of this requirement, the status of a
corporation for purposes of Section 216(b)(1) of the Code must be determined on
a year-to-year basis. Consequently, there can be no assurance that Cooperatives
relating to the Cooperative Loans will qualify under such section for any
particular year. In the event that such a Cooperative fails to qualify for one
or more years, the value of the collateral securing any related Cooperative
Loans could be significantly impaired because no deduction would be allowable to
tenant-stockholders under Section 216(a) of the Code with respect to those
years. In view of the significance of the tax benefits accorded
tenant-stockholders of a corporation that qualifies under Section 216(b)(1) of
the Code, the likelihood that such a failure would be permitted to continue over
a period of years appears remote.
 
FORECLOSURE
 
    Foreclosure may be accomplished by judicial action. The action is initiated
by the service of legal pleadings upon all parties having an interest in the
real property. Delays in completion of the foreclosure may occasionally result
from difficulties in locating necessary parties defendant. Judicial foreclosure
proceedings are generally not contested by any of the parties defendant.
However, when the lender's right to foreclose is contested, the legal
proceedings necessary to resolve the issue can be time consuming. After the
completion of judicial foreclosure, the court would issue a judgment of
foreclosure and would generally appoint a referee or other court officer to
conduct the sale of property.
 
    In many states, foreclosure of a mortgage or deed of trust may also be
accomplished by a nonjudicial sale under a specific provision in the mortgage or
deed of trust which authorizes the sale of the property at public auction upon
default by the mortgagor. The laws of the various states establish certain
notice requirements for non-judicial foreclosure sales. In some states, notice
of default must be recorded and sent to the mortgagor and to any person who has
recorded a request for a copy of a notice of default and notice of sale. In
addition, notice must be provided in some states to certain other persons
including junior lienholders and any other individual having an interest in the
real property. In some states, the mortgagor, or any other person having a
junior encumbrance on the real estate, may, during a reinstatement period, cure
the default by paying the entire amount in arrears, plus the costs and expenses
incurred in enforcing the obligation. Generally, state law controls the amount
of foreclosure expenses and costs, including limited attorneys' fees, which may
be recovered by a lender. Some states also require a notice of sale to be posted
in a public place and published for a specified period of time in one or more
newspapers. In addition, some state laws require that a copy of the notice of
sale be posted on the property and sent to all parties having an interest in the
real property.
 
    In case of foreclosure under either a mortgage or a deed of trust, the sale
by the receiver or other designated officer or by the trustee is a public sale.
However, because of a number of factors, including the difficulty a potential
buyer at the sale would have in determining the exact status of title and the
fact that the physical condition of the property may have deteriorated during
the foreclosure proceedings, it is uncommon for a third party to purchase the
property at the foreclosure sale. Rather, it is common for the lender to
purchase the property from the trustee or referee with a credit bid in an amount
equal to the principal amount of the mortgage or deed of trust, accrued and
unpaid interest and the expenses of foreclosure. Thereafter, the lender will
assume the burdens of ownership, including obtaining casualty insurance and
making such repairs at its own expense as are necessary to render the property
suitable for sale. The lender will commonly obtain the services of a real estate
broker and pay the broker's commission in connection with the sale of the
property. Depending upon market conditions, the ultimate proceeds of the sale of
the property may not equal the lender's investment in the property.
 
    Courts have imposed general equitable principles upon foreclosure
proceedings. These equitable principles are generally designed to relieve the
mortgagor from the legal effect of his defaults under the loan documents.
Examples of judicial remedies that have been fashioned include judicial
requirements that the lender undertake affirmative and sometimes expensive
actions to determine the causes for the mortgagor's default and the likelihood
that the mortgagor will be able to reinstate the loan. In some cases, courts
have substituted their judgment for the lender's judgment and have required that
lenders reinstate loans or recast payment schedules in order to accommodate
mortgagors who are suffering from a temporary financial disability. In other
cases, courts have limited the right of the lender to foreclose if the default
under the security instrument is not monetary, such as
 
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<PAGE>
the mortgagor failing to adequately maintain or insure the property or the
mortgagor executing a second mortgage or deed of trust affecting the property.
Some courts have been faced with the issue of whether or not federal or state
constitutional provisions reflecting due process concerns for adequate notice
require that mortgagors receive notices in addition to the statutorily
prescribed minimum. For the most part, these cases have upheld the notice
provisions as being reasonable or have found that the foreclosure sale does not
involve sufficient state action to afford constitutional protections to the
mortgagor.
 
FORECLOSURE ON SHARES OF COOPERATIVES
 
    The Cooperative shares owned by the tenant-stockholder, together with the
rights of the tenant-stockholder under the proprietary lease or occupancy
agreement, are pledged to the lender and are, in almost all cases, subject to
restrictions on transfer as set forth in the Cooperative's certificate of
incorporation and by-laws, as well as in the proprietary lease or occupancy
agreement. The proprietary lease or occupancy agreement, even while pledged, may
be cancelled by the Cooperative for failure by the tenant-stockholder to pay
maintenance or other obligations or charges owed by such tenant-stockholder,
including mechanics' liens against the Cooperative's building incurred by such
tenant-stockholder. Generally, maintenance and other obligations and charges
arising under a proprietary lease or occupancy agreement which are owed to the
Cooperative are made liens upon the shares to which the proprietary lease or
occupancy agreement relates. In addition, the proprietary lease or occupancy
agreement generally permits the Cooperative to terminate such lease or agreement
in the event the borrower defaults in the performance of covenants thereunder.
Typically, the lender and the Cooperative enter into a recognition agreement
which, together with any lender protection provisions contained in the
proprietary lease, establishes the rights and obligations of both parties in the
event of a default by the tenant-stockholder on its obligations under the
proprietary lease or occupancy agreement. A default by the tenant-stockholder
under the proprietary lease or occupancy agreement will usually constitute a
default under the security agreement between the lender and the
tenant-stockholder.
 
    The recognition agreement generally provides that, in the event that the
tenant-stockholder has defaulted under the proprietary lease or occupancy
agreement, the Cooperative will take no action to terminate such lease or
agreement until the lender has been provided with notice of and an opportunity
to cure the default. The recognition agreement typically provides that if the
proprietary lease or occupancy agreement is terminated, the Cooperative will
recognize the lender's lien against proceeds from a sale of the shares and the
proprietary lease or occupancy agreement allocated to the dwelling, subject,
however, to the Cooperative's right to sums due under such proprietary lease or
occupancy agreement or which have become liens on the shares relating to the
proprietary lease or occupancy agreement. The total amount owed to the
Cooperative by the tenant-stockholder, which the lender generally cannot
restrict and does not monitor, could reduce the amount realized upon a sale of
the collateral below the outstanding principal balance of the Cooperative Loan
and accrued and unpaid interest thereon.
 
    Recognition agreements also generally provide that in the event the lender
succeeds to the tenant-stockholder's shares and proprietary lease or occupancy
agreement as the result of realizing upon its collateral for a Cooperative Loan,
the lender must obtain the approval or consent of the board of directors of the
Cooperative as required by the proprietary lease before transferring the
Cooperative shares and assigning the proprietary lease. Such approval or consent
is usually based on the prospective purchaser's income and net worth, among
other factors, and may significantly reduce the number of potential purchasers,
which could limit the ability of the lender to sell and realize upon the value
of the collateral. Generally, the lender is not limited in any rights it may
have to dispossess the tenant-stockholder.
 
    Because of the nature of Cooperative Loans, lenders do not require the
tenant-stockholder (i.e., the borrower) to obtain title insurance of any type.
Consequently, the existence of any prior liens or other imperfections of title
affecting the Cooperative's building or real estate also may adversely affect
the marketability of the shares allocated to the dwelling unit in the event of
foreclosure.
 
    A foreclosure on the Cooperative shares is accomplished by public sale in
accordance with the provisions of Article 9 of the Uniform Commercial Code (the
"UCC") and the security agreement
 
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<PAGE>
relating to those shares. Article 9 of the UCC requires that a sale be conducted
in a "commercially reasonable" manner. Whether a sale has been conducted in a
"commercially reasonable" manner will depend on the facts in each case. In
determining commercial reasonableness, a court will look to the notice given the
debtor and the method, manner, time, place and terms of the sale and the sale
price. Generally, a sale conducted according to the usual practice of creditors
selling similar collateral will be considered reasonably conducted.
 
    Article 9 of the UCC provides that the proceeds of the sale will be applied
first to pay the costs and expenses of the sale and then to satisfy the
indebtedness secured by the lender's security interest. The recognition
agreement, however, generally provides that the lender's right to reimbursement
is subject to the right of the Cooperative corporation to receive sums due under
the proprietary lease or occupancy agreement. If there are proceeds remaining,
the lender must account to the tenant-stockholder for the surplus. Conversely,
if a portion of the indebtedness remains unpaid, the tenant-stockholder is
generally responsible for the deficiency. See "--Anti-Deficiency Legislation and
Other Limitations on Lenders" below.
 
RIGHTS OF REDEMPTION
 
    In some states, after sale pursuant to a deed of trust or foreclosure of the
mortgage, there are statutory periods during which the mortgagor and foreclosed
junior lienors may redeem the property from the foreclosure sale. One effect of
the statutory right of redemption is to diminish the ability of the lender to
sell the foreclosed property because the right of redemption would defeat the
title of any purchaser from the lender subsequent to foreclosure or sale under a
deed of trust. As a practical matter, the lender may therefore be forced to
retain the property and pay the expenses of ownership until the redemption
period has run.
 
ANTI-DEFICIENCY LEGISLATION AND OTHER LIMITATIONS ON
  LENDERS
 
    Certain states have imposed statutory prohibitions which restrict or
eliminate the remedies of a lender under a deed of trust or a mortgage. In some
states, statutes limit the right of the lender to obtain a deficiency judgment
against the mortgagor following sale under a deed of trust or foreclosure. A
deficiency judgment would be a personal judgment against the former mortgagor
equal in most cases to the difference between the net amount realized upon the
public sale of the real property and the amount due to the lender. Other
statutes may require the lender to exhaust the security afforded under a deed of
trust or mortgage by foreclosure in an attempt to satisfy the full debt before
bringing a personal action against the mortgagor. Some state statutes also
prohibit any deficiency judgment where the loan proceeds were used to purchase
an owner-occupied dwelling. Finally, other statutory provisions limit any
deficiency judgment against the former mortgagor following a judicial sale to
the excess of the outstanding debt over the fair market value of the property at
the time of the public sale. The basic purpose of these statutes is to prevent a
lender from obtaining a large deficiency judgment against the former mortgagor
as a result of low or no bids at the judicial sale.
 
    Generally, Article 9 of the UCC governs foreclosure on Cooperative shares
and the related proprietary lease or occupancy agreement. Some courts have
interpreted Article 9 to prohibit or limit a deficiency award in certain
circumstances, including circumstances where the disposition of the collateral
(which, in the case of a Cooperative Loan, would be the shares of the
Cooperative and the related proprietary lease or occupancy agreement) was not
conducted in a commercially reasonable manner.
 
    In addition to anti-deficiency and related legislation, numerous other
statutory provisions, including the federal bankruptcy laws and state laws
affording relief to debtors, may interfere with or affect the ability of the
secured mortgage lender to collect the full amount of interest due or realize
upon its security. For example, with respect to federal bankruptcy law, a court
with federal bankruptcy jurisdiction may permit a mortgagor through his or her
Chapter 11, Chapter 12 or Chapter 13 rehabilitative plan to cure a monetary
default in respect of a mortgage loan on the mortgagor's residence by paying
arrearages within a reasonable time period and reinstating the original mortgage
loan payment schedule even though the lender accelerated the mortgage loan and
foreclosure proceedings had occurred prior to the filing of the debtor's
petition. Some courts with federal bankruptcy jurisdiction have approved plans,
based on the particular facts of the reorganization case, that effected the
curing of a mortgage loan default by paying arrearages over a number of years.
 
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<PAGE>
    Courts with federal bankruptcy jurisdiction have also held that the terms of
a mortgage loan secured by property of the mortgagor may be modified. These
courts have held that such modifications may include reducing the amount of each
monthly payment, changing the rate of interest, altering the repayment schedule,
and reducing the lender's security interest to the value of the residence, thus
leaving the lender in the position of a general unsecured creditor for the
difference between the value of the residence and the outstanding balance of the
loan. Courts with federal bankruptcy jurisdiction similarly may be able to
modify the terms of a Cooperative Loan.
 
    The Code provides priority to certain tax liens over the lien of the
security instrument. Numerous federal and some state consumer protection laws
impose substantive requirements upon lenders in connection with the origination
and the servicing of mortgage loans. These laws include the federal
Truth-in-Lending Act, Real Estate Settlement Procedures Act, Equal Credit
Opportunity Act, Fair Credit Billing Act, Fair Credit Reporting Act and related
statutes. These federal laws impose specific statutory liabilities upon lenders
who originate mortgage loans and who fail to comply with the provisions of the
law. In some cases, this liability may affect assignees of the mortgage loans.
 
ENFORCEABILITY OF CERTAIN PROVISIONS
 
    The standard forms of note, mortgage and deed of trust used by lenders
generally contain "due-on-sale" clauses. These clauses permit the lender to
accelerate the maturity of the loan if the mortgagor sells, transfers or conveys
the property. The enforceability of these clauses was the subject of legislation
and litigation in many states, and in some cases the enforceability of these
clauses was limited or denied. However, the Garn-St Germain Depository
Institutions Act of 1982 (the "Garn-St Germain Act") purports to pre-empt state
statutory and case law that prohibits the enforcement of "due-on-sale" clauses
and permits lenders to enforce these clauses in accordance with their terms,
subject to certain limited exceptions. The Garn-St Germain Act does "encourage"
lenders to permit assumption of loans at the original rate of interest or at
some other rate less than the average of the original rate and the market rate.
In addition, certain states have continuing restrictions on the enforceability
of due-on-sale clauses for certain loans.
 
    The Garn-St Germain Act also sets forth nine specific instances in which a
mortgage lender covered by the act (including federal savings associations and
federal savings banks) may not exercise a "due-on-sale" clause, notwithstanding
the fact that a transfer of the property may have occurred. These include
intrafamily transfers, certain transfers by operation of law, leases of less
than three years and the creation of a junior encumbrance. Regulations
promulgated under the Garn-St Germain Act by the Federal Home Loan Bank Board
(now the Office of Thrift Supervision) and statutes in some states also prohibit
the imposition of a prepayment penalty upon the acceleration of a loan pursuant
to a "due-on-sale" clause. In addition, a few states have exercised their rights
under the Garn-St Germain Act to limit the enforceability of the due-on-sale
clauses in certain loans made prior to passage of the Garn-St Germain Act. As of
the date hereof, certain states have taken action to reimpose interest rate
limits and/or to limit discount points or other charges.
 
    A consequence of the inability to enforce a due-on-sale clause may be that a
mortgagor's buyer may assume the existing mortgage loan rather than paying it
off, if such existing loan bears an interest rate below the current market rate,
which may have an impact upon the average life of the Mortgage Loans and the
number of Mortgage Loans which may be outstanding until maturity.
 
    Under the terms of the Soldiers' and Sailors' Civil Relief Act of 1940, as
amended (the "Relief Act"), a Mortgagor who enters military service after the
origination of such Mortgagor's Mortgage Loan (including a Mortgagor who is a
member of the National Guard or is in reserve status at the time of the
origination of the Mortgage Loan and is later called to active duty) may not be
charged interest above an annual rate of 6% during the period of such
Mortgagor's active duty status, unless a court orders otherwise upon application
of the lender. Any shortfall in interest collections resulting from the
application of the Relief Act, to the extent not covered by any applicable
credit enhancements, could result in losses to the Holders of the Certificates.
In addition, the Relief Act imposes limitations which would impair the ability
of the Servicer to foreclose on an affected Mortgage Loan during the Mortgagor's
period of active duty status. Thus, in the event that such a Mortgage Loan goes
into default, there may be delays and losses occasioned by the inability to
realize upon the Mortgaged Property in a timely fashion.
 
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APPLICABILITY OF USURY LAWS
 
    Title V of the Depository Institutions Deregulation and Monetary Control Act
of 1980, enacted in March 1980 ("Title V"), provides that state usury
limitations shall not apply to certain types of residential first mortgage loans
originated by certain lenders after March 31, 1980. A similar federal statute
was in effect with respect to mortgage loans made during the first three months
of 1980. The Federal Home Loan Bank Board (now the Office of Thrift Supervision)
has issued regulations governing the implementation of Title V. The statute
authorizes any state to reimpose interest rate limits by adopting before April
1, 1983, a law or constitutional provision which expressly rejects application
of the federal law. In addition, even where Title V is not so rejected, any
state is authorized to adopt a provision limiting discount points or other
charges prior to origination on mortgage loans covered by Title V.
 
    Under the Company's mortgage purchase program, each Lender is required to
represent and warrant to the Company that all Mortgage Loans are originated in
full compliance with applicable state laws, including usury laws. Based upon
such representations and warranties from the Lenders, the Company will make a
similar representation and warranty in the Pooling Agreement for each Series to
the Trustee for the benefit of Certificateholders. See "Description of
Certificates-- Representations and Warranties".
 
ALTERNATIVE MORTGAGE INSTRUMENTS
 
    Alternative mortgage instruments, including adjustable-rate mortgage loans,
originated by non-federally chartered lenders have historically been subjected
to a variety of restrictions. Such restrictions differed from state to state,
resulting in difficulties in determining whether a particular alternative
mortgage instrument originated by a state-chartered lender was in compliance
with applicable law. These difficulties were alleviated substantially as a
result of the enactment of Title VIII of the Garn-St Germain Act ("Title VIII").
Title VIII provides that, notwithstanding any state law to the contrary,
state-chartered banks may originate alternative mortgage instruments in
accordance with regulations promulgated by the Comptroller of the Currency with
respect to origination of alternative mortgage instruments by national banks,
state-chartered credit unions may originate alternative mortgage instruments in
accordance with regulations promulgated by the National Credit Union
Administration with respect to origination of alternative mortgage instruments
by federal credit unions, and all other non-federally chartered housing
creditors, including state-chartered savings and loan associations,
state-chartered savings banks and mortgage banking companies, may originate
alternative mortgage instruments in accordance with the regulations promulgated
by the Federal Home Loan Bank Board (now the Office of Thrift Supervision) with
respect to origination of alternative mortgage instruments by federal savings
and loan associations. Title VIII provides that any state may reject
applicability of the provisions of Title VIII by adopting, prior to October 15,
1985, a law or constitutional provision expressly rejecting the applicability of
such provisions. Certain states have taken such action.
 
ENVIRONMENTAL RISKS
 
    Real property pledged as security to a lender may be subject to unforeseen
environmental risks. Under the laws of certain states, contamination of a
property may give rise to a lien on the property to assure the payment of costs
of clean-up. In several states such a lien has priority over the lien of an
existing mortgage against such property.
 
    In addition, under the laws of some states and under the federal
Comprehensive Environmental Response, Compensation and Liability Act of 1980
("CERCLA"), a lender may be liable, as an "owner" or "operator", for costs
arising out of releases or threatened releases of hazardous substances that
require remedy at a mortgaged property. CERCLA imposes liability for such costs
on any and all "responsible parties", including the current owner or operator of
a contaminated property, regardless of whether or not the environmental damage
was caused by a prior owner. However, CERCLA excludes from the definition of
"owner or operator" a secured creditor who holds indicia of ownership primarily
to protect its security interest, but does not "participate in the management"
of a mortgaged property. The conduct which constitutes "participation in the
management", such that the lender would lose the protection of the exclusion for
secured creditors, has been a matter of judicial interpretation of the statutory
language, and court decisions have historically been inconsistent. In
 
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<PAGE>
1990, the United States Court of Appeals for the Eleventh Circuit suggested, in
UNITED STATES v. FLEET FACTORS CORP., that the mere capacity of the lender to
influence a borrower's decisions regarding disposal of hazardous substances was
sufficient participation in the management of the borrower's business to deny
the protection of the secured creditor exclusion to the lender, regardless of
whether the lender actually exercised such influence. Other judicial decisions
did not interpret the secured creditor exclusion as narrowly as did the FLEET
FACTORS decision.
 
    This ambiguity appears to have been resolved by the enactment of the Asset
Conservation, Lender Liability and Deposit Insurance Protection Act of 1996 (the
"Asset Conservation Act"), which took effect on September 30, 1996. The Asset
Conservation Act provides that in order to be deemed to have participated in the
management of a mortgaged property, a lender must actually participate in the
operational affairs of the property or of the borrower. The Asset Conservation
Act also provides that participation in the management of the property does not
include "merely having the capacity to influence, or unexercised right to
control" operations. Rather, a lender will lose the protection of the secured
creditor exclusion only if it exercises decision making control over the
borrower's environmental compliance and hazardous substance handling and
disposal practices, or assumes day-to-day management of all operational
functions of the mortgaged property. It should also be noted, however, that
liability for costs associated with the investigation and clean-up of
environmental contamination may also be governed by state law, which may not
provide any specific protections to lenders, or, alternatively, may not impose
liability on lenders at all.
 
    CERCLA does not apply to petroleum products, and the secured creditor
exclusion, therefore, does not apply to liability for clean-up costs associated
with releases of petroleum contamination. Federal regulation of underground
petroleum storage tanks (other than heating oil tanks) is governed by Subtitle I
of the federal Resource Conservation and Recovery Act ("RCRA"). The United
States Environmental Protection Agency ("EPA") has promulgated a lender
liability rule for underground storage tanks regulated by Subtitle I of RCRA.
Under the EPA rule, a holder of a security interest in an underground storage
tank, or real property containing an underground storage tank, is not considered
an operator of the underground storage tank as long as petroleum is not added
to, stored in or dispensed from the tank by the holder of the security interest.
Moreover, amendments to RCRA, enacted in 1996, concurrently with the CERCLA
amendments discussed in the previous paragraph, extend to the holders of
security interests in petroleum underground storage tanks the same protections
accorded to secured creditors under CERCLA. Again, it should be noted, however,
that liability for clean-up of petroleum contamination may be governed by state
law, which may not provide any specific protection for lenders or,
alternatively, may not impose liability on lenders at all.
 
    Except as otherwise specified in the applicable Prospectus Supplement, at
the time the Mortgage Loans were originated, no environmental assessment or a
very limited environment assessment of the Mortgaged Properties will have been
conducted.
 
                              ERISA CONSIDERATIONS
 
    The Employee Retirement Income Security Act of 1974, as amended ("ERISA"),
imposes certain requirements on employee benefit plans and other benefit plans
or arrangements which are subject to ERISA or Section 4975 of the Code ("Plans")
and on those persons who are fiduciaries with respect to Plans or otherwise
responsible for the investment of "plan assets" of Plans ("Plan Assets"). In
accordance with the general fiduciary standards of ERISA, an ERISA Plan
fiduciary should consider whether an investment in the Certificates is permitted
by the documents and instruments governing the Plan, consistent with the Plan's
overall investment policy and appropriate in view of the composition of its
investment portfolio.
 
    Employee benefit plans which are governmental plans (as defined in Section
3(32) of ERISA) and certain church plans (as defined in Section 3(33) of ERISA)
are not subject to the requirements of ERISA or Section 4975 of the Code.
Accordingly, assets of such plans may be invested in the Certificates subject to
the provisions of applicable state law and, in the case of any such plan which
is qualified under Section 401(a) of the Code, the restrictions imposed under
Section 503 of the Code.
 
    In addition to imposing general fiduciary standards, ERISA prohibits a broad
range of transactions involving Plan Assets and certain persons ("Parties in
Interest") who have certain specified relationships to the Plan under Section
406 of ERISA, and taxes any such transaction under
 
                                       64
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Section 4975 of the Code, unless an exemption applies. If the assets of a
Mortgage Pool are treated for purposes of ERISA and Section 4975 of the Code as
Plans or other entities holding Plan Assets with respect to Plans, collective
investment funds, insurance company general or separate accounts (collectively,
"Plan Asset Investors") that purchase or hold Certificates of the applicable
Series, an investment in Certificates by any such Plan might constitute or give
rise to a prohibited transaction under ERISA or Section 4975 of the Code, unless
a statutory or administrative exemption applies. Violation of the prohibited
transaction rules could result in the imposition of excise taxes and/or other
penalties under ERISA and/or Section 4975 of the Code.
 
PLAN ASSETS REGULATION
 
    The United States Department of Labor ("DOL") has issued a final regulation
(the "Regulation") under which the assets of an entity in which a Plan Asset
Investor makes an equity investment will be treated as Plan Assets in certain
circumstances. Unless the Regulation provides an exemption from this "plan
asset" treatment, and if an exemption is not otherwise available under ERISA, an
undivided portion of the assets of a Mortgage Pool will be treated, for purposes
of applying the fiduciary standards and prohibited transaction rules of ERISA
and Section 4975 of the Code, as Plan Assets with respect to each Plan which
becomes a Certificateholder of the applicable Series.
 
    The Regulation provides an exemption from "plan asset" treatment for
securities issued by an entity if, immediately after the most recent acquisition
of any equity interest in the entity, less than 25% of the value of each class
of equity interests in the entity, excluding interests held by a person who has
discretionary authority or control with respect to the assets of the entity (or
any affiliate of such a person), is held by "benefit plan investors" (I.E.,
Plans, governmental, foreign and other employee benefit plans not subject to
ERISA and entities holding Plan Assets). Because the availability of this
exemption with respect to any Mortgage Pool depends upon the identity of the
Certificateholders of the applicable Series at any time, there can be no
assurance as to whether any Series or Class of Certificates will qualify for
this exemption.
 
PROHIBITED TRANSACTION CLASS EXEMPTION 83-1
 
    Prohibited Transaction Class Exemption 83-1 (Class Exemption for Certain
Transactions Involving Mortgage Pool Investment Trusts) ("PTCE 83-1") permits,
subject to certain conditions, certain transactions involving the creation,
maintenance and termination of certain residential mortgage pools and the
acquisition and holding of certain residential mortgage pool pass-through
certificates by Plan Asset Investors, regardless of whether (a) the mortgage
pool is exempt from "plan asset" treatment or (b) the transactions would
otherwise be prohibited under ERISA or Section 4975 of the Code. If the general
conditions (described below) of PTCE 83-1 are satisfied, an investment by a Plan
in Certificates (1) will be exempt from the prohibitions of Section 406(a) of
ERISA (relating generally to Plan Asset transactions involving Parties in
Interest who are not fiduciaries) if the Certificates are purchased at no more
than fair market value, and (2) will be exempt from the prohibitions of Sections
406(b)(1) and (2) of ERISA (relating generally to Plan Asset transactions with
fiduciaries) if, in addition, the purchase is approved by an independent
fiduciary, the Plan Asset Investor pays no more for the Certificates than would
be paid in an arm's length transaction with an unrelated party, no sales
commission is paid to the Company as Mortgage Pool sponsor, the Plan Asset
Investor does not purchase more than 25% of the Certificates of the applicable
Series, and at least 50% of the Certificates of that Series is purchased by
persons independent of the Company, the Trustee and the Insurer, as applicable.
 
    PTCE 83-1 sets forth three general conditions which must be satisfied for
any transaction to be eligible for exemption: (1) the existence of a pool
trustee who is not an affiliate of the pool sponsor; (2) the maintenance of a
system of insurance or other protection for the pooled mortgage loans and
property securing such loans, and for indemnifying certificateholders against
reductions in pass-through payments due to property damage or defaults in loan
payments; and (3) a limitation on the amount of the payment retained by the pool
sponsor, together with other funds inuring to its benefit, to not more than
adequate consideration for selling the mortgage loans plus reasonable
compensation for services provided by the pool sponsor to the mortgage pool.
 
    Unless otherwise specified in the applicable Prospectus Supplement, the
Trustee for each Series will be unaffiliated with the Company, and the first
general condition of PTCE 83-1 will be
 
                                       65
<PAGE>
satisfied for each such Series. With respect to the second general condition of
PTCE 83-1, the Company intends to use its best efforts to establish for each
Series of Certificates an insurance, indemnification, subordination or other
method of credit support which will adequately protect the Mortgage Pools and
indemnify Certificateholders of the applicable Series against pass-through
payment reductions resulting from property damage or defaults in loan payments.
See "Description of Credit Enhancements". The amount, method and description of
the credit support method applicable to a Series of Certificates will be set
forth in the related Prospectus Supplement. With respect to the third general
condition of PTCE 83-1, the Company intends to use its best efforts to establish
for each Series a compensation method which will produce for the Company total
compensation which will not exceed adequate consideration for forming the
Mortgage Pool, selling the Certificates and serving as Master Servicer of the
Mortgage Pool. However, the Company does not guarantee that its credit support
and compensation methods will be sufficient to meet the second and third general
conditions (described above) with respect to any Series.
 
    As indicated in the two preceding paragraphs, the continued maintenance of a
system of insurance or other protection for the pooled mortgage loans and
property securing such loans, and for indemnifying certificateholders against
reductions in pass-through payments due to property damage or defaults in loan
payments, is one of the three general conditions that must be satisfied for any
transaction involving a Mortgage Pool to remain eligible for exemption by PTCE
83-1 from the prohibited transaction rules of ERISA and Section 4975 of the
Code. If the credit support method established for any Series is cancelled or
terminated, or if the credit support is reduced to such an extent that its
coverage amount is less than the greater of (a) 1% of the aggregate unpaid
principal balance of the Mortgage Loans or (b) the unpaid principal balance of
the largest single Mortgage Loan (see "Description of Credit Enhancements"),
then the Mortgage Pool relating to that Series may no longer satisfy the general
conditions of PTCE 83-1. In such event, the exemption from the prohibited
transaction rules afforded by PTCE 83-1 may no longer be available.
 
    One or more Series of Certificates may be offered to Plan Asset Investors
through a forward delivery commitment contract, which is a contract for the
purchase of Certificates to be delivered at an agreed future settlement date.
PTCE 83-1 permits the sale of Certificates to a Plan Asset Investor pursuant to
such a contract, provided that the forward delivery commitment is expressly
approved by a fiduciary who is independent of the Company, the Trustee, the
Insurer (if any) and their respective affiliates, and who has the authority to
manage and control the Plan Assets being committed for investment in the
Certificates.
 
    PTCE 83-1 will not provide exemptive relief with respect to a Series of
Certificates evidencing interests in Trust Funds that include Cooperative Loans.
If a Series of Certificates is subdivided into two or more Classes which are
entitled to disproportionate allocations of the principal and interest payments
on the Mortgage Loans, the availability of the exemption afforded by PTCE 83-1
may be adversely affected, as described in the applicable Prospectus Supplement.
Moreover, if any Class of Certificates is entitled to pass-through payments of
principal (but no or only nominal interest) or interest (but no or only nominal
principal), PTCE 83-1 will not exempt holders of that Class of Certificates from
the prohibited transaction rules of ERISA and Section 4975 of the Code.
 
OTHER EXEMPTIONS
 
    If for any reason PTCE 83-1 does not provide an exemption for a particular
Certificateholder who is a Plan Asset Investor, one of five other prohibited
transaction class exemptions issued by the DOL might apply, I.E., PTCE 96-23
(Class Exemption for Plan Asset Transactions Determined by In-House Asset
Managers), PTCE 95-60 (Class Exemption for Certain Transactions Involving
Insurance Company General Accounts), PTCE 91-38 (Class Exemption for Certain
Transactions Involving Bank Collective Investment Funds), PTCE 90-1 (Class
Exemption for Certain Transactions Involving Insurance Company Pooled Separate
Accounts) or PTCE 84-14 (Class Exemption for Plan Asset Transactions Determined
by Independent Qualified Professional Asset Managers). There can be no assurance
that any of these class exemptions will apply with respect to any particular
Plan Asset Investor or, even if it were to apply, that the exemption would apply
to all transactions involving the Mortgage Pool. In addition, the underwriter
with respect to a particular Series may be the recipient of a final prohibited
transaction exemption which, if so specified in the applicable Prospectus
 
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<PAGE>
Supplement, may accord a Plan Asset Investor protection from violations of the
prohibited transaction rules of ERISA and Section 4975 of the Code if the Plan
Asset Investor satisfies the conditions described in the applicable Prospectus
Supplement.
 
GENERAL CONSIDERATIONS
 
    In summary, the Company, the Trustee, the Servicer, any insurer, the obligor
under any other credit enhancement instrument, any Seller/Servicer, any
underwriter for any Series of Certificates, as applicable, and their respective
affiliates might be considered or might become Parties in Interest with respect
to a Plan Asset Investor. In that event, the acquisition or holding of
Certificates of the applicable Series or Class by or on behalf of such Plan
Asset Investor might be viewed as giving rise to a prohibited transaction under
ERISA and Section 4975 of the Code, unless PTCE 83-1 or another exemption is
available. Accordingly, before a Plan Asset Investor makes the investment
decision to purchase, to commit to purchase or to hold Certificates of any
Series or Class, the Plan Asset Investor should determine (a) whether the second
and third general conditions and the specific conditions (described briefly
above) of PTCE 83-1 have been satisfied; (b) whether adequate protection is
accorded by any prohibited transaction exemption issued to the underwriter with
respect to the applicable Series, as described in the applicable Prospectus
Supplement; (c) whether any other prohibited transaction class exemption (if
required) is available under ERISA and Section 4975 of the Code; or (d) whether
an exemption from "plan asset" treatment is available to the applicable Mortgage
Pool. The Plan Asset Investor should also consult the ERISA discussion, if any,
in the applicable Prospectus Supplement for further information regarding the
application of ERISA and Section 4975 of the Code to any Series or Class of
Certificates.
 
    ANY PLAN ASSET INVESTOR THAT PROPOSES TO USE PLAN ASSETS TO PURCHASE
CERTIFICATES SHOULD CONSULT WITH ITS OWN COUNSEL WITH RESPECT TO THE POTENTIAL
CONSEQUENCES UNDER ERISA AND THE CODE OF THE ACQUISITION AND OWNERSHIP OF
CERTIFICATES.
 
                    CERTAIN FEDERAL INCOME TAX CONSEQUENCES
 
    The following is a general discussion of the anticipated material federal
income tax consequences of the purchase, ownership and disposition of the
Certificates offered hereunder. It does not purport to discuss all federal
income tax consequences that may be applicable to particular categories of
investors, some of which may be subject to special rules and does not address
the tax consequences of persons holding Certificates as part of a hedge or
hedging transaction. Further, the authorities on which this discussion is based
are subject to change or differing interpretations, which changes or differing
interpretations could apply retroactively. This discussion does not address the
state or local tax consequences of the purchase, ownership and disposition of
such Certificates. Investors should consult their own tax advisors in
determining the federal, state, local or other tax consequences to them of the
purchase, ownership and disposition of the Certificates offered hereunder.
 
    The following discussion addresses certificates ("REMIC Certificates")
representing interests in a Mortgage Pool ("REMIC Mortgage Pool") as to which
the Company, in the case where the Company will be a Master Servicer for a
Series or in the case where there will be no Master Servicer for a Series, or
the Servicing Entity, in the case where the Servicing Entity is the only Master
Servicer for a Series, will cause to elect treatment as a real estate mortgage
investment conduit ("REMIC") under Sections 860A through 860G ("REMIC
Provisions") of the Code. Under the REMIC Provisions, REMICs may issue "regular"
interests and must issue one and only one class of "residual" interests. A REMIC
Certificate representing a regular interest in a REMIC Mortgage Pool will be
referred to as a "REMIC Regular Certificate" and a REMIC Certificate
representing a residual interest in a REMIC Mortgage Pool will be referred to as
a "REMIC Residual Certificate".
 
    The following discussion is based in part upon the rules governing original
issue discount that are set forth in Code Sections 1271 through 1273 and 1275
and in Treasury regulations issued under the original issue discount provisions
of the Code (the "OID Regulations"), and the Treasury regulations issued under
the provisions of the Code relating to REMICs (the "REMIC Regulations"). The OID
Regulations generally are effective with respect to debt instruments issued on
or after April 4, 1994.
 
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  A. CLASSIFICATION OF REMIC TRUST FUNDS
 
    With respect to each Series of REMIC Certificates, Orrick, Herrington &
Sutcliffe LLP, special counsel to the Company, will deliver their opinion
generally to the effect that, assuming (i) a REMIC election is made timely in
the required form, (ii) each Master Servicer or Servicing Entity, as applicable,
complies with all provisions of the related Pooling Agreement, (iii) certain
representations set forth in the Pooling Agreement are true, and (iv) there is
continued compliance with applicable provisions of the Code, as it may be
amended from time to time, and applicable Treasury regulations issued
thereunder, the related REMIC Mortgage Pool will qualify as a REMIC and the
classes of interests offered will be considered to be regular interests or
residual interests in that REMIC Mortgage Pool within the meaning of the REMIC
Provisions.
 
    Holders of REMIC Certificates should be aware that, if an entity electing to
be treated as a REMIC fails to comply with one or more of the ongoing
requirements of the Code for REMIC status during any taxable year, the Code
provides that the entity will not be treated as a REMIC for such year and
thereafter. In such event, an entity electing to be treated as a REMIC may be
taxable as a separate corporation under Treasury regulations, and the related
REMIC Certificates may not be accorded the status described below under the
heading "Characterization of Investments in REMIC Certificates". In the case of
an inadvertent termination of REMIC status, the Code provides the Treasury
Department with authority to issue regulations providing relief. Any such
relief, however, may be accompanied by sanctions, such as the imposition of a
corporate tax on all or a portion of the REMIC's income for the period of time
in which the requirements for REMIC status are not satisfied.
 
  B. CHARACTERIZATION OF INVESTMENTS IN REMIC CERTIFICATES
 
    In general, REMIC Certificates are not treated for federal income tax
purposes as ownership interests in the assets of a REMIC Mortgage Pool. However,
(i) REMIC Certificates held by a domestic building and loan association will
constitute a "regular or residual interest in a REMIC" within the meaning of
Code Section 7701(a)(19)(C)(xi) in the same proportion that the Assets would be
treated as "loans . . . secured by an interest in real property" within the
meaning of Code Section 7701(a)(19)(C)(v) or as other assets described in Code
Section 7701(a)(19)(C); and (ii) REMIC Certificates held by a real estate
investment trust will constitute "real estate assets" within the meaning of Code
Section 856(c)(4)(A), and interest on the REMIC Certificates will be considered
"interest on obligations secured by mortgages on real property or on interests
in real property" within the meaning of Code Section 856(c)(3)(B) in the same
proportion that, for both purposes, the Assets would be treated as "interests in
real property" as defined in Code Section 856(c)(5)(C) (or, as provided in the
Committee Report, as "real estate assets" as defined in Code Section
856(c)(5)(B)). Moreover, if 95% or more of the Assets qualify for any of the
foregoing treatments, the REMIC Certificates will qualify for the corresponding
status in their entirety. Investors should be aware that the investment of
amounts in any reserve account in assets not so qualifying would, and holding
property acquired by foreclosure pending sale might, reduce the amount of the
REMIC Certificate that would qualify for the foregoing treatment. The REMIC
Regulations provide that payments on Mortgage Loans held pending distribution
are considered part of the Mortgage Loans for purposes of Code Section
856(c)(4)(A); it is unclear whether such collected payments would be so treated
for purposes of Code Section 7701(a)(19)(c)(v), but there appears to be no
reason why analogous treatment should not be given to such collected payments
under that provision. The determination as to the percentage of the REMIC's
assets that will constitute assets described in the foregoing sections of the
Code will be made with respect to each calendar quarter based on the average
adjusted basis of each category of the assets held by the REMIC during such
calendar quarter. The REMIC will report those determinations to
Certificateholders in the manner and at the times required by applicable
Treasury regulations. The applicable Prospectus Supplement or the related
Current Report on Form 8-K for each Series of REMIC Certificates will describe
the Assets as of the Cut-Off Date. REMIC Certificates held by certain financial
institutions will constitute "evidence of indebtedness" within the meaning of
Code Section 582(c)(1); in addition, REMIC Regular Certificates acquired by a
REMIC in accordance with the requirements of Section 860G(a)(3)(C) or Section
860G(a)(4)(B) of the Code will be treated as "qualified mortgages" for purposes
of Code Section 860D(a)(4).
 
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  C. TAXATION OF OWNERS OF REMIC REGULAR CERTIFICATES
 
    Except as otherwise stated in this discussion, the REMIC Regular
Certificates will be treated for federal income tax purposes as debt instruments
issued by the REMIC Mortgage Pool and not as ownership interests in the REMIC
Mortgage Pool or its Assets. In general, interest, original issue discount and
market discount paid or accrued on a REMIC Regular Certificate will be treated
as ordinary income to the holder of such REMIC Regular Certificate.
Distributions in reduction of the stated redemption price at maturity of the
REMIC Regular Certificate will be treated as a return of capital to the extent
of such holder's basis in such REMIC Regular Certificate. Holders of REMIC
Regular Certificates that otherwise report income under a cash method of
accounting will be required to report income with respect to REMIC Regular
Certificates under an accrual method.
 
   1. ORIGINAL ISSUE DISCOUNT
 
    Certain REMIC Regular Certificates may be issued with "original issue
discount" within the meaning of Code Section 1273(a). Any holders of REMIC
Regular Certificates issued with original issue discount generally will be
required to include original issue discount in income as it accrues, in
accordance with a constant interest method that takes into account the
compounding of interest, in advance of the receipt of the cash attributable to
such income. The Company will report annually (or more often if required) to the
Internal Revenue Service ("IRS") and to Certificateholders such information with
respect to the original issue discount accruing on the REMIC Regular
Certificates as may be required under Code Section 6049 and the regulations
thereunder. See "--Reporting and Other Administrative Matters of REMICS" below.
 
    Rules governing original issue discount are set forth in Code Sections 1271
through 1273 and 1275 and, to some extent, in the OID Regulations. Code Section
1272(a)(6) provides special original issue discount rules applicable to REMIC
Regular Certificates. Regulations have not yet been proposed or adopted under
Section 1272(a)(6) of the Code. Further, application of the OID Regulations to
the REMIC Regular Certificates remains unclear in some respects because the OID
Regulations generally purport not to apply to instruments to which section
1272(a)(6) applies such as REMIC Regular Certificates, and separately because
they either do not address, or are subject to varying interpretations with
regard to, several relevant issues.
 
    Code Section 1272(a)(6) requires that a mortgage prepayment assumption
("Prepayment Assumption") be used in computing the accrual of original issue
discount on REMIC Regular Certificates and for certain other federal income tax
purposes. The Prepayment Assumption is to be determined in the manner prescribed
in Treasury regulations. To date, no such regulations have been promulgated. The
Committee Report indicates that the regulations will provide that the Prepayment
Assumption, if any, used with respect to a particular transaction must be the
same as that used by the parties in pricing the transaction. Unless otherwise
specified in the applicable Prospectus Supplement, the Company will use a
percentage of the Basic Prepayment Assumption (or such other Prepayment
Assumption as may be specified in the applicable Prospectus Supplement) in
reporting original issue discount that is consistent with this standard.
However, the Company does not make any representation that the Mortgage Loans
will in fact prepay at that percentage of the Basic Prepayment Assumption or at
any other rate. Each investor must make its own decision as to the
appropriate prepayment assumption to be used in deciding whether or not to
purchase any of the REMIC Regular Certificates. The Prospectus Supplement with
respect to a Series of REMIC Certificates will disclose the percentage of the
Basic Prepayment Assumption (or such other Prepayment Assumption as may be
specified therein) to be used in reporting original issue discount, if any, and
for certain other federal income tax purposes.
 
    The total amount of original issue discount on a REMIC Regular Certificate
is the excess of the "stated redemption price at maturity" of the REMIC Regular
Certificate over its "issue price". Except as discussed in the following two
paragraphs, in general, the issue price of a particular Class of REMIC Regular
Certificates offered hereunder will be the price at which a substantial amount
of REMIC Regular Certificates of that Class are first sold to the public
(excluding bond houses and brokers).
 
    If a REMIC Regular Certificate is sold with accrued interest that relates to
a period prior to the issue date of such REMIC Regular Certificate, the amount
paid for the accrued interest will be treated
 
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instead as increasing the issue price of the REMIC Regular Certificate. In
addition, that portion of the first interest payment in excess of interest
accrued from the Closing Date to the first Distribution Date will be treated for
federal income tax reporting purposes as includible in the stated redemption
price at maturity of the REMIC Regular Certificate, and as excludible from
income when received as a payment of interest on the first Distribution Date.
The OID Regulations suggest that some or all of this pre-issuance accrued
interest "may" be treated as a separate asset (and hence not includible in a
REMIC Regular Certificate's issue price or stated redemption price at maturity),
whose cost is recovered entirely out of interest paid on the first Distribution
Date. It is unclear how such treatment would be elected under the OID
Regulations and whether an election could be made unilaterally by a
Certificateholder.
 
    The stated redemption price at maturity of a REMIC Regular Certificate is
equal to the total of all payments to be made on such Certificate other than
"qualified stated interest." Under the OID Regulations, "qualified stated
interest" is interest that is unconditionally payable at least annually during
the entire term of the Certificate at either (i) a single fixed rate that
appropriately takes into account the length of the interval between payments or
(ii) the current values of a single "qualified floating rate" or "objective
rate" (each, a "Single Variable Rate"). A "current value" is the value of a
variable rate on any day that is no earlier than three months prior to the first
day on which that value is in effect and no later than one year following that
day. A "qualified floating rate" is a rate whose variations can reasonably be
expected to measure contemporaneous variations in the cost of newly borrowed
funds in the currency in which the Certificate is denominated. Such a rate
remains qualified even though it is multiplied by a fixed, positive multiple not
exceeding 1.35, increased or decreased by a fixed rate, or both. Certain
combinations of rates constitute a single qualified floating rate, including (i)
interest stated at a fixed rate for an initial period of less than one year
followed by a qualified floating rate if the value of the floating rate at the
closing date is intended to approximate the fixed rate, and (ii) two or more
qualified floating rates that can be expected to have approximately the same
values throughout the term of the Certificate. A combination of such rates is
conclusively presumed to be a single floating rate if the values of all rates on
the closing date are within 0.25% of each other. A variable rate that is subject
to an interest rate cap, floor, "governor" or similar restriction on rate
adjustment may be a qualified floating rate only if such restriction is fixed
throughout the term of the instrument, or is not reasonably expected as of the
closing date to cause the yield on the debt instrument to differ significantly
from the expected yield absent the restriction. An "objective rate" is a rate
(other than a qualified floating rate) determined using a single formula fixed
for the life of the Certificate, which is based on (i) one or more qualified
floating rates (including a multiple or inverse of a qualified floating rate),
(ii) one or more rates each of which would be a qualified floating rate for a
debt instrument denominated in a foreign currency, (iii) the yield or changes in
price of one or more items of "actively traded" personal property, (iv) a
combination of rates described in (i), (ii) and (iii), or (v) a rate designated
by the IRS. However, a variable rate is not an objective rate if it is
reasonably expected that the average value of the rate during the first half of
the Certificate's term will differ significantly from the average value of such
rate during the final half of its term. A combination of interest stated at a
fixed rate for an initial period of less than one year followed by an objective
rate is treated as a single objective rate if the value of the objective rate at
the closing date is intended to approximate the fixed rate; such a combination
of rates is conclusively presumed to be a single objective rate if the objective
rate on the closing date does not differ from the fixed rate by more than 0.25%.
The qualified stated interest payable with respect to certain variable rate debt
instruments not bearing stated interest at a Single Variable Rate generally is
determined under the OID Regulations by converting such instruments into fixed
rate debt instruments. Instruments qualifying for such treatment generally
include those providing for stated interest at (i) more than one qualified
floating rates, or at (ii) a single fixed rate and (a) one or more qualified
floating rates or (b) a single "qualified inverse floating rate" (each, a
"Multiple Variable Rate"). A qualified inverse floating rate is an objective
rate equal to a fixed rate reduced by a qualified floating rate, the variations
in which can reasonably be expected to inversely reflect contemporaneous
variations in the cost of newly borrowed funds (disregarding permissible rate
caps, floors, governors and similar restrictions such as are described above).
Under these rules, some of the payments of interest on a Certificate bearing a
fixed rate of interest for an initial period followed by a qualified floating
rate of interest in subsequent periods could be treated as included in the
stated redemption price at maturity if the initial fixed rate were to differ
sufficiently from the rate that would have been set using the formula applicable
to
 
                                       70
<PAGE>
subsequent periods. See "--Variable Rate Certificates". REMIC Regular
Certificates offered hereby other than Certificates providing for variable rates
of interest or for the accretion of interest are not anticipated to have stated
interest other than "qualified stated interest", but if any such REMIC Regular
Certificates are so offered, appropriate disclosures will be made in the
Prospectus Supplement. Some or all of the payments on REMIC Regular Certificates
providing for the accretion of interest will be included in the stated
redemption price at maturity of such Certificates.
 
    Under a DE MINIMIS rule in the Code, as interpreted in the OID Regulations,
original issue discount on a REMIC Regular Certificate will be considered to be
zero if such original issue discount is less than 0.25% of the stated redemption
price at maturity of the REMIC Regular Certificate multiplied by the weighted
average life of the REMIC Regular Certificate. For this purpose, the weighted
average life of the REMIC Regular Certificate is computed as the sum of the
amounts determined by multiplying the amount of each payment under the
instrument (other than a payment of qualified stated interest) by a fraction,
whose numerator is the number of complete years from the issue date until such
payment is made, and whose denominator is the stated redemption price at
maturity of such REMIC Regular Certificate. The IRS may be anticipated to take
the position that this rule should be applied taking into account the Prepayment
Assumption and the effect of any anticipated investment income. Under the OID
Regulations, REMIC Regular Certificates bearing only qualified stated interest
except for any "teaser" rate, interest holiday or similar provision would be
treated as subject to the DE MINIMIS rule if the greater of the deferred or
foregone interest or the other original issue discount is less than such DE
MINIMIS amount.
 
    The OID Regulations generally would treat DE MINIMIS original issue discount
as includible in income as each principal payment is made, based on the product
of the total amount of such DE MINIMIS original issue discount and a fraction,
whose numerator is the amount of such principal payment and whose denominator is
the stated principal amount of the REMIC Regular Certificate. The OID
Regulations also would permit a Certificateholder to elect to accrue DE MINIMIS
original issue discount into income currently based on a constant yield method.
See "Taxation of Owners of REMIC Regular Certificates--Market Discount and
Premium".
 
    Each holder of a REMIC Regular Certificate must include in gross income the
sum of the "daily portions" of original issue discount on its REMIC Regular
Certificate for each day during its taxable year on which it held such REMIC
Regular Certificate. For this purpose, in the case of an original holder of a
REMIC Regular Certificate, the daily portions of original issue discount will be
determined as follows. A calculation will first be made of the portion of the
original issue discount that accrued during each accrual period, that is, unless
otherwise stated in the applicable Prospectus Supplement, each period that
begins or ends on a date that corresponds to a Distribution Date on the REMIC
Regular Certificate and begins on the first day following the immediately
preceding accrual period (beginning on the Closing Date in the case of the first
such period). For any accrual period such portion will equal the excess, if any,
of (i) the sum of (A) the present value of all of the distributions remaining to
be made on the REMIC Regular Certificate, if any, as of the end of the accrual
period and (B) the distribution made on such REMIC Regular Certificate during
the accrual period of amounts included in the stated redemption price at
maturity, over (ii) the adjusted issue price of such REMIC Regular Certificate
at the beginning of the accrual period. The present value of the remaining
payments referred to in the preceding sentence will be calculated based on (i)
the yield to maturity of the REMIC Regular Certificate, calculated as of the
settlement date, giving effect to the Prepayment Assumption, (ii) events
(including actual prepayments) that have occurred prior to the end of the
accrual period, and (iii) the Prepayment Assumption. The adjusted issue price of
a REMIC Regular Certificate at the beginning of any accrual period will equal
the issue price of such Certificate, increased by the aggregate amount of
original issue discount with respect to such REMIC Regular Certificate that
accrued in prior accrual periods, and reduced by the amount of any distributions
made on such REMIC Regular Certificate in prior accrual periods of amounts
included in the stated redemption price at maturity. The original issue discount
accruing during any accrual period will be allocated ratably to each day during
the period to determine the daily portion of original issue discount for each
day. With respect to an accrual period between the settlement date and the first
Distribution Date on the REMIC Regular Certificate (notwithstanding that no
distribution is scheduled to be made on such date) that is shorter than a full
accrual period, the OID Regulations permit the daily portions of original issue
discount to be determined according to any reasonable method.
 
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<PAGE>
    A subsequent purchaser of a REMIC Regular Certificate that purchases such
REMIC Regular Certificate at a cost (not including payment for accrued qualified
stated interest) less than its remaining stated redemption price at maturity
will also be required to include in gross income, for each day on which it holds
such REMIC Regular Certificate, the daily portions of original issue discount
with respect to such REMIC Regular Certificate, but reduced, if such cost
exceeds the "adjusted issue price", by an amount equal to the product of (i)
such daily portions and (ii) a constant fraction, whose numerator is such excess
and whose denominator is the sum of the daily portions of original issue
discount on such REMIC Regular Certificate for all days on or after the day of
purchase. The adjusted issue price of a REMIC Regular Certificate on any given
day is equal to the sum of the adjusted issue price (or, in the case of the
first accrual period, the issue price) of the REMIC Regular Certificate at the
beginning of the accrual period during which such day occurs and the daily
portions of original issue discount for all days during such accrual period
prior to such day, reduced by the aggregate amount of distributions previously
made other than distributions of qualified stated interest.
 
    VARIABLE RATE CERTIFICATES.  Purchasers of REMIC Regular Certificates
bearing a variable rate of interest should be aware that there is uncertainty
concerning the application of Section 1272(a)(6) of the Code and the OID
Regulations to such Certificates. In the absence of other authority, the Company
intends to be guided by the provisions of the OID Regulations governing variable
rate debt instruments in adapting the provisions of Section 1272(a)(6) of the
Code to such Certificates for the purpose of preparing reports furnished to
Certificateholders. The effect of the application of such provisions generally
will be to cause Certificateholders holding Certificates bearing interest at a
Single Variable Rate to take into account for each period an amount
corresponding approximately to the sum of (i) the qualified stated interest,
accruing on the outstanding face amount of the REMIC Regular Certificate as the
stated interest rate for that Certificate varies from time to time and (ii) the
amount of original issue discount that would have been attributable to that
period on the basis of a constant yield to maturity for a bond issued at the
same time and issue price as the REMIC Regular Certificate, having the same face
amount and schedule of payments of principal as such Certificate, subject to the
same Prepayment Assumption, and bearing interest at a fixed rate equal to the
value of the applicable qualified floating rate or qualified inverse floating
rate in the case of a Certificate providing for either such rate, or equal to
the fixed rate that reflects the reasonably expected yield on the Certificate in
the case of a Certificate providing for an objective rate other than an inverse
floating rate, in each case as of the issue date. Certificateholders holding
REMIC Regular Certificates bearing interest at a Multiple Variable Rate
generally will take into account interest and original issue discount under a
similar methodology, except that the amounts of qualified stated interest and
original issue discount attributable to such a Certificate first will be
determined for an equivalent fixed rate debt instrument, the assumed fixed rates
for which are (a) for each qualified floating rate, the value of each such rate
as of the closing date (with appropriate adjustment for any differences in
intervals between interest adjustment dates), (b) for a qualified inverse
floating rate, the value of the rate as of the closing date, (c) for any other
objective rate, the fixed rate that reflects the yield that is reasonably
expected for the Certificate, and (d) for an actual fixed rate, such
hypothetical fixed rate as would result under (a) or (b) if the actual fixed
rate were replaced by a hypothetical qualified floating rate or qualified
inverse floating rate such that the fair market value of the Certificate as of
the issue date would be approximately the same as that of an otherwise identical
debt instrument providing for the hypothetical variable rate rather than the
actual fixed rate. If the interest paid or accrued with respect to a Multiple
Variable Rate Certificate during an accrual period differs from the assumed
fixed interest rate, such difference will be an adjustment (to interest or
original issue discount, as applicable) to the Certificateholder's taxable
income for the taxable period or periods to which such difference relates.
Additionally, purchasers of such Certificates should be aware that the
provisions of the OID Regulations applicable to variable rate debt instruments
have been limited and may not apply to some REMIC Regular Certificates having
variable rates. If such a Certificate is not governed by the provisions of the
OID Regulations applicable to variable rate debt instruments, it may be subject
to provisions of proposed Treasury Regulations applicable to instruments having
contingent payments. The application of those provisions to instruments such as
variable rate REMIC Regular Certificates is subject to differing
interpretations. Prospective purchasers of variable rate REMIC Regular
Certificates are advised to consult their tax advisors concerning the tax
treatment of such Certificates.
 
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<PAGE>
   2. MARKET DISCOUNT AND PREMIUM
 
    A Certificateholder that purchases a REMIC Regular Certificate at a market
discount, that is, at a purchase price less than the adjusted issue price (as
defined under "--Taxation of Owners of REMIC Regular Certificates--Original
Issue Discount") of such REMIC Regular Certificate generally will recognize
market discount upon receipt of each distribution of principal. In particular,
such a holder will generally be required to allocate each payment of principal
on a REMIC Regular Certificate first to accrued market discount, and to
recognize ordinary income to the extent such principal payment does not exceed
the aggregate amount of accrued market discount on such REMIC Regular
Certificate not previously included in income. Such market discount must be
included in income in addition to any original issue discount includible in
income with respect to such REMIC Regular Certificate.
 
    A Certificateholder may elect to include market discount in income currently
as it accrues, rather than including it on a deferred basis in accordance with
the foregoing. If made, such election will apply to all market discount bonds
acquired by such Certificateholder on or after the first day of the first
taxable year to which such election applies. In addition, the OID Regulations
permit a Certificateholder to elect to accrue all interest, discount (including
DE MINIMIS market or original issue discount) and premium in income as interest,
based on a constant yield method. If such an election were made for a REMIC
Regular Certificate with market discount, the Certificateholder would be deemed
to have made an election to currently include market discount in income with
respect to all other debt instruments having market discount that such
Certificateholder acquires during the year of the election or thereafter.
Similarly, a Certificateholder that makes this election for a Certificate that
is acquired at a premium is deemed to have made an election to amortize bond
premium, as described below, with respect to all debt instruments having
amortizable bond premium that such Certificateholder owns or acquires. The
election to accrue interest, discount and premium on a constant yield method
with respect to a Certificate is irrevocable.
 
    Under a statutory DE MINIMIS exception, market discount with respect to a
REMIC Regular Certificate will be considered to be zero for purposes of Code
Sections 1276 through 1278 if such market discount is less than 0.25% of the
stated redemption price at maturity of such REMIC Regular Certificate multiplied
by the number of complete years to maturity remaining after the date of its
purchase. In interpreting a similar DE MINIMIS rule with respect to original
issue discount on obligations payable in installments, the OID Regulations refer
to the weighted average maturity of obligations, and it is likely that the same
rule will be applied in determining whether market discount is DE MINIMIS. It
appears that DE MINIMIS market discount on a REMIC Regular Certificate would be
treated in a manner similar to original issue discount of a DE MINIMIS amount.
See "Taxation of Holders of REMIC Regular Certificates--Original Issue
Discount". Such treatment would result in discount being included in income at a
slower rate than discount would be required to be included using the method
described above. However, Treasury regulations implementing the market discount
DE MINIMIS exception have not been issued in proposed or temporary form, and the
precise treatment of DE MINIMIS market discount on obligations payable in more
than one installment therefore remains uncertain.
 
    The 1986 Act grants authority to the Treasury Department to issue
regulations providing for the method for accruing market discount of more than a
DE MINIMIS amount on debt instruments, the principal of which is payable in more
than one installment. Until such time as regulations are issued by the Treasury
Department, certain rules described in the Committee Report will apply. Under
those rules, the holder of a bond purchased with more than DE MINIMIS market
discount may elect to accrue such market discount either on the basis of a
constant yield method or on the basis of the appropriate proportionate method
described below. Under the proportionate method for obligations issued with
original issue discount, the amount of market discount that accrues during a
period is equal to the product of (i) the total remaining market discount,
multiplied by (ii) a fraction, the numerator of which is the original issue
discount accruing during the period and the denominator of which is the total
remaining original issue discount at the beginning of the period. Under the
proportionate method for obligations issued without original issue discount, the
amount of market discount that accrues during a period is equal to the product
of (i) the total remaining market discount, multiplied by (ii) a fraction, the
numerator of which is the amount of stated interest paid during the accrual
period and the denominator of which is the total amount of stated interest
remaining to be paid at the
 
                                       73
<PAGE>
beginning of the period. The Prepayment Assumption, if any, used in calculating
the accrual of original issue discount is to be used in calculating the accrual
of market discount under any of the above methods. Because the regulations
referred to in this paragraph have not been issued, it is not possible to
predict what effect such regulations might have on the tax treatment of a REMIC
Regular Certificate purchased at a discount in the secondary market.
 
    Further, a purchaser generally will be required to treat a portion of any
gain on sale or exchange of a REMIC Regular Certificate as ordinary income to
the extent of the market discount accrued to the date of disposition under one
of the foregoing methods, less any accrued market discount previously reported
as ordinary income. Such purchaser also may be required to defer a portion of
its interest deductions for the taxable year attributable to any indebtedness
incurred or continued to purchase or carry such REMIC Regular Certificate. Any
such deferred interest expense is, in general, allowed as a deduction not later
than the year in which the related market discount income is recognized. If such
holder elects to include market discount in income currently as it accrues on
all market discount instruments acquired by such holder in that taxable year or
thereafter, the interest deferral rule described above will not apply.
 
    A REMIC Regular Certificate purchased at a cost (not including payment for
accrued qualified stated interest) greater than its remaining stated redemption
price at maturity will be considered to be purchased at a premium. The holder of
such a REMIC Regular Certificate may elect to amortize such premium under the
constant yield method. The OID Regulations also permit Certificateholders to
elect to include all interest, discount and premium in income based on a
constant yield method, further treating the Certificateholder as having made the
election to amortize premium generally, as discussed above. The Committee Report
indicates a Congressional intent that the same rules that will apply to accrual
of market discount on installment obligations will also apply in amortizing bond
premium under Code Section 171 on installment obligations such as the REMIC
Regular Certificates.
 
   3. REALIZED LOSSES
 
    Under Code Section 166, both corporate holders of REMIC Regular Certificates
and noncorporate holders of REMIC Regular Certificates that acquire such
Certificates in connection with a trade or business should be allowed to deduct,
as ordinary losses, any losses sustained during a taxable year in which their
Certificates become wholly or partially worthless as a result of one or more
realized losses on the Mortgage Loans. However, it appears that a noncorporate
holder that does not acquire a REMIC Regular Certificate in connection with a
trade or business will not be entitled to deduct a loss under Code Section 166
until such holder's Certificate becomes wholly worthless (I.E., until its
outstanding principal balance has been reduced to zero) and that the loss will
be characterized as a short-term capital loss.
 
    Each holder of a REMIC Regular Certificate will be required to accrue
interest and original issue discount with respect to such Certificate without
regard to any reduction in distributions attributable to defaults or
delinquencies on the Mortgage Loans or the underlying assets until it can be
established that any such reduction ultimately will not be recoverable. As a
result, the amount of taxable income reported in any period by the holder of a
REMIC Regular Certificate could exceed the amount of economic income actually
realized by the holder in such period. Although the holder of a REMIC Regular
Certificate eventually will recognize a loss or reduction in income attributable
to previously accrued and included income that, as a result of a realized loss,
ultimately will not be realized, the law is unclear with respect to the timing
and character of such loss or reduction in income.
 
   4. CALLABLE CLASS CERTIFICATES
 
    An entity electing to be treated as a REMIC may either itself directly, or
indirectly through the use of a trust owned by such entity, enter into a
redemption agreement pursuant to which the counterparty will have the right to
cause a redemption of the outstanding Certificates (as used herein, each such
right a "Call Right", and each such Certificate, a "Callable Class Certificate")
beginning on the Distribution Date and subject to payment of the redemption
price and other conditions that may be specified in the applicable Prospectus
Supplement. See "Description of the Certificates-Redemption Agreement." In the
event the trust issues the Call Right, counsel to the Depositor will
 
                                       74
<PAGE>
deliver its opinion generally to the effect that, assuming compliance with all
provisions of the related Pooling Agreement, the trust will be treated as a
grantor trust under subpart E, part 1 of Subchapter J of the Code and, as a
result, the REMIC will be treated as having directly issued the Call Right.
 
    The REMIC will be treated as (i) owning an interest in the underlying
Mortgage Loans and (ii) writing a call option on its interest in the underlying
Mortgage Loans, represented by the right of the holder of the Call Right to
direct the Depositor to redeem the outstanding Certificates as described under
"Description of the Certificates--Redemption Agreement."
 
    Under these circumstances, the REMIC should be considered to have acquired
its interest in the underlying Mortgage Loans for an amount equal to its initial
aggregate basis in its assets, determined as described more fully hereunder,
PLUS the fair market value at the time of purchase of such REMIC's assets of the
call option the REMIC is deemed to have written, which amount the REMIC is
deemed also to have received. Accordingly, the REMIC's basis in its interest in
the underlying Mortgage Loans will actually be greater than the aggregate issue
price of the REMIC Certificates it issues, resulting in less discount income or
greater premium deductions to the REMIC than it would have recognized had the
call option not been written. Under current federal income tax law, the REMIC
will not be required to include immediately in income the amount of the option
premium it is deemed to have received. However, although the treatment of these
items is not entirely clear, it appears that as the REMIC receives principal
payments on the underlying Mortgage Assets, and if the REMIC sells or
distributes in kind any of the underlying Mortgage Loans, the REMIC will be
deemed to have received (in addition to the amount of such payment, the sales
price or the fair market value of the asset, as the case may be) an amount equal
to the corresponding portion of the payment it was deemed to receive at the time
the call option was originally written. Accordingly, the amount realized by the
REMIC with respect to its interest in the underlying Mortgage Loans, will be
greater than the amount of cash received by it, and over the life of the REMIC
the entire amount of the deemed payment received when the call option was
written will be reported by the REMIC, although not at the times that a
corresponding amount of income would be reported based on a constant yield
method. Investors should be aware that, subject to certain specific exceptions
in the REMIC regulations, it is not anticipated that the REMIC will sell or
transfer or otherwise dispose of any of the underlying Mortgage Loans except
pursuant to an exercise of the Call Right. See "Prohibited Transactions and
Other Possible REMIC Taxes." In the event that the holder of the Call Right
chooses to effect such a redemption of the underlying Mortgage Loans, the
transactions by which the Certificates are retired and the related Trust Fund
terminated will constitute a "qualified liquidation" of the REMIC within the
meaning of Section 860F(a)(4) of the Code.
 
    TAXATION OF CALL OPTION PREMIUM.  Under current federal income tax law, the
REMIC will not be required to include immediately in income the option premium
with respect to the Call Right that it is deemed to receive. Instead, such
premium will be taken into account when the Call Right lapses, is exercised or
is otherwise terminates with respect to the REMIC. As indicated above, an amount
equal to the option premium that is deemed to be received by the REMIC would be
included in the REMIC's basis in the Mortgage Loans. The REMIC's recovery of
such basis will not occur at the same rate as its inclusion in income of the
option premium.
 
    As a grantor of an option, the REMIC must include the option premium in
income when the option lapses, which with respect to the REMIC is no later than
the redemption by a holder of the Call Right. Although the Call Right will not
expire by its terms during the period in which the Certificates remain
outstanding the Mortgage Assets to which the Call Right relates will be reduced
over time through principal payments. Although it is not entirely clear whether
the Call Right would thus be deemed to lapse as the Mortgage Loans are paid
down, and if so, at what rate, the Depositor intends to report income to the
REMIC based on the assumption that the Call Right lapses, and the related
premium is recognized by the REMIC, proportionately as principal is paid on the
Mortgage Loans (as prepayments prior to the date on which the Call Right may
first be exercised or as scheduled principal payments or prepayments after the
first date on which the Call Right may be exercised). There is no assurance that
the IRS would agree with this method of reporting income from the lapse of the
Call Right, and furthermore, it should be noted that the IRS currently is
examining the rules regarding the taxation of option premiums.
 
                                       75
<PAGE>
    If the Call Right is exercised, the REMIC will add an amount equal to the
unamortized portion of the option premium to the amount realized from the sale
of the underlying Mortgage Loans.
 
    If the REMIC transfers one of the underlying Mortgage Loans, such transfer
will be treated as a "closing transaction" with respect to the option the REMIC
is deemed to have written. Accordingly, the REMIC will recognize gain or loss
equal to the difference between the unamortized amount of option premium and the
amount the REMIC is deemed to pay, under the rules discussed above, to be
relieved from its obligations under the option. However, as discussed above,
subject to certain specified exceptions (including in connection with the
issuance of the Call Right), it is not anticipated that the REMIC will transfer
any of the underlying Mortgage Loans. See "Prohibited Transactions and Other
Possible REMIC Taxes."
 
    Certificateholders are urged to consult their tax advisors before purchasing
an interest in any Callable Class Certificate.
 
  D. TAXATION OF OWNERS OF REMIC RESIDUAL CERTIFICATES
 
   1. GENERAL
 
    An owner of a REMIC Residual Certificate ("Residual Owner") generally will
be required to report its daily portion of the taxable income or, subject to the
limitation described below in "--Taxation of Owners of REMIC Residual
Certificates--Basis Rules and Distributions", the net loss of the REMIC Mortgage
Pool for each day during a calendar quarter that the Residual Owner owned such
REMIC Residual Certificate. For this purpose, the daily portion will be
determined by allocating to each day in the calendar quarter, using a 30 days
per month/90 days per quarter/360 days per year counting convention (unless
otherwise disclosed in the applicable Prospectus Supplement), its ratable
portion of the taxable income or net loss of the REMIC Mortgage Pool for such
quarter, and by allocating the daily portions among the Residual Owners (on such
day) in accordance with their percentage of ownership interests on such day. Any
amount included in the gross income or allowed as a loss of any Residual Owner
by virtue of this paragraph will be treated as ordinary income or loss.
Purchasers of REMIC Residual Certificates should be aware that taxable income
from such Certificates could exceed cash distributions thereon in any taxable
year. For example, if Mortgage Loans are acquired by a REMIC at a discount, then
the holder of a residual interest may recognize income without corresponding
cash distributions. This result could occur because a payment produces
recognition of discount on the Mortgage Loan while the payment could be used in
whole or in part to make principal payments on REMIC Regular Certificates issued
without substantial discount. Taxable income may also be greater in earlier
years as a result of the fact that interest expense deductions, expressed as a
percentage of the outstanding principal amount of the REMIC Regular
Certificates, will increase over time as the lower yielding sequences of
Certificates are paid, whereas interest income with respect to any given fixed
rate Mortgage Loan will remain constant over time as a percentage of the
outstanding principal amount of that loan.
 
    Any payments received by a holder of a REMIC Residual Certificate in
connection with the acquisition of such Certificate will be taken into account
in determining the income of such holder for federal income tax purposes.
Although it appears likely that any such payment would be includible in income
immediately upon its receipt, the IRS might assert that such payment should be
included in income over time according to an amortization schedule or according
to some other method. Because of the uncertainty concerning the treatment of
such payments, holders of REMIC Residual Certificates should consult their tax
advisors concerning the treatment of such payments for income tax purposes.
 
    If so specified in the applicable Prospectus Supplement for a Series, the
underlying Mortgage Loans may be subject to redemption at the direction of the
holder of certain redemption right. As a direct owner in the underlying Mortgage
Loans for federal income purposes, the REMIC will also be treated as having
written the call option on such underlying Mortgage Loans. See "Callable Class
Certificates."
 
                                       76
<PAGE>
   2. TAXABLE INCOME OR NET LOSS OF THE REMIC TRUST FUND
 
    The taxable income or net loss of the REMIC Mortgage Pool will reflect a
netting of income from the Mortgage Loans, any cancellation of indebtedness
income due to the allocation of Realized Losses to REMIC Regular Certificates,
and deductions and losses allowed to the REMIC Mortgage Pool. Such taxable
income or net loss for a given calendar quarter will be determined in the same
manner as for an individual having the calendar year as his taxable year and
using the accrual method of accounting, with certain modifications. The first
modification is that a deduction will be allowed for accruals of interest
(including original issue discount) on the REMIC Regular Certificates. Second,
market discount equal to the excess of any Mortgage Loan's adjusted issue price
(as determined under "Taxation of Owners of REMIC Regular Certificates--Market
Discount and Premium") over its fair market value at the time of their transfer
to the REMIC Mortgage Pool generally will be included in income as it accrues,
based on a constant yield and on the Prepayment Assumption. For this purpose,
the Company intends to treat the fair market value of the Mortgage Loans as
being equal to the aggregate issue prices of the REMIC Regular Certificates and
REMIC Residual Certificates; if one or more classes of REMIC Regular
Certificates or REMIC Residual Certificates are retained by the Company, it will
estimate the value of such retained interests in order to determine the fair
market value of the Mortgage Loans for this purpose. Third, no item of income,
gain, loss or deduction allocable to a prohibited transaction (see "--Prohibited
Transactions and Other Possible REMIC Taxes", below) will be taken into account.
Fourth, the REMIC Mortgage Pool generally may not deduct any item that would not
be allowed in calculating the taxable income of a partnership by virtue of Code
Section 703(a)(2). Fifth, the REMIC Regulations provide that the limitation on
miscellaneous itemized deductions imposed on individuals by Code Section 67 will
not be applied at the Mortgage Pool level to the servicing fees paid to the
Master Servicer or sub-servicers, if any. (See, however, "--Pass-Through of
Servicing Fees", below.) If the deductions allowed to the REMIC Mortgage Pool
exceed its gross income for a calendar quarter, such excess will be the net loss
for the REMIC Mortgage Pool for that calendar quarter.
 
   3. BASIS RULES AND DISTRIBUTIONS
 
    Any distribution by a REMIC Mortgage Pool to a Residual Owner will not be
included in the gross income of such Residual Owner to the extent it does not
exceed the adjusted basis of such Residual Owner's interest in a REMIC Residual
Certificate. Such distribution will reduce the adjusted basis of such interest,
but not below zero. To the extent a distribution exceeds the adjusted basis of
the REMIC Residual Certificate, it will be treated as gain from the sale of the
REMIC Residual Certificate. (See "--Sales of REMIC Certificates", below.) The
adjusted basis of a REMIC Residual Certificate is equal to the amount paid for
such REMIC Residual Certificate, increased by amounts included in the income of
the Residual Owner (See "--Taxation of Owners of REMIC Residual
Certificates--Daily Portions", above) and decreased by distributions and by net
losses taken into account with respect to such interest.
 
    A Residual Owner is not allowed to take into account any net loss for any
calendar quarter to the extent such net loss exceeds such Residual Owner's
adjusted basis in its REMIC Residual Certificate as of the close of such
calendar quarter (determined without regard to such net loss). Any loss
disallowed by reason of this limitation may be carried forward indefinitely to
future calendar quarters and, subject to the same limitation, may be used only
to offset income from the REMIC Residual Certificate.
 
    The effect of these basis and distribution rules is that a Residual Owner
may not amortize its basis in a REMIC Residual Certificate, but may only recover
its basis through distributions, through the deduction of any net losses of the
REMIC Mortgage Pool or upon the sale of its REMIC Residual Certificate (See
"--Sales of REMIC Certificates", below). The residual holder does, however,
receive reduced taxable income over the life of the REMIC, because the REMIC's
basis in the underlying REMIC Mortgage Pool includes the fair market value of
the REMIC Regular Certificates and REMIC Residual Certificates.
 
   4. EXCESS INCLUSIONS
 
    Any "excess inclusions" with respect to a REMIC Residual Certificate are
subject to certain special tax rules. With respect to a Residual Owner, the
excess inclusion for any calendar quarter is
 
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defined as the excess (if any) of the daily portions of taxable income over the
sum of the "daily accruals" for each day during such quarter that such REMIC
Residual Certificate was held by such Residual Owner. The daily accruals are
determined by allocating to each day during a calendar quarter its ratable
portion of the product of the "adjusted issue price" of the REMIC Residual
Certificate at the beginning of the calendar quarter and 120 percent of the
long-term "applicable federal rate" (generally, an average of current yields on
Treasury securities of comparable maturity) (the "AFR") in effect at the time of
issuance of the REMIC Residual Certificate. For this purpose, the adjusted issue
price of a REMIC Residual Certificate as of the beginning of any calendar
quarter is the issue price of the REMIC Residual Certificate, increased by the
amount of daily accruals for all prior quarters and decreased by any
distributions made with respect to such REMIC Residual Certificate before the
beginning of such quarter. The issue price of a REMIC Residual Certificate is
the initial offering price to the public (excluding bond houses and brokers) at
which a substantial amount of the REMIC Residual Certificates were sold.
 
    An excess inclusion cannot be offset by deductions, losses or loss
carryovers from other activities. For Residual Owners that are subject to tax on
unrelated business taxable income (as defined in Code Section 511), an excess
inclusion of such Residual Owner is treated as unrelated business taxable
income. For Residual Owners that are nonresident alien individuals or foreign
corporations generally subject to United States 30% withholding tax, even if
interest paid to such Residual Owners is generally eligible for exemptions from
such tax, an excess inclusion will be subject to such tax and no tax treaty rate
reduction or exemption may be claimed with respect thereto. See "--Foreign
Investors in REMIC Certificates".
 
    Although it has not done so, the Treasury also has authority to issue
regulations that, if REMIC Residual Certificates are found in the aggregate not
to have "significant value", would treat as excess inclusions with respect to
such REMIC Residual Certificates the entire daily portion of taxable income for
such REMIC Residual Certificates. In order to have significant value, the REMIC
Residual Certificates must have an aggregate issue price, at issuance, at least
equal to two percent of the aggregate issue prices of all of the related REMIC
Regular and Residual Certificates. In addition, the anticipated weighted average
life of the REMIC Residual Certificates must equal or exceed 20 percent of the
anticipated weighted average life of the REMIC, based on the Prepayment
Assumption and on any required or permitted clean up calls or required
liquidation provided for in the REMIC's organizational documents. Each
Prospectus Supplement pursuant to which REMIC Residual Certificates are offered
will state whether such REMIC Residual Certificates will have, or may be
regarded as having, "significant value" under the REMIC Regulations; provided,
however, that any disclosure that a REMIC Residual Certificate will have
"significant value" will be based upon certain assumptions, and the Company will
make no representation that a REMIC Residual Certificate will have "significant
value" for purposes of the above described rules or that a Residual Owner will
receive distributions of amounts calculated pursuant to those assumptions.
 
    In the case of any REMIC Residual Certificates held by a real estate
investment trust, the aggregate excess inclusions with respect to such REMIC
Residual Certificates, reduced (but not below zero) by the real estate
investment trust taxable income (within the meaning of Code Section 857(b)(2),
excluding any net capital gain), will be allocated among the shareholders of
such trust in proportion to the dividends received by such shareholders from
such trust, and any amount so allocated will be treated as an excess inclusion
with respect to a REMIC Residual Certificate as if held directly by such
shareholder.
 
   5. NONECONOMIC REMIC RESIDUAL CERTIFICATES
 
    Under the REMIC Regulations, transfers of "noneconomic" REMIC Residual
Certificates will be disregarded for all federal income tax purposes if "a
significant purpose of the transfer was to enable the transferor to impede the
assessment or collection of tax". If such transfer is disregarded, the purported
transferor will continue to remain liable for any taxes due with respect to the
income on such "noneconomic" REMIC Residual Certificate. The REMIC Regulations
provide that a REMIC Residual Certificate will be considered a noneconomic
residual interest unless, at the time of its transfer and based on the
Prepayment Assumption and any required or permitted clean up calls or required
liquidation provided for in the REMIC's organizational documents, (1) the
present value of the expected future distributions (discounted using the AFR) on
the REMIC Residual Certificate
 
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equals at least the present value of the expected tax on the anticipated excess
inclusions, and (2) the transferor reasonably expects that the transferee will
receive distributions with respect to the REMIC Residual Certificate at or after
the time the taxes accrue on the anticipated excess inclusions in an amount
sufficient to satisfy the accrued taxes. Accordingly, all transfers of REMIC
Residual Certificates that may constitute noneconomic residual interests will be
subject to certain restrictions under the terms of the related Pooling and
Servicing Agreement that are intended to reduce the possibility of any such
transfer being disregarded. Such restrictions will require each party to a
transfer to provide an affidavit that no purpose of such transfer is to impede
the assessment or collection of tax, including certain representations as to the
financial condition of the prospective transferee. Prior to purchasing a REMIC
Residual Certificate, prospective purchasers should consider the possibility
that a purported transfer of such REMIC Residual Certificate by such a purchaser
to another purchaser at some future date may be disregarded in accordance with
the above-described rules, which would result in the retention of tax liability
by such purchaser. The applicable Prospectus Supplement will disclose whether
offered REMIC Residual Certificates may be considered "noneconomic" residual
interests under the REMIC Regulations; provided, however, that any disclosure
that a REMIC Residual Certificate will or will not be considered "noneconomic"
will be based upon certain assumptions, and the Company will make no
representation that a REMIC Residual Certificate will not be considered
"noneconomic" for purposes of the above-described rules or that a REMIC Residual
Owner will receive distributions calculated pursuant to such assumptions. See
"Foreign Investors in REMIC Certificates" below for additional restrictions
applicable to transfers of certain REMIC Residual Certificates to foreign
persons.
 
   6. TAX-EXEMPT INVESTORS
 
    Generally, tax exempt organizations that are not subject to Federal income
taxation on "unrelated business taxable income" pursuant to Code Section 511 are
treated as "disqualified organizations" under provisions of the 1988 Act. Under
provisions of the Pooling Agreement, such organizations generally are prohibited
from owning Residual Certificates. For Residual Owners that are subject to tax
on unrelated business taxable income (as defined in Code Section 511), an excess
inclusion of such Residual Owner is treated as unrelated business taxable
income. See "--Sales of REMIC Certificates".
 
   7. REAL ESTATE INVESTMENT TRUSTS
 
    If the applicable Prospectus Supplement so provides, a Mortgage Pool may
hold Mortgage Loans bearing interest based wholly or partially on Mortgagor
profits, Mortgaged Property appreciation, or similar contingencies. Such
interest, if earned directly by a real estate investment trust ("REIT"), would
be subject to the limitations of Code sections 856 (f) and 856 (j). Treasury
Regulations treat a REIT holding a REMIC Residual Certificate for a principal
purpose of avoiding such Code provisions as receiving directly the income of the
REMIC Mortgage Pool, hence potentially jeopardizing its qualification for
taxation as a REIT and exposing such income to taxation as a prohibited
transaction at a 100 percent rate.
 
   8. MARK-TO-MARKET RULES
 
    Treasury regulations provide that any REMIC Residual Certificate acquired
after January 3, 1995 will not be treated as a security and therefore generally
may not be marked to market.
 
  E. SALES OF REMIC CERTIFICATES
 
    If a REMIC Certificate is sold, the seller will recognize gain or loss equal
to the difference between the amount realized on the sale and its adjusted basis
in the REMIC Certificate. The adjusted basis of a REMIC Regular Certificate
generally will equal the cost of such REMIC Regular Certificate to the seller,
increased by any original issue discount or market discount included in the
seller's gross income with respect to such REMIC Regular Certificate and reduced
by premium amortization deductions and distributions previously received by the
seller of amounts included in the stated redemption price at maturity of such
REMIC Regular Certificate. The adjusted basis of a REMIC Residual Certificate
will be determined as described under "--Taxation of Owners of REMIC Residual
Certificates--Basis Rules and Distributions", above. Gain from the disposition
of a REMIC Regular Certificate that might otherwise be treated as a capital gain
will be treated as ordinary income to the extent that such gain
 
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does not exceed the excess, if any, of (i) the amount that would have been
includible in such holder's income had income accrued at a rate equal to 110% of
the AFR as of the date of purchase over (ii) the amount actually includible in
such holder's income. Except as otherwise provided under "--Taxation of Owners
of REMIC Regular Certificates--Market Discount and Premium" and under Code
Section 582(c), any additional gain or any loss on the sale or exchange of a
REMIC Certificate will be capital gain or loss, provided such REMIC Certificate
is held as a capital asset (generally, property held for investment) within the
meaning of Code Section 1221. The distinction between a capital gain or loss and
ordinary income or loss is also relevant for other purposes, including
limitations on the use of capital losses to offset ordinary income.
 
    A portion of any gain from the sale of a REMIC Regular Certificate that
might otherwise be capital gain may be treated as ordinary income to the extent
that such Certificate is held as part of a "conversion transaction" within the
meaning of Code Section 1258. A conversion transaction generally is one in which
the taxpayer has taken two or more positions in Certificates or similar property
that reduce or eliminate market risk, if substantially all of the taxpayer's
return is attributable to the time value of the taxpayer's net investment in
such transaction. The amount of gain so realized in a conversion transaction
that is recharacterized as ordinary income generally will not exceed the amount
of interest that would have accrued on the taxpayer's net investment at 120% of
the AFR at the time the taxpayer enters into the conversion transaction, subject
to appropriate reduction for prior inclusion of interest and other ordinary
income items from the transaction.
 
    A taxpayer may elect to have net capital gain taxed at ordinary income rates
rather than capital gains rates in order to include such net capital gain in
total net investment income for that taxable year, for purposes of the
limitation on the deduction of interest on indebtedness incurred to purchase or
carry property held for investment to a taxpayer's net investment income.
 
    The Omnibus Budget Reconciliation Act of 1993 (the "Budget Act") revised the
rules for deducting interest on indebtedness allocable to property held for
investment. Generally, deductions for such interest are limited to a taxpayer's
net investment income for each taxable year. As amended by the Budget Act, net
investment income for each taxable year includes net capital gain attributable
to the disposition of investment property only if the taxpayer elects to have
such net capital gain taxed at ordinary income rates rather than capital gains
rates.
 
    If a Residual Owner sells a REMIC Residual Certificate at a loss, the loss
will not be recognized if, within six months before or after the sale of the
REMIC Residual Certificate, such Residual Owner purchases another residual
interest in any REMIC or any interest in a taxable mortgage pool (as defined in
Code Section 7701(i)) comparable to a residual interest in a REMIC. Such
disallowed loss will be allowed upon the sale of the other residual interest (or
comparable interest) if the rule referred to in the preceding sentence does not
apply to that sale. While the Committee Report states that this rule may be
modified by Treasury regulations, the REMIC Regulations do not address this
issue and it is not clear whether any such modification will in fact be
implemented or, if implemented, what the precise nature or effective date of it
would be.
 
    The 1988 Act makes transfers of a residual interest to certain "disqualified
organizations" subject to an additional tax on the transferor in an amount equal
to the maximum corporate tax rate applied to the present value of the total
anticipated excess inclusions (discounted using the applicable Federal rate)
with respect to such residual interest for the periods after the transfer. For
this purpose, "disqualified organizations" includes the United States, any state
or political subdivision of a state, any foreign government or international
organization or any agency or instrumentality of any of the foregoing; any
tax-exempt entity (other than a Code Section 521 cooperative) which is not
subject to the tax on unrelated business income; and any rural electrical and
telephone cooperative. The anticipated excess inclusions must be determined as
of the date that the REMIC Residual Certificate is transferred and must be based
on events that have occurred up to the time of such transfer, the Prepayment
Assumption, and any required or permitted clean up calls or required liquidation
provided for in the REMIC's organizational documents. The tax generally is
imposed on the transferor of the REMIC Residual Certificate, except that it is
imposed on an agent for a disqualified organization if the transfer occurs
through such agent. The Pooling and Servicing Agreement requires, as a
prerequisite to any transfer of a Residual Certificate, the delivery to the
Trustee of an
 
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affidavit of the transferee to the effect that it is not a disqualified
organization and contains other provisions designed to render any attempted
transfer of a Residual Certificate to a disqualified organization void.
 
    In addition, if a "pass-through entity" includes in income excess inclusions
with respect to a REMIC Residual Certificate, and a disqualified organization is
the record holder of an interest in such entity, then a tax will be imposed on
such entity equal to the product of (i) the amount of excess inclusions on the
REMIC Residual Certificate that are allocable to the interest in the
pass-through entity held by such disqualified organization and (ii) the highest
marginal federal income tax rate imposed on corporations. A pass-through entity
will not be subject to this tax for any period, however, if the record holder of
an interest in such entity furnishes to such entity (i) such holder's social
security number and a statement under penalties of perjury that such social
security number is that of the record holder or (ii) a statement under
penalities of perjury that such record holder is not a disqualified
organization. For these purposes, a "pass-through entity" means any regulated
investment company, real estate investment trust, trust, partnership or certain
other entities described in Section 860E(e)(6) of the Code. In addition, a
person holding an interest in a pass-through entity as a nominee for another
person shall, with respect to such interest, be treated as a pass-through
entity. Legislation presently pending before the United States Congress, the Tax
Simplification and Technical Corrections Bill of 1993 (the "Simplification
Act"), would apply this tax on an annual basis to "large partnerships".
Generally, the Simplification Act would treat partnerships that have, or have
had, 250 or more partners as a large partnership for this purpose. The
Simplification Act would not limit application of the tax to excess inclusions
allocable to disqualified organizations, and in fact would apply the tax to
large partnerships having no disqualified organizations as partners. If enacted
in its present form, the Simplification Act would apply to partnership taxable
years ending on or after December 31, 1994.
 
  F. PASS-THROUGH OF SERVICING FEES
 
    The general rule is that Residual Certificateholders take into account
taxable income or net loss of the related REMIC Mortgage Pool. Under that rule,
servicing compensation of the Company and the subservicers (if any) would be
allocated to the holders of the REMIC Residual Certificates, and therefore would
not affect the income or deductions of holders of REMIC Regular Certificates.
However, in the case of a "single-class REMIC", such expenses and an equivalent
amount of additional gross income will be allocated among all holders of REMIC
Regular Certificates and REMIC Residual Certificates for purposes of the
limitations on the deductibility of certain miscellaneous itemized deductions by
individuals contained in Code Sections 56(b)(1) and 67. Generally, any holder of
a REMIC Certificate who is an individual, estate or trust will be able to deduct
such expenses in determining regular tax liability only to the extent that such
expenses together with certain other miscellaneous itemized deductions of such
individual, estate or trust exceed 2% of adjusted gross income; such a holder
may not deduct such expenses to any extent in determining liability for
alternative minimum tax. Accordingly, REMIC Residual Certificates, and REMIC
Regular Certificates receiving an allocation of servicing compensation, may not
be appropriate investments for individuals, estates or trusts, and such persons
should carefully consult with their own tax advisors regarding the advisability
of an investment in such Certificates.
 
    A "single-class REMIC" is a REMIC that either (i) would be treated as a
pass-through trust under the provisions of Treasury Regulation Section
301.7701-4(c) in the absence of a REMIC election, or (ii) is substantially
similar to such a pass-through trust and is structured with the principal
purpose of avoiding the allocation of investment expenses to holders of REMIC
Regular Certificates. Unless otherwise stated in the related Prospectus
Supplement, the Company intends to treat a REMIC Mortgage Pool as other than a
"single-class REMIC", consequently allocating servicing compensation expenses
and related income amounts entirely to REMIC Residual Certificates and in no
part to REMIC Regular Certificates.
 
  G. PROHIBITED TRANSACTIONS AND OTHER POSSIBLE REMIC TAXES
 
    The Code imposes a tax on REMIC Mortgage Pools equal to 100 percent of the
net income derived from "prohibited transactions". In general, a prohibited
transaction means the disposition of a Mortgage Loan other than pursuant to
certain specified exceptions, the receipt of income from a
 
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<PAGE>
source other than a Mortgage Loan or certain other permitted investments, the
receipt of compensation for services, or gain from the disposition of an asset
purchased with the payments on the Mortgage Loans for temporary investment
pending distribution on the REMIC Certificates. The Code also imposes a 100
percent tax on the value of any contribution of assets to the REMIC after the
"start-up day" (the day on which the regular and residual interests are issued),
other than pursuant to specified exceptions, and subjects "net income from
foreclosure property" to tax at the highest corporate rate. It is not
anticipated that a REMIC Mortgage Pool will engage in any such transactions or
receive any such income.
 
  H. TERMINATION OF A REMIC TRUST FUND
 
    In general, no special tax consequences will apply to a holder of a REMIC
Regular Certificate upon the termination of the REMIC Mortgage Pool by virtue of
the final payment or liquidation of the last Mortgage Loan remaining in the
REMIC Mortgage Pool. If a Residual Owner's adjusted basis in its REMIC Residual
Certificate at the time such termination occurs exceeds the amount of cash
distributed to such Residual Owner in liquidation of its interest, then,
although the matter is not entirely free from doubt, it appears that the
Residual Owner would be entitled to a loss (which would be a capital loss) equal
to the amount of such excess.
 
  I. REPORTING AND OTHER ADMINISTRATIVE MATTERS OF REMICS
 
    Reporting of interest income, including any original issue discount, with
respect to REMIC Regular Certificates is required annually, and may be required
more frequently under Treasury regulations. In addition to those holders of
REMIC Regular Certificates to whom information reporting generally applies,
certain holders of REMIC Regular Certificates who are generally exempt from
information reporting on debt instruments, such as corporations, banks,
registered securities or commodities brokers, real estate investment trusts,
registered investment companies, common trust funds, charitable remainder
annuity trusts and unitrusts, will be provided interest and original issue
discount income information and the information set forth in the following
paragraph upon request in accordance with the requirements of the Treasury
regulations. The information must be provided by the later of 30 days after the
end of the quarter for which the information was requested, or two weeks after
the receipt of the request. The REMIC Mortgage Pool must also comply with rules
requiring the face of a REMIC Certificate issued at more than a DE MINIMIS
discount to disclose the amount of original issue discount and the issue date
and requiring such information to be reported to the Treasury Department.
 
    The REMIC Regular Certificate information reports must include a statement
of the "adjusted issue price" of the REMIC Regular Certificate at the beginning
of each accrual period. In addition, the reports must include information
necessary to compute the accrual of any market discount that may arise upon
secondary trading of REMIC Regular Certificates. Because exact computation of
the accrual of market discount on a constant yield method would require
information relating to the holder's purchase price which the REMIC Mortgage
Pool may not have, it appears that this provision will only require information
pertaining to the appropriate proportionate method of accruing market discount.
 
    The responsibility for complying with the foregoing reporting rules will be
borne by the Company.
 
    For purposes of the administrative provisions of the Code, REMIC Mortgage
Pools will be treated as partnerships and the holders of Residual Certificates
will be treated as partners. Unless otherwise stated in the applicable
Prospectus Supplement, the Company will file federal income tax information
returns on behalf of the related REMIC Mortgage Pool, and will be designated as
agent for, and will act on behalf of the "tax matters person" with respect to
the REMIC Mortgage Pool in all respects.
 
    As agent for the tax matters person, the Company will, subject to certain
notice requirements and various restrictions and limitations, generally have the
authority to act on behalf of the REMIC and the Residual Owners in connection
with the administrative and judicial review of items of income, deduction, gain
or loss of the REMIC Mortgage Pool, as well as the REMIC Mortgage Pool's
classification. Residual Owners will generally be required to report such REMIC
Mortgage Pool items consistently with their treatment on the REMIC Mortgage
Pool's federal income tax information return and may in some circumstances be
bound by a settlement agreement between the Master
 
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Servicer, as agent for the tax matters person, and the IRS concerning any such
REMIC Mortgage Pool item. Adjustments made to the REMIC Mortgage Pool tax return
may require a Residual Owner to make corresponding adjustments on its return,
and an audit of the REMIC Mortgage Pool's tax return, or the adjustments
resulting from such an audit, could result in an audit of a Residual Owner's
return.
 
  J. BACKUP WITHHOLDING WITH RESPECT TO REMIC CERTIFICATES
 
    Payments of interest and principal on REMIC Regular Certificates, as well as
payments of proceeds from the sale of REMIC Certificates, may be subject to the
"backup withholding tax" under Section 3406 of the Code at a rate of 31 percent
if recipients of such payments fail to furnish to the payor certain information,
including their taxpayer identification numbers, or otherwise fail to establish
an exemption from such tax. Any amounts deducted and withheld from a
distribution to a recipient would be allowed as a credit against such
recipient's federal income tax. Furthermore, certain penalties may be imposed by
the IRS on a recipient of payments that is required to supply information but
that does not do so in the proper manner.
 
  K. FOREIGN INVESTORS IN REMIC CERTIFICATES
 
   1. REMIC REGULAR CERTIFICATES
 
    Except as qualified below, payments made on a REMIC Regular Certificate to a
REMIC Regular Certificateholder that is not a U.S. Person, as hereinafter
defined (a "Non-U.S. Person"), or to a person acting on behalf of such a
Certificateholder, generally will be exempt from U.S. federal income and
withholding taxes, provided (a) the holder of the Certificate is not subject to
U.S. tax as a result of a connection to the United States other than ownership
of such Certificate, (b) the holder of such Certificate signs a statement under
penalties of perjury that certifies that such holder is a Non-U.S. Person, and
provides the name and address of such holder, and (c) the last U.S. Person in
the chain of payment to the holder received such statement from such holder or a
financial institution holding on its behalf and does not have actual knowledge
that such statement is false. If the holder does not qualify for exemption,
distributions of interest, including distributions in respect of accrued
original issue discount, to such holder may be subject to a withholding tax rate
of 30 percent, subject to reduction under any applicable tax treaty.
 
    "U.S. Person" means (i) a citizen or resident of the United States, (ii) a
corporation or partnership (including any entity treated as a partnership or
corporation for federal income tax purposes) created or organized in or under
the laws of the United States, any state or the District of Columbia, or (iii)
an estate or trust that is subject to U.S. federal income tax regardless of the
source of its income.
 
    Holders of REMIC Regular Certificates should be aware that the IRS might
take the position that exemption from U.S. withholding taxes does not apply to
such a holder that also directly or indirectly owns 10 percent or more of the
REMIC Residual Certificates of a particular Series of Certificates. Further, the
foregoing rules will not apply to exempt a United States shareholder of a
controlled foreign corporation from taxation on such United States shareholder's
allocable portion of the interest or original issue discount income earned by
such controlled foreign corporation.
 
   2. REMIC RESIDUAL CERTIFICATES
 
    Amounts paid to a Residual Owner that is a Non-U.S. Person generally will be
treated as interest for purposes of applying the withholding tax on Non-U.S.
Persons with respect to income on its REMIC Residual Certificate. However, it is
unclear whether distributions on REMIC Residual Certificates will be eligible
for the general exemption from withholding tax that applies to REMIC Regular
Certificates as described above. Treasury regulations provide that, for purposes
of the portfolio interest exception, payments to the foreign owner of a REMIC
Residual Certificate are to be considered paid on the obligations held by the
REMIC, rather than on the Certificate itself. Such payments would thus only
qualify for the portfolio interest exception if the underlying obligations held
by the REMIC would so qualify. Such withholding tax generally would be imposed
at a rate of 30 percent but would be subject to reduction under any tax treaty
applicable to the Residual Owner.
 
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<PAGE>
However, there is no exemption from withholding tax nor may the rate of such tax
be reduced, under a tax treaty or otherwise, with respect to any distribution of
income that is an excess inclusion. See "--Taxation of Owners of REMIC Residual
Certificates--Excess Inclusions".
 
    Certain restrictions relating to transfers of REMIC Residual Certificates to
and by investors who are not U.S. Persons are also imposed by the REMIC
Regulations. First, transfers of REMIC Residual Certificates to Non-U.S. Persons
that have "tax avoidance potential" are disregarded for all federal income tax
purposes. If such transfer is disregarded, the purported transferor of such a
REMIC Residual Certificate to a Non-U.S. Person would continue to remain liable
for any taxes due with respect to the income on such REMIC Residual Certificate.
A REMIC Residual Certificate has tax avoidance potential unless, at the time of
the transfer, the transferor reasonably expects that the REMIC will distribute
to the transferee amounts that will equal at least 30 percent of each excess
inclusion, and that such amounts will be distributed at or after the time at
which the excess inclusion accrues and not later than the close of the calendar
year following the calendar year of accrual. This rule does not apply to
transfers if the income from the REMIC Residual Certificate is taxed in the
hands of the transferee as income effectively connected with the conduct of a
U.S. trade or business. Second, if a Non-U.S. Person transfers a REMIC Residual
Certificate to a U.S. Person, and the transfer has the effect of allowing the
transferor to avoid tax on accrued excess inclusions, that transfer is
disregarded for all federal income tax purposes and the purported Non-U.S.
Person transferor continues to be treated as the owner of the REMIC Residual
Certificate. Thus, the REMIC's liability to withhold 30 percent of the accrued
excess inclusions is not terminated even though the REMIC Residual Certificate
is no longer held by a Non-U.S. Person.
 
  L. STATE AND LOCAL TAXATION
 
    Many states do not automatically conform to changes in the federal income
tax laws. Consequently, a REMIC Mortgage Pool which would not qualify as a fixed
investment trust for federal income tax purposes may be characterized as a
corporation, a partnership, or some other entity for purposes of state income
tax law. Such characterization could result in entity level income or franchise
taxation of a REMIC Mortgage Pool formed in, owning mortgages or property in, or
having servicing activity performed in a state without conforming REMIC
provisions in its income or franchise tax law. Further, REMIC Regular
Certificateholders resident in nonconforming states may have their ownership of
REMIC Regular Certificates characterized as an interest other than debt of the
REMIC such as stock or a partnership interest. Investors are advised to consult
their tax advisors concerning the state and local income tax consequences of
their purchase and ownership of REMIC Regular Certificates.
 
CALL RIGHT
 
    The holder of the Call Right will be treated as having purchased a call
option on all the underlying Mortgage Loans. The price paid by the holder of the
Call Right to purchase such call option will be treated as an option premium and
accordingly will be added to the purchase price of the Mortgage Loans(in
addition to any exchange fee) if the Mortgage Loans are purchased upon exercise
of the Call Right, and will be treated as a loss as the Call Right lapses. For a
discussion of when the Call Right may be deemed to lapse, see "Callable Class
Certificates" above. Assuming that the underlying Mortgage Loans, if acquired,
would be a capital asset in such holder's hands, then loss recognized with
respect to such lapse will be treated as a capital loss.
 
    In light of the above, a thrift, REMIC, real estate investment trust or
regulated investment company should consult its tax advisors before purchasing
any Call Class.
 
                            METHODS OF DISTRIBUTION
 
    Certificates are being offered hereby in Series from time to time (each
Series evidencing a separate Mortgage Pool) through any of the following
methods:
 
        1.  By negotiated firm commitment underwriting and public reoffering by
    underwriters;
 
        2.  By agency placements through one or more placement agents primarily
    with institutional investors and dealers; and
 
        3.  By placement directly by the Company with institutional investors.
 
                                       84
<PAGE>
    A Prospectus Supplement will be prepared for each Series which will describe
the method of offering being used for that Series and will set forth the
identity of any underwriters thereof and either the price at which such Series
is being offered, the nature and amount of any underwriting discounts or
additional compensation to such underwriters and the proceeds of the offering to
the Company, or the method by which the price at which the underwriters will
sell the Certificates will be determined. Each Prospectus Supplement for an
underwritten offering will also contain information regarding the nature of the
underwriters' obligations, any material relationship between the Company and any
underwriter and, where appropriate, information regarding any discounts or
concessions to be allowed or reallowed to dealers or others and any arrangements
to stabilize the market for the Certificates so offered. In firm commitment
underwritten offerings, the underwriters will be obligated to purchase all of
the Certificates of such Series if any such Certificates are purchased.
Certificates may be acquired by the underwriters for their own accounts and may
be resold from time to time in one or more transactions, including negotiated
transactions, at a fixed public offering price or at varying prices determined
at the time of sale.
 
    PNC Capital Markets, Inc., an affiliate of the Company, may from time to
time act as agent or underwriter in connection with the sale of the
Certificates. This Prospectus and the related Prospectus Supplement may be used
by PNC Capital Markets, Inc. in connection with offers and sales related to
secondary market transactions in any Series of Certificates. PNC Capital
Markets, Inc. may act as principal or agent in such transactions. Such sales
will be made at prices related to prevailing market prices at the time of sale
or otherwise.
 
    Underwriters and agents may be entitled under agreements entered into with
the Company to indemnification by the Company against certain civil liabilities,
including liabilities under the Securities Act of 1933, as amended (the "Act"),
or to contribution with respect to payments which such underwriters or agents
may be required to make in respect thereof.
 
    If a Series is offered other than through underwriters, the Prospectus
Supplement relating thereto will contain information regarding the nature of
such offering and any agreements to be entered into between the Company and
purchasers of Certificates of such Series.
 
                        TRANSFERABILITY OF CERTIFICATES
 
    The Company anticipates that the Certificates will be sold primarily to
institutional investors. Purchasers of Certificates, including dealers, may,
depending on the facts and circumstances of such purchases, be deemed to be
"underwriters" within the meaning of the Act, in connection with reoffers and
sales by them of Certificates. Certain purchasers will be required to give the
Company prior notice of their intention to resell their Certificates, and to
represent to the Company that they will observe certain prospectus delivery and
anti-manipulative requirements of the Act and the Securities Exchange Act of
1934, as amended. The Company will charge any Certificateholder requesting
amended or updated Prospectuses or Prospectus Supplements all expenses incurred
by the Company for preparation and delivery of such documents.
Certificateholders should consult with their legal advisors in this regard prior
to any such reoffer or resale.
 
                                 LEGAL MATTERS
 
    Certain legal matters will be passed upon for the Company by Thomas G.
Lehmann, General Counsel, Vice President and Secretary of the Company, and by
its special counsel, Orrick, Herrington & Sutcliffe LLP, San Francisco,
California.
 
                             FINANCIAL INFORMATION
 
    The Company has determined that its financial statements are not material to
the offering made hereby. However, any prospective investor who desires to
review financial information concerning the Company will be provided, upon
request, with a copy of the consolidated balance sheet of the Company as of
December 31, 1994 or the end of its last fiscal year, whichever is later, and a
copy of the most recent statement of earnings of the Company. Such requests
should be directed to PNC Mortgage Securities Corp., Controller's Department, 75
North Fairway Drive, Vernon Hills, Illinois 60061.
 
                             ADDITIONAL INFORMATION
 
    This Prospectus, together with the Prospectus Supplement for each Series of
Certificates, contains a summary of the material terms of the applicable
exhibits to the Registration Statement and the documents referred to herein and
therein. Copies of such exhibits are on file at the offices of the Securities
and Exchange Commission in Washington, D.C., may be obtained at rates prescribed
by the Commission upon request to the Commission and may be inspected, without
charge, at the Commission's offices.
 
                                       85
<PAGE>
                                    GLOSSARY
 
    Set forth below is a list of certain of the more significant terms used in
this Prospectus and the pages on which the definitions of such terms may be
found.
<TABLE>
<CAPTION>
                                                    PAGE
                                                    -----
<S>                                              <C>
Act............................................          85
Advance Claims Endorsement.....................          50
Advances.......................................          15
AFR............................................          78
Agency Certificates............................           8
Bankruptcy Bond................................           7
Bankruptcy Instrument..........................          49
Bankruptcy Loss................................          49
Basic Prepayment Assumption....................          19
BPA............................................          19
Buydown Fund...................................          13
Buydown Fund Account...........................          25
Buydown Loans..................................           6
Callable Class Certificate.....................          74
CERCLA.........................................          63
Certificate Account............................          31
Certificate Administrator......................           4
Certificate Administrator Fee..................          14
Certificates...................................           1
Class..........................................           1
Code...........................................           8
Commission.....................................          14
Company........................................           1
Compensating Interest..........................          18
Conversion Fee.................................          15
Cooperative....................................          12
Cooperative Loan...............................           1
Cooperative Note...............................          12
Curtailment....................................          17
Custodial Account for P&I......................          28
Cut-Off Date...................................           8
Defaulted Mortgage Loss........................          48
Determination Date.............................          34
Distribution Date..............................           5
Distribution Period............................          33
DOL............................................          65
Eligible Investments...........................          31
ERISA..........................................           9
Extraordinary Losses...........................          49
FDIC...........................................          19
FHA............................................          12
FHA Approved Mortgagees........................          20
FHA Insurance Policies.........................          12
FHLMC..........................................           8
FHLMC Approved Mortgagees......................          20
FNMA...........................................           8
FNMA Approved Mortgagees.......................          20
Fraud Bond.....................................           6
Fraud Instrument...............................          49
 
<CAPTION>
                                                    PAGE
                                                    -----
<S>                                              <C>
Fraud Loss.....................................          49
Garn-St. Germain Act...........................          62
GNMA...........................................           8
Indemnified Parties............................          40
Insurance Proceeds.............................          29
Investment Account.............................          30
Investment Period..............................          30
IRS............................................          69
Lenders........................................          20
Letter of Credit...............................           7
Letter of Credit Bank..........................          53
Liquidation Proceeds...........................          28
Loss...........................................          44
Master Servicer................................           4
Master Servicing Fee...........................          14
Mortgage Loan Servicing Group..................           4
Mortgage Loans.................................           1
Mortgage Notes.................................          11
Mortgage Pool..................................           1
Mortgage Pool Insurance Policy.................           6
Mortgaged Properties...........................          11
Mortgages......................................          11
Mortgagor......................................           7
Net Rate.......................................          28
Non-U.S. Person................................          83
OID Regulations................................          67
Parties in Interest............................          64
Paying Agent...................................          23
Payoff.........................................          17
Plans..........................................          64
Pooling Agreement..............................          15
Prepayment Assumption..........................          69
Primary Insurance Policy.......................           6
Principal Prepayment...........................          19
Private Certificates...........................           8
PTCE 83-1......................................          65
Record Date....................................          23
Regulation.....................................          65
Relief Act.....................................          62
REMIC..........................................           1
REMIC Certificates.............................          67
REMIC Mortgage Pool............................          67
REMIC Provisions...............................          67
REMIC Regulations..............................          67
Remittance Rate................................           1
Reserve Account................................          51
Reserve Fund...................................           7
Residual Owner.................................          76
Retained Yield.................................          28
</TABLE>
 
                                       86
<PAGE>
<TABLE>
<CAPTION>
                                                    PAGE
                                                    -----
<S>                                              <C>
Sellers........................................           4
Seller/Servicers...............................           4
Selling and Servicing Contracts................          22
Senior Certificates............................          51
Series.........................................           1
Servicer.......................................           4
Servicing Contracts............................          14
Servicing Entity...............................           4
Servicing Fee..................................          14
Special Hazard Instrument......................          49
Special Hazard Insurance Policy................           7
<CAPTION>
                                                    PAGE
                                                    -----
<S>                                              <C>
Special Hazard Loss............................          48
Subordinated Certificates......................          51
Title V........................................          63
Title VIII.....................................          63
Trustee........................................          15
Trust Fund.....................................           1
UCC............................................          60
VA.............................................          12
VA Guaranties..................................          12
VA Loans.......................................          12
Withdrawal Date................................          29
</TABLE>
 
                                       87
<PAGE>
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                                  PNC MORTGAGE
                                SECURITIES CORP.
 
                          DEPOSITOR, A MASTER SERVICER
                         AND CERTIFICATE ADMINISTRATOR
 
                                    MORTGAGE
                           PASS-THROUGH CERTIFICATES
 
                                 SERIES 1997-8
                                  $828,189,236
                                 (APPROXIMATE)
 
                               ------------------
 
                             PROSPECTUS SUPPLEMENT
 
                             ---------------------
 
                          DONALDSON, LUFKIN & JENRETTE
      SECURITIES CORPORATION
 
                               NOVEMBER 24, 1997
 
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