BA MORTGAGE SECURITIES INC/
424B5, 1998-11-23
ASSET-BACKED SECURITIES
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<PAGE>   1
                                                Filed Pursuant to Rule 424(b)(5)
                                                      Registration No. 333-53933

          PROSPECTUS SUPPLEMENT TO PROSPECTUS DATED NOVEMBER 18, 1998
 
                          BA MORTGAGE SECURITIES, INC.
                                   Depositor
 
                              BANK OF AMERICA, FSB
                                Master Servicer
 
               MORTGAGE PASS-THROUGH CERTIFICATES, SERIES 1998-6
                                  $397,395,732
                                 (APPROXIMATE)
 CONSIDER CAREFULLY THE RISK
 FACTORS BEGINNING ON PAGE S-9
 IN THIS PROSPECTUS SUPPLEMENT
 AND PAGE 5 IN THE
 PROSPECTUS.
 A certificate is not a deposit
 and is not insured or
 guaranteed by the Federal
 Deposit Insurance Corporation
 or any other governmental
 agency.
 The certificates will
 represent interests only in
 the trust created for Series
 1998-6 and will not represent
 interests in or obligations of
 BA Mortgage Securities, Inc.,
 Bank of America, FSB or any of
 their affiliates.
 This prospectus supplement may
 be used to offer and sell the
 offered certificates only if
 
 accompanied by the prospectus.
                                  THE SERIES 1998-6 TRUST WILL CONSIST PRIMARILY
                                  OF CONVENTIONAL ONE-TO FOUR-FAMILY RESIDENTIAL
                                  MORTGAGE LOANS. THE TRUST WILL ISSUE TWENTY-
                                  THREE CLASSES OF OFFERED CERTIFICATES. EACH
                                  CLASS OF OFFERED CERTIFICATES WILL RECEIVE
                                  MONTHLY DISTRIBUTIONS OF INTEREST, PRINCIPAL
                                  OR BOTH. THE TABLE ON PAGE S-4 OF THIS
                                  PROSPECTUS SUPPLEMENT CONTAINS A LIST OF THE
                                  CLASSES OF OFFERED CERTIFICATES, INCLUDING THE
                                  INITIAL PRINCIPAL BALANCE, INTEREST RATE,
                                  INITIAL RATING AND DESIGNATIONS OF EACH CLASS.
 
<TABLE>
<CAPTION>
                                                               OFFERED CERTIFICATES
                                                               --------------------
                                                   <S>                                          <C>
                                                   Total initial principal balance              $397,395,732
                                                     (approximate)
                                                   First payment date                           December 28, 1998
                                                   Interest and/or principal paid               Monthly
                                                   Last possible payment date                   December 26, 2028
</TABLE>
 
The trust will also issue three classes of certificates that will not be offered
                                  by this prospectus supplement. The total
                                  initial principal balance of the private
                                  certificates is approximately $3,204,805.
                                  These private certificates are subordinated to
                                  the offered certificates and provide credit
                                  enhancement for the offered certificates.
 
The underwriter listed below will offer the offered certificates at varying
prices to be determined at the time of sale. The proceeds to BA Mortgage
Securities, Inc. from the sale of the offered certificates will be approximately
98.41% of the principal balance of the offered certificates plus accrued
interest, net of expenses payable by the depositor. The underwriter's commission
will be the difference between the price it pays to BA Mortgage Securities, Inc.
for the offered certificates and the amount it receives from the sale of the
offered certificates to the public. BA Mortgage Securities, Inc. and Bank of
America, FSB have agreed to indemnify the underwriter against certain
liabilities. See "METHOD OF DISTRIBUTION" in this prospectus supplement.
 
NEITHER THE SECURITIES AND EXCHANGE COMMISSION NOR ANY STATE SECURITIES
COMMISSION HAS APPROVED OR DISAPPROVED OF THE OFFERED CERTIFICATES OR DETERMINED
THAT THIS PROSPECTUS SUPPLEMENT OR THE PROSPECTUS IS ACCURATE OR COMPLETE. ANY
REPRESENTATION TO THE CONTRARY IS A CRIMINAL OFFENSE.
 
                                  Underwriter
 
                          DONALDSON, LUFKIN & JENRETTE
                             SECURITIES CORPORATION
 
                               November 18, 1998
<PAGE>   2
 
                  IMPORTANT NOTICE ABOUT INFORMATION PRESENTED
         IN THIS PROSPECTUS SUPPLEMENT AND THE ACCOMPANYING PROSPECTUS
 
     We provide information to you about the offered certificates in two
separate documents that progressively provide more detail: (a) the accompanying
prospectus, which provides general information, some of which may not apply to
your series of certificates and (b) this prospectus supplement, which describes
the specific terms of your series of certificates.
 
     IF THE TERMS OF YOUR CERTIFICATES VARY BETWEEN THIS PROSPECTUS SUPPLEMENT
AND THE ACCOMPANYING PROSPECTUS, YOU SHOULD RELY ON THE INFORMATION IN THIS
PROSPECTUS SUPPLEMENT.
 
     We include cross-references in this prospectus supplement and the
accompanying prospectus to captions in these materials where you can find
further related discussions. The following table of contents and the table of
contents included in the accompanying prospectus provide the pages on which
these captions are located.
 
     You can find a listing of the pages where capitalized terms used in this
prospectus supplement and the accompanying prospectus are defined under the
caption "INDEX OF PRINCIPAL DEFINITIONS" in this prospectus supplement and under
the caption "INDEX OF PRINCIPAL DEFINITIONS" in the accompanying prospectus.
 
     BA Mortgage Securities, Inc.'s principal offices are located at 345
Montgomery Street, Lower Level #2, Unit #8152, San Francisco, California 94104
and its phone number is (415) 622-3676.
                            ------------------------
 
     This prospectus supplement and the accompanying prospectus contain
forward-looking statements within the meaning of Section 27A of the Securities
Act of 1933, as amended. Such forward-looking statements, together with related
qualifying language and assumptions, are found in the material, including each
of the tables, set forth under "RISK FACTORS," "RECENT DEVELOPMENTS" and
"CERTAIN YIELD AND PREPAYMENT CONSIDERATIONS." Forward-looking statements are
also found elsewhere in this prospectus supplement and the prospectus, and may
be identified by, among other things, accompanying language including the words
"expects," "intends," "anticipates," "estimates" or analogous expressions, or by
qualifying language or assumptions. Such statements involve known and unknown
risks, uncertainties and other important factors that could cause the actual
results or performance to differ materially from such forward-looking
statements. Such risks, uncertainties and other factors include, among others,
general economic and business conditions, competition, changes in political,
social and economic conditions, regulatory initiatives and compliance with
government regulations, customer preference and various other matters, many of
which are beyond the Depositor's control. These forward-looking statements speak
only as of the date of this prospectus supplement. The Depositor expressly
disclaims any obligation or undertaking to disseminate any updates or revisions
to such forward-looking statements to reflect any change in the Depositor's
expectations with regard thereto or any change in events, conditions or
circumstances on which any forward-looking statement is based.
 
                                       S-2
<PAGE>   3
 
                               TABLE OF CONTENTS
 
<TABLE>
<CAPTION>
                                        PAGE
                                        ----
<S>                                     <C>
OFFERED CERTIFICATES..................   S-4
SUMMARY INFORMATION...................   S-5
RISK FACTORS..........................   S-9
RECENT DEVELOPMENTS...................  S-11
  BankAmerica Corporation.............  S-11
  Year 2000 Project...................  S-11
DESCRIPTION OF THE MORTGAGE POOL......  S-13
  General.............................  S-13
  Primary Mortgage Insurance and
     Primary Hazard Insurance.........  S-17
  Additional Information..............  S-18
DESCRIPTION OF THE CERTIFICATES.......  S-18
  General.............................  S-18
  Book-Entry Registration.............  S-19
  Available Distribution Amount.......  S-20
  Priority of Distributions...........  S-20
  Interest Distributions..............  S-22
  LIBOR...............................  S-23
  Principal Distributions.............  S-24
  Distributions in Reduction of the
     Special Retail Certificates......  S-29
  Allocation of Losses;
     Subordination....................  S-32
  Advances............................  S-34
  Last Scheduled Distribution Date....  S-35
CERTAIN YIELD AND PREPAYMENT
  CONSIDERATIONS......................  S-35
</TABLE>
 
<TABLE>
<CAPTION>
                                        PAGE
                                        ----
<S>                                     <C>
  LIBOR Certificate Yield
     Considerations...................  S-43
  Yield Considerations with Respect to
     the Principal Only
     Certificates.....................  S-44
  Yield Considerations with Respect to
     the Senior Subordinate
     Certificates.....................  S-45
POOLING AGREEMENT.....................  S-48
  General.............................  S-48
  The Master Servicer.................  S-48
  Servicing and Other Compensation and
     Payment of Expenses..............  S-48
  Special Servicing Agreements........  S-48
  Termination; Optional Repurchase of
     Mortgage Loans...................  S-49
FEDERAL INCOME TAX CONSEQUENCES.......  S-49
  Special Tax Considerations
     Applicable to the Class R
     Certificates.....................  S-51
 
METHOD OF DISTRIBUTION................  S-52
 
LEGAL OPINIONS........................  S-53
 
RATING................................  S-53
 
LEGAL INVESTMENT......................  S-53
 
ERISA CONSIDERATIONS..................  S-54
 
INDEX OF PRINCIPAL DEFINITIONS........  S-57
</TABLE>
 
                                       S-3
<PAGE>   4
 
                              OFFERED CERTIFICATES
 
<TABLE>
<CAPTION>
                           APPROXIMATE                      INITIAL RATING
                       INITIAL CERTIFICATE   PASS-THROUGH     (MOODY'S/
        CLASS           PRINCIPAL BALANCE        RATE       FITCH IBCA)(1)     DESIGNATION(S)
<S>                    <C>                   <C>            <C>              <C>
- -----------------------------------------------------------------------------------------------
A-1                       $106,336,443           6.250%       Aaa/AAA              Senior
- -----------------------------------------------------------------------------------------------
A-2                       $169,854,628           6.250%       Aaa/AAA              Senior
- -----------------------------------------------------------------------------------------------
A-3                       $  3,780,005           7.000%       Aaa/AAA              Senior
- -----------------------------------------------------------------------------------------------
A-4                       $ 38,457,652           6.250%       Aaa/AAA          Senior/Lockout
- -----------------------------------------------------------------------------------------------
A-5                       $  9,871,494           6.750%       Aaa/AAA              Senior
- -----------------------------------------------------------------------------------------------
A-6                       $  2,381,997           0.000%       Aaa/AAA             Senior/
                                                                               Principal Only
- -----------------------------------------------------------------------------------------------
A-7                       $  4,560,673           6.500%       Aaa/AAA              Senior
- -----------------------------------------------------------------------------------------------
A-8                       $ 20,030,000           6.250%       Aaa/AAA              Senior
- -----------------------------------------------------------------------------------------------
A-9                       $ 10,015,013           6.500%       Aaa/AAA              Senior
- -----------------------------------------------------------------------------------------------
A-10                      $    400,601           0.000%       Aaa/AAA             Senior/
                                                                               Principal Only
- -----------------------------------------------------------------------------------------------
A-11                      $  3,780,006           6.500%       Aaa/AAA              Senior
- -----------------------------------------------------------------------------------------------
A-12                      $  4,839,027           7.000%       Aaa/AAA             Senior/
                                                                               Special Retail
- -----------------------------------------------------------------------------------------------
A-13                      $    179,224           0.000%       Aaa/AAA             Senior/
                                                                               Principal Only
- -----------------------------------------------------------------------------------------------
A-14                      $  2,244,655           6.250%       Aaa/AAA              Senior
- -----------------------------------------------------------------------------------------------
A-15                      $  3,093,004           6.500%       Aaa/AAA             Senior/
                                                                               Special Retail
- -----------------------------------------------------------------------------------------------
A-16                      $  2,328,283           7.000%       Aaa/AAA              Senior
- -----------------------------------------------------------------------------------------------
A-17                      $    179,099           0.000%       Aaa/AAA             Senior/
                                                                               Principal Only
- -----------------------------------------------------------------------------------------------
A-18                      $  1,893,933              (2)       Aaa/AAA           Senior/LIBOR
- -----------------------------------------------------------------------------------------------
A-19                      $    350,729              (3)       Aaa/AAA          Senior/LIBOR/
                                                                              Inverse Floater
- -----------------------------------------------------------------------------------------------
M                         $  7,811,709           6.250%        NA/AA         Senior Subordinate
- -----------------------------------------------------------------------------------------------
B-1                       $  3,405,105           6.250%        NA/A          Senior Subordinate
- -----------------------------------------------------------------------------------------------
B-2                       $  1,602,402           6.250%       NA/BBB         Senior Subordinate
- -----------------------------------------------------------------------------------------------
R                         $         50           6.250%       Aaa/AAA           Senior/REMIC
                                                                                  Residual
- -----------------------------------------------------------------------------------------------
</TABLE>
 
(1) See "RATING" in this prospectus supplement.
 
(2) The pass-through rate on the Class A-18 Certificates for the initial
    distribution date will be 6.175% per annum, and for all subsequent
    distribution dates will be a per annum rate equal to LIBOR (as defined in
    "DESCRIPTION OF THE CERTIFICATES--LIBOR" in this prospectus supplement) plus
    0.800%, with a minimum pass-through rate of 0.800% per annum and a maximum
    pass-through rate of 8.000% per annum.
 
(3) The pass-through rate on the Class A-19 Certificates for the initial
    distribution date will be 9.855% per annum, and for all subsequent
    distribution dates will be a per annum rate equal to 38.880% minus the
    product of LIBOR and 5.4, with a minimum pass-through rate of 0.000% per
    annum and a maximum pass-through rate of 38.880% per annum.
 
                                       S-4
<PAGE>   5
 
                              SUMMARY INFORMATION
 
THE FOLLOWING SUMMARY HIGHLIGHTS SELECTED INFORMATION FROM THIS PROSPECTUS
SUPPLEMENT AND DOES NOT CONTAIN ALL OF THE INFORMATION THAT YOU NEED TO CONSIDER
IN MAKING YOUR INVESTMENT DECISION. THE CALCULATIONS, CASH FLOWS AND OTHER
INFORMATION IN THIS SUMMARY ARE QUALIFIED BY THE FULL DESCRIPTION OF THESE
CALCULATIONS, CASH FLOWS AND OTHER INFORMATION IN THIS PROSPECTUS SUPPLEMENT AND
THE ACCOMPANYING PROSPECTUS. TO UNDERSTAND THE TERMS OF THE OFFERED
CERTIFICATES, READ CAREFULLY THIS ENTIRE PROSPECTUS SUPPLEMENT AND THE
ACCOMPANYING PROSPECTUS.
 
CAPITALIZED TERMS USED IN THIS PROSPECTUS SUPPLEMENT AND NOT OTHERWISE DEFINED
HEREIN HAVE THE MEANINGS ASSIGNED IN THE PROSPECTUS.
 
<TABLE>
  <S>                    <C>
  TITLE OF               Mortgage Pass-Through
  SERIES:                Certificates, Series 1998-6
  DEPOSITOR:             BA Mortgage Securities, Inc.
  SELLERS:               Bank of America, FSB
                         Bank of America National
                         Trust and Savings
                         Association
  MASTER
  SERVICER:              Bank of America, FSB
  TRUSTEE:               The Bank of New York
  CUT-OFF DATE:          November 1, 1998
  CLOSING DATE:          On or about November 20,
                         1998
  DISTRIBUTION DATES:    The 25th day of each month,
                         beginning in December, 1998.
                         If the 25th day is not a
                         business day, then the
                         distribution date will be
                         the next business day.
</TABLE>
 
WHAT YOU OWN
 
Your certificates will represent ownership of a
portion of the Series 1998-6 Trust. The trust will contain a pool of mortgage
loans secured by
residential properties with original terms to maturity of not more than 30
years.
 
THE OFFERED CERTIFICATES WILL REPRESENT INTERESTS ONLY IN THE ASSETS OF THE
TRUST. ALL PAYMENTS TO YOU WILL COME ONLY FROM THE AMOUNTS RECEIVED IN
CONNECTION WITH THOSE ASSETS.
 
INFORMATION ABOUT THE MORTGAGE POOL
 
The mortgage loans have the following characteristics as of cut-off date:
 
<TABLE>
<S>                          <C>
Number of mortgage loans...  1,186
Minimum principal balance
  at origination...........  $41,289
Maximum principal balance
  at origination...........  $1,000,000
Average principal balance
  at origination...........  $338,210
Range of mortgage rates....  6.625% to 8.500%
Weighted average mortgage
  rate.....................  7.266%
Weighted average remaining
  term to maturity.........  357 months
</TABLE>
 
For a further description of the mortgage loans, see "DESCRIPTION OF THE
MORTGAGE POOL" in this prospectus supplement.
 
THE CERTIFICATES
 
The depositor will deposit the mortgage loans into the trust. The trust has been
created for the purpose of issuing the Mortgage Pass-Through Certificates,
Series 1998-6.
 
The senior certificates in the aggregate and the Class M, Class B-1 and Class
B-2 Certificates, will have initial certificate principal balances which
represent 96.00%, 1.95%, 0.85% and 0.40%, respectively, of the initial aggregate
principal balance of the mortgage loans.
 
THE OFFERED CERTIFICATES
 
As of the cut-off date, the offered certificates will have the initial
certificate principal balances, pass-through rates, initial ratings and
designations shown in the table on page S-4 of this prospectus supplement.
 
THE PRIVATE CERTIFICATES
 
In addition to the offered certificates, the trust will issue the Class B-3,
Class B-4 and Class B-5 Certificates. These private certificates will be
subordinated to the offered certificates and provide credit enhancement for the
offered certificates. The Class B-3, Class B-4 and Class B-5 Certificates are
not being offered by this prospectus supplement.
 
                                       S-5
<PAGE>   6
 
DISTRIBUTIONS ON THE OFFERED
CERTIFICATES
 
PRIORITY OF DISTRIBUTIONS
 
General:  Mortgagors will pay interest and principal during the month to a
subservicer or, if there is not a subservicer for a mortgage loan, to the master
servicer. Each month, if there is a subservicer, the subservicer will subtract
its servicing fee and send the remainder to the master servicer. The master
servicer will then subtract its master servicing fee and, if there is not a
subservicer, its servicing fee, and send the remainder to the trustee. On the
distribution date for that month, the trustee will subtract its trustee fee and
distribute the remaining amount to the certificate holders, as follows:
 
Step 1: The senior certificates entitled to interest will receive accrued and
unpaid interest.
 
Step 2: The senior certificates entitled to principal will receive principal.
NOT ALL CLASSES OF SENIOR CERTIFICATES WILL RECEIVE PRINCIPAL DISTRIBUTIONS ON
EACH DISTRIBUTION DATE.
 
Step 3: Each class of subordinate certificates will receive interest and then
principal in the following order of seniority, with both interest and principal
being paid to one class before any payments are made to the next class: Class M,
Class B-1, Class B-2, Class B-3, Class B-4 and Class B-5.
 
Step 4: The Class R Certificates will receive any remaining amount on each
distribution date, which is expected to be zero.
 
For a complete description of the order and priority of distributions, see
"DESCRIPTION OF THE CERTIFICATES--Priority of Distributions" in this prospectus
supplement.
 
DISTRIBUTIONS OF INTEREST
 
Each class of offered certificates entitled to interest will be entitled to
receive monthly distributions of interest on each distribution date. However,
each class of offered certificates will receive such distributions in the order
described above. It is possible that on any given distribution date, there will
be insufficient payments from the mortgage loans so that some class of
certificates, most likely the subordinate certificates, may not receive the full
amount of such interest distributions. If this happens, those certificates will
be entitled to receive any shortfall in interest distributions in the following
month in the same priority as their distribution of current interest. However,
there will be no extra interest paid to make up for the delay.
The amount of interest each class of certificates accrues each month will equal
1/12th of the annual interest rate for that class of certificates multiplied by
the related certificate principal balance. The certificate principal balance
used for this calculation on the first distribution date will be the applicable
balance as of November 20, 1998. The certificate principal balance used for this
calculation on any other distribution date will be the applicable balance
immediately after the preceding distribution date. The annual interest rate for
each class of offered certificates entitled to interest is set forth in the
table on page S-4 of this prospectus supplement.
 
Compensating Interest and Interest Shortfalls. When mortgagors make prepayments
in full or in part, they need not pay a full month's interest. Instead, they are
required to pay interest only to the date of such prepayment. In order to
compensate certificateholders for the shortfall in interest this will cause, the
master servicer will pay compensating interest to the certificateholders out of
a portion of the servicing fee it will collect. See "DESCRIPTION OF THE
CERTIFICATES--
Interest Distributions" and "CERTAIN YIELD AND PREPAYMENT CONSIDERATIONS" in
this prospectus supplement for a description of how compensating interest will
be allocated among the certificates as well as important limitations on the
amount of compensating interest that will be allocated among the certificates.
 
DISTRIBUTIONS OF PRINCIPAL
 
General. As the mortgagors pay principal on the mortgage loans in the trust,
that principal will be passed on to the certificateholders. HOWEVER, NOT EVERY
CLASS OF CERTIFICATES WILL RECEIVE PRINCIPAL ON EACH DISTRIBUTION DATE.
 
Senior Certificates. On each distribution date, the senior certificates in the
aggregate will receive a certain amount of the principal received on all of the
mortgage loans. Not all senior certificates will receive principal on each
distribution date. See "CERTAIN YIELD AND PREPAYMENT CONSIDERATIONS" in this
prospectus supplement for a table showing for each class of offered certificates
the projected weighted average life at different rates of prepayments on the
mortgage loans.
 
                                       S-6
<PAGE>   7
 
Subordinate Certificates. On each distribution date, the subordinate
certificates in the aggregate will receive a certain amount of the principal
received on all of the mortgage loans pro rata according to their certificate
principal balances. However, under certain conditions, the amount of principal
prepayments owed to some classes of subordinate certificates will be paid to
other classes of subordinate certificates with a higher priority.
 
Each class of certificates will receive its principal entitlements described
above in the priority described in "DESCRIPTION OF THE CERTIFICATES--Priority of
Distributions." It is therefore possible that on any given distribution date,
there will be insufficient payments from the mortgage loans so that some
certificates (most likely the subordinate certificates) may not receive the full
amount of principal distributions to which they would otherwise be entitled.
 
For a more detailed description of how distributions of principal will be
allocated among the various classes of certificates, see "DESCRIPTION OF THE
CERTIFICATES--Principal Distributions" in this prospectus supplement.
 
ALLOCATION OF LOSSES
 
A loss will be realized on a mortgage loan when the subservicer or master
servicer determines that it has received all amounts it expects to recover from
that loan and that amount is less than the outstanding principal balance of such
loan and accrued and unpaid interest. LOSSES WILL BE ALLOCATED TO THE
CERTIFICATES BY DEDUCTING SUCH LOSSES FROM THE PRINCIPAL BALANCE OF THE
CERTIFICATES WITHOUT MAKING ANY PAYMENTS TO THE CERTIFICATEHOLDERS. In general,
the amount of such losses will be allocated to the most junior class of
subordinate certificates then outstanding. Except for specified amounts of
certain losses as described herein, generally losses will be allocated to the
senior certificates only after the principal balances of all of the subordinate
certificates have been reduced to zero.
 
For a more detailed description of the allocation of realized losses among the
certificates, see "DESCRIPTION OF THE CERTIFICATES--Allocation of Losses;
Subordination" in this prospectus supplement.
 
CREDIT ENHANCEMENTS
 
Subordination. The senior certificates will receive all distributions of
interest and principal before the subordinate certificates are entitled to
receive any distributions of interest or principal. This provides credit
enhancement to the senior certificates. In a similar fashion, each class of
subordinate certificates will provide credit enhancement to all other
subordinate certificates with a higher payment priority.
 
Shifting of Interests. The senior certificates in the aggregate will receive
100% of principal prepayments received on the mortgage loans until the fifth
anniversary of the first distribution date. During the next four years, the
senior certificates in the aggregate will receive a disproportionately large,
but decreasing, share of principal prepayments. This will result in a quicker
return of principal to the senior certificates and increases the likelihood that
holders of the senior certificates will be paid the full amount of principal to
which they are entitled. For a more detailed description of how principal
prepayments are allocated among the senior certificates and the subordinate
certificates, see "DESCRIPTION OF THE CERTIFICATES--Principal Distributions" in
this prospectus supplement.
 
ADVANCES
 
For any month, if a subservicer or the master servicer receives a payment on a
mortgage loan that is less than the full scheduled payment or if no payment is
received at all, such subservicer or the master servicer will advance its own
funds to cover that shortfall. However, a subservicer or the master servicer
will make advances only so long as it determines that such advance will be
recoverable from future payments or collections on that mortgage loan. See
"DESCRIPTION OF THE CERTIFICATES--Advances" in this prospectus supplement.
 
OPTIONAL TERMINATION
 
On any distribution date on which the aggregate outstanding principal balance of
the mortgage loans is less than 10% of their aggregate principal balance as of
the cut-off date, the master servicer may, but will not be required to, purchase
from the trust all remaining mortgage loans and thereby cause an early
retirement of the certificates. An optional repurchase will cause the
outstanding principal balance of the certificates to be paid in full with
accrued interest. However, there will be no reimbursement of principal
reductions or related interest that resulted from losses allocated to the
certificates. See "POOLING AGREEMENT--Termination; Optional Repurchase of
Mortgage Loans" in
                                       S-7
<PAGE>   8
 
this prospectus supplement and "THE POOLING AGREEMENT--Termination" in the
prospectus.
 
YIELD CONSIDERATIONS
 
The yield to maturity of each class of offered certificates will depend upon,
among other things:
 
- - the price at which such certificates are purchased;
 
- - the applicable interest rate, if any; and
 
- - the rate of prepayments on the mortgage loans.
 
Certain classes of offered certificates will be especially sensitive to the rate
of prepayments. For a discussion of special yield and prepayment considerations
applicable to these classes of certificates, see "RISK FACTORS" and "CERTAIN
YIELD AND PREPAYMENT CONSIDERATIONS" in this prospectus supplement.
 
FORM OF CERTIFICATES
 
In general, the offered certificates, other than the Class R Certificates, will
be available only in book-entry form through the facilities of The Depository
Trust Company. See "DESCRIPTION OF THE CERTIFICATES--Book-Entry Registration" in
this prospectus supplement. The Class R Certificates will be available only in
registered, certificated form.
 
DENOMINATIONS
 
The offered certificates, other than the Class A-3, Class A-7, Class A-11, Class
A-12, Class A-14, Class A-15, Class A-16 and Class R Certificates, are offered
in minimum denominations of $100,000 each and multiples of $1 in excess of that
amount. The Class A-3, Class A-7, Class A-11, Class A-12, Class A-14, Class A-15
and Class A-16 are offered in minimum denominations of $1,000 each and multiples
of $1 in excess of that amount. The Class R Certificates will have an initial
principal balance of $50 and will be offered in a single certificate that
represents a 99.99% interest in the class.
 
RATING
 
When issued, the offered certificates will receive the initial ratings from
Moody's Investors Service and Fitch IBCA, Inc. indicated in the table on page S-
4 of this prospectus supplement. The ratings on the offered certificates address
the likelihood of the receipt by holders of offered certificates of all
distributions on the underlying mortgage loans to which they are entitled. They
do not address the likely actual rate of prepayments. Such rate of prepayments,
if different than originally anticipated, could adversely affect the yield
realized by holders of the offered certificates.
 
LEGAL INVESTMENT
 
When issued, the senior certificates and Class M Certificates will, and the
Class B-1 and Class B-2 Certificates will not, constitute "mortgage related
securities" for purposes of the Secondary Mortgage Market Enhancement Act of
1984. See "LEGAL INVESTMENT" in this prospectus supplement for important
information concerning possible restrictions on ownership of the offered
certificates by regulated institutions. You should consult your own legal
advisors in determining whether and to what extent the offered certificates
constitute legal investments for you.
 
ERISA CONSIDERATIONS
 
The senior certificates other than the Class R Certificates may be eligible for
purchase by persons investing assets of employee benefit plans or individual
retirement accounts, subject to important considerations. Sales of the Class M,
Class B-1, Class B-2 and Class R Certificates to most such plans or retirement
accounts are prohibited, except as may be permitted under an exemption available
to insurance companies using general accounts.
 
See "ERISA CONSIDERATIONS" in this prospectus supplement and in the prospectus.
 
TAX STATUS
 
For federal income tax purposes, an election will be made to treat the trust as
a real estate mortgage investment conduit. The certificates, other than the
Class R Certificates, will represent ownership of regular interests in the
trust. 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 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.
 
For further information regarding the federal income tax consequences of
investing in the offered certificates, including important information regarding
the tax treatment of the Class R Certificates, see "FEDERAL INCOME TAX
CONSEQUENCES" in this prospectus supplement and in the accompanying prospectus.
 
                                       S-8
<PAGE>   9
 
                                  RISK FACTORS
 
THE OFFERED CERTIFICATES ARE NOT SUITABLE INVESTMENTS FOR ALL INVESTORS. IN
PARTICULAR, YOU SHOULD NOT PURCHASE ANY CLASS OF OFFERED CERTIFICATES UNLESS YOU
UNDERSTAND AND ARE ABLE TO BEAR THE PREPAYMENT, CREDIT, LIQUIDITY AND MARKET
RISKS ASSOCIATED WITH THAT CLASS.
THE OFFERED CERTIFICATES ARE COMPLEX SECURITIES AND IT IS IMPORTANT THAT YOU
POSSESS, EITHER ALONE OR TOGETHER WITH AN INVESTMENT ADVISOR, THE EXPERTISE
NECESSARY TO EVALUATE THE INFORMATION CONTAINED IN THIS PROSPECTUS SUPPLEMENT
AND THE ACCOMPANYING PROSPECTUS IN THE CONTEXT OF YOUR FINANCIAL SITUATION.
THE YIELD ON THE
OFFERED CERTIFICATES
IS
DIRECTLY RELATED TO
THE RATE OF
PREPAYMENTS ON THE
MORTGAGE LOANS       The offered certificates will represent an interest in a
                     trust containing mortgage loans. As the mortgagors make
                     payments of interest and principal on their mortgage loans,
                     payments will be made to the certificateholders. Because
                     the mortgagors are free to make those payments faster than
                     expected, certificateholders may receive distributions
                     faster than expected. There is no guarantee that
                     certificateholders will receive principal payments on their
                     certificates at any specific rate.
 
                     The yield to maturity on the offered certificates is
                     directly related to the rate at which the mortgagors pay
                     principal on the mortgage loans. Payment of principal on
                     the mortgage loans may be in the following forms:
 
                     - scheduled payments of principal;
                     - the principal portion of repurchase proceeds, which are
                       amounts paid by the master servicer or a seller upon a
                       repurchase of any mortgage loan in accordance with the
                       pooling and servicing agreement; and
                     - principal prepayments which generally consist of:
                          - prepayments in full on a mortgage loan;
                          - partial prepayments on a mortgage loan; and
                          - liquidation principal, which is the principal
                            recovered after foreclosing on or otherwise
                            liquidating a defaulted mortgage loan.
 
                     In general, as prevailing mortgage interest rates decline
                     significantly below the interest rates on the mortgage
                     loans, the rate of prepayments increases. General economic
                     conditions and homeowner mobility will also affect the rate
                     of prepayments. All of the mortgage loans contain
                     "due-on-sale" clauses. Therefore, the sale of any mortgaged
                     property will cause a prepayment in full on the related
                     mortgage loan. See "MATURITY AND PREPAYMENT CONSIDERATIONS"
                     in the prospectus and "CERTAIN YIELD AND PREPAYMENT
                     CONSIDERATIONS" in this prospectus supplement. The rate of
                     prepayments will affect the yield on all of the offered
                     certificates. However, if you purchase a Class A-6, Class
                     A-10, Class A-13 or Class A-17 Certificate, the rate of
                     prepayments will be especially important to you.
 
SLOW PREPAYMENTS
WILL REDUCE THE
YIELD ON THE
CLASS A-6,
CLASS A-10,
CLASS A-13 AND
CLASS A-17
CERTIFICATES         Because holders of the Class A-6, Class A-10, Class A-13
                     and Class A-17 Certificates receive only distributions of
                     principal, they will be adversely affected by slower than
                     expected prepayments of principal. See "CERTAIN YIELD AND
                     PREPAYMENT CONSIDERATIONS--Yield Considerations with
                     Respect to the Principal Only Certificates" in this
                     prospectus supplement for a table showing expected yields
                     at different rates of prepayment.
 
                                       S-9
<PAGE>   10
 
CERTIFICATES BOUGHT
AT
PREMIUMS AND
DISCOUNTS MAY
RECEIVE A LOWER YIELD
THAN EXPECTED        If you purchase a certificate at a discount from its
                     original principal balance and the rate of principal
                     payments is slower than you expected, you may receive a
                     lower yield than you anticipated. If you purchase a
                     certificate at a premium over its original principal
                     balance and the rate of principal payments is faster than
                     you expected, you may receive a lower yield than you
                     anticipated.
 
LOSSES ON THE
MORTGAGE LOANS WILL
REDUCE THE YIELD ON
THE OFFERED
CERTIFICATES         The yield to maturity on the subordinate certificates that
                     are offered will be extremely sensitive to realized losses
                     on the mortgage loans other than certain types of losses as
                     described herein. After the principal balance of all of the
                     privately offered certificates has been reduced to zero,
                     most losses on the mortgage loans will be allocated
                     exclusively to the publicly offered subordinate
                     certificates, other than certain types of losses as
                     described herein. In addition, if the principal balance of
                     all of the subordinate certificates has been reduced to
                     zero, all losses on the mortgage loans will be allocated to
                     the senior certificates. See "DESCRIPTION OF THE
                     CERTIFICATES--Allocation of Losses; Subordination" in this
                     prospectus supplement.
 
CLASS A-12 AND
CLASS A-15
CERTIFICATES MAY NOT
RECEIVE PRINCIPAL
DISTRIBUTIONS WHEN
REQUESTED            WHEN CONSIDERING INVESTING IN THE CLASS A-12 OR CLASS A-15
                     CERTIFICATES YOU SHOULD NOTE THAT, BASED ON THE STRUCTURING
                     ASSUMPTIONS AND A PREPAYMENT ASSUMPTION OF 275% SPA, NO
                     DISTRIBUTIONS OF PRINCIPAL ARE EXPECTED TO BE MADE ON THE
                     CLASS A-12 AND CLASS A-15 CERTIFICATES UNTIL THE
                     DISTRIBUTION DATES IN JUNE 2016 AND AUGUST 2012,
                     RESPECTIVELY. Once principal distributions begin on these
                     classes, distributions of principal to each of the Class
                     A-12 and Class A-15 Certificates will, in general, be paid
                     first to those estates of deceased certificateholders of
                     each such class who request such a distribution and then to
                     those living certificateholders of such class who request
                     such a distribution. In general, priority will be given to
                     the estates of deceased certificateholders of each such
                     class in the order their requests are received. After the
                     requests by the estates of deceased certificateholders of
                     each such class have been met, requests by living
                     certificateholders of such class will be given priority in
                     the order they are received. See "DESCRIPTION OF THE
                     CERTIFICATES--Distributions in Reduction of the Special
                     Retail Certificates--Priority of Requested Distributions"
                     and "--Procedure for Requesting Distributions" in this
                     prospectus supplement. There is no assurance that if you
                     submit a request for a principal distribution on a Class
                     A-12 or Class A-15 Certificate you will receive the
                     requested distribution within any particular time after it
                     is submitted.
 
THE PASS-THROUGH
RATES ON THE
CLASS A-18 AND
CLASS A-19
CERTIFICATES WILL
CHANGE               The pass-through rate on the Class A-18 Certificates will
                     increase directly with, and the pass-through rate on the
                     Class A-19 Certificates will decrease at a multiple with,
                     increases in the level of LIBOR. Accordingly, the yield to
                     maturity on the Class A-18 Certificates will increase, and
                     the yield to maturity on the Class A-19 Certificates will
                     dramatically decrease, with increases in the level of
                     LIBOR. See "CERTAIN YIELD AND PREPAYMENT
                     CONSIDERATIONS--LIBOR Certificate Yield Considerations"
                     herein.
 
THE LACK OF PHYSICAL
CERTIFICATES FOR
CERTAIN OFFERED
CERTIFICATES MAY
CAUSE DELAYS IN
PAYMENT AND CAUSE
DIFFICULTIES IN
PLEDGING OR SELLING
YOUR CERTIFICATE     You will not have a physical certificate if you purchase an
                     offered certificate other than the Class R Certificates. As
                     a result, you will be able to transfer your certificates
                     only through The Depository Trust Company, participating
                     organizations, indirect participants and certain banks.
                     Your ability to pledge your certificate to a person that
                     does not participate in The Depository Trust Company system
                     may be limited because of the lack of a physical
                     certificate. In addition, you may experience some delay in
                     receiving distributions on these certificates because the
                     trustee will not send distributions directly to you.
                     Instead, the trustee will send all distributions to The
                     Depository Trust Company, which will then credit those
                     distributions to the participating organizations. Those
                     organizations will in turn credit accounts you have either
                     directly or indirectly through indirect participants. Also,
                     because investors may be unwilling to purchase securities
                     without delivery of a physical certificate, your
                     certificates may be less liquid in any secondary market
                     that may develop.
                                      S-10
<PAGE>   11
 
                              RECENT DEVELOPMENTS
 
BANKAMERICA CORPORATION
 
     On September 30, 1998, the former BankAmerica Corporation ("BankAmerica"),
the parent corporation of the Sellers, consummated its merger with NationsBank
Corporation ("NationsBank"), and the combined corporation was named BankAmerica
Corporation (the "Corporation").
 
YEAR 2000 PROJECT
 
     General. Because computers frequently use only two digits to recognize
years, on January 1, 2000, many computer systems, as well as equipment that uses
embedded computer chips, may be unable to distinguish between 1900 and 2000. If
not remediated, this problem could create system errors and failures resulting
in the disruption of normal business operations. Since the Year 2000 is a leap
year, there could also be business disruptions as a result of the inability of
many computer systems to recognize February 29, 2000.
 
     In October 1995 and February 1996, respectively, NationsBank and
BankAmerica established project teams to address these issues. Each of these
teams remains in place and continues to work on solving problems related to the
Year 2000. Although each of these Year 2000 teams will proceed according to its
respective work plan, they will capitalize on the best practices of both teams.
 
     Personnel from the Corporation's business segments and project teams are
identifying, analyzing, correcting and testing computer systems throughout the
Corporation ("Systems"). Personnel are also taking inventory of equipment that
uses embedded computer chips (i.e., "non-information technology systems" or
"Infrastructure") and scheduling remediation or replacement of this
Infrastructure, as necessary. Examples of Infrastructure include ATMs, building
security systems, fire alarm systems, identification and access cards, date
stamps and elevators. The NationsBank team tracks Systems and Infrastructure
separately, whereas the BankAmerica team tracks Systems and Infrastructure
collectively ("Projects"). For purposes of this section, the information
provided for Systems and Projects is generally provided on a combined basis.
 
     State of Readiness. The Corporation's Year 2000 efforts are generally
divided into phases for analysis, remediation, testing and compliance. In the
analysis phase, the Corporation identifies Systems/Projects and Infrastructure
that have Year 2000 issues and determines the steps necessary to remediate these
issues. In the remediation phase, the Corporation replaces, modifies or retires
Systems/Projects or Infrastructure, as necessary. During the testing phase, the
Corporation performs testing to ensure that the remediated System/Projects and
Infrastructure accurately process and identify dates. In the compliance phase,
the Corporation internally certifies the Systems/Projects and Infrastructure
that are Year 2000 compliant and implements processes to ensure that the
compliant Systems/Projects and Infrastructure will continue to identify and
process dates accurately through the Year 2000 and thereafter.
 
     As of September 30, 1998, the NationsBank team has identified over 1,500
Systems, and the BankAmerica team has identified approximately 2,900 Projects,
for a total of approximately 4,400 Systems/Projects. In addition, the
NationsBank team has identified over 19,000 Infrastructure items that may have
Year 2000 implications. For Systems/Projects, as of September 30, 1998, the
analysis phase was substantially complete, the remediation phase was
approximately 95% complete, the testing phase was approximately 74% complete and
the compliance phase was approximately 65% complete. For Infrastructure, as of
September 30, 1998, the analysis phase was approximately 80% complete, the
remediation phase was approximately 64% complete, the testing phase was
approximately 70% complete and the compliance phase was approximately 47%
complete. The Corporation expects to substantially complete all phases by June
30, 1999, in accordance with guidelines established by the Federal Financial
Institutions Examination Council.
 
     The Corporation tracks Systems/Projects and Infrastructure for Year
2000-required changes based on a risk evaluation. Of the identified
Systems/Projects and Infrastructure, approximately 1,900 Systems/Projects and
1,800 Infrastructure items have been designated "mission critical" (i.e., if not
made Year 2000 compliant, these Systems/Projects or Infrastructure items would
impact the normal conduct of business). For mission critical Systems/Projects,
as of September 30, 1998, the analysis phase was substantially complete, the
 
                                      S-11
<PAGE>   12
 
remediation phase was approximately 97% complete, the testing phase was
approximately 74% complete and the compliance phase was approximately 65%
complete. The Corporation will also perform "time machine testing" (i.e.,
emulate Year 2000 conditions in a dedicated environment) on selected mission
critical Systems. For mission critical Infrastructure items, as of September 30,
1998, the analysis phase was approximately 89% complete, the remediation phase
was approximately 34% complete, the testing phase was approximately 43% complete
and the compliance phase was approximately 17% complete.
 
     Ultimately, the potential impact of Year 2000 issues will depend not only
on the corrective measures the Corporation undertakes, but also on the way in
which Year 2000 issues are addressed by governmental agencies, businesses and
other entities which provide data to, or receive data from, the Corporation, or
whose financial condition or operational capability is important to the
Corporation as borrowers, vendors, customers or investment opportunities (either
for the Corporation's accounts or for the accounts of others). Accordingly, the
Corporation is communicating with certain of these parties to evaluate any
potential impact on the Corporation.
 
     In particular, the Corporation is contacting its service providers and
software vendors (collectively, "Vendors") and requesting information on their
Year 2000 project plans. Any Vendor which has not provided appropriate
documentation, has not responded timely to the Corporation's inquiries or does
not expect to be compliant until 1999 is placed in an "at risk" category. As of
September 30, 1998, the Corporation has received assurances that approximately
61% of its Vendors, and approximately 75% of its mission critical Vendors, are
Year 2000 ready. As of September 30, 1998, the Corporation has placed
approximately 17% of its Vendors, and approximately 8% of its mission critical
Vendors, in an "at risk" category. In accordance with its contingency plans, the
Corporation will be focusing on these "at risk" mission critical Vendors during
the fourth quarter of 1998 in order to mitigate any potential risk.
 
     In addition, the Corporation has completed Year 2000 risk assessments for
the majority of its commercial credit customers. For any customers deemed higher
risk, on a quarterly basis, the Corporation's Credit Review Committee reviews
the results of customer assessments prepared by the customers' relationship
managers. Weakness in a borrower's Year 2000 strategy is part of the overall
risk assessment process. Risk ratings and exposure strategy are adjusted as
required after consideration of all risk issues. Any impact on the allowance for
credit losses is determined through the normal risk rating process.
 
     The Corporation is also assessing potential Year 2000 risks associated with
its investment advisory and fiduciary activities. Each investment subsidiary has
a defined investment process and is integrating the consideration of Year 2000
issues into that process. When making investment decisions or recommendations,
the Corporation's investment research areas consider the Year 2000 issue as a
factor in their analysis, and may take certain steps to investigate Year 2000
readiness, such as reviewing ratings, research reports and other publicly
available information. In the fiduciary area, the Corporation is assessing Year
2000 risks for business interests, real estate, and mineral interests that are
held in trust.
 
     Costs. The Corporation currently estimates the total cost of the Year 2000
project to be approximately $550 million. Of this amount, the Corporation has
incurred cumulative Year 2000 costs of approximately $353 million through
September 30, 1998. A significant portion of the foregoing cost is not expected
to be incremental to the Corporation but instead will constitute a reallocation
of existing internal systems technology resources and, accordingly, will be
funded from normal operations.
 
     Contingency Plans. The Corporation has existing business continuity plans
that address its response to disruptions to business due to natural disasters,
civil unrest, utility outages or other occurrences. The Corporation is
developing business continuity plans specific to Year 2000 issues that are based
on those existing plans.
 
     The Corporation has made substantial progress on an inventory and
assessment of the existing business contingency plans. Supplements to the
existing plans to address Year 2000 issues are in various stages of development
and will include detailed plans to respond to these events. The Corporation
intends to complete these supplemental business continuity plans by January 31,
1999. During the remainder of 1999, the business
 
                                      S-12
<PAGE>   13
 
continuity plans will be tested and validated with particular attention to event
management and communication processes.
 
     Risks. Although the Corporation's remediation efforts are directed at
reducing its Year 2000 exposure, there can be no assurance that these efforts
will fully mitigate the effect of Year 2000 issues. In the event the Corporation
fails to identify or correct a material Year 2000 problem, there could be
disruptions in normal business operations, which could have a material adverse
effect on the Corporation's results of operations, liquidity or financial
condition. In addition, there can be no assurance that significant foreign and
domestic third parties will adequately address their Year 2000 issues. Further,
there may be some such parties, such as governmental agencies, utilities,
telecommunication companies, financial services vendors and other providers,
where alternative arrangements or resources are not available. Also, risks
associated with some foreign third parties may be greater since there is general
concern that some entities operating outside the United States are not
addressing Year 2000 issues on a timely basis.
 
     In addition to the foregoing, the Corporation is subject to credit risk to
the extent borrowers fail to adequately address Year 2000 issues, to fiduciary
risk to the extent fiduciary assets fail to adequately address Year 2000 issues,
and to liquidity risk to the extent of deposit withdrawals and to the extent its
lenders are unable to provide the Corporation with funds due to Year 2000
issues. Although it is not possible to quantify the potential impact of these
risks at this time, in future years, there may be increases in problem loans,
credit losses, losses in the fiduciary business and liquidity problems, as well
as the risk of litigation and potential losses from litigation related to the
foregoing.
 
     The Trustee has informed the Depositor and the Master Servicer that it will
use commercially reasonable efforts to (i) make the computer hardware and
software owned by the Trustee and used to provide its services under the Pooling
Agreement Year 2000 ready before December 31, 1999, (ii) test software that the
Trustee licenses from third parties to provide services under the Pooling
Agreement and subject to certain conditions, if any such software is not Year
2000 ready by September 30, 1999, obtain replacement software that is warranted
by its vendor as Year 2000 ready and (iii) contact third party service providers
that the Trustee may use to provide services under the Pooling Agreement to
obtain assurances from them that the computer hardware and software used to
provide services under the Pooling Agreement are Year 2000 ready. However, there
can be no assurance that the systems of the Trustee or third parties with which
the Trustee deals will be Year 2000 ready.
 
     If the Master Servicer, any Subservicer, the Trustee or any of their
respective vendors or third party service providers are not Year 2000 ready, the
ability to service the Mortgage Loans (in the case of the Master Servicer, any
Subservicer or any of their respective vendors or third party service providers)
and to make distributions (in the case of the Trustee or any of its vendors or
third party service providers) may be materially and adversely affected.
 
     Forward-looking statements contained in the foregoing "--Year 2000 Project"
section should be read in conjunction with the cautionary statements included in
the introductory paragraphs under "IMPORTANT NOTICE ABOUT INFORMATION PRESENTED
IN THIS PROSPECTUS SUPPLEMENT AND THE ACCOMPANYING PROSPECTUS" on page S-2.
 
                        DESCRIPTION OF THE MORTGAGE POOL
 
GENERAL
 
     The Mortgage Pool will consist of Mortgage Loans with an aggregate
principal balance outstanding as of the Cut-off Date, after deducting payments
of principal due on such date, of approximately $400,600,537.57. The Mortgage
Pool will consist of conventional, fully-amortizing, level monthly payment
one-to four-family first Mortgage Loans with fixed interest rates which have
terms to maturity of not more than 30 years from the date of origination. All of
the Mortgage Loans were originated or acquired by the Sellers, as more fully
described herein and in the Prospectus.
 
                                      S-13
<PAGE>   14
 
     Pursuant to the terms of the Pooling Agreement (as defined herein), the
Depositor shall assign the representations and warranties relating to the
Mortgage Loans made by the Sellers to the Trustee for the benefit of the
Certificateholders as of the Closing Date. To the extent that the applicable
Seller is not able to repurchase a Mortgage Loan in the event of a breach of its
representations and warranties with respect to such Mortgage Loan, none of the
Depositor, the Master Servicer nor any of their affiliates will be required to
repurchase such Mortgage Loan. If there was fraud in the origination of such
Mortgage Loans a limited amount of losses on such Mortgage Loans will be covered
by the Subordination (as defined herein) provided by the Subordinate
Certificates as described herein under "DESCRIPTION OF THE
CERTIFICATES--Allocation of Losses; Subordination."
 
     The description herein of the Mortgage Pool and the Mortgaged Properties is
based upon the Mortgage Loans expected to be included in the Mortgage Pool at
the time the Certificates are issued, using the principal balances of such
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 specially stated or required by
the context. References herein to percentages of Mortgage Loans or percentages
of the Mortgage Pool refer in each case to the approximate percentage of the
aggregate principal balance of all Mortgage Loans, based on the outstanding
principal balances of the Mortgage Loans after giving effect to scheduled
principal payments due on or prior to the Cut-off Date, whether or not actually
received. Unless otherwise stated, 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).
In the following tables, individual balances and percentages may not sum to the
total due to rounding. Prior to the issuance of the Certificates, Mortgage Loans
may be removed from the Mortgage Pool as a result of Principal Prepayments in
full, delinquencies or otherwise. In such event, other Mortgage Loans may be
included in the Mortgage Pool. The actual Mortgage Pool at the time the
Certificates are issued will not vary by more than 5%, based on the principal
balances of the Mortgage Loans constituting the Mortgage Pool at such time, from
the Mortgage Pool described herein. The Depositor 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 Rates and
certain other characteristics of the Mortgage Loans in the Mortgage Pool may
vary. See "--Additional Information" herein.
 
                                 MORTGAGE RATES
 
<TABLE>
<CAPTION>
                                           NUMBER OF       SCHEDULED UNPAID     PERCENTAGE OF
            MORTGAGE RATES               MORTGAGE LOANS    PRINCIPAL BALANCE    MORTGAGE POOL
            --------------               --------------    -----------------    -------------
<S>                                      <C>               <C>                  <C>
6.501 to 6.750%........................         43          $ 14,038,341.86          3.50%
6.751 to 7.000.........................        198            68,083,202.51         17.00
7.001 to 7.250.........................        413           140,572,586.86         35.09
7.251 to 7.500.........................        423           143,257,805.15         35.76
7.501 to 7.750.........................         78            25,589,949.94          6.39
7.751 to 8.000.........................         17             4,941,520.15          1.23
8.001 to 8.250.........................         12             3,582,687.32          0.89
8.251 to 8.500.........................          2               534,443.78          0.13
                                             -----          ---------------         -----
          Total........................      1,186          $400,600,537.57           100%
                                             =====          ===============         =====
</TABLE>
 
     As of the Cut-off Date, the weighted average Mortgage Rate of the Mortgage
Loans will be approximately 7.266% per annum.
 
                                      S-14
<PAGE>   15
 
                   ORIGINAL MORTGAGE LOAN PRINCIPAL BALANCES
 
<TABLE>
<CAPTION>
        ORIGINAL MORTGAGE LOAN             NUMBER OF       SCHEDULED UNPAID     PERCENTAGE OF
           PRINCIPAL BALANCE             MORTGAGE LOANS    PRINCIPAL BALANCE    MORTGAGE POOL
- ---------------------------------------  --------------    -----------------    -------------
<S>                                      <C>               <C>                  <C>
$        0.01 to  100,000.00...........          3          $    231,411.37          0.06%
  200,000.01 to  300,000.00............        581           155,026,662.90         38.70
  300,000.01 to  400,000.00............        380           131,277,394.66         32.77
  400,000.01 to  500,000.00............        127            56,827,245.86         14.19
  500,000.01 to  600,000.00............         52            28,993,534.66          7.24
  600,000.01 to  700,000.00............         39            24,832,932.11          6.20
  700,000.01 to  800,000.00............          2             1,506,136.94          0.38
  900,000.01 to 1,000,000.00...........          2             1,905,219.07          0.48
                                             -----          ---------------         -----
          Total........................      1,186          $400,600,537.57           100%
                                             =====          ===============         =====
</TABLE>
 
     As of the Cut-off Date, the average unpaid principal balance of the
Mortgage Loans will be approximately $337,774.48.
 
                          ORIGINAL LOAN-TO-VALUE RATIO
 
<TABLE>
<CAPTION>
               ORIGINAL
             LOAN-TO-VALUE                 NUMBER OF       SCHEDULED UNPAID     PERCENTAGE OF
               RATIO(%)                  MORTGAGE LOANS    PRINCIPAL BALANCE    MORTGAGE POOL
- ---------------------------------------  --------------    -----------------    -------------
<S>                                      <C>               <C>                  <C>
 0.01 to 60.00% .......................        143          $  51,341,971.17        12.82%
60.01 to 65.00.........................         79             29,129,312.84         7.27
65.01 to 70.00.........................        105             36,102,742.19         9.01
70.01 to 75.00.........................        190             65,537,986.51        16.36
75.01 to 80.00.........................        479            163,916,429.06        40.92
80.01 to 85.00.........................         24              7,299,987.01         1.82
85.01 to 90.00.........................        128             37,215,309.75         9.29
90.01 to 95.00.........................         38             10,056,799.04         2.51
                                             -----          ----------------        -----
          Total........................      1,186          $ 400,600,537.57          100%
                                             =====          ================        =====
</TABLE>
 
     The weighted average Loan-to-Value Ratio at origination of the Mortgage
Loans will be approximately 73.62%.
 
                GEOGRAPHIC DISTRIBUTIONS OF MORTGAGED PROPERTIES
 
<TABLE>
<CAPTION>
                                              NUMBER OF      SCHEDULED UNPAID    PERCENTAGE OF
                  STATE                     MORTGAGE LOANS   PRINCIPAL BALANCE   MORTGAGE POOL
                  -----                     --------------   -----------------   -------------
<S>                                         <C>              <C>                 <C>
Arizona...................................         28         $  8,626,891.86         2.15%
California................................        690          238,798,468.74        59.61
Connecticut...............................         18            6,278,126.11         1.57
Illinois..................................         22            7,932,285.28         1.98
Massachusetts.............................         88           28,385,242.64         7.09
New Jersey................................         33           10,131,879.62         2.53
New York..................................         48           16,527,814.99         4.13
Oregon....................................         23            7,660,596.26         1.91
Texas.....................................         21            6,684,669.97         1.67
Washington................................         61           20,710,195.63         5.17
Others(1).................................        154           48,864,366.47        12.20
                                                -----         ---------------        -----
          Total...........................      1,186         $400,600,537.57          100%
                                                =====         ===============        =====
</TABLE>
 
- ------------------------------
(1) Other includes states and the District of Columbia with under 1.45%
    concentrations individually.
 
                                      S-15
<PAGE>   16
 
     No more than 1.26% of the Mortgage Loans are secured by Mortgaged
Properties located in any one zip code area in California and no more than 0.39%
of the Mortgage Loans are secured by Mortgaged Properties located in any one zip
code area outside of California.
 
                            MORTGAGED PROPERTY TYPES
 
<TABLE>
<CAPTION>
                                               NUMBER OF      SCHEDULED UNPAID    PERCENTAGE OF
               PROPERTY TYPE                 MORTGAGE LOANS   PRINCIPAL BALANCE   MORTGAGE POOL
               -------------                 --------------   -----------------   -------------
<S>                                          <C>              <C>                 <C>
Single-family detached.....................        859         $290,201,332.83        72.44%
Planned Unit Developments..................        255           86,264,413.03        21.53
Condo......................................         57           18,233,751.90         4.55
Two-family units...........................         10            3,875,011.12         0.97
Three-family units.........................          3            1,362,409.64         0.34
Townhouse..................................          1              413,800.00         0.10
Co-op......................................          1              249,819.05         0.06
                                                 -----         ---------------        -----
          Total............................      1,186         $400,600,537.57          100%
                                                 =====         ===============        =====
</TABLE>
 
     In connection with the Mortgage Loans that are secured by a leasehold
interest, the related Seller shall have represented to the Depositor that, among
other things: the use of leasehold estates for residential properties is an
accepted practice in the area where the related Mortgaged Property is located;
residential property in such area consisting of leasehold estates is readily
marketable; the lease is recorded and no party is in any way in breach of any
provision of such lease; the leasehold is in full force and effect and is not
subject to any prior lien or encumbrance by which the leasehold could be
terminated or subject to any charge or penalty; and the remaining term of the
lease does not terminate less than ten years after the maturity date of each
such Mortgage Loan.
 
     No Mortgage Loan will have a stated remaining term to maturity as of the
Cut-off Date of less than 238 months. The weighted average remaining term to
stated maturity of the Mortgage Loans as of the Cut-off Date will be
approximately 357 months.
 
     As of the Cut-off Date, no Mortgage Loan will be one month or more
delinquent in payment of principal and interest.
 
     None of the Mortgage Loans will be Buydown Mortgage Loans.
 
     Approximately 14.63% of the Mortgage Loans were equity refinance mortgage
loans made to mortgagors who used less than the entire amount of the proceeds to
refinance an existing mortgage loan. The weighted average Loan-to-Value Ratio at
origination of such Mortgage Loans, as of the Cut-off Date, is approximately
67.06%. Approximately 34.45% of the Mortgage Loans were made to Mortgagors who
used the entire proceeds to refinance an existing Mortgage Loan. The weighted
average Loan-to-Value Ratio at origination of such Mortgage Loans, as of the
Cut-off Date, is approximately 68.89%.
 
     Approximately 93.49% of the Mortgage Loans have FICO Scores. The weighted
average FICO Score for the Mortgage Loans that were scored is approximately 728.
"FICO Scores" are statistical credit scores obtained by many mortgage lenders in
connection with the loan application to help assess a borrower's credit-
worthiness. FICO Scores are generated by models developed by a third party and
are made available to lenders through three national credit bureaus. The models
were derived by analyzing data on consumers in order to establish patterns which
are believed to be indicative of the borrower's probability of default. The FICO
Score is based on a borrower's historical credit data, including, among other
things, payment history, delinquencies on accounts, levels of outstanding
indebtedness, length of credit history, types of credit, and bankruptcy
experience. FICO Scores range from approximately 250 to approximately 900, with
higher scores indicating an individual with a more favorable credit history
compared to an individual with a lower score. However, a FICO Score purports
only to be a measurement of the relative degree of risk a borrower represents to
a lender, i.e., that a borrower with a higher score is statistically expected to
be less likely to default in
 
                                      S-16
<PAGE>   17
 
payment than a borrower with a lower score. In addition, it should be noted that
FICO Scores were developed to indicate a level of default probability over a
two-year period which does not correspond to the life of a mortgage loan.
Furthermore, FICO Scores were not developed specifically for use in connection
with mortgage loans, but for consumer loans in general. Therefore, a FICO Score
does not take in consideration the effect of mortgage loan characteristics on
the probability of repayment by the borrower. Neither the Depositor nor any
Seller makes any representations or warranties as to the actual performance of
any Mortgage Loan or that a particular FICO Score should be relied upon as a
basis for an expectation that the borrower will repay the Mortgage Loan
according to its terms.
 
     Approximately 61.44% of the Mortgage Loans will have been underwritten
under the Rapid Processing Program. The remainder of the Mortgage Loans will
have been underwritten under the Sellers' full loan documentation program. See
"MORTGAGE LOAN PROGRAM--Underwriting Standards" in the Prospectus. The weighted
average Loan-to-Value Ratio at origination of the Mortgage Loans which were
underwritten under the Rapid Processing Program loan documentation program will
be approximately 73.63%. Approximately 57.04% of the Mortgage Loans underwritten
under the Rapid Processing Program will be secured by Mortgaged Properties
located in California. See "POOLING AGREEMENT--The Master Servicer" herein.
 
     Approximately 1.89% of the Mortgage Loans are Mortgage Loans for which the
related Mortgagors have previously elected to convert the adjustable rates
thereon to fixed rates. See "THE MORTGAGE POOLS--The Mortgage Loans" in the
Prospectus.
 
     Approximately 1.51% of the Mortgage Loans will be secured by vacation or
second homes. Approximately 0.27% of the Mortgage Loans will be secured by
non-owner-occupied residences.
 
     Certain aspects of the Cooperative Loan included in the Mortgage Pool
differ from those of other types of Mortgage Loans. See "CERTAIN LEGAL ASPECTS
OF MORTGAGE LOANS--The Mortgage Loans--Cooperative Loans" in the Prospectus.
 
PRIMARY MORTGAGE INSURANCE AND PRIMARY HAZARD INSURANCE
 
     Each Mortgage Loan is required to be covered by a standard hazard insurance
policy (a "Primary Hazard Insurance Policy"). In addition, each Mortgage Loan
with a Loan-to-Value Ratio at origination in excess of 80% is required to be
covered by a primary mortgage insurance policy covering the amount of such
Mortgage Loan in excess of 75% of the value of the related Mortgaged Property
used in determining such Loan-to-Value Ratio (a "Primary Insurance Policy"),
except as set forth in the following sentences. As of the Cut-off Date,
approximately 13.62% of the Mortgage Loans, by aggregate principal balance, were
required to be covered by Primary Insurance Policies. To the best of the
Depositor's knowledge, as of the Cut-off Date, all such Mortgage Loans were so
covered. Substantially all of such Primary Insurance Policies were issued by
General Electric Mortgage Insurance Corporation, Mortgage Guaranty Insurance
Corporation, PMI Mortgage Insurance Company, United Guaranty Insurance Company,
Amerin Guaranty Corporation, Republic Mortgage Insurance Company and
Commonwealth Mortgage Assurance Company (together with the other primary
mortgage guaranty insurers for the Mortgage Loans, the "Primary Insurers"). The
Master Servicer shall keep or cause to be kept in full force and effect each
such Primary Insurance Policy until the principal balance of the related
Mortgage Loan secured by a Mortgaged Property is reduced to 80% or less of the
appraised value in the case of such a Mortgage Loan having a Loan-to-Value Ratio
at origination in excess of 80%, provided that such Primary Insurance Policy was
in place as of the Cut-off Date and the Depositor had knowledge of such Primary
Insurance Policy. In the event that the Depositor gains knowledge subsequent to
the Closing Date that as of the Closing Date, a Mortgage Loan had a
Loan-to-Value Ratio at origination in excess of 80% and was not the subject of a
Primary Insurance Policy and that such Mortgage Loan has a then current
Loan-to-Value Ratio in excess of 80%, then the Master Servicer 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. Each Primary
Insurer has a claims-paying ability currently acceptable to the Rating Agencies
that have been requested to rate the Certificates; however, there is no
assurance as to the actual ability of any Primary Insurer to pay claims. See
"PRIMARY MORTGAGE INSURANCE, HAZARD INSURANCE; CLAIMS THEREUNDER" in the
Prospectus.
 
                                      S-17
<PAGE>   18
 
ADDITIONAL INFORMATION
 
     A Current Report on Form 8-K will be available to purchasers of the Offered
Certificates and will be filed, together with the Pooling Agreement, with the
Securities and Exchange Commission within fifteen days after the initial
issuance of the Offered Certificates. In the event Mortgage Loans are removed
from or added to the Mortgage Pool as set forth in the last paragraph under
"DESCRIPTION OF THE MORTGAGE POOL--General" herein, such removal or addition
will be noted in the Current Report on Form 8-K.
 
                        DESCRIPTION OF THE CERTIFICATES
 
GENERAL
 
     The Series 1998-6 Mortgage Pass-Through Certificates (the "Certificates")
will consist of the following twenty-six Classes: (i) the Class A-1, Class A-2,
Class A-3, Class A-4, Class A-5, Class A-6, Class A-7, Class A-8, Class A-9,
Class A-10, Class A-11, Class A-12, Class A-13, Class A-14, Class A-15, Class
A-16, Class A-17, Class A-18 and Class A-19 Certificates (the "Class A
Certificates"), (ii) the Class M, Class B-1 and Class B-2 Certificates (the
"Senior Subordinate Certificates"), (iii) the Class B-3, Class B-4 and Class B-5
Certificates (the "Junior Subordinate Certificates" and together with the Senior
Subordinate Certificates, the "Subordinate Certificates") and (iv) the Class R
Certificates. The Class A Certificates and Class R Certificates are sometimes
referred to as the "Senior Certificates." The Class A-18 and Class A-19
Certificates are sometimes referred to as the "LIBOR Certificates." The Class
A-19 Certificates are sometimes referred to as the "Inverse Floater
Certificates." The Class A-4 Certificates are sometimes referred to as the
"Lockout Certificates." The Class A-6, Class A-10, Class A-13 and Class A-17
Certificates are sometimes referred to as the "Principal Only Certificates." The
Class A-12 and Class A-15 Certificates are sometimes referred to as the "Special
Retail Certificates." Only the Senior Certificates and Senior Subordinate
Certificates (collectively, the "Offered Certificates") are offered hereby. The
approximate initial Certificate Principal Balance, Pass-Through Rate and initial
rating for each Class of Offered Certificates is set forth or described in the
table on page S-4 hereof.
 
     The Certificates will evidence in the aggregate the entire beneficial
ownership interest in the Trust Fund which will consist of (i) the Mortgage
Loans; (ii) such assets as from time to time are identified as deposited in
respect of the Mortgage Loans in the Custodial Account and in the Certificate
Account and belonging to the Trust Fund; (iii) property acquired by foreclosure
of such Mortgage Loans or deed in lieu of foreclosure; and (iv) any applicable
Primary Insurance Policies and Primary Hazard Insurance Policies and all
proceeds thereof. The Senior Certificates in the aggregate and the Class M,
Class B-1 and Class B-2 Certificates will evidence initial undivided interests
of approximately 96.00%, 1.95%, 0.85% and 0.40%, respectively, in the Trust
Fund.
 
     The Offered Certificates, other than the Class R Certificates (the
"Book-Entry Certificates"), will be issued, maintained and transferred on the
book-entry records of DTC and its Participants. The Book-Entry Certificates,
other than the Class A-3, Class A-7, Class A-11, Class A-12, Class A-14, Class
A-15 and Class A-16 Certificates, are offered in minimum denominations
equivalent to not less than $100,000 initial Certificate Principal Balance each
and multiples of $1 in excess thereof. The Class A-3, Class A-7, Class A-11,
Class A-12, Class A-14, Class A-15 and Class A-16 Certificates are offered in
minimum denominations equivalent to not less than $1,000 initial Certificate
Principal Balance and multiples of $1 in excess thereof. The Class R
Certificates are "Physical Certificates" and 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 Master Servicer, as set forth herein under "FEDERAL INCOME TAX
CONSEQUENCES."
 
     The Book-Entry Certificates will be represented by one or more certificates
registered in the name of the nominee of DTC. The Depositor has been informed by
DTC that DTC's nominee will be Cede & Co. ("Cede"). No Owner will be entitled to
receive a certificate representing such person's interest (a "Definitive
Certificate"), except as set forth in the Prospectus under "DESCRIPTION OF THE
CERTIFICATES--Form of Certificates." Unless and until Definitive Certificates
are issued for the Book-Entry
                                      S-18
<PAGE>   19
 
Certificates under the limited circumstances described herein, all references to
actions by Certificateholders with respect to the Book-Entry Certificates shall
refer to actions taken by DTC upon instructions from its Participants, and all
references herein to distributions, notices, reports and statements to
Certificateholders with respect to the Book-Entry Certificates shall refer to
distributions, notices, reports and statements to DTC or Cede, as the registered
holder of the Book-Entry Certificates, for distribution to Owners by DTC in
accordance with DTC procedures.
 
BOOK-ENTRY REGISTRATION
 
     General. Owners that are not Participants or Indirect Participants but
desire to purchase, sell or otherwise transfer ownership of, or other interests
in, the related Book-Entry Certificates may do so only through Participants and
Indirect Participants. In addition, Owners will receive all distributions of
principal of and interest on the related Book-Entry Certificates from the Paying
Agent through DTC and Participants. Accordingly, Owners may experience delays in
their receipt of payments. Unless and until Definitive Certificates are issued
for the related Book-Entry Certificates, it is anticipated that the only
registered Certificateholder of such Book-Entry Certificates will be Cede, as
nominee of DTC. Owners will not be recognized by the Trustee or the Master
Servicer as Certificateholders, as such term is used in the Pooling Agreement,
and Owners will be permitted to receive information furnished to
Certificateholders and to exercise the rights of Certificateholders only
indirectly through DTC, its Participants and Indirect Participants.
 
     Under the rules, regulations and procedures creating and affecting DTC and
its operations (the "Rules"), DTC is required to make book-entry transfers of
Book-Entry Certificates among Participants and to receive and transmit
distributions of principal of, and interest on, such Book-Entry Certificates.
Participants and Indirect Participants with which Owners have accounts with
respect to such Book-Entry Certificates similarly are required to make
book-entry transfers and receive and transmit such distributions on behalf of
their respective Owners. Accordingly, although Owners will not possess physical
certificates evidencing their interests in Book-Entry Certificates, the Rules
provide a mechanism by which Owners, through their Participants and Indirect
Participants, will receive distributions and will be able to transfer their
interests in the Book-Entry Certificates.
 
     DTC management is aware that some computer applications, systems, and the
like for processing data (the "DTC Systems") that are dependent upon calendar
dates, including dates before, on, and after January 1, 2000, may encounter
"Year 2000 problems." DTC has informed its Participants and other members of the
financial community (the "Industry") that it has developed and is implementing a
program so that the DTC Systems, as the same relate to the timely payment of
distributions (including principal and income payments) to securityholders,
book-entry deliveries, and settlement of trades within DTC ("DTC Services"),
continue to function appropriately. This program includes a technical assessment
and a remediation plan, each of which is complete. Additionally, DTC's plan
includes a testing phase, which is expected to be completed within appropriate
time frames.
 
     However, DTC's ability to perform properly its services is also dependent
upon other parties, including but not limited to issuers and their agents, as
well as third party vendors from whom DTC licenses software and hardware, and
third party vendors on whom DTC relies for information or the provision of
services, including telecommunication and electrical utility service providers,
among others. DTC has informed the Industry that it is contacting (and will
continue to contact) third party vendors from whom DTC acquires services to: (i)
impress upon them the importance of such services being Year 2000 compliant; and
(ii) determine the extent of their efforts for Year 2000 remediation (and, as
appropriate, testing) of their services. In addition, DTC is in the process of
developing such contingency plans as it deems appropriate.
 
     According to DTC, the foregoing information with respect to DTC has been
provided to the Industry for informational purposes only and is not intended to
serve as a representation, warranty, or contract modification of any kind.
 
     None of the Depositor, the Master Servicer, the Trustee or the Paying Agent
will have any liability for any actions taken by DTC or its nominee, including,
without limitation, actions for any aspect of the records
                                      S-19
<PAGE>   20
 
relating to or payments made on account of beneficial ownership interests in the
Book-Entry Certificates held by Cede, as nominee for DTC, or for maintaining,
supervising or reviewing any records relating to such beneficial ownership
interests.
 
     Definitive Certificates. Definitive Certificates will be issued to Owners
or their nominees, respectively, rather than to DTC or its nominee, only under
the limited conditions set forth in the Prospectus under "DESCRIPTION OF THE
CERTIFICATES--Form of Certificates."
 
     Upon the occurrence of an event described in the Prospectus in the eleventh
paragraph under "DESCRIPTION OF THE CERTIFICATES--Form of Certificates," the
Trustee is required to notify, through DTC, Participants who have ownership of
Book-Entry Certificates as indicated on the records of DTC of the availability
of Definitive Certificates for their Book-Entry Certificates. Upon surrender by
DTC of the definitive certificates representing the Book-Entry Certificates and
upon receipt of instructions from DTC for re-registration, the Trustee will
reissue the Book-Entry Certificates as Definitive Certificates issued in the
respective principal amounts owned by individual Owners, and thereafter the
Trustee and the Master Servicer will recognize the holders of such Definitive
Certificates as Certificateholders under the Pooling Agreement.
 
     For additional information regarding DTC and the Book-Entry Certificates,
see "DESCRIPTION OF THE CERTIFICATES--Form of Certificates" in the Prospectus.
 
AVAILABLE DISTRIBUTION AMOUNT
 
     The "Available Distribution Amount" for any Distribution Date is equal to
(i) the aggregate amount of scheduled payments on the Mortgage Loans due on the
related Due Date and received on or prior to the related Determination Date,
after deduction of (a) servicing compensation payable to the Master Servicer in
respect of its master servicing activities (the "Master Servicing Fee"), (b)
subservicing and other related compensation payable to any Subservicer
(including such compensation paid to the Master Servicer as the direct servicer
of a Mortgage Loan for which there is no Subservicer (the "Primary Servicing
Fee," and together with the Master Servicing Fee, the "Servicing Fee")), and (c)
compensation payable to the Trustee in respect of its obligations with respect
to the Trust Fund ((a), (b) and (c) collectively, the "Administration Fee"),
(ii) certain unscheduled payments, including Mortgagor prepayments on the
Mortgage Loans, Insurance Proceeds, Liquidation Proceeds and proceeds from
repurchases of and substitutions for the Mortgage Loans occurring during the
preceding calendar month, (iii) all Advances made for such Distribution Date, in
each case net of amounts reimbursable therefrom to the Master Servicer and any
Subservicer and (iv) any amounts payable as Compensating Interest on such
Distribution Date. With respect to any Distribution Date, (i) the "Due Date" is
the first day of the month in which such Distribution Date occurs and (ii) the
"Determination Date" is the 16th day of the month in which such Distribution
Date occurs or, if such day is not a day other than (a) a Saturday or a Sunday
or (b) a day on which banking institutions in the State of California or State
of New York (and such other state or states in which the Custodial Account or
the Certificate Account are at the time located) are required or authorized by
law or executive order to be closed (a "Business Day"), the immediately
preceding Business Day.
 
PRIORITY OF DISTRIBUTIONS
 
     Commencing in December 1998, 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"), prior to the Credit Support Depletion Date (as defined
herein), distributions will be made in the order and priority as follows,
subject, in each case, to the extent of the related Available Distribution
Amount following prior distributions, if any, on such Distribution Date:
 
          (i) first, to the Senior Certificates entitled to interest, Accrued
     Certificate Interest (as defined below) and any portion of the Unpaid
     Accrued Certificate Interest (as defined herein) remaining unpaid from
     prior Distribution Dates;
 
                                      S-20
<PAGE>   21
 
          (ii) second, to the Senior Certificates, the Senior Principal
     Distribution Amount (as defined herein) in the order described in
     "--Principal Distributions--Senior Principal Distribution Amount" herein;
 
          (iii) third, to the Class M Certificates, Accrued Certificate Interest
     and Unpaid Accrued Certificate Interest;
 
          (iv) fourth, to the Class M Certificates, their pro rata share, based
     on their Certificate Principal Balance, of the Subordinate Principal
     Distribution Amount (as defined herein);
 
          (v) fifth, to the Class B-1 Certificates, Accrued Certificate Interest
     and Unpaid Accrued Certificate Interest;
 
          (vi) sixth, to the Class B-1 Certificates, their pro rata share, based
     on their Certificate Principal Balance, of the Subordinate Principal
     Distribution Amount;
 
          (vii) seventh, to the Class B-2 Certificates, Accrued Certificate
     Interest and Unpaid Accrued Certificate Interest;
 
          (viii) eighth, to the Class B-2 Certificates, their pro rata share,
     based on their Certificate Principal Balance, of the Subordinate Principal
     Distribution Amount;
 
          (ix) ninth, to the Class B-3 Certificates, Accrued Certificate
     Interest and Unpaid Accrued Certificate Interest;
 
          (x) tenth, to the Class B-3 Certificates, their pro rata share, based
     on their Certificate Principal Balance, of the Subordinate Principal
     Distribution Amount;
 
          (xi) eleventh, to the Class B-4 Certificates, Accrued Certificate
     Interest and Unpaid Accrued Certificate Interest;
 
          (xii) twelfth, to the Class B-4 Certificates, their pro rata share,
     based on their Certificate Principal Balance, of the Subordinate Principal
     Distribution Amount;
 
          (xiii) thirteenth, to the Class B-5 Certificates, Accrued Certificate
     Interest and Unpaid Accrued Certificate Interest;
 
          (xiv) fourteenth, to the Class B-5 Certificates, their pro rata share,
     based on their Certificate Principal Balance, of the Subordinate Principal
     Distribution Amount;
 
          (xv) fifteenth, to each Class of Subordinate Certificates, in order of
     seniority, the remaining portion, if any, of the Available Distribution
     Amount, up to the amount of unreimbursed Realized Losses (as defined
     herein) previously allocated to such Class; and
 
          (xvi) sixteenth, to the Class R Certificates the remaining portion, if
     any, of the Available Distribution Amount for such Distribution Date;
     provided, however, that there is not expected to be any such remaining
     portion available for distribution to the Class R Certificates pursuant to
     this clause (xvi).
 
     With respect to the Subordinate Certificates, notwithstanding the
foregoing, on any Distribution Date on which the Subordination Level for any
Class of Subordinate Certificates is less than such percentage as of the Closing
Date, the pro rata share of the Subordinate Principal Prepayment Distribution
Amount (as defined below under "--Principal Distributions") of the Subordinate
Principal Amount otherwise allocable to the Class or Classes junior to such
Class will be allocated to the most senior Class of Subordinate Certificates for
which the Subordination Level is less than such percentage as of the Closing
Date and to the Class or Classes of Subordinate Certificates senior thereto, pro
rata according to the Certificate Principal Balances of such Classes. The
"Subordination Level" on any specified date with respect to any Class of
Subordinate Certificates is the percentage obtained by dividing the sum of the
aggregate Certificate Principal Balance of all Classes of Certificates which are
subordinate in right of payment to such Class by the sum of the aggregate
Certificate Principal Balances of all Classes of Certificates as of such date
prior to giving effect to distributions or allocations of Realized Losses on the
Mortgage Loans on such date.
 
                                      S-21
<PAGE>   22
 
     On each Distribution Date on or after the Credit Support Depletion Date,
distributions will be made in the order and priority as follows, subject, in
each case, to the extent of the Available Distribution Amount remaining
following prior distributions, if any, on such Distribution Date:
 
          (i) first, to the Senior Certificates entitled to interest, Accrued
     Certificate Interest and Unpaid Accrued Certificate Interest;
 
          (ii) second, to the Senior Certificates, the Senior Principal
     Distribution Amount, pro rata according to their respective Certificate
     Principal Balances; and
 
          (iii) third, to the Class R Certificates, the remaining portion of the
     Available Distribution Amount for such Distribution Date; provided,
     however, that there is not expected to be any such remaining portion
     available for distribution to the Class R Certificates pursuant to this
     clause (iii).
 
     The "Credit Support Depletion Date" is the first Distribution Date on which
the aggregate of the Certificate Principal Balances of the Subordinate
Certificates has been or will be reduced to zero.
 
INTEREST DISTRIBUTIONS
 
     General. The Pass-Through Rate for each Class of Offered Certificates for
each Distribution Date (the "Pass-Through Rate") is as set forth or described in
the table on page S-4 hereof. Accrued Certificate Interest distributed to the
Certificates on each Distribution Date will have accrued during the preceding
calendar month.
 
     Holders of each class of Certificates entitled to interest will be entitled
to receive distributions in an amount equal to the Accrued Certificate Interest
on such Class for such Distribution Date. With respect to any Distribution Date,
"Accrued Certificate Interest" will be equal to one month's interest on the
Certificate Principal Balance of the Certificates of such Class at the
Pass-Through Rate on such Class; in each case less interest shortfalls, if any,
for such Distribution Date not covered by the Subordination provided by the
Subordinate Certificates, including in each case (i) any Net Prepayment Interest
Shortfall (as defined below); (ii) the interest portions of Realized Losses
(including Special Hazard Losses in excess of the Special Hazard Amount ("Excess
Special Hazard Losses"), Fraud Losses in excess of the Fraud Loss Amount
("Excess Fraud Losses"), Bankruptcy Losses in excess of the Bankruptcy Amount
("Excess Bankruptcy Losses"), losses not covered by the errors and omissions and
fidelity policy required to be maintained by the Master Servicer, and losses
occasioned by war, civil insurrection, certain governmental actions, nuclear
reaction and certain other risks ("Extraordinary Losses")) not covered by
Subordination (as defined herein); (iii) the interest portion of any Advances
that were made with respect to delinquencies that were ultimately determined to
be Excess Special Hazard Losses, Excess Fraud Losses, Excess Bankruptcy Losses
or Extraordinary Losses; and (iv) any other interest shortfalls not covered by
Subordination, including interest shortfalls relating to the Relief Act or
similar legislation or regulations, all allocated as described below. Accrued
Certificate Interest is calculated on the basis of a 360-day year consisting of
twelve 30-day months.
 
     The "Certificate Principal Balance" of any Certificate as of any date of
determination is equal to the initial Certificate Principal Balance thereof,
reduced by the aggregate of (a) all amounts allocable to principal previously
distributed with respect to such Certificate and (b) any reductions in the
Certificate Principal Balance thereof deemed to have occurred in connection with
allocations of Realized Losses in the manner described herein.
 
     If the amount available for distributions of interest on any Classes of
Certificates in the priority described herein is less than the related Accrued
Certificate Interest, the shortfall will be allocated among all Classes of equal
priority pro rata on the basis of the respective amounts of Accrued Certificate
Interest. Any such shortfall ("Unpaid Accrued Certificate Interest") will be
distributable to holders of the Certificates of such Classes, on subsequent
Distribution Dates, to the extent of available funds. Shortfalls could occur,
for example, if losses realized on the Mortgage Loans in the Trust Fund were
exceptionally high and were concentrated in a particular month and if Advances
by the Master Servicer did not cover the shortfall. Any such amount so carried
forward will not bear interest.
 
                                      S-22
<PAGE>   23
 
     Compensating Interest. With respect to prepayments in full or in part on
the Mortgage Loans, the Master Servicer is obligated to reduce its aggregate
Servicing Fee to the extent necessary to fund any Prepayment Interest Shortfall
(adjusted to the related Net Mortgage Rate (as defined below)) on each
Distribution Date; provided, however, that the Master Servicer shall not be
obligated to reduce its aggregate Servicing Fee by more than the aggregate
Primary Servicing Fee for all of the Mortgage Loans on such Distribution Date.
The amount so passed through will hereinafter be referred to as "Compensating
Interest." The "Net Mortgage Rate" for any Mortgage Loan is the Mortgage Rate
thereof less the Administration Fee for such Mortgage Loan.
 
     The "Net Prepayment Interest Shortfall" for any Distribution Date is the
Prepayment Interest Shortfall for such Distribution Date not funded by the
Master Servicer or a Subservicer as Compensating Interest. The Net Prepayment
Interest Shortfall, the interest portions of Realized Losses not covered by
Subordination, interest shortfalls relating to the Relief Act or similar
legislation and other interest shortfalls not covered by Subordination on any
Distribution Date will be allocated among the holders of all Classes of
Certificates (including the Subordinate and Class R Certificates), in proportion
to the respective amounts of Accrued Certificate Interest for such Distribution
Date on each such Class, before taking into account any such reduction.
 
LIBOR
 
     The Pass-Through Rates on the LIBOR Certificates for any Distribution Date
after the initial Distribution Date will be determined on the LIBOR Business Day
(as defined below) immediately prior to the 25th day of the month preceding such
Distribution Date (a "LIBOR Rate Adjustment Date").
 
     On each LIBOR Rate Adjustment Date, LIBOR shall be established by the
Trustee and, as to any Distribution Date, will equal the rate for one month U.S.
dollar deposits that appears on the Telerate Screen Page 3750 as of 11:00 a.m.,
London time, on such LIBOR Rate Adjustment Date. "Telerate Screen Page 3750"
means the display designated as page 3750 on the Telerate Service (or such other
page as may replace page 3750 on that service for the purpose of displaying
London interbank offered rates of major banks). If such rate does not appear on
such page (or such other page as may replace that page on that service, or if
such service is no longer offered, such other service for displaying LIBOR or
comparable rates as may be selected by the Trustee after consultation with the
Master Servicer), the rate will be the Reference Bank Rate. The "Reference Bank
Rate" will be determined on the basis of the rates at which deposits in U.S.
dollars are offered by the reference banks (which shall be three major banks
that are engaged in transactions in the London interbank market, selected by the
Trustee after consultation with the Master Servicer) as of 11:00 a.m., London
time, on the LIBOR Rate Adjustment Date to prime banks in the London interbank
market for a period of one month in amounts approximately equal to the aggregate
Certificate Principal Balance of the LIBOR Certificates then outstanding. The
Trustee will request the principal London office of each of the reference banks
to provide a quotation of its rate. If at least two such quotations are
provided, the rate will be the arithmetic mean of the quotations. If on such
date fewer than two quotations are provided as requested, the rate will be the
arithmetic mean of the rates quoted by one or more major banks in New York City,
selected by the Trustee after consultation with the Master Servicer, as of 11:00
a.m., New York City time, on such date for loans in U.S. Dollars to leading
European banks for a period of one month in amounts approximately equal to the
aggregate Certificate Principal Balance of the LIBOR Certificates then
outstanding. If no such quotations can be obtained, the rate will be LIBOR for
the prior Distribution Date. "LIBOR Business Day" means any day other than (i) a
Saturday or a Sunday or (ii) a day on which banking institutions in the city of
London, England are required or authorized by law to be closed.
 
     The establishment of LIBOR by the Trustee and the Trustee's subsequent
calculation of the Pass-Through Rate applicable to the LIBOR Certificates for
the relevant Distribution Date, in the absence of manifest error, will be final
and binding.
 
     Listed below are some historical values of LIBOR since January 1993. Such
values were not determined in accordance with the provisions set forth above and
are intended only to provide a historical summary of the
 
                                      S-23
<PAGE>   24
 
movement in yields on LIBOR. The monthly figures set forth below are the values
of LIBOR as derived from various sources.
 
<TABLE>
<CAPTION>
                                                                  YEAR
                                         ------------------------------------------------------
               MONTH                     1998      1997      1996      1995      1994      1993
               -----                     ----      ----      ----      ----      ----      ----
<S>                                      <C>       <C>       <C>       <C>       <C>       <C>
January............................      5.59%     5.44%     5.56%     5.93%     3.15%     3.19%
February...........................      5.59      5.40      5.31      6.09      3.38      3.15
March..............................      5.63      5.52      5.37      6.11      3.63      3.20
April..............................      5.61      5.67      5.43      6.10      3.83      3.17
May................................      5.62      5.68      5.38      6.07      4.31      3.12
June...............................      5.63      5.66      5.44      6.06      4.38      3.18
July...............................      5.61      5.64      5.46      5.91      4.54      3.18
August.............................      5.61      5.62      5.38      5.91      4.71      3.18
September..........................      5.53      5.62      5.47      5.86      4.92      3.15
October............................      5.29      5.60      5.37      5.85      5.07      3.17
November...........................                5.65      5.39      5.81      5.48      3.18
December...........................                5.91      5.63      5.85      6.08      3.35
</TABLE>
 
PRINCIPAL DISTRIBUTIONS
 
     General. On each Distribution Date, Certificateholders will be entitled to
receive principal distributions from the Available Distribution Amount to the
extent described herein. See "--Priority of Distributions" herein. All
distributions of principal will be made only to the extent of the Available
Distribution Amount.
 
     Senior Principal Distribution Amount. On each Distribution Date prior to
the Credit Support Depletion Date, the Senior Principal Distribution Amount (as
defined below) for such Distribution Date will be distributed as principal to
the following Classes of Senior Certificates in the following order of priority:
 
          (i) first, to the Class A-4 Certificates, an amount, up to the Class
     A-4 Priority Amount (as defined below) for such Distribution Date, until
     the Certificate Principal Balance thereof has been reduced to zero;
 
          (ii) second, concurrently, until the Certificate Principal Balances of
     the Class A-2, Class A-9 and Class A-10 Certificates have been reduced to
     zero, as follows:
 
             (A) 35.5880180674% of the amount distributable under clause (ii)
        sequentially as follows:
 
                (I) until the Certificate Principal Balance of the Class A-8
           Certificates has been reduced to zero, concurrently as follows:
 
                    (a) 79.5723443384% of the amount distributable under clause
               (ii)(A)(I) to the Class A-1 Certificates; and
 
                    (b) 20.4276556616% of the amount distributable under clause
               (ii)(A)(I) to the Class A-8 Certificates;
 
                (II) an aggregate amount of $2,352,105.44 distributed pursuant
           to this clause (ii)(A)(II) from the initial Distribution Date to the
           Class A-1 Certificates; and
 
                (III) an aggregate amount of $15,795,041 distributed pursuant to
           this clause (ii)(A)(III) from the initial Distribution Date
           concurrently as follows:
 
                    (a) 56.4613783637% of the amount distributable under clause
               (ii)(A)(III) sequentially as follows:
 
                        i) to the Class A-7 Certificates until the Certificate
                   Principal Balance thereof has been reduced to zero;
 
                                      S-24
<PAGE>   25
 
                        ii) to the Class A-14, Class A-18 and Class A-19
                   Certificates, pro rata, based on their respective Certificate
                   Principal Balances, until the Certificate Principal Balances
                   thereof have been reduced to zero; and
 
                        iii) to the Class A-15, Class A-16 and Class A-17
                   Certificates, pro rata, based on their respective Certificate
                   Principal Balances, until the Certificate Principal Balances
                   thereof have been reduced to zero;
 
                    (b) 5.3162503849% of the amount distributable under clause
               (ii)(A)(III) to the Class A-6 Certificates;
 
                    (c) 38.0439490256% of the amount distributable under clause
               (ii)(A)(III) to the Class A-5 Certificates; and
 
                    (d) 0.1784222258% of the amount distributable under clause
               (ii)(A)(III) sequentially as follows:
 
                        i) to the Class A-3 and Class A-11 Certificates, pro
                   rata, based on their respective Certificate Principal
                   Balances, until the Certificate Principal Balances thereof
                   have been reduced to zero; and
 
                        ii) to the Class A-12 and Class A-13 Certificates, pro
                   rata, based on their respective Certificate Principal
                   Balances, until the Certificate Principal Balances thereof
                   have been reduced to zero;
 
             (B) 9.2017116171% of the amount distributable under clause (ii)
        sequentially as follows:
 
                (I) to the Class R Certificates until the Certificate Principal
           Balance thereof has been reduced to zero;
 
                (II) an aggregate amount of $25,960,991 distributed pursuant to
           this clause (ii)(B)(II) from the initial Distribution Date to the
           Class A-1 Certificates; and
 
                (III) the remainder of the amount distributable under clause
           (ii)(B) concurrently as follows:
 
                    (a) 7.4074076800% of the amount distributable under clause
               (ii)(B)(III) to the Class A-6 Certificates; and
 
                    (b) 92.5925923200% of the amount distributable under clause
               (ii)(B)(III) sequentially as follows:
 
                        i) to the Class A-3 and Class A-11 Certificates, pro
                   rata, based on their respective Certificate Principal
                   Balances, until the Certificate Principal Balances thereof
                   have been reduced to zero; and
 
                        ii) to the Class A-12 and Class A-13 Certificates, pro
                   rata, based on their respective Certificate Principal
                   Balances, until the Certificate Principal Balances thereof
                   have been reduced to zero; and
 
             (C) 55.2102703155% of the amount distributable under clause (ii) to
        the Class A-2, Class A-9 and Class A-10 Certificates, pro rata, based on
        their respective Certificate Principal Balances, until the Certificate
        Principal Balances thereof have been reduced to zero;
 
          (iii) third, an aggregate amount of $5,063,822 distributed pursuant to
     this clause (iii) from the initial Distribution Date concurrently as
     follows:
 
             (A) 56.4613783637% of the amount distributable under clause (iii)
        sequentially as follows:
 
                (I) to the Class A-7 Certificates until the Certificate
           Principal Balance thereof has been reduced to zero;
 
                                      S-25
<PAGE>   26
 
                (II) to the Class A-14, Class A-18 and Class A-19 Certificates,
           pro rata, based on their respective Certificate Principal Balances,
           until the Certificate Principal Balances thereof have been reduced to
           zero; and
 
                (III) to the Class A-15, Class A-16 and Class A-17 Certificates,
           pro rata, based on their respective Certificate Principal Balances,
           until the Certificate Principal Balances thereof have been reduced to
           zero;
 
             (B) 5.3162503849% of the amount distributable under clause (iii) to
        the Class A-6 Certificates;
 
             (C) 38.0439490256% of the amount distributable under clause (iii)
        to the Class A-5 Certificates; and
 
             (D) 0.1784222258% of the amount distributable under clause (iii)
        sequentially as follows:
 
                (I) to the Class A-3 and Class A-11 Certificates, pro rata,
           based on their respective Certificate Principal Balances, until the
           Certificate Principal Balances thereof have been reduced to zero; and
 
                (II) to the Class A-12 and Class A-13 Certificates, pro rata,
           based on their respective Certificate Principal Balances, until the
           Certificate Principal Balances thereof have been reduced to zero;
 
          (iv) fourth, an aggregate amount of $14,539,267 distributed pursuant
     to this clause (iv) from the initial Distribution Date concurrently as
     follows:
 
             (A) 6.6755026915% of the amount distributable under clause (iv) to
        the Class A-6 Certificates until the Certificate Principal Balance
        thereof has been reduced to zero;
 
             (B) 60.2476356472% of the amount distributable under clause (iv)
        sequentially as follows:
 
                (I) to the Class A-3 and Class A-11 Certificates, pro rata,
           based on their respective Certificate Principal Balances, until the
           Certificate Principal Balances thereof have been reduced to zero; and
 
                (II) to the Class A-12 and Class A-13 Certificates, pro rata,
           based on their respective Certificate Principal Balances, until the
           Certificate Principal Balances thereof have been reduced to zero;
 
             (C) 19.7614806798% of the amount distributable under clause (iv)
        sequentially as follows:
 
                (I) to the Class A-7 Certificates until the Certificate
           Principal Balance thereof has been reduced to zero;
 
                (II) to the Class A-14, Class A-18 and Class A-19 Certificates,
           pro rata, based on their respective Certificate Principal Balances,
           until the Certificate Principal Balances thereof have been reduced to
           zero; and
 
                (III) to the Class A-15, Class A-16 and Class A-17 Certificates,
           pro rata, based on their respective Certificate Principal Balances,
           until the Certificate Principal Balances thereof have been reduced to
           zero; and
 
             (D) 13.3153809815% of the amount distributable under clause (iv) to
        the Class A-5 Certificates until the Certificate Principal Balance
        thereof has been reduced to zero; and
 
          (v) fifth, to the Class A-4 Certificates until the Certificate
     Principal Balance thereof has been reduced to zero.
 
     As to each of the Class A-12 and Class A-15 Certificates, the aggregate
principal distributions allocable to such Class will be distributed among the
Owners or Holders of such Class in accordance with the special rules described
below under "--Distribution in Reduction of the Special Retail Certificates."
                                      S-26
<PAGE>   27
 
     On each Distribution Date on and after the Credit Support Depletion Date,
an amount up to the Senior Principal Distribution Amount for such Distribution
Date will be distributed as principal to the Senior Certificates, pro rata
according to their respective Certificate Principal Balances.
 
     The "Senior Principal Distribution Amount" for any Distribution Date will
equal the sum of (i) the Senior Percentage (as defined herein) of the Principal
Payment Amount (as defined below), (ii) the Senior Prepayment Percentage (as
defined below) of the Principal Prepayment Amount (as defined below) and (iii)
the Senior Liquidation Amount (as defined below).
 
     The "Principal Payment Amount" with respect to each Distribution Date is
the sum 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 during the preceding calendar month, other than full and partial
Principal Prepayments or Liquidation Principal. For any Distribution Date, the
"Principal Prepayment Amount" is the sum of all full and partial Principal
Prepayments which were received during the preceding calendar month.
 
     The "Senior Liquidation Amount" is the aggregate of, for each Mortgage Loan
which became a Liquidated Mortgage Loan (as defined herein) during the calendar
month preceding the month of the Distribution Date, the lesser of (i) the Senior
Percentage of the principal balance of such Mortgage Loan and (ii) the 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 (but not in excess of the principal balance thereof) during the calendar
month preceding the month of the Distribution Date. A "Liquidated Mortgage Loan"
is a Mortgage Loan as to which the Master Servicer or a Subservicer 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 "Senior Percentage" for any Distribution Date will equal the sum of the
Certificate Principal Balances of the Senior Certificates divided by the
aggregate Certificate Principal Balances of the Certificates, in each case
immediately prior to the Distribution Date.
 
     The "Senior Prepayment Percentage" for any Distribution Date occurring
during the five years beginning on the first Distribution Date will equal 100%.
The "Senior Prepayment Percentage" on the Distribution Date in each of the
months of the fifth through ninth anniversaries of the first Distribution Date
will be as follows:
 
<TABLE>
<CAPTION>
       DISTRIBUTION DATE OCCURRING IN                       SENIOR PREPAYMENT PERCENTAGE
       ------------------------------                       ----------------------------
<S>                                           <C>
December 1998 through November 2003.........  100%
December 2003 through November 2004.........  Senior Percentage + 70% of Subordinate Percentage
December 2004 through November 2005.........  Senior Percentage + 60% of Subordinate Percentage
December 2005 through November 2006.........  Senior Percentage + 40% of Subordinate Percentage
December 2006 through November 2007.........  Senior Percentage + 20% of Subordinate Percentage
December 2007 and thereafter................  Senior Percentage
</TABLE>
 
     Notwithstanding the foregoing, if on any Distribution Date the Senior
Percentage for such Distribution Date exceeds the initial Senior Percentage as
of the Closing Date, then the Senior Prepayment Percentage for such Distribution
Date will equal 100%. The scheduled reductions in the Senior Prepayment
Percentage for Distribution Dates occurring on or after the fifth anniversary of
the month of the first Distribution Date will be subject to the conditions set
forth in the immediately following paragraph. If on any Distribution Date the
allocation to the Senior Certificates in the percentage required would reduce
the sum of the Certificate Principal Balances of such Senior Certificates below
zero, the Senior Prepayment Percentage for such Distribution Date will be
limited to the percentage necessary to reduce such sum to zero.
 
     No decrease in the Senior Prepayment Percentage will occur unless both of
the following conditions (the "Step Down Conditions") are satisfied: (i) the
outstanding principal balance of all Mortgage Loans
 
                                      S-27
<PAGE>   28
 
delinquent 60 days or more (averaged over the preceding six month period), as a
percentage of the aggregate principal balance of the Subordinate Certificates on
such Distribution Date, does not equal or exceed 50%, and (ii) cumulative
Realized Losses with respect to the Mortgage Loans do not exceed (a) with
respect to the Distribution Date occurring in the month of the fifth anniversary
of the first Distribution Date, 30% of the aggregate of the principal balances
of the Subordinate Certificates as of the Cut-off Date (the "Original
Subordinate Principal Balance"), (b) with respect to the Distribution Date
occurring in the month of the sixth anniversary of the first Distribution Date,
35% of the Original Subordinate Principal Balance, (c) with respect to the
Distribution Date occurring in the month of the seventh anniversary of the first
Distribution Date, 40% of the Original Subordinate Principal Balance, (d) with
respect to the Distribution Date occurring in the month of the eighth
anniversary of the first Distribution Date, 45% of the Original Subordinate
Principal Balance, and (e) with respect to the Distribution Date occurring in
the month of the ninth anniversary of the first Distribution Date, 50% of the
Original Subordinate Principal Balance.
 
     The "Class A-4 Priority Amount" for any Distribution Date will equal the
sum of (i) the Class A-4 Percentage (as defined below) of the Principal Payment
Amount, (ii) the Class A-4 Prepayment Percentage (as defined below) of the
Principal Prepayment Amount and (iii) the Class A-4 Liquidation Amount (as
defined below).
 
     The "Class A-4 Percentage" will equal (i) for any Distribution Date prior
to the Distribution Date occurring in December 2003, 0% and (ii) for any
Distribution Date occurring on or after the Distribution Date in December 2003,
the Class A-4 Certificate Principal Balance divided by the aggregate Certificate
Principal Balances of the Certificates, in each case immediately prior to the
Distribution Date.
 
     The "Class A-4 Liquidation Amount" will equal the aggregate, for each
Mortgage Loan which became a Liquidated Mortgage Loan during the calendar month
preceding the month of the Distribution Date, the Class A-4 Prepayment
Percentage of the Liquidation Principal with respect to such Mortgage Loan.
 
     The "Class A-4 Prepayment Percentage" for any Distribution Date will equal
the product of (a) the Class A-4 Percentage for such Distribution Date and (b)
the applicable 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 1998 through November 2003...............            0%
December 2003 through November 2004...............           30%
December 2004 through November 2005...............           40%
December 2005 through November 2006...............           60%
December 2006 through November 2007...............           80%
December 2007 and thereafter......................          100%
</TABLE>
 
     Subordinate Principal Distribution Amount. On each Distribution Date, an
amount, up to the Subordinate Principal Distribution Amount (as defined below)
for such Distribution Date, will be distributed as principal to the Subordinate
Certificates. On each Distribution Date, except Distribution Dates on which the
Subordination Level for any Class of Subordinate Certificates is less than such
Subordination Level as of the Closing Date, each Class of Subordinate
Certificates will be entitled to receive its pro rata (by Certificate Principal
Balance of such Classes) share of the Subordinate Principal Distribution Amount,
to the extent of the Available Distribution Amount remaining after distributions
of interest and principal to the Senior Certificates, distributions of interest
and principal to all Classes of Subordinate Certificates senior to such Class
and distributions of interest to such Class. See "--Priority of Distribution"
herein. The relative seniority, from highest to lowest, of the Subordinate
Certificates shall be as follows: Class M, Class B-1, Class B-2, Class B-3,
Class B-4 and Class B-5.
 
     The "Subordinate Principal Distribution Amount" for any Distribution Date
will be equal to the sum of (i) the Subordinate Percentage (as defined herein)
of the Principal Payment Amount, (ii) the Subordinate Prepayment Percentage (as
defined herein) of the Principal Prepayment Amount and (iii) the Subordinate
Liquidation Amount (as defined below). The portion of the Subordinate Principal
Distribution Amount
 
                                      S-28
<PAGE>   29
 
described in clause (ii) of the definition thereof is referred to herein as the
"Subordinate Principal Prepayment Distribution Amount."
 
     The "Subordinate Percentage" for any Distribution Date will equal the
excess of 100% over the Senior Percentage.
 
     The "Subordinate Prepayment Percentage" for any Distribution Date will
equal the excess of 100% over the Senior Prepayment Percentage; provided,
however, that if the Certificate Principal Balances of the Senior Certificates
have been reduced to zero, then the Subordinate Prepayment Percentage will equal
100%.
 
     The "Subordinate Liquidation Amount" will equal the excess, if any, of the
aggregate Liquidation Principal for all Mortgage Loans which became Liquidated
Mortgage Loans during the calendar month preceding the month of the Distribution
Date, over the Senior Liquidation Amount for such Distribution Date.
 
     The rights of the holders of Subordinate Certificates to receive
distributions of interest and principal are subordinated to the rights of the
holders of the Senior Certificates to receive distributions of interest and
principal. The rights of the holders of any Class of Subordinate Certificates to
receive distributions of interest and principal are also subordinated to the
rights of the holders of all Classes of Subordinate Certificates with a higher
priority to receive distributions of interest and principal. The priority of the
Subordinate Certificates from highest to lowest is as follows: Class M, Class
B-1, Class B-2, Class B-3, Class B-4 and Class B-5. See "--Allocation of Losses;
Subordination herein."
 
DISTRIBUTIONS IN REDUCTION OF THE SPECIAL RETAIL CERTIFICATES
 
     General. As to distributions of principal among holders of each Class of
the Special Retail Certificates prior to the earlier of (i) the Credit Support
Depletion Date and (ii) the date on which any loss is allocated to such Class by
pro rata allocation of such loss among all Classes of Certificates (as described
under "--Allocation of Losses; Subordination" below), Deceased Holders (as
defined below) will be entitled to first priority (up to a limit of
approximately $25,000 as described below) and Owners other than Deceased Holders
("Living Holders") will be entitled to second priority (up to a limit of
approximately $10,000 as described below). Owners of each Class of the Special
Retail Certificates have the right to request that distributions of principal be
made with respect to their Special Retail Certificates on each Distribution Date
on which distributions of principal are made with respect to such Class. All
such requested distributions are subject to the priorities described below under
"--Priority of Requested Distributions" and are further subject to the
limitations (i) that they be made only in lots equal to $1,000 of initial
principal balance and (ii) that aggregate distributions on each Class of the
Special Retail Certificates on a Distribution Date will not exceed the portion
of the Senior Principal Distribution Amount allocated to such Class on such
Distribution Date (plus any amounts available from the applicable Rounding
Account (as defined below)). To the extent that amounts available for
distributions of principal on either Class of the Special Retail Certificates on
any Distribution Date exceed the aggregate requests by Deceased Holders and
Living Holders of such Class for principal distributions applicable to such
Distribution Date, such excess amounts will be distributed to the Owners of such
Class by random lot, as described below under "--Mandatory Distributions of
Principal on the Special Retail Certificates."
 
     On each Distribution Date (prior to the earlier of (i) the Credit Support
Depletion Date and (ii) the date on which any loss is allocated to the
applicable Class of Special Retail Certificates as part of an allocation of such
loss on a pro rata basis among all Classes of Certificates) on which amounts are
available for distributions of principal on either Class of the Special Retail
Certificates, the aggregate amount allocable to such distributions will be
rounded upward, as necessary, to an amount equal to an integral multiple of
$1,000, except as provided below, in accordance with the priorities and
limitations set forth herein. Such rounding will be accomplished on the first
Distribution Date on which distributions of principal on each Class of the
Special Retail Certificates are made by withdrawing, from a non-interest bearing
account to be established on the Closing Date for each Class of the Special
Retail Certificates with a $999.99 deposit by the Underwriter (each, a "Rounding
Account"), the amount of funds, if any, needed to round the amount otherwise
available for such distributions upward to the next higher integral multiple of
$1,000. On each succeeding Distribution
                                      S-29
<PAGE>   30
 
Date on which distributions of principal on either Class of the Special Retail
Certificates are to be made, the aggregate amount allocable to such Class will
be applied first to repay any funds withdrawn from the applicable Rounding
Account on the prior Distribution Date, and then the remainder of such allocable
amount, if any, will be similarly rounded upward through another withdrawal from
the applicable Rounding Account and distributed as principal on such Class. This
process will continue on succeeding Distribution Dates with respect to each
Class of the Special Retail Certificates until the Class Principal Balance of
each such Class has been reduced to zero. Thus, the aggregate distribution made
in reduction of the Class Principal Balance of each Class of the Special Retail
Certificates on each Distribution Date may be slightly more or less than would
be the case in the absence of such rounding procedures, but such difference will
be no more than $999.99 for each such Class on such Distribution Date. Under no
circumstances will the sum of all distributions of principal on either Class of
the Special Retail Certificates through any Distribution Date be less than the
sum that would have resulted in the absence of such rounding procedures.
 
     There is no assurance that an Owner of a Special Retail Certificate who has
submitted a request for a principal distribution will receive such distribution
at any particular time after such distribution is requested, since there can be
no assurance that funds will be available for making principal distributions on
the applicable Class of the Special Retail Certificates on any particular
Distribution Date, or, even if funds are available for making such
distributions, that such distributions with respect to the Special Retail
Certificates owned by any particular Owner will be made. Also, due to the
procedure for mandatory distributions described below, there can be no assurance
that on any Distribution Date on which the funds available for distribution of
principal on either Class of the Special Retail Certificates exceed the
aggregate amount of distributions requested by Owners of such Class, any
particular Owner will not receive a principal distribution from such excess
funds even if such Owner has not submitted a request for distribution. Thus, the
timing of distributions of principal with respect to any particular Special
Retail Certificate is highly uncertain, and such distributions may be made
earlier or later than the date that may be desired by an Owner of such
Certificate.
 
     OWNERS OF THE SPECIAL RETAIL CERTIFICATES SHOULD NOTE THAT, BASED ON THE
STRUCTURING ASSUMPTIONS AND AN ASSUMED PREPAYMENT RATE OF 275% SPA, NO
DISTRIBUTIONS OF PRINCIPAL ARE EXPECTED TO BE MADE ON THE CLASS A-12 AND CLASS
A-15 CERTIFICATES UNTIL THE DISTRIBUTION DATES IN JUNE 2016 AND AUGUST 2012,
RESPECTIVELY.
 
     Notwithstanding any provisions herein to the contrary, on each Distribution
Date on and after the earlier of (i) the Credit Support Depletion Date and (ii)
the date on which any loss is allocated to the applicable Class of Special
Retail Certificates as part of an allocation of such loss on a pro rata basis
among all Classes of Certificates, distributions of principal on the Special
Retail Certificates will be made pro rata among the holders of the Special
Retail Certificates and will not be made in integral multiples of $1,000 nor
pursuant to requested distributions or mandatory distributions.
 
     Priority of Requested Distributions. Subject to the limitations described
herein, including the order of the receipt of the request for distributions as
described below under "--Procedure for Requesting Distributions," Owners of the
Special Retail Certificates have the right to request that distributions of
principal on their Special Retail Certificates be made. On each Distribution
Date (prior to the earlier of (i) the Credit Support Depletion Date and (ii) the
date on which any loss is allocated to the applicable Class of Special Retail
Certificates as part of an allocation of such loss on a pro rata basis among all
Classes of Certificates) on which distributions of principal on either Class of
the Special Retail Certificates are made, priority of payment on such Class will
be given to Owners for whom principal payment requests are in effect. For each
Class of the Special Retail Certificates, DTC will honor requests in the
following order of priority:
 
          First, DTC will honor requests submitted on behalf of Deceased Holders
     in the order of their receipt by DTC, until such requests have been honored
     in an amount up to $25,000 for each requesting Deceased Holder; and
 
          Second, DTC will honor requests submitted on behalf of Living Holders
     in the order of their receipt by DTC, until such requests have been honored
     in an amount up to $10,000 for each requesting Living Holder.
 
                                      S-30
<PAGE>   31
 
     Thereafter, DTC will honor requests submitted on behalf of each Deceased
Holder as provided in step First up to a second $25,000 and requests submitted
on behalf of each Living Holder as provided in step Second up to a second
$10,000. This sequence of priorities will be repeated until all principal
payment requests for each Class of the Special Retail Certificates have been
honored to the extent of amounts available in reduction of each such Class. In
no event will distributions exceed the amount of principal available for
distribution to the applicable Class of the Special Retail Certificates on such
Distribution Date. See "--Principal Distributions--Senior Principal Distribution
Amount." In no event will the Owner of a Special Retail Certificate receive a
distribution of principal in an amount greater than the Certificate Principal
Balance of such Special Retail Certificate.
 
     If the amount of principal available for payment on either Class of the
Special Retail Certificates on a given Distribution Date is insufficient to
honor all requests, such requests will be honored on succeeding Distribution
Dates as principal becomes available. A Special Retail Certificate principal
payment request submitted on behalf of a Living Holder who later dies will
become entitled to the priority of a newly submitted request on behalf of a
Deceased Holder. Such priority will be effective for each subsequent
Distribution Date if DTC has received a certified copy of the death certificate
for such Deceased Holder and any additional appropriate evidence of death and
any requested tax waivers by the last Business Day of the preceding calendar
month.
 
     Procedure for Requesting Distributions. An Owner may request that
distributions of principal on such Owner's Special Retail Certificates be made
on a Distribution Date by delivering a written request therefor to the
Participant or Indirect Participant that maintains such Owner's account in the
Special Retail Certificates so that the request for such distribution is
received by the Trustee on or before the Record Date for such Distribution Date.
In the case of a request on behalf of a Deceased Holder, a certified copy of the
death certificate and any additional appropriate evidence of death and any tax
waivers are required to be forwarded to the Trustee under separate cover.
Furthermore, such requests of Deceased Holders that are incomplete may not be
honored by the Trustee and, if not honored, will lose their priority and must be
rerequested. The Participant will in turn make the request of DTC (or, in the
case of an Indirect Participant, such firm must notify the related Participant
of such request, which Participant will make the request of DTC) on a form
required by DTC and provided to the Participant. Upon receipt of such request,
DTC will date and time stamp such request and forward such request to the
Trustee. DTC may establish such procedures as it deems fair and equitable to
establish the order of receipt of requests for such distributions received by it
on the same day. Neither the Depositor, the Master Servicer nor the Trustee will
be liable for any delay by DTC, any Participant or any Indirect Participant in
the delivery of requests for distributions to the Trustee. Requests for
distributions of principal forwarded to the Trustee from DTC after the Record
Date for such Distribution Date and requests for distributions of principal
received in a timely manner but not accepted with respect to a given
Distribution Date, will be treated as requests for distributions of principal on
the next succeeding Distribution Date and each succeeding Distribution Date
thereafter until each request is accepted or is withdrawn as described below.
Each request for distributions of principal on a Special Retail Certificate
submitted by an Owner of a Special Retail Certificate will be held by the
Trustee until such request has been accepted or has been withdrawn in writing,
in the manner set forth below. The principal amount covered by such request will
continue to bear interest at the related Pass-Through Rate through the last
calendar date of the month preceding the month of such Distribution Date.
 
     With respect to Special Retail Certificates for which Owners have requested
distributions on a particular Distribution Date on which distributions of
principal on the applicable Class of Special Retail Certificates are being made,
the Trustee will notify DTC and the Participants prior to such Distribution Date
whether, and the extent to which, such Special Retail Certificates have been
accepted for distributions. Participants and Indirect Participants holding
Special Retail Certificates are required to forward such notices to the Owners
of such Certificates. Special Retail Certificates that have been accepted for a
distribution will be due and payable on the applicable Distribution Date and
will cease to bear interest after the last calendar date of the month preceding
the month of such Distribution Date.
 
     Any Owner of a Special Retail Certificate that has requested a distribution
may withdraw such request by so notifying in writing the Participant or Indirect
Participant that maintains such Owner's account. The
                                      S-31
<PAGE>   32
 
Participant will forward the withdrawal, on a form required by DTC, to the
Trustee. In the event that such account is maintained by an Indirect
Participant, such Indirect Participant must notify the related Participant,
which in turn must forward the withdrawal of such request on such form to the
Trustee. If such notice of withdrawal of a request for distribution has not been
received by the Trustee on or before the Record Date for such Distribution Date,
the previously made request for distribution will be irrevocable with respect to
the making of distributions of principal on the applicable Class of the Special
Retail Certificates on the applicable Distribution Date.
 
     Mandatory Distributions of Principal on the Special Retail Certificates. To
the extent, if any, that distributions of principal on either Class of the
Special Retail Certificates on a Distribution Date exceed the aggregate amount
of distribution requests for such Class which have been received by DTC on or
before the applicable Record Date, additional Special Retail Certificates in
lots equal to $1,000 will be selected to receive principal distributions in
accordance with the then-applicable established random lot procedures of DTC,
and the then-applicable established procedures of the Participants and Indirect
Participants, which may or may not be by random lot. Investors may ask such
Participants or Indirect Participants which allocation procedures they use.
Participants and Indirect Participants holding Special Retail Certificates
selected for mandatory distributions of principal are required to provide notice
of such mandatory distributions to the affected Owners.
 
     Deceased Holder. A "Deceased Holder" is a beneficial owner of a Special
Retail Certificate who was living at the time such interest was acquired and
whose executor or other authorized representative causes to be furnished to the
Trustee a certified copy of the death certificate for such Deceased Holder and
any additional evidence of death satisfactory to the Trustee and any tax waivers
requested by the Trustee. Special Retail Certificates beneficially owned by
tenants by the entirety, joint tenants or tenants in common will be considered
to be beneficially owned by a single owner. The death of a tenant by the
entirety, joint tenant or tenant in common will be deemed to be the death of the
Owner, and the Special Retail Certificates so beneficially owned will be
eligible for priority with respect to distributions of principal, subject to the
limitations described herein. Special Retail Certificates beneficially owned by
a trust will be considered to be beneficially owned by each beneficiary of the
trust to the extent of such beneficiary's beneficial interest therein, but in no
event will a trust's beneficiaries collectively be deemed to be Owners of a
number of Special Retail Certificates greater than the number of Special Retail
Certificates of which such trust is the owner. The death of the beneficiary of a
trust will be deemed to be the death of an Owner of the Special Retail
Certificates beneficially owned by the trust to the extent of such beneficiary's
beneficial interest in such trust. The death of an individual who was a tenant
by the entirety, joint tenant or tenant in common in a tenancy that is the
beneficiary of a trust will be deemed to be the death of the beneficiary of the
trust. The death of a person who, during his or her lifetime, was entitled to
substantially all of the beneficial ownership interest in a Special Retail
Certificate will be deemed to be the death of the Owner of the Special Retail
Certificate regardless of the registration of the ownership, if such beneficial
ownership interest can be established to the satisfaction of the Trustee.
Expenses incurred by the Trustee in an effort to determine the beneficial
ownership interest, including, without limitation, attorney's fees, shall be
paid by the Owner. Such beneficial interest will be deemed to exist in typical
cases of street name or nominee ownership, ownership by a trustee, ownership
under the Uniform Gift to Minors Act and community property or other joint
ownership arrangements between a husband and wife. Beneficial interest shall
include the power to sell, transfer, or otherwise dispose of a Special Retail
Certificate and the right to receive the proceeds therefrom, as well as interest
and distributions in reduction of principal balance payable with respect
thereto. As used in this Prospectus Supplement, a request for a distribution of
principal of a Special Retail Certificate by a Deceased Holder shall mean a
request by the personal representative, surviving tenant by the entirety,
surviving joint tenant or surviving tenant in common of such Deceased Holder.
 
ALLOCATION OF LOSSES; SUBORDINATION
 
     Any Realized Losses which are not Excess Special Hazard Losses, Excess
Fraud Losses, Excess Bankruptcy Losses or Extraordinary Losses will be allocated
as follows: first, to the Class B-5 Certificates until the Class B-5 Certificate
Principal Balance has been reduced to zero; second, to the Class B-4
Certificates until the Class B-4 Certificate Principal Balance has been reduced
to zero; third, to the Class B-3 Certificates
 
                                      S-32
<PAGE>   33
 
until the Class B-3 Certificate Principal Balance has been reduced to zero;
fourth, to the Class B-2 Certificates until the Class B-2 Certificate Principal
Balance has been reduced to zero; fifth, to the Class B-1 Certificates until the
Class B-1 Certificate Principal Balance has been reduced to zero; sixth, to the
Class M Certificates until the Class M Certificate Principal Balance has been
reduced to zero; and seventh, to the Senior Certificates, pro rata according to
their Certificate Principal Balances in reduction thereof.
 
     Any allocation of a Realized Loss (other than a Debt Service Reduction (as
defined below)) to a Certificate will be made by reducing the Certificate
Principal Balance thereof in the case of the principal portion of such Realized
Loss, and the Accrued Certificate Interest thereon, in the case of the interest
portion of such Realized Loss, by the amount so allocated as of the Distribution
Date occurring in the month following the calendar month in which such Realized
Loss was incurred. Allocations of Debt Service Reductions (as defined below) to
the Subordinate Certificates will result from the priority of distributions to
the Senior Certificateholders of the Available Distribution Amount as described
under the captions "--Interest Distributions" and "--Principal Distributions"
herein.
 
     Any Excess Special Hazard Losses, Excess Fraud Losses, Excess Bankruptcy
Losses, Extraordinary Losses or other losses of a type not covered by
Subordination will be allocated on a pro rata basis among all of the
Certificates without priority among the various Classes of Certificates.
 
     With respect to any defaulted Mortgage Loan that is finally liquidated,
through foreclosure sale, disposition of the related Mortgaged Property if
acquired on behalf of the Certificateholders by deed in lieu of foreclosure, or
otherwise, the amount of loss realized, if any, will equal the portion of the
Stated Principal Balance (as defined below) remaining, if any, plus interest
thereon through the last day of the month in which such Mortgage Loan was
finally liquidated, after application of all amounts recovered (net of amounts
reimbursable to the Master Servicer or any Subservicer for Advances and
expenses, including attorneys' fees) towards interest and principal owing on the
Mortgage Loan. Such amount of loss realized and any Special Hazard Losses, Fraud
Losses, Bankruptcy Losses and Extraordinary Losses are referred to herein as
"Realized Losses." As used herein, "Debt Service Reductions" means reductions in
the amount of monthly payments due to certain bankruptcy proceedings, but does
not include any forgiveness of principal.
 
     The "Stated Principal Balance" of any Mortgage Loan as of any date of
determination is equal to the principal balance thereof as of the Cut-off Date,
after application of all scheduled principal payments due on or before the
Cut-off Date, whether or not received, reduced by all amounts allocable to
principal that have been distributed to Certificateholders with respect to such
Mortgage Loan on or before such date, and as further reduced to the extent that
any Realized Loss thereon has been allocated to one or more Classes of
Certificates on or before the date of determination.
 
     In order to maximize the likelihood of distribution in full of the Senior
Principal Distribution Amount and Accrued Certificate Interest thereon, holders
of Senior Certificates will have a prior right, on each Distribution Date, to
the Available Distribution Amount, to the extent necessary to satisfy the
Accrued Certificate Interest thereon and the Senior Principal Distribution
Amount. The Senior Principal Distribution Amount is subject to adjustment on
each Distribution Date to reflect the then applicable Senior Percentage and
Senior Prepayment Percentage, as described herein under "--Principal
Distributions," each of which may be increased (to not more than 100%) in the
event of delinquencies or Realized Losses on the Mortgage Loans. The application
of the Senior Prepayment Percentage when it exceeds the Senior Percentage to
determine the Senior Principal Distribution Amount will accelerate the
amortization of the Senior Certificates (except the Lockout Certificates)
relative to the actual amortization of the Mortgage Loans. To the extent that
the Senior Certificates are amortized faster than the Mortgage Loans, the
percentage interest evidenced by such Senior Certificates in the Trust Fund will
be decreased (with a corresponding increase in the interest evidenced by the
Subordinate Certificates), thereby increasing, as a relative matter, the
Subordination afforded by the related Subordinate Certificates.
 
     The total amount of Realized Losses which may be allocated solely to the
Subordinate Certificates through the operation of the subordination provisions
described above ("Subordination") in connection with Special Hazard Losses (the
"Special Hazard Amount") will equal $5,046,949 less the sum of (A) any amounts
allocated solely to the Subordinate Certificates through Subordination in
respect of Special Hazard
                                      S-33
<PAGE>   34
 
Losses and (B) the Adjustment Amount. The Adjustment Amount on each anniversary
of the Cut-off Date will be equal to the amount, if any, by which the Special
Hazard Amount, without giving effect to the deduction of the related Adjustment
Amount for such anniversary, exceeds the greater of (i) 1% (or, if greater than
1%, the highest percentage of Mortgage Loans, by principal balance, in any
California zip code area) times the aggregate principal balance of all of the
Mortgage Loans in the Mortgage Pool on such anniversary and (ii) twice the
principal balance of the single Mortgage Loan in the Mortgage Pool having the
largest principal balance. As used in this Prospectus Supplement, "Special
Hazard Losses" has the same meaning set forth in the Prospectus except that
Special Hazard Losses will not include and the Subordination will not cover
Extraordinary Losses, and Special Hazard Losses will not exceed the lesser of
the cost of repair or replacement of the related Mortgaged Properties.
 
     The total amount of Realized Losses which may be allocated solely to the
Subordinate Certificates in connection with Fraud Losses (the "Fraud Loss
Amount") from Subordination will initially be equal to $8,012,011. As of any
date of determination after the Cut-off Date the Fraud Loss Amount will equal
(X) prior to the first anniversary of the Cut-off Date an amount equal to 2% of
the aggregate principal balance of all of the Mortgage Loans as of the Cut-off
Date minus the aggregate amounts allocated solely to the Subordinate
Certificates through Subordination with respect to Fraud Losses up to such date
of determination, and (Y) from the first through fifth anniversary of the
Cut-off Date, an amount equal to (1) the lesser of (a) the Fraud Loss Amount as
of the most recent anniversary of the Cut-off Date and (b) 1% of the aggregate
principal balance of all of the Mortgage Loans as of the most recent anniversary
of the Cut-off Date minus (2) the aggregate amounts allocated solely to the
Subordinate Certificates through Subordination with respect to Fraud Losses
since the most recent anniversary of the Cut-off Date up to such date of
determination. After the fifth anniversary of the Cut-off Date the Fraud Loss
Amount for the Mortgage Loans will be zero and no allocation solely to the
Subordinate Certificates through Subordination will be made with respect to
Fraud Losses.
 
     The total amount of Realized Losses which may be allocated solely to the
Subordinate Certificates in connection with Bankruptcy Losses (the "Bankruptcy
Amount") from Subordination will equal $100,000 less the sum of any amounts
allocated solely to the Subordinate Certificates through Subordination for such
losses up to such date of determination.
 
     Notwithstanding the foregoing, the provisions relating to Subordination
will not be applicable in connection with a Bankruptcy Loss so long as the
Master Servicer has notified the Trustee in writing that it is diligently
pursuing any remedies that may exist in connection with the representations and
warranties made regarding the related Mortgage Loan and either (A) the related
Mortgage Loan is not in default with regard to payments due thereunder or (B)
delinquent payments of principal and interest under the related Mortgage Loan
and any premiums on any applicable Primary Hazard Insurance Policy and any
related escrow payments in respect of such Mortgage Loan are being advanced on a
current basis by the Master Servicer or a Subservicer.
 
ADVANCES
 
     Prior to each Distribution Date, the Master Servicer is required to make
Advances (out of its own funds, advances made by a Subservicer, or funds held in
the Custodial Account (as described in the Prospectus) for future distribution
or withdrawal) with respect to any payments of principal and interest (net of
the related master servicing fees and any subservicing fees) which were due on
the Mortgage Loans on the immediately preceding Due Date and delinquent on the
Business Day next preceding the related Determination Date, but only if the
Master Servicer believes that the amount advanced will be recoverable from
related late collections, Insurance Proceeds or Liquidation Proceeds.
 
     The purpose of making such Advances is to maintain a regular cash flow to
the Certificateholders, rather than to guarantee or insure against losses. The
Master Servicer will not be required to make any Advances with respect to
reductions in the amount of the monthly payments on the Mortgage Loans due to
Debt Service Reductions or the application of the Relief Act or similar
legislation. Any failure by the Master Servicer to make an Advance as required
under the Pooling Agreement will constitute an Event of Default thereunder, in
 
                                      S-34
<PAGE>   35
 
which case the Trustee, as successor to the Master Servicer, will be obligated
to make any such advance, in accordance with the terms of the Pooling Agreement.
 
     All Advances will be reimbursable to the Master Servicer or any applicable
Subservicer on a first priority basis from either (a) late collections,
Insurance Proceeds and Liquidation Proceeds from the Mortgage Loan as to which
such unreimbursed Advance was made or (b) as to any Advance that remains
unreimbursed following the final liquidation of the related Mortgage Loan, from
amounts otherwise distributable on the Subordinate Certificates; provided,
however, that only the Subordinate Percentage, of such Advances are reimbursable
from amounts otherwise distributable on such Subordinate Certificates in the
event that such Advances were made with respect to delinquencies which
ultimately were determined to be Excess Special Hazard Losses, Excess Fraud
Losses, Excess Bankruptcy Losses or Extraordinary Losses and the Senior
Percentage of such Advances which may not be so reimbursed from amounts
otherwise distributable on the related Subordinate Certificates may be
reimbursed to the Master Servicer or the applicable Subservicer out of any funds
in the Custodial Account or Certificate Account prior to distributions on the
Senior Certificates. In the latter event, the aggregate amount otherwise
distributable on the Senior Certificates will be reduced by an amount equal to
the Senior Percentage of such Advances. In addition, if the Certificate
Principal Balances of the Subordinate Certificates have been reduced to zero,
any Advances previously made which are deemed by the Master Servicer or any
applicable Subservicer to be nonrecoverable from late collections, Insurance
Proceeds and Liquidation Proceeds may be reimbursed to the Master Servicer or
such Subservicer out of any funds in the Custodial Account or Certificate
Account prior to distributions on the Senior Certificates.
 
LAST SCHEDULED DISTRIBUTION DATE
 
     The Last Scheduled Distribution Date for the Certificates is the
Distribution Date in December 2028, which is the Distribution Date occurring in
the month after the scheduled maturity date for the latest maturing Mortgage
Loan.
 
     The actual last Distribution Date on the Certificates will depend on the
rate of payments of principal (including Principal Prepayments) on the 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.
 
                  CERTAIN YIELD AND PREPAYMENT CONSIDERATIONS
 
     The effective yield to the holders of Offered Certificates will be lower
than the yield otherwise produced by the applicable Pass-Through Rate and
purchase price because monthly distributions will not be made to such holders
until the 25th day (or if such day is not a Business Day, then on the next
succeeding Business Day) of the month following the month in which interest
accrues on the Mortgage Loans (without any additional distributions of interest
or earnings thereon in respect of such delay). See "YIELD CONSIDERATIONS" in the
Prospectus.
 
     The yield to maturity and the aggregate amount of distributions on the
Offered Certificates will be directly related to the rate of payment of
principal on the Mortgage Loans. Such yield may be adversely affected by a
higher or lower than anticipated rate of payment of principal on the Mortgage
Loans. The rate of payment of principal on such Mortgage Loans will in turn be
affected by the amortization schedules of the Mortgage Loans, the rate of
Principal Prepayments thereon by the Mortgagors, liquidations of defaulted
Mortgage Loans and purchases of Mortgage Loans due to certain breaches of
representations and warranties. The Mortgage Loans may be prepaid by the
Mortgagors at any time without payment of any prepayment fee or penalty. All of
the Mortgage Loans contain due-on-sale clauses. In addition, the amortization
schedule of a Mortgage Loan may be changed in connection with the receipt of a
partial prepayment thereon, provided however that such changes will not include
a change in the maturity date of the related Mortgage Loan. See "DESCRIPTION OF
THE MORTGAGE POOL--General" herein. As described under "DESCRIPTION OF THE
CERTIFICATES--Principal Distributions" herein, all Principal Prepayments on the
Mortgage Loans will generally be distributed to the Senior Certificates during
at least the first five years after the Closing Date.
                                      S-35
<PAGE>   36
 
     Factors affecting prepayment of mortgage loans include changes in
mortgagors' housing needs, job transfers, mortgage market interest rates,
unemployment, mortgagors' net equity in the mortgaged properties, changes in the
value of the mortgaged properties and servicing decisions. If prevailing
mortgage rates fell significantly below the Mortgage Rates on the Mortgage
Loans, the rate of prepayment (and refinancing) would be expected to increase.
Conversely, if prevailing mortgage rates rose significantly above the Mortgage
Rates on the Mortgage Loans, the rate of prepayment on the Mortgage Loans would
be expected to decrease. There can be no certainty as to the rate of prepayments
on the Mortgage Loans during any period or over the life of the Certificates.
 
     Investors in the Lockout Certificates should be aware that because the
Lockout Certificates generally do not receive any distributions of scheduled
principal payments or Principal Prepayments prior to the Distribution Date
occurring in December 2003, the weighted average life of the Lockout
Certificates will be significantly 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 Senior Certificates entitled to such
distributions.
 
     The yields to investors on all of the Offered Certificates entitled to
interest will also be adversely affected by any interest shortfalls of a type
not covered by Subordination, including Net Prepayment Interest Shortfalls.
There can be no assurance that the Mortgage Loans will prepay at any particular
rate or that the cash flows on the Certificates will conform to the cash flows
described herein.
 
     Because the Mortgage Rates on the Mortgage Loans and the Pass-Through Rates
on the Offered Certificates (other than the LIBOR Certificates) are fixed, such
rates will not change in response to changes in market interest rates.
Accordingly, if market interest rates or market yields for securities similar to
the Offered Certificates were to rise, the market value of such Offered
Certificates may decline.
 
     The rate of defaults on the Mortgage Loans will also affect the rate of
payment of principal on the Mortgage Loans. In general, defaults on mortgage
loans are expected to occur with greater frequency in their early years. The
rate of default on mortgage loans that are equity refinance mortgage loans may
be higher than for other types of mortgage loans. Prepayments, liquidations and
purchases of the Mortgage Loans will result in distributions to
Certificateholders of principal amounts which would otherwise be distributed
over the remaining terms of the Mortgage Loans. Furthermore, the rate of
prepayments, defaults and liquidations on the Mortgage Loans will be affected by
the general economic condition of the region of the country in which the related
Mortgaged Properties are located. The risk of delinquencies and loss is greater
and prepayments are less likely in regions where a weak or deteriorating economy
exists, as may be evidenced by, among other factors, increasing unemployment or
falling property values. See "MATURITY AND PREPAYMENT CONSIDERATIONS" in the
Prospectus. Since the rates of payment of principal on the Mortgage Loans will
depend on future events and on a variety of factors (as described more fully
herein and in the Prospectus under "YIELD CONSIDERATIONS" and "MATURITY AND
PREPAYMENT CONSIDERATIONS"), no assurance can be given as to such rate or the
rate of principal prepayments on the Certificates.
 
     The amount of interest otherwise payable to holders of the Certificates
will be reduced by any interest shortfalls not covered by Subordination,
including Net Prepayment Interest Shortfalls. Such shortfalls will not be offset
by a reduction in the Servicing Fee payable to the Master Servicer or any
applicable Subservicer or otherwise. Net Prepayment Interest Shortfalls on any
Distribution Date will be allocated among the holders of all Classes of
Certificates (including the Subordinate and Class R Certificates), in proportion
to the respective amounts of Accrued Certificate Interest for such Distribution
Date on each such Class. See "YIELD CONSIDERATIONS" in the Prospectus and
"DESCRIPTION OF THE CERTIFICATES--Interest Distributions" herein for a
discussion of the effect of principal prepayments on the Mortgage Loans on the
yield to maturity of the Certificates and certain possible shortfalls in the
collection of interest.
 
     The timing of changes in the rate of prepayments, liquidations and
repurchases of the 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. Because all or a
disproportionate percentage of principal prepayments will generally be allocated
to the Senior Certificates during at least the first five years
 
                                      S-36
<PAGE>   37
 
after the Closing Date, the rate of principal prepayments on the Mortgage Loans
during this period may significantly affect the yield to maturity of the Offered
Certificates.
 
     AS DESCRIBED HEREIN UNDER "DESCRIPTION OF THE CERTIFICATES--DISTRIBUTIONS
IN REDUCTION OF THE SPECIAL RETAIL CERTIFICATES," THE TIMING OF DISTRIBUTIONS OF
PRINCIPAL WITH RESPECT TO A PARTICULAR SPECIAL RETAIL CERTIFICATE IS HIGHLY
UNCERTAIN. SUCH UNCERTAINTY ARISES FROM THE UNPREDICTABILITY OF PRINCIPAL
PAYMENTS (INCLUDING PREPAYMENTS) AS WELL AS THE SPECIAL METHOD OF ALLOCATING
AMONG THE OWNERS OF EACH CLASS OF SPECIAL RETAIL CERTIFICATES THE AMOUNT OF
PRINCIPAL AVAILABLE FOR DISTRIBUTION ON SUCH CLASS OF SPECIAL RETAIL
CERTIFICATES. SEE "RISK FACTORS--CLASS A-12 AND CLASS A-15 CERTIFICATES MAY NOT
RECEIVE PRINCIPAL DISTRIBUTIONS WHEN REQUESTED."
 
     In addition, the yield to maturity of the Certificates will depend on the
price paid by the holders of the Certificates and the related Pass-Through Rate.
The extent to which the yield to maturity of a Certificate may vary from the
anticipated yield thereon will depend upon the degree to which it is purchased
at a discount or premium and the degree to which the timing of payments thereon
is sensitive to prepayments. Because principal distributions are paid to certain
Classes of Offered Certificates before other Classes, holders of Classes of
Offered Certificates having a later priority of payment bear a greater risk of
losses than holders of Classes of Offered Certificates having earlier priorities
for distribution of principal. For additional considerations relating to the
yield on the Certificates, see "YIELD CONSIDERATIONS" and "MATURITY AND
PREPAYMENT CONSIDERATIONS" in the Prospectus.
 
     Weighted average life refers to the average amount of time that will elapse
from the date of issuance of a security until a dollar amount in payment of
principal equal to the original principal balance of such security (less losses)
is distributed to the investor. The weighted average life of the Certificates
will be influenced by among other things, the rate at which principal of the
Mortgage Loans is paid, which may be in the form of scheduled amortization,
prepayments or liquidations.
 
     Prepayments on mortgage loans are commonly measured relative to a
prepayment standard or model. The model used in this Prospectus Supplement, the
standard prepayment assumption ("SPA"), represents an assumed rate of prepayment
each month relative to the then outstanding principal balance of a pool of new
mortgage loans. A prepayment assumption of 100% SPA assumes constant 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 thirtieth month.
Beginning in the thirtieth month and in each month thereafter during the life of
the mortgage loans, 100% SPA assumes a constant prepayment rate of 6% per annum
each month. As used in the table below, "100% SPA" assumes prepayment rates
equal to 100% of SPA and "200% SPA" assumes prepayment rates equal to 200% of
SPA. Correspondingly, "275% SPA" assumes prepayment rates equal to 275% of SPA,
and so forth. SPA does not purport to be a historical description of prepayment
experience or a prediction of the anticipated rate of prepayment of any pool of
mortgage loans, including the Mortgage Loans.
 
     Unless otherwise specified, the information in the tables in this
Prospectus Supplement has been prepared on the basis of the following assumed
characteristics of the Mortgage Loans and the following additional assumptions
(collectively, the "Structuring Assumptions"): the Mortgage Loans are comprised
of a group of hypothetical mortgage loans which have the common characteristics
indicated:
 
                          HYPOTHETICAL MORTGAGE LOANS
 
<TABLE>
<CAPTION>
                     AMORTIZED
UNPAID PRINCIPAL   REMAINING TERM    CALCULATED      MORTGAGE     NET MORTGAGE
    BALANCE           (MONTHS)      AGE (MONTHS)       RATE           RATE
- ----------------   --------------   ------------     --------     ------------
<S>                <C>              <C>            <C>            <C>
$400,600,537.57         357              1         7.2662343096%  6.2500000000%
</TABLE>
 
and that (i) scheduled payments on all Mortgage Loans are received on the first
day of each month beginning December 1, 1998, (ii) any Principal Prepayments in
full on the Mortgage Loans are received on the last day of each month beginning
in November 1998 and include 30 days of interest thereon, (iii) there are no
defaults or delinquencies on the Mortgage Loans, (iv) optional termination of
the Trust Fund does not occur, (v) there
 
                                      S-37
<PAGE>   38
 
are no partial Principal Prepayments on the Mortgage Loans and Principal
Prepayments in full are computed after giving effect to scheduled payments
received on the following day, (vi) the Mortgage Loans prepay at the indicated
constant percentages of SPA, (vii) the date of issuance for the Certificates is
November 30, 1998, (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 Rate and amortized remaining term such that the
Mortgage Loan will fully amortize on its maturity date. SOME OF THE FOREGOING
ASSUMPTIONS REGARDING THE CHARACTERISTICS OF THE MORTGAGE LOANS AND THE
CERTIFICATES DIFFER FROM THE ACTUAL CHARACTERISTICS THEREOF.
 
     The discrepancies between the Structuring Assumptions and the actual
characteristics of the Mortgage Loans and the Certificates underscore the
hypothetical nature of the following tables, which are provided to give a
general sense of principal cash flows under varying prepayment scenarios.
Likewise, it is very unlikely that the Mortgage Loans will prepay at a constant
level of SPA until maturity or that all of the Mortgage Loans will prepay at the
same level of SPA. Any difference between such assumptions and the actual
characteristics of the Mortgage Loans or of the Certificates, or the actual
prepayment experience of the Mortgage Loans may result in percentages of the
initial Certificate Principal Balance outstanding and weighted average lives of
the Offered Certificates different from those shown.
 
     Based upon the foregoing assumptions, the following table sets forth the
percentages of the initial Certificate Principal Balance of each such Class of
Offered Certificates that would be outstanding after each of the Distribution
Dates shown at various percentages of SPA and the corresponding weighted average
lives.
 
     The weighted average lives of the Special Retail Certificates shown in the
table below apply to each such Class taken as a whole. Because principal
distributions may be required by the Owners of the Special Retail Certificates
and because Owners of a Class of Special Retail Certificates will receive
principal distributions by random lot, the weighted average life of any Special
Retail Certificate beneficially owned by an individual investor may vary
significantly from the weighted average life of such Class of Special Retail
Certificates taken as a whole. There can be no assurance with respect to any
particular scenario of the rate of principal distributions on the Special Retail
Certificates, any particular weighted average life for the Special Retail
Certificates or the date or dates on which any particular Owner will receive
distributions in reduction of the principal balance of its Special Retail
Certificates. Investors in the Special Retail Certificates should understand
that they are assuming all risks and benefits associated with the rate of
principal distributions on such Certificates and variations in such rate from
time to time.
 
                                      S-38
<PAGE>   39
 
          PERCENT OF INITIAL CERTIFICATE PRINCIPAL BALANCE OUTSTANDING
                      AT THE FOLLOWING PERCENTAGES OF SPA
<TABLE>
<CAPTION>
                                                  CLASS A-1                       CLASS A-2, CLASS A-9 AND CLASS A-10
                                  ------------------------------------------   ------------------------------------------
       DISTRIBUTION DATE           100%     200%     275%     400%     500%     100%     200%     275%     400%     500%
       -----------------          ------   ------   ------   ------   ------   ------   ------   ------   ------   ------
<S>                               <C>      <C>      <C>      <C>      <C>      <C>      <C>      <C>      <C>      <C>
Initial Percentage..............     100      100      100      100      100      100      100      100      100      100
November 25, 1999...............      97       94       93       90       88       97       95       94       92       90
November 25, 2000...............      90       83       77       69       62       91       85       80       73       67
November 25, 2001...............      81       67       57       42       31       83       71       63       50       40
November 25, 2002...............      72       53       40       21        9       76       59       48       32       21
November 25, 2003...............      64       40       26        6        0       69       48       36       18        7
November 25, 2004...............      57       31       15        0        0       62       40       26        9        *
November 25, 2005...............      50       22        7        0        0       57       33       19        4        0
November 25, 2006...............      44       15        *        0        0       52       27       14        *        0
November 25, 2007...............      39       10        0        0        0       47       22       10        0        0
November 25, 2008...............      34        6        0        0        0       43       18        7        0        0
November 25, 2009...............      29        1        0        0        0       39       15        5        0        0
November 25, 2010...............      25        0        0        0        0       35       12        3        0        0
November 25, 2011...............      21        0        0        0        0       31        9        1        0        0
November 25, 2012...............      17        0        0        0        0       28        7        0        0        0
November 25, 2013...............      13        0        0        0        0       25        5        0        0        0
November 25, 2014...............      10        0        0        0        0       22        3        0        0        0
November 25, 2015...............       7        0        0        0        0       19        2        0        0        0
November 25, 2016...............       4        0        0        0        0       16        *        0        0        0
November 25, 2017...............       *        0        0        0        0       14        0        0        0        0
November 25, 2018...............       0        0        0        0        0       11        0        0        0        0
November 25, 2019...............       0        0        0        0        0        9        0        0        0        0
November 25, 2020...............       0        0        0        0        0        7        0        0        0        0
November 25, 2021...............       0        0        0        0        0        5        0        0        0        0
November 25, 2022...............       0        0        0        0        0        3        0        0        0        0
November 25, 2023...............       0        0        0        0        0        1        0        0        0        0
November 25, 2024...............       0        0        0        0        0        0        0        0        0        0
November 25, 2025...............       0        0        0        0        0        0        0        0        0        0
November 25, 2026...............       0        0        0        0        0        0        0        0        0        0
November 25, 2027...............       0        0        0        0        0        0        0        0        0        0
November 25, 2028...............       0        0        0        0        0        0        0        0        0        0
 
Weighted Average Life
 (Years)(1).....................     8.1      4.8      3.7      2.8      2.4     10.0      6.0      4.6      3.3      2.8
 
<CAPTION>
                                           CLASS A-3 AND CLASS A-11                            CLASS A-4
                                  ------------------------------------------   ------------------------------------------
       DISTRIBUTION DATE           100%     200%     275%     400%     500%     100%     200%     275%     400%     500%
       -----------------          ------   ------   ------   ------   ------   ------   ------   ------   ------   ------
<S>                               <C>      <C>      <C>      <C>      <C>      <C>      <C>      <C>      <C>      <C>
Initial Percentage..............     100      100      100      100      100      100      100      100      100      100
November 25, 1999...............     100      100      100      100      100      100      100      100      100      100
November 25, 2000...............     100      100      100      100      100      100      100      100      100      100
November 25, 2001...............     100      100      100      100      100      100      100      100      100      100
November 25, 2002...............     100      100      100      100      100      100      100      100      100      100
November 25, 2003...............     100      100      100      100       77      100      100      100      100      100
November 25, 2004...............     100      100      100       85       50       97       95       93       91       89
November 25, 2005...............     100      100      100       63        0       93       89       85       80       76
November 25, 2006...............     100      100      100       50        0       88       81       75       67       59
November 25, 2007...............     100      100       86       38        0       82       71       64       53       39
November 25, 2008...............     100      100       75       11        0       75       61       52       39       27
November 25, 2009...............     100      100       66        0        0       69       53       43       29       18
November 25, 2010...............     100       93       59        0        0       63       45       35       21       13
November 25, 2011...............     100       83       53        0        0       58       39       28       16        9
November 25, 2012...............     100       75       50        0        0       53       33       23       12        6
November 25, 2013...............     100       68       49        0        0       48       28       18        9        4
November 25, 2014...............     100       62       28        0        0       43       24       15        6        3
November 25, 2015...............     100       56        9        0        0       39       20       12        5        2
November 25, 2016...............     100       51        0        0        0       35       17        9        3        1
November 25, 2017...............     100       50        0        0        0       31       14        7        2        1
November 25, 2018...............      92       49        0        0        0       27       11        6        2        1
November 25, 2019...............      84       28        0        0        0       24        9        4        1        *
November 25, 2020...............      76       10        0        0        0       20        7        3        1        *
November 25, 2021...............      68        0        0        0        0       17        6        3        1        *
November 25, 2022...............      61        0        0        0        0       14        5        2        *        *
November 25, 2023...............      55        0        0        0        0       11        3        1        *        *
November 25, 2024...............      50        0        0        0        0        9        2        1        *        *
November 25, 2025...............      39        0        0        0        0        6        2        1        *        *
November 25, 2026...............       0        0        0        0        0        4        1        *        *        *
November 25, 2027...............       0        0        0        0        0        2        *        *        *        *
November 25, 2028...............       0        0        0        0        0        0        0        0        0        0
Weighted Average Life
 (Years)(1).....................    24.8     17.8     13.2      8.0      5.9     15.6     12.7     11.3      9.9      9.0
</TABLE>
 
- ------------------------------
 *  Indicates an amount above zero and less than 0.5% of the Initial Certificate
    Principal Balance outstanding.
 
(1) The weighted average life of any Class of Certificates is determined by (i)
    multiplying the amount of each assumed reduction in Certificate Principal
    Balance 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 such
    reductions on such Class of Certificates.
 
                                      S-39
<PAGE>   40
 
        PERCENT OF INITIAL CERTIFICATE PRINCIPAL BALANCE OR OUTSTANDING
                      AT THE FOLLOWING PERCENTAGES OF SPA
<TABLE>
<CAPTION>
                                                    CLASS A-5                                    CLASS A-6
                                    ------------------------------------------   ------------------------------------------
        DISTRIBUTION DATE            100%     200%     275%     400%     500%     100%     200%     275%     400%     500%
        -----------------           ------   ------   ------   ------   ------   ------   ------   ------   ------   ------
<S>                                 <C>      <C>      <C>      <C>      <C>      <C>      <C>      <C>      <C>      <C>
Initial Percentage................     100      100      100      100      100      100      100      100      100      100
November 25, 1999.................     100      100      100      100      100      100      100      100      100      100
November 25, 2000.................     100      100      100      100      100      100      100      100      100      100
November 25, 2001.................     100      100      100      100      100      100      100      100      100      100
November 25, 2002.................     100      100      100      100      100      100      100      100      100      100
November 25, 2003.................     100      100      100      100       72      100      100      100      100       78
November 25, 2004.................     100      100      100       82       39      100      100      100       86       52
November 25, 2005.................     100      100      100       55        8      100      100      100       65       16
November 25, 2006.................     100      100      100       39        0      100      100      100       52        0
November 25, 2007.................     100      100       83       18        0      100      100       87       37        0
November 25, 2008.................     100      100       70       13        0      100      100       76       27        0
November 25, 2009.................     100      100       59       10        0      100      100       68       20        0
November 25, 2010.................     100       91       51        7        0      100       93       61       15        0
November 25, 2011.................     100       80       43        5        0      100       84       55       11        0
November 25, 2012.................     100       70       34        4        0      100       76       49        8        0
November 25, 2013.................     100       61       20        3        0      100       69       41        6        0
November 25, 2014.................     100       54       16        2        0      100       63       33        4        0
November 25, 2015.................     100       47       13        2        0      100       58       26        3        0
November 25, 2016.................     100       41       10        1        0      100       54       21        2        0
November 25, 2017.................     100       32        8        1        0      100       48       17        2        0
November 25, 2018.................      90       20        6        1        0       92       41       13        1        0
November 25, 2019.................      80       16        5        *        0       85       33       10        1        0
November 25, 2020.................      71       13        4        *        0       77       27        8        1        0
November 25, 2021.................      62       10        3        *        0       70       21        6        *        0
November 25, 2022.................      53        8        2        *        0       63       16        4        *        0
November 25, 2023.................      45        6        1        *        0       57       12        3        *        0
November 25, 2024.................      35        4        1        *        0       49        9        2        *        0
November 25, 2025.................      18        3        1        *        0       37        6        1        *        0
November 25, 2026.................      11        2        *        *        0       23        3        1        *        0
November 25, 2027.................       5        1        *        *        0       10        1        *        *        0
November 25, 2028.................       0        0        0        0        0        0        0        0        0        0
 
Weighted Average Life
  (Years)(1)......................    24.2     17.1     12.8      8.0      5.7     25.2     18.7     14.3      9.0      6.0
 
<CAPTION>
                                                    CLASS A-7
                                    ------------------------------------------
        DISTRIBUTION DATE            100%     200%     275%     400%     500%
        -----------------           ------   ------   ------   ------   ------
<S>                                 <C>      <C>      <C>      <C>      <C>
Initial Percentage................     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      100
November 25, 2003.................     100      100      100      100       11
November 25, 2004.................     100      100      100       41        0
November 25, 2005.................     100      100      100        0        0
November 25, 2006.................     100      100      100        0        0
November 25, 2007.................     100      100       45        0        0
November 25, 2008.................     100      100        4        0        0
November 25, 2009.................     100      100        0        0        0
November 25, 2010.................     100       72        0        0        0
November 25, 2011.................     100       35        0        0        0
November 25, 2012.................     100        3        0        0        0
November 25, 2013.................     100        0        0        0        0
November 25, 2014.................     100        0        0        0        0
November 25, 2015.................     100        0        0        0        0
November 25, 2016.................     100        0        0        0        0
November 25, 2017.................     100        0        0        0        0
November 25, 2018.................      69        0        0        0        0
November 25, 2019.................      37        0        0        0        0
November 25, 2020.................       6        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
November 25, 2028.................       0        0        0        0        0
Weighted Average Life
  (Years)(1)......................    20.6     12.7      9.0      6.0      4.8
</TABLE>
 
- ------------------------------
 *  Indicates an amount above zero and less than 0.5% of the Initial Certificate
    Principal Balance outstanding.
 
(1) The weighted average life of any Class of Certificates is determined by (i)
    multiplying the amount of each assumed reduction in Certificate Principal
    Balance 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 such
    reductions on such Class of Certificates.
 
                                      S-40
<PAGE>   41
 
          PERCENT OF INITIAL CERTIFICATE PRINCIPAL BALANCE OUTSTANDING
                      AT THE FOLLOWING PERCENTAGES OF SPA
<TABLE>
<CAPTION>
                                                    CLASS A-8                            CLASS A-12 AND CLASS A-13
                                    ------------------------------------------   ------------------------------------------
        DISTRIBUTION DATE            100%     200%     275%     400%     500%     100%     200%     275%     400%     500%
        -----------------           ------   ------   ------   ------   ------   ------   ------   ------   ------   ------
<S>                                 <C>      <C>      <C>      <C>      <C>      <C>      <C>      <C>      <C>      <C>
Initial Percentage................     100      100      100      100      100      100      100      100      100      100
November 25, 1999.................      96       94       93       90       88      100      100      100      100      100
November 25, 2000.................      90       82       77       68       61      100      100      100      100      100
November 25, 2001.................      80       66       56       40       29      100      100      100      100      100
November 25, 2002.................      71       51       38       19        6      100      100      100      100      100
November 25, 2003.................      63       39       24        3        0      100      100      100      100      100
November 25, 2004.................      56       29       13        0        0      100      100      100      100      100
November 25, 2005.................      49       20        4        0        0      100      100      100      100       69
November 25, 2006.................      43       13        0        0        0      100      100      100      100        0
November 25, 2007.................      37        7        0        0        0      100      100      100      100        0
November 25, 2008.................      32        3        0        0        0      100      100      100      100        0
November 25, 2009.................      27        0        0        0        0      100      100      100       87        0
November 25, 2010.................      23        0        0        0        0      100      100      100       64        0
November 25, 2011.................      19        0        0        0        0      100      100      100       47        0
November 25, 2012.................      15        0        0        0        0      100      100      100       35        0
November 25, 2013.................      11        0        0        0        0      100      100      100       26        0
November 25, 2014.................       7        0        0        0        0      100      100      100       19        0
November 25, 2015.................       4        0        0        0        0      100      100      100       14        0
November 25, 2016.................       1        0        0        0        0      100      100       90       10        0
November 25, 2017.................       0        0        0        0        0      100      100       71        7        0
November 25, 2018.................       0        0        0        0        0      100      100       55        5        0
November 25, 2019.................       0        0        0        0        0      100      100       43        4        0
November 25, 2020.................       0        0        0        0        0      100      100       33        2        0
November 25, 2021.................       0        0        0        0        0      100       91       25        2        0
November 25, 2022.................       0        0        0        0        0      100       70       18        1        0
November 25, 2023.................       0        0        0        0        0      100       53       13        1        0
November 25, 2024.................       0        0        0        0        0      100       38        9        *        0
November 25, 2025.................       0        0        0        0        0      100       25        6        *        0
November 25, 2026.................       0        0        0        0        0       98       15        3        *        0
November 25, 2027.................       0        0        0        0        0       41        6        1        *        0
November 25, 2028.................       0        0        0        0        0        0        0        0        0        0
 
Weighted Average Life
  (Years)(1)......................     7.8      4.6      3.6      2.7      2.4     28.9     25.5     21.2     13.8      7.3
 
<CAPTION>
                                      CLASS A-14, CLASS A-18 AND CLASS A-19
                                    ------------------------------------------
        DISTRIBUTION DATE            100%     200%     275%     400%     500%
        -----------------           ------   ------   ------   ------   ------
<S>                                 <C>      <C>      <C>      <C>      <C>
Initial Percentage................     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      100
November 25, 2003.................     100      100      100      100      100
November 25, 2004.................     100      100      100      100        3
November 25, 2005.................     100      100      100       55        0
November 25, 2006.................     100      100      100        3        0
November 25, 2007.................     100      100      100        0        0
November 25, 2008.................     100      100      100        0        0
November 25, 2009.................     100      100       69        0        0
November 25, 2010.................     100      100       40        0        0
November 25, 2011.................     100      100       17        0        0
November 25, 2012.................     100      100        0        0        0
November 25, 2013.................     100       75        0        0        0
November 25, 2014.................     100       50        0        0        0
November 25, 2015.................     100       29        0        0        0
November 25, 2016.................     100       10        0        0        0
November 25, 2017.................     100        0        0        0        0
November 25, 2018.................     100        0        0        0        0
November 25, 2019.................     100        0        0        0        0
November 25, 2020.................     100        0        0        0        0
November 25, 2021.................      77        0        0        0        0
November 25, 2022.................      49        0        0        0        0
November 25, 2023.................      23        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
November 25, 2028.................       0        0        0        0        0
Weighted Average Life
  (Years)(1)......................    24.0     16.2     11.8      7.2      5.6
</TABLE>
 
- ------------------------------
  *  Indicates an amount above zero and less than 0.5% of the Initial
     Certificate Principal Balance outstanding.
 
 (1) The weighted average life of any Class of Certificates is determined by (i)
     multiplying the amount of each assumed reduction in Certificate Principal
     Balance 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 such
     reductions on such Class of Certificates.
 
                                      S-41
<PAGE>   42
 
          PERCENT OF INITIAL CERTIFICATE PRINCIPAL BALANCE OUTSTANDING
                      AT THE FOLLOWING PERCENTAGES OF SPA
<TABLE>
<CAPTION>
                                       CLASS A-15, CLASS A-16 AND CLASS A-17           CLASS M, CLASS B-1 AND CLASS B-2
                                     ------------------------------------------   ------------------------------------------
         DISTRIBUTION DATE            100%     200%     275%     400%     500%     100%     200%     275%     400%     500%
         -----------------           ------   ------   ------   ------   ------   ------   ------   ------   ------   ------
<S>                                  <C>      <C>      <C>      <C>      <C>      <C>      <C>      <C>      <C>      <C>
Initial Percentage.................     100      100      100      100      100      100      100      100      100      100
November 25, 1999..................     100      100      100      100      100       99       99       99       99       99
November 25, 2000..................     100      100      100      100      100       98       98       98       98       98
November 25, 2001..................     100      100      100      100      100       97       97       97       97       97
November 25, 2002..................     100      100      100      100      100       96       96       96       96       96
November 25, 2003..................     100      100      100      100      100       94       94       94       94       94
November 25, 2004..................     100      100      100      100      100       91       89       88       86       84
November 25, 2005..................     100      100      100      100       20       87       84       81       75       71
November 25, 2006..................     100      100      100      100        0       83       76       71       63       57
November 25, 2007..................     100      100      100       46        0       77       67       60       50       42
November 25, 2008..................     100      100      100       34        0       71       58       49       37       29
November 25, 2009..................     100      100      100       26        0       65       50       40       27       20
November 25, 2010..................     100      100      100       19        0       60       43       33       20       13
November 25, 2011..................     100      100      100       14        0       55       36       26       15        9
November 25, 2012..................     100      100       89       10        0       50       31       21       11        6
November 25, 2013..................     100      100       53        8        0       45       26       17        8        4
November 25, 2014..................     100      100       42        5        0       41       22       14        6        3
November 25, 2015..................     100      100       33        4        0       37       19       11        4        2
November 25, 2016..................     100      100       26        3        0       33       16        9        3        1
November 25, 2017..................     100       83       21        2        0       29       13        7        2        1
November 25, 2018..................     100       51       16        1        0       25       11        5        2        1
November 25, 2019..................     100       42       13        1        0       22        9        4        1        *
November 25, 2020..................     100       34       10        1        0       19        7        3        1        *
November 25, 2021..................     100       27        7        *        0       16        6        2        1        *
November 25, 2022..................     100       21        5        *        0       13        4        2        *        *
November 25, 2023..................     100       16        4        *        0       11        3        1        *        *
November 25, 2024..................      91       11        3        *        0        8        2        1        *        *
November 25, 2025..................      46        7        2        *        0        6        2        1        *        *
November 25, 2026..................      29        4        1        *        0        4        1        *        *        *
November 25, 2027..................      12        2        *        *        0        2        *        *        *        *
November 25, 2028..................       0        0        0        0        0        0        0        0        0        0
 
Weighted Average Life (Years)(1)...    27.3     21.5     16.8     10.2      6.6     14.8     12.1     10.8      9.5      8.8
 
<CAPTION>
                                                      CLASS R
                                     ------------------------------------------
         DISTRIBUTION DATE            100%     200%     275%     400%     500%
         -----------------           ------   ------   ------   ------   ------
<S>                                  <C>      <C>      <C>      <C>      <C>
Initial Percentage.................     100      100      100      100      100
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
November 25, 2028..................       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 the Initial
     Certificate Principal Balance outstanding.
 
 (1) The weighted average life of any Class of Certificates is determined by (i)
     multiplying the amount of each assumed reduction in Certificate Principal
     Balance 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 such
     reductions on such Class of Certificates.
 
                                      S-42
<PAGE>   43
 
LIBOR CERTIFICATE YIELD CONSIDERATIONS
 
     The yield to investors on the Class A-18 Certificates will be sensitive,
and the yield to investors on the Class A-19 Certificates will be particularly
sensitive, to fluctuations in the level of LIBOR. THE PASS-THROUGH RATE ON THE
CLASS A-18 CERTIFICATES WILL VARY WITH LIBOR AND THE PASS-THROUGH RATE ON THE
CLASS A-19 CERTIFICATES WILL VARY INVERSELY WITH, AND AT A MULTIPLE OF, LIBOR.
The Pass-Through Rates on the LIBOR Certificates are subject to maximum and
minimum Pass-Through Rates, and are therefore subject to limitation despite
changes in LIBOR in certain circumstances.
 
     Changes in the level of LIBOR may not correlate with changes in prevailing
mortgage interest rates or changes in other indices. 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.
Investors in the LIBOR Certificates should also fully consider the effect on the
yields on such Certificates of changes in the level of LIBOR.
 
     To illustrate the significance of changes in the level of LIBOR and
prepayments on the yield to maturity on the Class A-19 Certificates, the
following table indicates the approximate pre-tax yields to maturity (on a
corporate bond equivalent basis) under the different constant percentages of SPA
and varying levels of LIBOR indicated. Because the rate of distribution of
principal on the Certificates will be related to the actual amortization
(including prepayments) of the Mortgage Loans, which will include Mortgage Loans
that have remaining terms to maturity shorter or longer than as assumed and
mortgage rates higher or lower than as assumed, the pre-tax yields to maturity
on the Class A-19 Certificates are likely to differ from those shown in the
following table, even if all the Mortgage Loans prepay at constant percentages
of SPA and the level of LIBOR and the weighted average remaining term to
maturity of the Mortgage Loans is as assumed. Any differences between such
assumptions and the actual characteristics and performance of the Mortgage Loans
and of the Certificates may result in yields being different from those shown in
such tables. Discrepancies between assumed and actual characteristics and
performance underscore the hypothetical nature of the tables, which is provided
only to give a general sense of the sensitivity of yields in varying prepayment
scenarios and different levels of LIBOR. In addition, it is highly unlikely that
the Mortgage Loans will prepay at a constant level of SPA until maturity, that
all the Mortgage Loans will prepay at the same rate, or that the level of LIBOR
will remain constant. The timing of changes in the rate of prepayments may
significantly affect the actual yield to maturity to an investor, even if the
average rate of principal prepayments is consistent with an investor's
expectation. In general, the earlier the payment of principal of the Mortgage
Loans, the greater the effect on an investor's yield to maturity. As a result,
the effect on an investor's yield 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 will not be equally
offset by a subsequent like reduction (or increase) in the rate of principal
prepayments.
 
     The table set forth below is based on the Structuring Assumptions and
assumes further that (i) on each Rate Adjustment Date, LIBOR will be at the
level shown, (ii) the aggregate purchase price of the Class A-19 Certificates is
$347,376, including accrued interest, and (iii) the initial Pass-Through Rate on
the Class A-19 Certificates is 9.855% per annum. There can be no assurance that
the Mortgage Loans will have the assumed characteristics, will prepay at any of
the rates shown in the tables or at any other particular rate, that the pre-tax
yield to maturity on the Class A-19 Certificates will correspond to any of the
pre-tax yields to maturity shown herein, that the level of LIBOR will correspond
to the levels shown in the table or that the aggregate purchase price of the
Class A-19 Certificates will be as assumed. In addition to any other factors an
investor may deem material, each investor must make its own decision as to the
appropriate prepayment assumption to be used and the appropriate levels of LIBOR
to be assumed in deciding whether or not to purchase the Class A-19
Certificates.
 
                                      S-43
<PAGE>   44
 
           SENSITIVITY OF PRE-TAX YIELD TO MATURITY OF THE CLASS A-19
                      CERTIFICATES TO PREPAYMENT AND LIBOR
 
<TABLE>
<CAPTION>
                                                       PERCENTAGE OF THE SPA
                                             -----------------------------------------
                  LIBOR                      100%     200%     275%     400%     500%
                  -----                      -----    -----    -----    -----    -----
<S>                                          <C>      <C>      <C>      <C>      <C>
3.375%...................................    21.64%   21.65%   21.65%   21.67%   21.68%
4.375%...................................    15.87%   15.88%   15.89%   15.93%   15.96%
5.375%...................................    10.18%   10.20%   10.23%   10.28%   10.33%
6.375%...................................     4.60%    4.63%    4.66%    4.74%    4.80%
7.200% and above.........................     0.07%    0.11%    0.15%    0.25%    0.32%
</TABLE>
 
     Each pre-tax yield to maturity set forth in the preceding table was
calculated by determining the monthly discount rate which, when applied to the
assumed stream of cash flows to be paid on the Class A-19 Certificates, would
cause the discounted present values of such assumed stream of cash flows to
equal the assumed purchase price for such Certificates. These yields 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 A-19 Certificates,
and thus do not reflect the return on any investment in the Class A-19
Certificates when any reinvestment rates other than the discount rates are
considered.
 
YIELD CONSIDERATIONS WITH RESPECT TO THE PRINCIPAL ONLY CERTIFICATES
 
     The yields to maturity on the Principal Only Certificates will be extremely
sensitive to the level of both the timing of and overall rate of receipt of
principal prepayments on the Mortgage Loans. Because the Principal Only
Certificates receive only distributions of principal, the yield to maturity on
each such Class of Certificates will be adversely affected by slower than
expected principal payments (including prepayments) on the Mortgage Loans.
 
     To illustrate the significance of different rates of prepayment on the
distributions on the Principal Only Certificates, the following tables indicate
the approximate pre-tax yields to maturity (on a corporate bond equivalent
basis) under the different percentages of the SPA indicated. Because the rate of
distribution of principal on the Principal Only Certificates will be directly
related to the actual amortization (including prepayments) of the Mortgage
Loans, 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 Principal Only Certificates
are likely to differ from those shown in the following tables even if all the
Mortgage Loans prepay at the indicated constant percentages of the SPA and the
weighted average remaining terms to maturity of the Mortgage Loans are as
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. In addition, it is highly unlikely that the Mortgage Loans
will prepay at a constant level of the SPA until maturity or that all of such
Mortgage Loans will prepay at the same rate. The timing of changes to the rate
of prepayments on the Mortgage Loans may significantly affect the actual yield
to maturity to an investor, even if the average rate of Principal Prepayments on
the Mortgage Loans is consistent with an investor's expectation. In general, the
earlier a payment of principal of the Mortgage Loans, 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 on the Mortgage Loans occurring at a rate
higher (or lower) than the rate anticipated by the investor during the period
immediately following the issuance of the Certificates will not be equally
offset by a subsequent like reduction (or increase) in the rate of Principal
Prepayments on the Mortgage Loans.
 
     The tables set forth below are based on the Structuring Assumptions and
assume further that the Certificates are purchased at the approximate prices
equal to those set forth in the tables. 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 purchase prices of the Certificates will be as
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 Principal Only
 
                                      S-44
<PAGE>   45
 
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 in deciding
whether or not to purchase a Class of Certificates.
 
                    SENSITIVITY OF PRE-TAX YIELD TO MATURITY
               OF THE CLASS A-6 CERTIFICATES TO PREPAYMENTS AT A
                            SPECIFIED ASSUMED PRICE
 
<TABLE>
<CAPTION>
                                                         PERCENTAGE OF THE SPA
                 ASSUMED PRICE                   -------------------------------------
                 -------------                   100%    200%    275%    400%    500%-
<S>                                              <C>     <C>     <C>     <C>     <C>
$1,048,079.....................................  3.31%   4.57%   6.08%   9.87%   14.27%
</TABLE>
 
                    SENSITIVITY OF PRE-TAX YIELD TO MATURITY
               OF THE CLASS A-10 CERTIFICATES TO PREPAYMENTS AT A
                            SPECIFIED ASSUMED PRICE
 
<TABLE>
<CAPTION>
                                                         PERCENTAGE OF THE SPA
                 ASSUMED PRICE                    ------------------------------------
                 -------------                    100%    200%    275%    400%    500%
<S>                                               <C>     <C>     <C>     <C>     <C>
$328,493........................................  2.11%   3.49%   4.59%   6.30%   7.47%
</TABLE>
 
                    SENSITIVITY OF PRE-TAX YIELD TO MATURITY
               OF THE CLASS A-13 CERTIFICATES TO PREPAYMENTS AT A
                            SPECIFIED ASSUMED PRICE
 
<TABLE>
<CAPTION>
                                                         PERCENTAGE OF THE SPA
                 ASSUMED PRICE                    ------------------------------------
                 -------------                    100%    200%    275%    400%    500%
<S>                                               <C>     <C>     <C>     <C>     <C>
$116,496........................................  1.50%   1.70%   2.05%   3.18%   6.01%
</TABLE>
 
                    SENSITIVITY OF PRE-TAX YIELD TO MATURITY
               OF THE CLASS A-17 CERTIFICATES TO PREPAYMENTS AT A
                            SPECIFIED ASSUMED PRICE
 
<TABLE>
<CAPTION>
                                                         PERCENTAGE OF THE SPA
                 ASSUMED PRICE                    ------------------------------------
                 -------------                    100%    200%    275%    400%    500%
<S>                                               <C>     <C>     <C>     <C>     <C>
$98,504.........................................  2.20%   2.81%   3.63%   6.06%   9.29%
</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 Principal Only Certificates, would cause the discounted present values of
such assumed streams of cash flows to equal the assumed purchase price. 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 Principal Only Certificates and thus do not reflect the
return on any investment in the Principal Only Certificates when any
reinvestment rates other than the discount rates are considered.
 
YIELD CONSIDERATIONS RELATING TO THE SENIOR SUBORDINATE CERTIFICATES
 
     Defaults on mortgage loans may be measured relative to a default standard
or model. The model used in this Prospectus Supplement, the standard default
assumption ("SDA"), represents an assumed rate of default each month relative to
the then outstanding performing principal balance of a pool of new mortgage
loans. A default assumption of 100% SDA assumes constant default rates of 0.02%
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
 
                                      S-45
<PAGE>   46
 
0.02% per annum in each month thereafter until the 30th month. Beginning in the
30th month and in each month thereafter through the 60th month of the life of
the mortgage loans, 100% SDA assumes a constant default rate of 0.60% per annum
each month. Beginning in the 61st month and in each month thereafter through the
120th month of the life of the mortgage loans, 100% SDA assumes that the
constant default rate declines each month by 0.0095% per annum, and that the
constant default rate remains at 0.03% per annum in each month after the 120th
month. For the purposes of the tables below, it is assumed that there is no
delay between the default and liquidation of the mortgage loans.
 
     SDA does not purport to be a historical description of default experience
or a prediction of the anticipated rate of default of any pool of mortgage
loans, including the Mortgage Loans. Investors should note that SDA produces
less aggregate losses as the assumed rate of prepayment is increased because the
amount of losses is expressed as a percentage of a smaller pool balance
(reflecting the increasing amount of prepayments). Investors should consider the
possibility that aggregate losses incurred may not in fact be materially reduced
by higher prepayment speeds because mortgage loans that would otherwise
ultimately default and be liquidated may be less likely to be prepaid. Any
differences between such assumptions and the actual characteristics and
performance of the Mortgage Loans and of the Certificates may result in yields
different from those shown in such tables. Discrepancies between assumed and
actual characteristics and performance underscore the hypothetical nature of the
tables, which are provided only to give a general sense of the sensitivity of
yields in varying Realized Loss and prepayment scenarios. No representation is
made regarding the appropriateness of SDA or the underlying assumptions, the
rate, timing or severity of Realized Losses, the relationship, if any, to the
rate and timing of prepayments or as to the resulting yield to maturity of any
Class of Offered Certificates.
 
     The following tables indicate the sensitivity of the yields to maturity on
each Class of Senior Subordinate Certificates to various rates of prepayment and
varying levels of aggregate Realized Losses on the Mortgage Loans by projecting
the monthly aggregate cash flows on each such Class of Certificates and
computing the corresponding pre-tax yields to maturity on a corporate bond
equivalent basis. The tables are based on the Structuring Assumptions excluding
assumption (iii), including the assumptions regarding the characteristics and
performance of the Mortgage Loans, which differ from the actual characteristics
and performance thereof, and assume further that (i) defaults and final
liquidations occur on the last day of each month at the respective SDA
percentages set forth in the tables, (ii) each liquidation results in a Realized
Loss allocable to principal equal to the percentage indicated (the "Loss
Severity Percentage") multiplied by the principal balances of the Mortgage Loans
assumed to be liquidated, (iii) there are no delinquencies on the Mortgage
Loans, and principal payments on the Mortgage Loans (other than those on
Mortgage Loans assumed to be liquidated) will be timely received together with
prepayments, if any, at the respective constant percentages of SPA set forth in
the tables before giving effect to defaults in such periods, (iv) there are no
Excess Special Hazard Losses, Excess Fraud Losses, Excess Bankruptcy Losses or
Extraordinary Losses, (v) the purchase prices of the Class M, Class B-1 and
Class B-2 Certificates will be approximately $7,479,983, $3,192,404 and
$1,406,163, respectively, including accrued interest, if any, and (vi) the
initial Certificate Principal Balances of the Class B-3, Class B-4 and Class B-5
Certificates are $1,201,801, $1,001,501 and $1,001,504, respectively.
 
                SENSITIVITY OF PRE-TAX YIELD TO MATURITY OF THE
            CLASS M CERTIFICATES TO PREPAYMENTS AND REALIZED LOSSES
 
<TABLE>
<CAPTION>
                                                                      PERCENTAGE OF SPA
          PERCENTAGE OF                                              --------------------
               SDA               LOSS SEVERITY PERCENTAGE            100%    275%    500%
          -------------          ------------------------            ----    ----    ----
<S>       <C>             <C>                                        <C>     <C>     <C>
                 0%       N/A....................................    6.84%   6.94%   7.03%
                50        20%....................................    6.85    6.95    7.03
                50        40 ....................................    6.86    6.95    7.03
               100        20 ....................................    6.86    6.95    7.03
               100        40 ....................................    6.88    6.95    7.03
               150        20 ....................................    6.87    6.95    7.03
               150        40 ....................................    6.81    6.95    7.03
</TABLE>
 
                                      S-46
<PAGE>   47
 
                SENSITIVITY OF PRE-TAX YIELD TO MATURITY OF THE
           CLASS B-1 CERTIFICATES TO PREPAYMENTS AND REALIZED LOSSES
 
<TABLE>
<CAPTION>
                                                                     PERCENTAGE OF SPA
          PERCENTAGE OF                                            ----------------------
               SDA              LOSS SEVERITY PERCENTAGE           100%     275%    500%
          -------------         ------------------------           -----    ----    -----
<S>       <C>             <C>                                      <C>      <C>     <C>
                 0%       N/A..................................     7.09%   7.24%    7.37%
                50        20%..................................     7.10    7.24     7.37
                50        40 ..................................     7.11    7.25     7.37
               100        20 ..................................     7.11    7.25     7.37
               100        40 ..................................     6.54    7.25     7.37
               150        20 ..................................     7.05    7.25     7.37
               150        40 ..................................    (1.97)   5.84     7.37
</TABLE>
 
                SENSITIVITY OF PRE-TAX YIELD TO MATURITY OF THE
           CLASS B-2 CERTIFICATES TO PREPAYMENTS AND REALIZED LOSSES
 
<TABLE>
<CAPTION>
                                                                    PERCENTAGE OF SPA
          PERCENTAGE OF                                          ------------------------
               SDA             LOSS SEVERITY PERCENTAGE           100%      275%     500%
          -------------        ------------------------          ------    ------    ----
<S>       <C>             <C>                                    <C>       <C>       <C>
                 0%       N/A................................      7.88%     8.19%   8.45%
                50        20%................................      7.91      8.20    8.45
                50        40 ................................      7.73      8.20    8.45
               100        20 ................................      7.73      8.20    8.45
               100        40 ................................    (17.08)     6.02    8.45
               150        20 ................................      5.30      8.21    8.45
               150        40 ................................    (37.97)   (26.98)   5.43
</TABLE>
 
     Each pre-tax yield to maturity set forth in the preceding table was
calculated by determining the monthly discount rate which, when applied to the
assumed stream 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 purchase price referred to above, and converting
such rate to a semi-annual corporate bond equivalent yield. Accrued interest, if
any, is included in the assumed purchase price and is used in computing the
corporate bond equivalent yields shown. These yields 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 Senior Subordinate Certificates, and
thus do not reflect the return on any investment in the Senior Subordinate
Certificates when any reinvestment rates other than the discount rates are
considered.
 
     The following table sets forth the amount of Realized Losses that would be
incurred with respect to the Certificates in the aggregate under each of the
scenarios in the preceding tables, expressed as a percentage of the aggregate
outstanding principal balance of the Mortgage Loans as of the Cut-off Date:
 
                    AGGREGATE MORTGAGE LOAN REALIZED LOSSES
 
<TABLE>
<CAPTION>
                                                                      PERCENTAGE OF SPA
          PERCENTAGE OF                                              --------------------
               SDA               LOSS SEVERITY PERCENTAGE            100%    275%    500%
          -------------          ------------------------            ----    ----    ----
<S>       <C>             <C>                                        <C>     <C>     <C>
                50%       20%....................................    0.31%   0.22%   0.15%
                50        40 ....................................    0.62    0.44    0.30
               100        20 ....................................    0.61    0.43    0.29
               100        40 ....................................    1.23    0.87    0.59
               150        20 ....................................    0.91    0.65    0.44
               150        40 ....................................    1.82    1.29    0.88
</TABLE>
 
                                      S-47
<PAGE>   48
 
     Notwithstanding the assumed percentages of SDA, Loss Severity and
prepayment reflected in the preceding tables, it is highly unlikely that the
Mortgage Loans will be prepaid or that Realized Losses will be incurred
according to one particular pattern. For this reason, and because the timing of
cash flows is critical to determining yields, the pre-tax yields to maturity on
the Senior Subordinate Certificates are likely to differ from those shown in the
tables. There can be no assurance that the Mortgage Loans will prepay at any
particular rate or that Realized Losses will be incurred at any particular level
or that the yields on the Senior Subordinate Certificates will conform to the
yields described herein. Moreover, the various remaining terms to maturity and
interest rates of the Mortgage Loans could produce slower or faster principal
distributions than indicated in the preceding tables at the various constant
percentages of SPA specified.
 
                               POOLING AGREEMENT
 
GENERAL
 
     The Certificates will be issued pursuant to a Pooling and Servicing
Agreement (the "Pooling Agreement") dated as of November 1, 1998, among the
Depositor, the Master Servicer and the Trustee. Reference is made to the
Prospectus for important information additional to that set forth herein
regarding the terms and conditions of the Pooling Agreement and the Offered
Certificates. The Offered Certificates will be transferable and exchangeable at
the corporate trust office of the Trustee, which will serve as Certificate
Registrar and Paying Agent. The Depositor will provide a prospective or actual
Certificateholder without charge, on written request, a copy (without exhibits)
of the Pooling Agreement. Requests should be addressed to BA Mortgage
Securities, Inc., 345 Montgomery Street, Lower Level, Unit #8152, San Francisco,
California, 94104, Attention: Russell Thompson.
 
THE MASTER SERVICER
 
     Pursuant to the Pooling Agreement, Bank of America, FSB, the corporate
parent of the Depositor, will act as Master Servicer for the Mortgage Loans. For
a general description of Bank of America, FSB and its activities, as well as
certain information regarding its delinquency, foreclosure and loss experience
on the portfolio of one- to four-family first mortgage loans owned by Affiliated
Sellers and serviced or subserviced by them, see "MORTGAGE LOAN PROGRAM--Bank of
America, FSB," "--Residential Mortgage Loan Servicing Activities" and
"--Delinquency, Foreclosure and Loss Experience" in the Prospectus.
 
SERVICING AND OTHER COMPENSATION AND PAYMENT OF EXPENSES
 
     The Administration Fee for each Mortgage Loan is payable out of the
interest payments on such Mortgage Loan. The Administration Fee with respect of
each Mortgage Loan will be at least 0.25% and not more than 2.25% per annum of
the outstanding principal balance of each Mortgage Loan. The Primary Servicing
Fee with respect to each Mortgage Loan will be at least 0.25% per annum of the
outstanding balance of each Mortgage Loan. The Master Servicer is obligated to
pay certain ongoing expenses associated with the Trust Fund and incurred by the
Master Servicer in connection with its responsibilities under the Pooling
Agreement. See "THE POOLING AGREEMENT--Servicing and Other Compensation and
Payment of Expenses; Retained Yield" in the Prospectus for information regarding
other possible compensation to the Master Servicer and Subservicers and for
information regarding expenses payable by the Master Servicer.
 
SPECIAL SERVICING AGREEMENTS
 
     The Pooling Agreement will permit the Master Servicer to enter into one or
more special servicing agreements with an unaffiliated holder of one or more
Classes of Subordinate Certificates or of a class of securities representing
interests in one or more Classes of Subordinate Certificates. Pursuant to the
terms of such agreements, such holder may, with respect to delinquent Mortgage
Loans:
 
          (a) instruct the Master Servicer to commence or delay foreclosure
     proceedings; provided, that, the holder deposits a specified amount of cash
     with the Master Servicer which will be available for
 
                                      S-48
<PAGE>   49
 
     distribution to Certificateholders if Liquidation Proceeds are less than
     they otherwise may have been had the Master Servicer acted pursuant to its
     normal servicing procedures;
 
          (b) purchase such Mortgage Loans from the Trust Fund immediately prior
     to the commencement of foreclosure proceedings at a price equal to the
     aggregate outstanding principal balance of such Mortgage Loans, plus
     accrued interest thereon at the applicable Mortgage Rates through the last
     day of the month in which such Mortgage Loans are purchased; or
 
          (c) assume all of the primary servicing rights and obligations with
     respect to such Mortgage Loans so long as (i) assumption of such servicing
     rights and obligations by such holder will not result in the suspension or
     downgrade of any then-current rating on any Class of Certificates and (ii)
     such holder will service the Mortgage Loans according to a servicing
     agreement consistent with the Pooling Agreement and the Master Servicer's
     servicing practices.
 
TERMINATION; OPTIONAL REPURCHASE OF MORTGAGE LOANS
 
     The circumstances under which the obligations created by the Pooling
Agreement will terminate in respect of the Certificates are described in "THE
POOLING AGREEMENT--Termination; Retirement of Certificates" in the Prospectus.
The Master Servicer will have the option to purchase all remaining Mortgage
Loans and other assets in the Trust Fund, thereby effecting the termination of
the Trust Fund and the early retirement of the Certificates, but such option
will not be exercisable until such time as the aggregate principal balance of
the Mortgage Loans as of the Distribution Date on which the purchase proceeds
are to be distributed to the Certificateholders is less than 10% of the
aggregate principal balance of the Mortgage Loans as of the Cut-off Date. Any
such purchase of Mortgage Loans and other assets of the Trust Fund shall be made
at a price equal to the sum of (a) 100% of the unpaid principal balance of each
Mortgage Loan (other than any Mortgage Loan as to which title to the related
Mortgaged Property has been acquired), or with respect to Mortgaged Properties
acquired in connection with defaulted Mortgage Loans the fair market value of
each Mortgaged Property if such fair market value is less than such unpaid
principal balance (net of any unreimbursed Advances attributable to principal),
in each case less any Realized Losses that have not previously been allocated to
the Certificates on the day of repurchase plus (b) accrued interest thereon at
the weighted average Net Mortgage Rate to, but not including, the first day of
the month of repurchase. Certificateholders may suffer a loss if the fair market
value of the REO Properties is less than the unpaid principal balance.
 
     Upon presentation and surrender of the Certificates in connection with the
termination of the Trust Fund under the circumstances described above, the
holders of each Class of Offered Certificates will receive an amount equal to
the Certificate Principal Balance of such Class plus, for those Certificates
entitled to interest, one month's interest thereon at the applicable
Pass-Through Rate plus any previously unpaid Accrued Certificate Interest.
 
                        FEDERAL INCOME TAX CONSEQUENCES
 
     With respect to the Offered Certificates, Orrick, Herrington & Sutcliffe
LLP, counsel to the Depositor ("Special Tax Counsel"), is of the opinion that,
assuming compliance with all provisions of the Pooling Agreement, for federal
income tax purposes, the Trust Fund will qualify as a REMIC under the Code. The
following general discussion of the anticipated federal income tax consequences
of the purchase, ownership and disposition of the Offered Certificates together
with the discussion under the heading "FEDERAL INCOME TAX CONSEQUENCES--REMICs"
in the Prospectus represents the opinion of Special Tax Counsel, subject to any
qualifications set forth herein and therein. Special Tax Counsel has prepared or
reviewed the statements in this Prospectus Supplement under the heading "FEDERAL
INCOME TAX CONSEQUENCES" and in the Prospectus under the heading "FEDERAL INCOME
TAX CONSEQUENCES--REMICs," and is of the opinion that such statements are
correct in all material respects. Such statements are intended as an explanatory
discussion of the possible effects of the classification of the Trust Fund as a
REMIC for federal income tax purposes on investors generally and of related tax
matters affecting investors generally, but do not purport to furnish information
in the level of detail or with attention to an
                                      S-49
<PAGE>   50
 
investor's specific tax circumstances that would be provided by an investor's
own tax advisor. Accordingly, each investor is advised to consult its own tax
advisors with regard to the tax consequences to it of investing in the Offered
Certificates.
 
     For federal income tax purposes, the Class R Certificates will constitute
the sole class of "residual interests" in the REMIC, and each Class of Offered
Certificates (other than the Class R Certificates) will represent ownership of
"regular interests" in the REMIC. See "FEDERAL INCOME TAX CONSEQUENCES--REMICs"
in the Prospectus.
 
     For federal income tax reporting purposes, the Class A Certificates other
than the Principal Only Certificates and Inverse Floater Certificates, will not
be treated as having been issued with original issue discount for federal income
tax reporting purposes. The Principal Only Certificates, Senior Subordinate
Certificates and Inverse Floater Certificates will be treated as having been
issued with original issue discount for federal income tax reporting purposes.
The prepayment assumption that will be used in determining the rate of accrual
of original issue discount, market discount and premium, if any, for federal
income tax purposes will be based on the assumption that subsequent to the date
of any determination the Mortgage Loans will prepay at a rate equal to 275% SPA.
No representation is made that the Mortgage Loans will prepay at that rate or at
any other rate. See "FEDERAL INCOME TAX CONSEQUENCES--REMICs--Taxation of Owners
of REMIC Regular Certificates--Original Issue Discount" in the Prospectus.
 
     Purchasers of the Class A-18 and Class A-19 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 applicable to, prepayable securities
bearing a variable rate of interest such as the Class A-18 and Class A-19
Certificates. In the absence of other authority, the Master Servicer 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 Class A-18 and Class A-19
Certificates should be governed by some other method not yet set forth in
regulations. Prospective purchasers of the Class A-18 and Class A-19
Certificates are advised to consult their tax advisors concerning the tax
treatment of such Certificates.
 
     The Master Servicer believes that, it is appropriate with respect to the
Class A-19 Certificates, and if the Class A-18 Certificates were treated as
issued with original issue discount, it would be appropriate, to report all
income with respect to such 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 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. See "FEDERAL INCOME TAX
CONSEQUENCES--REMICs--Taxation of Owners of REMIC Regular Certificates--Original
Issue Discount" in the Prospectus.
 
     If the method for computing original issue discount described in the
Prospectus results in a negative amount for any period with respect to a
Certificateholder, the amount of original issue discount allocable to such
period would be zero and such Certificateholder will be permitted to offset such
negative amount only against future original issue discount (if any)
attributable to such Certificates.
 
     Although they are unclear on the issue, the OID Regulations in certain
circumstances appear to 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 Master Servicer in preparing reports to
                                      S-50
<PAGE>   51
 
the Certificateholders and the IRS. See "FEDERAL INCOME TAX
CONSEQUENCES--REMICs--Taxation of Owners of REMIC Regular Certificates--Original
Issue Discount" in the Prospectus.
 
     Certain Classes of the Offered Certificates may be treated for federal
income tax purposes as having been issued at a premium. Whether any holder of
such a Class of Certificates 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 such premium. See "FEDERAL INCOME TAX
CONSEQUENCES--REMICs--Taxation of Owners of REMIC Regular Certificates" and
"--Premium" in the Prospectus.
 
     The Offered Certificates will be assets described in Section 7701(a)(19)(C)
of the Code and "real estate assets" under Section 856(c)(4)(A) of the Code
generally in the same proportion that the assets of the Trust Fund would be so
treated. In addition, interest on the Offered Certificates will be treated as
"interest on obligations secured by mortgages on real property" under Section
856(c)(3)(B) of the Code generally to the extent that such Offered Certificates
are treated as "real estate assets" under Section 856(c)(4)(A) of the Code.
Moreover, the Offered Certificates (other than the Class R Certificates) will be
"qualified mortgages" within the meaning of Section 860G(a)(3) of the Code. See
"POOLING AGREEMENT--Termination" herein and "FEDERAL INCOME TAX
CONSEQUENCES--REMICs--Characterization of Investments in REMIC Certificates" in
the Prospectus.
 
     For further information regarding the federal income tax consequences of
investing in the Offered Certificates, see "FEDERAL INCOME TAX
CONSEQUENCES--REMICs" in the Prospectus.
 
SPECIAL TAX CONSIDERATIONS APPLICABLE TO CLASS R CERTIFICATES
 
     The IRS has issued regulations under the provisions of the Code related to
REMICs (the "REMIC Regulations") that significantly affect holders of 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 REMIC Regulations provide for the determination of whether a residual
interest has "significant value" for purposes of applying the rules relating to
"excess inclusions" with respect to residual interests. Based on the REMIC
Regulations, the Class R Certificates do not have significant value. Excess
inclusions are expected to be equal to all or virtually all of the taxable
income includable by holders of the Class R Certificates. See "FEDERAL INCOME
TAX CONSEQUENCES--REMICs--Taxation of Owners of REMIC Residual
Certificates--Excess Inclusions" in the Prospectus.
 
     The REMIC Regulations also 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 "FEDERAL INCOME
TAX CONSEQUENCES--REMICs--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 Trust Fund's
term that significantly exceeds the amount of cash distributions
 
                                      S-51
<PAGE>   52
 
received by the Class R Certificateholders from the Trust Fund with respect to
such periods. Furthermore, the tax on such income may exceed the cash
distributions with respect to such periods. Consequently, Class R
Certificateholders should have other sources of funds sufficient to pay any
federal income taxes due in the earlier years of the Trust Fund's term as a
result of their ownership of the Class R Certificates. In addition, the required
inclusion of this amount of taxable income during the Trust Fund'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 Certificateholder's 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 the Class R
Certificates over their life.
 
     The Master Servicer will be designated as the "tax matters person" with
respect to the Trust Fund as defined in the REMIC Provisions (as defined in the
Prospectus), and in connection therewith will be required to hold not less than
0.01% 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
the Class R Certificates.
 
     For further information regarding the federal income tax consequences of
investing in the Class R Certificates, see "FEDERAL INCOME TAX
CONSEQUENCES--REMICs--Taxation of Owners of REMIC Residual Certificates" in the
Prospectus.
 
                             METHOD OF DISTRIBUTION
 
     Subject to the terms and conditions set forth in the Underwriting Agreement
dated November 18, 1998, the Underwriter has agreed to purchase and the
Depositor has agreed to sell to the Underwriter each Class of Offered
Certificates.
 
     The Underwriting Agreement provides that the obligation of the Underwriter
to pay for and accept delivery of the Offered Certificates is subject to, among
other things, the receipt of certain legal opinions and to the conditions, among
others, that no stop order suspending the effectiveness of the Depositor's
Registration Statement shall be in effect, and that no proceedings for such
purpose shall be pending before or threatened by the Securities and Exchange
Commission.
 
     The distribution of the Offered Certificates by the Underwriter may be
effected from time to time in one or more negotiated transactions, or otherwise,
at varying prices to be determined at the time of sale. Proceeds to the
Depositor from the sale of the Offered Certificates, before deducting expenses
payable by the Depositor, will be approximately 98.41% of the aggregate
Certificate Principal Balance of the Offered Certificates plus accrued interest
thereon from the Cut-off Date. The Underwriter may effect such transactions by
selling the Offered Certificates to or through dealers, and such dealers may
receive compensation in the form of underwriting discounts, concessions or
commissions from the Underwriter for whom they act as agent. In connection with
the sale of the Offered Certificates, the Underwriter may be deemed to have
received compensation from the Depositor in the form of underwriting
compensation. The Underwriter and any dealers that participate with the
Underwriter in the distribution of the Offered Certificates may be deemed to be
underwriters, and any profit on the resale of the Offered Certificates
positioned by them may be deemed to be underwriting discounts and commissions
under the Securities Act of 1933.
 
     The Underwriting Agreement provides that the Depositor and Bank of America,
FSB will indemnify the Underwriter, and under limited circumstances the
Underwriter will indemnify the Depositor and Bank of America, FSB, against
certain civil liabilities under the Securities Act of 1933, or contribute to
payments required to be made in respect thereof.
 
     There can be no assurance that a secondary market for the Offered
Certificates will develop or, if it does develop, that it will continue or
provide sufficient liquidity of investment. The primary source of information
available to investors concerning the Offered Certificates will be the monthly
statements discussed in the
 
                                      S-52
<PAGE>   53
 
Prospectus under "DESCRIPTION OF THE CERTIFICATES--Reports to
Certificateholders," which will include information as to the outstanding
principal balance of the Offered Certificates and the status of the applicable
form of credit enhancement. There can be no assurance that any additional
information regarding the Offered Certificates will be available through any
other source. In addition, the Depositor is not aware of any source through
which price information about the Offered Certificates will be generally
available on an ongoing basis. The limited nature of such information regarding
the Offered Certificates may adversely affect the liquidity of the Offered
Certificates, even if a secondary market for the Offered Certificates becomes
available.
 
                                 LEGAL OPINIONS
 
     Certain legal matters relating to the Certificates will be passed upon for
the Depositor by Orrick, Herrington & Sutcliffe LLP, San Francisco, California
and for the Underwriter by Thacher Proffitt & Wood, New York, New York.
 
                                     RATING
 
     It is a condition to the issuance of the Offered Certificates that the
Senior Certificates each be rated (i) "Aaa" by Moody's Investors Service
("Moody's") and (ii) "AAA" by Fitch IBCA, Inc. ("Fitch") and that the Class M
Certificates be rated not less than "AA," the Class B-1 Certificates be rated
not less than "A" and the Class B-2 Certificates be rated not less than "BBB" by
Fitch.
 
     The ratings of Moody's and Fitch on mortgage pass-through certificates
address the likelihood of the receipt by certificateholders of all distributions
on the underlying mortgage loans to which they are entitled. Ratings on
pass-through certificates do not represent any assessment of the likelihood that
principal prepayments will be made by mortgagors or the degree to which such
prepayments might differ from that originally anticipated. The ratings do not
address the possibility that Certificateholders might suffer a lower than
anticipated yield. In addition, in the case of the Principal Only Certificates,
the rating does not assess the likelihood of return to investors except to the
extent of the Certificate Principal Balances thereof.
 
     The Depositor has not requested a rating on the Offered Certificates by any
rating agency other than Moody's 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 Moody's and Fitch.
 
     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
organization. Each security rating should be evaluated independently of any
other security rating. In the event that the rating initially assigned to the
Offered Certificates is subsequently lowered for any reason, no person or entity
is obligated to provide any additional support or credit enhancement with
respect to the Offered Certificates.
 
                                LEGAL INVESTMENT
 
     The Senior Certificates and the Class M Certificates will constitute
"mortgage related securities" for purposes of SMMEA so long as they are rated in
at least the second highest rating category by one of the Rating Agencies, and,
as such, are legal investments for certain entities to the extent provided by
SMMEA. SMMEA provides, however, that states could override its provisions on
legal investment and restrict or condition investment in mortgage related
securities by taking statutory action on or prior to October 3, 1991. Certain
states have enacted legislation which overrides the preemption provisions of
SMMEA. The Class B Certificates will not constitute "mortgage related
securities" for purposes of SMMEA.
 
     The Depositor makes no representation as to the proper characterization of
any Class of the Offered Certificates for legal investment or other purposes, or
as to the ability of particular investors to purchase any Class of the Offered
Certificates under applicable legal investment restrictions. These uncertainties
may affect
                                      S-53
<PAGE>   54
 
the liquidity of any Class of Offered Certificates. Accordingly, all
institutions whose investment activities are subject to legal investment laws
and regulations, regulatory capital requirements or review by regulatory
authorities should consult with their legal advisors in determining whether and
to what extent any Class of the Offered Certificates constitutes a legal
investment or is subject to investment, capital or other restrictions.
 
     See "LEGAL INVESTMENT MATTERS" in the Prospectus.
 
                              ERISA CONSIDERATIONS
 
     Any fiduciary or other Plan Asset Investor that proposes to use Plan Assets
to acquire any Offered Certificates should consult with its counsel with respect
to the potential consequences under the Employee Retirement Income Security Act
of 1974, as amended ("ERISA"), and Section 4975 of the Internal Revenue Code of
1986, as amended (the "Code"), of the acquisition and ownership of such
Certificates with Plan Assets. See "ERISA CONSIDERATIONS" in the Prospectus.
 
PROHIBITED TRANSACTION CLASS EXEMPTIONS
 
     To qualify for exemption under PTCE 83-1 (see "ERISA
CONSIDERATIONS--Prohibited Transaction Class Exemptions" 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 and (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. See "ERISA CONSIDERATIONS--Prohibited Transaction Class
Exemption 83-1" in the Prospectus.
 
     Because the Principal Only Certificates, which are not entitled to
interest, the Senior Subordinate Certificates, which are subordinated to the
extent specified herein (see "DESCRIPTION OF THE CERTIFICATES--Subordination and
Allocation of Losses" herein) and the Class R Certificates, do not qualify for
exemption under PTCE 83-1, exemptive relief will not be available under PTCE
83-1 to Plans or other persons that use Plan Assets to acquire such Certificates
from the prohibited transaction rules of ERISA and Section 4975 of the Code. See
"ERISA CONSIDERATIONS--Prohibited Transaction Class Exemption 83-1" in the
Prospectus.
 
UNDERWRITER'S PTE
 
     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 or
Plan Asset Investors that acquire Offered Certificates (other than the Senior
Subordinate or Class R Certificates). Plans or Plan Asset Investors that acquire
Offered Certificates (other than the Senior Subordinate or Class R Certificates)
may be eligible for protection under the Underwriter's PTE if:
 
          (a) Such Certificates are 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 or Plan Asset Investor is an "accredited investor" (as
     defined in Rule 501(a)(1) of Regulation D under the Securities Act of 1933,
     as amended (the "Act"));
 
          (c) At the time of such acquisition, such Certificates have received a
     rating in one of the three highest generic rating categories from Standard
     & Poor's Ratings Services, Moody's Investors Service, Inc., Duff & Phelps
     Credit Rating Co. or Fitch IBCA, Inc. (collectively, the "Exemption Rating
     Agencies);
 
          (d) The Trustee is not an affiliate of any member of the Restricted
     Group (as defined in paragraph (3) below);
 
          (e) Such Certificates evidence ownership in Trust assets that do not
     include subordinate certificates backed by mortgages or mortgage
     participations (unless interest and principal payable with respect to such
     mortgage certificates are guaranteed by the GNMA, FHLMC or FNMA);
 
                                      S-54
<PAGE>   55
 
          (f) The acquisition of such Certificates is on terms (including the
     price paid for the Certificates) that are at least as favorable to the Plan
     or Plan Asset Investor as they would be in an arm's length transaction with
     an unrelated party;
 
          (g) 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 Depositor pursuant to the sale of
     the Mortgage Loans to the Trust Fund represents not more than the fair
     market value of the Mortgage Loans; and the sum of all payments made to and
     retained by the Master Servicer and any Subservicer represents not more
     than reasonable compensation for their services under the Pooling Agreement
     and reimbursement of its reasonable expenses in connection therewith; and
 
          (h)(1) the Trust Fund must consist solely of assets of the type that
     have been included in other investment pools; (2) certificates evidencing
     interests in such other investment pools must have been rated in one of the
     three highest categories of one of the Exemption Rating Agencies for at
     least one year prior to the acquisition of Certificates by or with Plan
     Assets of a Plan; and (3) certificates in such other investment pools must
     have been purchased by investors (other than Plans) for at least one year
     prior to any acquisition of Certificates by or with Plan Assets of a Plan.
 
     In addition, the Underwriter's PTE will not provide exemptive relief for
certain transactions prohibited by Section 406(b) of ERISA or Section
4975(c)(1)(E) or (F) of the Code which may result from a Plan's investment in
such Certificates if:
 
          (1) The Plan's investment in any Class of such Certificates exceeds
     25% of the outstanding Certificates of that Class at the time of
     acquisition;
 
          (2) Immediately after such acquisition, 25% or more of the Plan Assets
     with respect to which the investing fiduciary or other Plan Asset Investor
     has discretionary authority or renders investment advice are invested in
     certificates evidencing interests in trusts sponsored or containing assets
     sold or serviced by the same entity;
 
          (3) The Plan is sponsored by the Depositor, the Underwriter, the
     Trustee, the Master Servicer, any Subservicer, any Pool, Special Hazard or
     Primary Insurer or the obligor under any credit support mechanism, a
     Mortgagor with respect to obligations constituting more than 5% of the
     aggregate unamortized principal balance of the Trust Fund on the Closing
     Date (a "Major Obligor"), or any of their affiliates (together, the
     "Restricted Group");
 
          (4) The fiduciary or other Plan Asset Investor responsible for the
     decision to invest any Plan Assets in Certificates, or any of its
     affiliates, is a Major Obligor; or
 
          (5) In the case of an acquisition in connection with the initial
     issuance of Certificates, at least 50% of each Class of Certificates in
     which Plans have invested is acquired by persons independent of the members
     of the Restricted Group and at least 50% of the aggregate interest in the
     Trust Fund is acquired by persons independent of the Restricted Group.
 
     Whether the conditions of the Underwriter's PTE will be satisfied with
respect to Offered Certificates (other than the Senior Subordinate and Class R
Certificates, for which the Underwriter's PTE will not afford protection) of a
particular Class will depend upon the facts and circumstances existing at the
time Plan Assets are used to acquire Certificates of that Class. Any fiduciary
or other Plan Asset Investor that proposes to use Plan Assets to acquire such
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.
 
     Because the Senior Subordinate and Class R Certificates will not qualify
for the exemptive relief available under PTCE 83-1 or the Underwriter's PTE,
transfers of such Certificates to any purchaser or other transferee will not be
registered unless the Trustee receives from the transferee (i) an opinion of
counsel, which opinion will not be at the expense of the Master Servicer, the
Depositor or the Trustee, satisfactory to the Trustee and the Depositor that the
purchase of any such Certificate by, on behalf of or with Plan Assets of
                                      S-55
<PAGE>   56
 
any 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 Master Servicer, the Depositor or the Trustee to any
obligation in addition to those undertaken in the Pooling Agreement, (ii) a
representation to the effect that the transferee is not, and is not acquiring
such Certificates on behalf of or with Plan Assets of, a Plan or Plan Asset
Investor, or (iii) with respect to a Senior Subordinate Certificate, a
representation that the transferee is an insurance company, and the source of
funds used to purchase such Certificates is an "insurance company general
account" (as such term is defined in PTCE 95-60) and the conditions set forth in
Sections I and III of PTCE 95-60 have been satisfied. By a purchaser's or
transferee's acceptance of a Senior Subordinate Certificate, the transferee
shall be deemed to have either (x) warranted to the Master Servicer, the
Depositor and the Trustee that it has provided the opinion described in clause
(i) above to the Trustee or (y) made the representation described in clause (ii)
above or (iii) above.
 
                                      S-56
<PAGE>   57
 
                         INDEX OF PRINCIPAL DEFINITIONS
 
<TABLE>
<S>                                     <C>
Accrued Certificate Interest..........  S-22
Act...................................  S-54
Administration Fee....................  S-20
Available Distribution Amount.........  S-20
BankAmerica...........................  S-11
Bankruptcy Amount.....................  S-34
Book-Entry Certificates...............  S-18
Business Day..........................  S-20
Cede..................................  S-18
Certificate Principal Balance.........  S-22
Certificates..........................  S-18
Class A Certificates..................  S-18
Class A-4 Liquidation Amount..........  S-28
Class A-4 Percentage..................  S-28
Class A-4 Prepayment Percentage.......  S-28
Class A-4 Priority Amount.............  S-28
Closing Date..........................   S-5
Code..................................  S-54
Compensating Interest.................  S-23
Corporation...........................  S-11
Credit Support Depletion Date.........  S-22
Cut-off Date..........................   S-5
Debt Service Reductions...............  S-33
Deceased Holder.......................  S-32
Definitive Certificate................  S-18
Depositor.............................   S-5
Determination Date....................  S-20
Distribution Date.....................   S-5
DTC Services..........................  S-19
DTC Systems...........................  S-19
Due Date..............................  S-20
ERISA.................................  S-54
Excess Bankruptcy Losses..............  S-22
Excess Fraud Losses...................  S-22
Excess Special Hazard Loss............  S-22
Exemption Rating Agencies.............  S-54
Extraordinary Losses..................  S-22
FICO Scores...........................  S-16
Fitch.................................  S-53
Fraud Loss Amount.....................  S-34
Industry..............................  S-19
Infrastructure........................  S-11
Inverse Floater Certificates..........  S-18
Junior Subordinate Certificates.......  S-18
LIBOR Business Day....................  S-23
LIBOR Certificates....................  S-18
LIBOR Rate Adjustment Date............  S-23
Liquidated Mortgage Loan..............  S-27
Liquidation Principal.................  S-27
Living Holders........................  S-29
Lockout Certificates..................  S-18
Loss Severity Percentage..............  S-46
Master Servicer.......................   S-5
Master Servicing Fee..................  S-20
Major Obligor.........................  S-55
Moody's...............................  S-53
NationsBank...........................  S-11
Net Mortgage Rate.....................  S-23
Net Prepayment Interest Shortfall.....  S-23
Offered Certificates..................  S-18
Original Subordinate Principal
  Balance.............................  S-28
Pass-Through Rate.....................  S-22
Physical Certificates.................  S-18
Pooling Agreement.....................  S-48
Primary Hazard Insurance Policy.......  S-17
Primary Insurance Policy..............  S-17
Primary Insurers......................  S-17
Primary Servicing Fee.................  S-20
Principal Only Certificates...........  S-18
Principal Payment Amount..............  S-27
Principal Prepayment Amount...........  S-27
Projects..............................  S-11
Qualified Mortgages...................  S-51
Realized Losses.......................  S-33
REMIC Regulations.....................  S-51
Restricted Group......................  S-55
Rounding Account......................  S-29
Rules.................................  S-19
SDA...................................  S-45
Sellers...............................   S-5
Senior Certificates...................  S-18
Senior Liquidation Amount.............  S-27
Senior Percentage.....................  S-27
Senior Prepayment Percentage..........  S-27
Senior Principal Distribution
  Amount..............................  S-27
Senior Subordinate Certificates.......  S-18
Servicing Fee.........................  S-20
SPA...................................  S-37
Special Hazard Amount.................  S-33
Special Hazard Losses.................  S-34
Special Retail Certificates...........  S-18
Special Tax Counsel...................  S-49
Stated Principal Balance..............  S-33
Step Down Conditions..................  S-27
Step Down Percentage..................  S-28
Structuring Assumptions...............  S-37
Subordinate Certificates..............  S-18
Subordinate Percentage................  S-29
Subordinate Prepayment Percentage.....  S-29
Subordinate Principal Distribution-
  Amount..............................  S-28
Subordinate Principal Prepayment
  Distribution Amount.................  S-29
Subordinate Liquidation Amount........  S-29
Subordination.........................  S-33
Subordination Level...................  S-21
Systems...............................  S-11
Trustee...............................   S-5
Underwriter's PTE.....................  S-54
Unpaid Accrued Certificate Interest...  S-22
Vendors...............................  S-12
</TABLE>
 
                                      S-57
<PAGE>   58
 
                                   PROSPECTUS
 
                          BA MORTGAGE SECURITIES, INC.
                                   Depositor
 
                       MORTGAGE PASS-THROUGH CERTIFICATES
 CONSIDER CAREFULLY THE
 RISK FACTORS BEGINNING ON
 PAGE 5 IN THIS PROSPECTUS.
 A certificate is not a
 deposit and is not insured
 or guaranteed by the
 Federal Deposit Insurance
 Corporation or any other
 governmental agency.
 A certificate will
 represent an interest
 solely in the trust
 created for that series of
 certificates. A
 certificate will not
 represent an interest in
 or an obligation of BA
 Mortgage Securities, Inc.,
 Bank of America, FSB or
 any of their affiliates.
 This prospectus may be
 used to offer and sell a
 series of certificates
 only if accompanied by the
 prospectus supplement for
 
 that series.
                             BA MORTGAGE SECURITIES, INC. MAY PERIODICALLY ISSUE
                             CERTIFICATES REPRESENTING INTERESTS IN A TRUST THAT
                             CONSISTS PRIMARILY OF MORTGAGE LOANS. THE
                             CERTIFICATES WILL BE ISSUED IN SERIES, AND EACH
                             SERIES OF CERTIFICATES WILL REPRESENT INTERESTS IN
                             A DIFFERENT TRUST ESTABLISHED BY BA MORTGAGE
                             SECURITIES, INC.
                             EACH TRUST WILL CONSIST OF:
                             - a pool of mortgage loans secured by one- to
                               four-family residential properties, which may
                               include cooperative apartments, described in
                               detail in the accompanying prospectus supplement;
                             - related property and interests; and
                             - other property as described in the accompanying
                               prospectus supplement.
                             THE CERTIFICATES IN A SERIES:
                             - will represent interests in a trust and will be
                               paid only from the assets of that trust; and
                             - may be divided into multiple classes of
                               certificates, and, if so, each class may:
                                - receive a different fixed or variable rate of
                                  interest;
                                - be subordinated to other classes of
                                  certificates in that series;
                                - represent interests in only certain of the
                                  assets of the trust;
                                - receive principal at different times; and
                                - have different forms of credit enhancement.
 
The certificates may be offered to the public through different methods as
described in "METHODS OF DISTRIBUTION" in this prospectus. NationsBanc
Montgomery Securities LLC, an affiliate of BA Mortgage Securities, Inc., may act
as agent or underwriter in connection with the sale of the certificates. This
prospectus and the accompanying prospectus supplement may be used by NationsBanc
Montgomery Securities LLC in secondary market transactions in connection with
the offer and sale of any certificates. NationsBanc Montgomery Securities LLC
may act as principal or agent in such transactions and such sales will be made
at prevailing market prices or otherwise.
 
NEITHER THE SECURITIES AND EXCHANGE COMMISSION NOR ANY STATE SECURITIES
COMMISSION HAS APPROVED OR DISAPPROVED OF THESE CERTIFICATES OR DETERMINED THAT
THIS PROSPECTUS IS ACCURATE OR COMPLETE. ANY REPRESENTATION TO THE CONTRARY IS A
CRIMINAL OFFENSE.
 
                               November 18, 1998
<PAGE>   59
 
                  IMPORTANT NOTICE ABOUT INFORMATION PRESENTED
         IN THIS PROSPECTUS AND THE ACCOMPANYING PROSPECTUS SUPPLEMENT
 
     We provide information to you about the certificates in two separate
documents that progressively provide more detail: (a) this prospectus, which
provides general information, some of which may not apply to your series of
certificates and (b) the accompanying prospectus supplement, which describes the
specific terms of your series of certificates.
 
     IF THE TERMS OF A PARTICULAR SERIES OF CERTIFICATES VARY BETWEEN THIS
PROSPECTUS AND THE ACCOMPANYING PROSPECTUS SUPPLEMENT, YOU SHOULD RELY ON THE
INFORMATION IN THE PROSPECTUS SUPPLEMENT.
 
     We include cross-references in this prospectus and the accompanying
prospectus supplement to captions in these materials where you can find further
related discussions. The following table of contents and the table of contents
included in the accompanying prospectus supplement provide the pages on which
these captions are located.
 
     You can find a listing of the pages where capitalized terms used in this
prospectus are defined under the caption "INDEX OF PRINCIPAL DEFINITIONS" in
this prospectus.
 
     BA Mortgage Securities, Inc.'s principal offices are located at 345
Montgomery Street, Lower Level #2, Unit #8152, San Francisco, California 94104
and its phone number is (415) 622-3676.
 
                               TABLE OF CONTENTS
 
<TABLE>
<CAPTION>
                                        PAGE
                                        ----
<S>                                     <C>
PROSPECTUS SUPPLEMENT.................    3
AVAILABLE INFORMATION.................    3
REPORTS TO CERTIFICATEHOLDERS.........    3
INCORPORATION OF CERTAIN DOCUMENTS BY
  REFERENCE...........................    3
RISK FACTORS..........................    5
THE MORTGAGE POOLS....................    8
THE DEPOSITOR.........................   11
MORTGAGE LOAN PROGRAM.................   12
DESCRIPTION OF THE CERTIFICATES.......   19
SUBORDINATION.........................   33
DESCRIPTION OF CREDIT ENHANCEMENTS....   35
PRIMARY MORTGAGE INSURANCE, HAZARD
  INSURANCE; CLAIMS THEREUNDER........   41
THE POOLING AGREEMENT.................   44
</TABLE>
 
<TABLE>
<CAPTION>
                                        PAGE
                                        ----
<S>                                     <C>
YIELD CONSIDERATIONS..................   49
MATURITY AND PREPAYMENT
  CONSIDERATIONS......................   51
CERTAIN LEGAL ASPECTS OF MORTGAGE
  LOANS AND RELATED MATTERS...........   52
FEDERAL INCOME TAX CONSEQUENCES.......   60
STATE AND OTHER TAX CONSEQUENCES......   85
ERISA CONSIDERATIONS..................   85
LEGAL INVESTMENT MATTERS..............   89
USE OF PROCEEDS.......................   90
METHODS OF DISTRIBUTION...............   90
RATING................................   91
LEGAL MATTERS.........................   91
FINANCIAL INFORMATION.................   92
ADDITIONAL INFORMATION................   92
INDEX OF PRINCIPAL DEFINITIONS........   93
</TABLE>
 
                                        2
<PAGE>   60
 
                             PROSPECTUS SUPPLEMENT
 
     The Prospectus Supplement relating to the Certificates (as defined herein)
of each Series (as defined herein) to be offered hereunder will, among other
things, set forth with respect to such Certificates, as appropriate: (i) a
description of the Class or Classes of Certificates and the Pass-Through Rate or
method of determining the amount of interest, if any, to be passed through to
each such Class; (ii) the aggregate initial principal amount and Distribution
Dates relating to such Series, the method used to calculate the aggregate amount
of principal to be distributed with respect to the Certificates of such Series
on each Distribution Date, the order of the application of principal
distributions to the respective Classes and the allocation of principal to be so
applied, and, if applicable, the initial and final scheduled Distribution Dates
for each Class; (iii) information as to the assets comprising the Trust Fund,
including the general characteristics of the Mortgage Loans included therein
and, if applicable, included in the Trust Fund; (iv) the circumstances, if any,
under which the Trust Fund may be subject to early termination; (v) additional
information with respect to the plan of distribution of such Certificates; (vi)
whether a REMIC election will be made and designation of the regular interests
and residual interests; (vii) the aggregate original percentage ownership
interest in the Trust Fund to be evidenced by each Class of Certificates; (viii)
information as to the Trustee; and (ix) information as to the nature and extent
of subordination with respect to any Class of Certificates that is subordinate
in right of payment to any other Class.
 
                             AVAILABLE INFORMATION
 
     The Depositor has filed with the Securities and Exchange Commission (the
"Commission") a Registration Statement under the Securities Act of 1933, as
amended, with respect to the Certificates. This Prospectus and the Prospectus
Supplement relating to each Series of Certificates contain summaries of the
material terms of the documents referred to herein and therein, but do not
contain all of the information set forth in the Registration Statement of which
this Prospectus is a part. For further information, reference is made to such
Registration Statement and the exhibits thereto. In addition, the Depositor will
be subject to the information requirements of the Securities Exchange Act of
1934, as amended, and in accordance therewith, will file reports and other
information with the Commission. Such Registration Statement, the exhibits
thereto and any reports or other information filed with the Commission can be
inspected and copied at prescribed rates at the public reference facilities
maintained by the Commission at its Public Reference Section, 450 Fifth Street,
N.W., Washington, D.C. 20549, and at its Regional Offices located as follows:
Midwest Regional Office, Northwestern Atrium Center, 500 West Madison Avenue,
Chicago, Illinois 60661-2511; and Northeast Regional Office, 7 World Trade
Center, Suite 1300, New York, New York 10048. In addition, such Registration
Statement, the exhibits thereto and any reports or other information filed with
the Commission through its Electronic Data Gathering, Analysis, and Retrieval
system are publicly available through the Commission's Web site
(http://www.sec.gov).
 
                         REPORTS TO CERTIFICATEHOLDERS
 
     The trustee for each Series of Certificates (the "Trustee") will provide or
cause to be provided to holders of the Certificates (the "Certificateholders")
of such Series monthly reports concerning the Mortgage Pool underlying their
respective Certificates. See "DESCRIPTION OF THE CERTIFICATES -- Reports to
Certificateholders" herein.
 
                INCORPORATION OF CERTAIN DOCUMENTS BY REFERENCE
 
     All documents filed or caused to be filed by the Depositor with the
Commission relating to the offering of Certificates referred to in the
accompanying Prospectus Supplement pursuant to Section 13(a), 13(c), 14 or 15(d)
of the Securities Exchange Act of 1934, prior to the termination of any offering
of the Certificates described in such Prospectus Supplement, shall be
incorporated by reference in this Prospectus and be a part of this Prospectus
from the date of the filing of such documents. Copies of the documents
incorporated herein by reference, other than the exhibits to such documents,
unless such exhibits are specifically incorporated by
 
                                        3
<PAGE>   61
 
reference in such documents, will be provided to each person to whom this
Prospectus and the related Prospectus Supplement is delivered in connection with
the offering of one or more Classes of Certificates upon written or oral request
of such person. Requests should be directed to: BA Mortgage Securities, Inc.,
345 Montgomery Street, Lower Level #2, Unit #8152, San Francisco, California
94104, Attention: Russell Thompson, telephone number (415) 622-3676.
 
     Each Series of Certificates will be issued under a separate Pooling and
Servicing Agreement (each a "Pooling Agreement"), among the Depositor, the
Master Servicer and the Trustee, substantially in the form (the "Form of Pooling
Agreement") filed as an exhibit to the Registration Statement of which this
Prospectus is a part. The summaries of certain provisions of the Certificates
and such Form of Pooling Agreement included in this Prospectus do not purport to
be complete and are subject to, and qualified in their entirety by reference to,
all of the provisions of the Form of Pooling Agreement, and the final Pooling
Agreement executed in connection with the issuance of a Series. Section
references herein are references to the Form of Pooling Agreement. An index
indicating where certain terms used herein are defined appears at the end of
this Prospectus. Terms used but not defined herein have the meanings assigned to
them in the Form of Pooling Agreement. References herein to the Master Servicer,
the Trustee or the Depositor include, unless otherwise specified, any agents
acting on behalf of the Master Servicer, the Trustee or the Depositor, any
subcontractor of the Master Servicer, the Trustee or the Depositor, any of which
agents or subcontractors may be the Depositor or one of its affiliates.
 
                                        4
<PAGE>   62
 
                                  RISK FACTORS
 
YOU SHOULD CONSIDER THE FOLLOWING RISK FACTORS (IN ADDITION TO THE RISK FACTORS
IN THE PROSPECTUS SUPPLEMENT) IN DECIDING WHETHER TO PURCHASE ANY OF THE
CERTIFICATES.
 
LACK OF SECONDARY
MARKETS MAY LIMIT
YOUR ABILITY TO RESELL
YOUR CERTIFICATES      A secondary market for the certificates of any series may
                       not develop. If a secondary market does develop, it might
                       not continue or it might not be sufficiently liquid to
                       allow you to resell any of your certificates. An
                       underwriter may decide to establish a secondary market
                       for a particular series of certificates. If so, the
                       prospectus supplement for that series of certificates
                       will indicate this intention. However, no underwriter
                       will be obligated to do so. The certificates will not be
                       listed on any securities exchange.
 
THERE IS NO SOURCE OF
PAYMENTS FOR YOUR
CERTIFICATES OTHER THAN
PAYMENTS ON THE
MORTGAGE LOANS IN THE
TRUST                  When you buy a certificate, you will not own an interest
                       in BA Mortgage Securities, Inc., Bank of America, FSB or
                       any of their affiliates. You will own an interest in the
                       trust established for that series of certificates. Your
                       payments come only from assets in the trust. Therefore,
                       the mortgagors' payments on the mortgage loans included
                       in the trust (and any credit enhancements) will be the
                       sole source of payments to you. If those amounts are
                       insufficient to make required payments of interest or
                       principal to you, there is no other source of payments.
 
                       Moreover, no governmental agency either guarantees or
                       insures payments on the certificates or any of the
                       mortgage loans.
 
                       BA Mortgage Securities, Inc., the master servicer and/or
                       the institutions from which the depositor acquires the
                       assets of any mortgage pool will have limited
                       obligations. These will usually include:
 
                            - the obligation under certain circumstances to
                              repurchase the mortgage loans if there has been a
                              breach of representations and warranties;
 
                            - advancing payments on the mortgage loans when the
                              mortgagor is delinquent if the master servicer
                              believes the advance is recoverable; and
 
                            - various servicing and/or administrative
                              obligations made in the pooling agreement and/or
                              subservicing contracts.
 
YOU BEAR THE RISK OF
CERTAIN MORTGAGOR
DEFAULTS; CERTAIN OF
THE
MORTGAGE LOANS MAY
BE ESPECIALLY PRONE TO
DEFAULTS               Because your certificates represent an interest in the
                       mortgage loans, your investment may be affected by a
                       decline in real estate values and changes in individual
                       mortgagors' financial conditions. You should be aware
                       that the value of the mortgaged properties may decline.
                       If the outstanding balance of a mortgage loan and any
                       secondary financing on the underlying property is greater
                       than the value of the property, there is an increased
                       risk of delinquency, foreclosure and losses. If the
                       residential real estate market experiences an overall
                       decline in property values, the rates of delinquencies,
                       foreclosures and losses could be higher than those now
                       generally experienced in the mortgage lending industry.
                       To the extent your certificates are not covered by credit
                       enhancements, you will bear all of the risks resulting
                       from defaults by mortgagors. In addition, certain types
                       of mortgage loans which have higher than average rates of
                       default may be included in the trust that issues your
                       certificate. The following types of loans may be
                       included:
 
                            - mortgage loans that are subject to "negative
                              amortization." The principal balances of such
                              loans may be increased to amounts greater than the
                              value of the underlying property. This increases
                              the likelihood of default;
 
                                        5
<PAGE>   63
 
                            - mortgage loans that do not fully amortize over
                              their terms to maturity which are sometimes
                              referred to as balloon loans. Such loans require a
                              large payment at their stated maturity. These
                              loans involve a greater degree of risk because the
                              ability of a mortgagor to make this final payment
                              typically depends on the ability to refinance the
                              loan or sell the related mortgaged property;
 
                            - mortgage loans that provide for escalating or
                              variable payments by the mortgagor. The mortgagor
                              may have qualified for such loans based on an
                              income level sufficient to make the initial
                              payments only. As the payments increase, the
                              likelihood of default will increase; and
 
                            - mortgage loans that are concentrated in certain
                              regions, states or zip code areas of the United
                              States. Such geographic units may experience weak
                              economic conditions and housing markets. This may
                              cause higher rates of loss and delinquency.
 
                       See "DESCRIPTION OF THE MORTGAGE POOLS" in the prospectus
                       supplement to see if any of these or other types of
                       special risk loans are present in the mortgage pool
                       applicable to your certificates.
 
CREDIT ENHANCEMENTS
MAY BE LIMITED OR
REDUCED AND THIS MAY
CAUSE YOUR CERTIFICATES
TO BEAR MORE RISK OF
MORTGAGOR DEFAULTS     The prospectus supplement related to your certificates
                       may specify that credit enhancements will provide some
                       protection to cover certain losses on the underlying
                       mortgage loans. The forms of credit enhancement include
                       (but are not limited to) the following: subordination of
                       one or more classes of certificates to other classes of
                       certificates in the same series; an insurance policy on a
                       particular class of certificates; a letter of credit; a
                       mortgage pool insurance policy; a special hazard
                       insurance policy; a fraud bond; a bankruptcy bond; a
                       reserve fund; or any combination thereof. See
                       "SUBORDINATION" and "DESCRIPTION OF CREDIT ENHANCEMENTS"
                       herein.
 
                       Regardless of the form of credit enhancement, you should
                       be aware that:
 
                            - The amount of coverage is usually limited;
 
                            - The amount of coverage will usually be reduced
                              over time according to a schedule or formula;
 
                            - The particular form of credit enhancements may
                              provide coverage only to certain types of losses
                              on the mortgage loans, and not to other types of
                              losses;
 
                            - The particular form of credit enhancements may
                              provide coverage only to certain certificates and
                              not other certificates of the same series; and
 
                            - If the applicable rating agencies believe that the
                              rating on the certificates will not be adversely
                              affected, certain types of credit enhancements may
                              be reduced or terminated.
 
IF THE RATE OF
PREPAYMENTS ON THE
MORTGAGE LOANS IS
DIFFERENT THAN
EXPECTED,
YOUR YIELD MAY BE
CONSIDERABLY LOWER THAN
ANTICIPATED            The yield to maturity of your certificates will depend
                       primarily on the price you paid for your certificates and
                       the rate of principal payments on the mortgage loans in
                       the applicable trust. The rate of principal payments
                       includes scheduled payments of interest and principal,
                       prepayments, liquidations dues to defaults and
                       repurchases. If the rate of prepayments on the mortgage
                       loans related to your certificates is higher or lower
                       than anticipated, the yield to maturity may be adversely
                       affected. The yield on some types of certificates are
                       more sensitive to variations in prepayments than others.
                       For example, certificates that receive only payments of
                       interest are especially sensitive to variations in the
                       rate of
 
                                        6
<PAGE>   64
 
                       prepayments. If the rate of prepayments is high or if a
                       call feature of the underlying mortgage loans is
                       exercised, the holders of such certificates may not fully
                       recoup their initial investment. See "YIELD
                       CONSIDERATIONS" and "MATURITY AND PREPAYMENT
                       CONSIDERATIONS" in this prospectus. See also "RISK
                       FACTORS" and "CERTAIN YIELD AND PREPAYMENT
                       CONSIDERATIONS" in the prospectus supplement for more
                       information concerning the prepayment risks pertaining to
                       your certificates.
 
THE PURCHASE OF THE
UNDERLYING MORTGAGE
LOANS WILL AFFECT YOUR
YIELD                  The underlying mortgage loans for any series may be
                       subject to a call feature which would result in the
                       retirement of the certificates. The exercise of such a
                       call feature would affect the average life and yield of
                       each class of certificates in such series. See "THE
                       POOLING AGREEMENT--Termination; Retirement of
                       Certificates" and "MATURITY AND PREPAYMENT
                       CONSIDERATIONS" in this prospectus.
 
                                        7
<PAGE>   65
 
                               THE MORTGAGE POOLS
 
GENERAL
 
     BA Mortgage Securities, Inc. (the "Depositor") intends to sell from time to
time, as described in the related Prospectus Supplement and on terms to be
determined at the time of sale, one or more Series (each, a "Series") of
certificates (the "Certificates") consisting of one or more Classes (each, a
"Class") evidencing beneficial ownership interests in a trust (the "Trust
Fund"), to be created by the Depositor. The property of each Trust Fund will
consist of a segregated pool (a "Mortgage Pool") of conventional one- to
four-family residential first mortgage loans (the "Mortgage Loans"), minus any
portion of the interest payable thereon retained by the Depositor or a Seller
(the "Retained Yield"), if any, evidenced by promissory notes (the "Mortgage
Notes") secured by first mortgages or first deeds of trust or other similar
security instruments (the "Mortgages") creating a first lien on one- to
four-family residential properties (the "Mortgaged Properties"), or interests in
such Mortgage Loans. The Mortgaged Properties will consist primarily of
owner-occupied attached or detached single-family dwelling units, two- to
four-family dwelling units, condominiums, townhouses, row houses, individual
units in planned-unit developments and certain other dwelling units, and the
fee, leasehold or other interests in the underlying real property. The Mortgaged
Properties may include vacation, second and non-owner-occupied homes. If
specified in the Prospectus Supplement relating to a Series of Certificates, a
Mortgage Pool may contain cooperative apartment loans ("Cooperative Loans")
evidenced by promissory notes ("Cooperative Notes") secured by securities
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
"Mortgage" includes a security agreement with respect to a Cooperative Note.
 
     Each Mortgage Loan will be selected by the Depositor for inclusion in a
Mortgage Pool from among those originated by Bank of America, FSB or another
affiliate of the Depositor (each, an "Affiliated Seller") or purchased either
directly or through its affiliates from banks, savings associations, mortgage
bankers, investment banking firms, the FDIC and other mortgage loan originators
or sellers not affiliated with the Depositor ("Unaffiliated Sellers" and,
together with the Affiliated Sellers, the "Sellers"), all as described below
under "MORTGAGE LOAN PROGRAM." Affiliated Sellers and Unaffiliated Sellers are
collectively referred to herein as "Sellers". The characteristics of the
Mortgage Loans are as described in the related Prospectus Supplement. Other
mortgage loans available for purchase by the Depositor may have characteristics
which would make them eligible for inclusion in a Mortgage Pool but were not
selected for inclusion in such Mortgage Pool.
 
     Each Series of Certificates will evidence interests in one Mortgage Pool
including Mortgage Loans having an aggregate principal balance of not less than
approximately $10,000,000 as of the Cut-off Date. Each Certificate will evidence
an interest in only the related Mortgage Pool and corresponding Trust Fund, and
not in any other Mortgage Pool or Trust Fund. The Depositor's only obligations
with respect to a Series of Certificates will be pursuant to certain
representations and warranties made by the Depositor. The master servicer (the
"Master Servicer") for each Series of Certificates will be Bank of America, FSB.
The principal obligations of the Master Servicer will be pursuant to its
contractual servicing obligations (which include its limited obligation to make
certain advances in the event of delinquencies in payment on the Mortgage
Loans).
 
THE MORTGAGE LOANS
 
     All of the Mortgage Loans in a Mortgage Pool will (i) have monthly payments
due on the first of each month, (ii) be secured by Mortgaged Properties located
in any of the 50 states or the District of Columbia and (iii) be of one of the
following types of mortgage loans described or referred to in paragraphs
numbered (1) through (4):
 
                                        8
<PAGE>   66
 
          (1) Fixed-rate, fully-amortizing mortgage loans (which may include
     mortgage loans converted from adjustable-rate mortgage loans) providing for
     level monthly payments of principal and interest over the terms of such
     Mortgage Loans;
 
          (2) Fully-amortizing adjustable-rate mortgage loans ("ARM Loans")
     having an original term to maturity of not more than 40 years, with a
     related interest rate (a "Mortgage Rate") which generally adjusts initially
     either one, three or six months or one, three, five, seven or ten years
     subsequent to the initial payment date, and thereafter at either one-month,
     six-month, one-year or other intervals (with corresponding adjustments in
     the amount of monthly payments) over the term of the mortgage loan to equal
     the sum of a fixed percentage set forth in the related Mortgage Note (the
     "Note Margin") and an index*. The related Prospectus Supplement will set
     forth the relevant index and the highest, lowest and weighted average Note
     Margin with respect to the ARM Loans in the related Mortgage Pool. The
     related Prospectus Supplement will also indicate any periodic or lifetime
     limitations on changes in any per annum Mortgage Rate at the time of any
     adjustment. If specified in the related Prospectus Supplement, an ARM Loan
     may include a provision that allows the Mortgagor to convert the adjustable
     Mortgage Rate to a fixed rate at some point during the term of such ARM
     Loan generally during the period from one to twelve years subsequent to the
     initial payment date;
 
          (3) Mortgage Loans having an original term to maturity of not more
     than 30 years with a Mortgage Rate which adjusts initially five years
     subsequent to the initial payment date, and thereafter at one-month,
     six-month, one-year or other intervals (with corresponding adjustments in
     the amount of monthly payments) over the term of the mortgage loan to equal
     the sum of the related Note Margin and Index, and providing for monthly
     payments of interest only prior to the date of the initial Mortgage Rate
     adjustment and monthly payments of principal and interest thereafter
     sufficient to fully-amortize the Mortgage Loans over their remaining terms
     to maturity ("Net 5 Loans"). The related Prospectus Supplement will set
     forth the relevant index and the highest, lowest and weighted average Note
     Margin with respect to the Net 5 Loans in the related Mortgage Pool. The
     related Prospectus Supplement will also indicate any periodic or lifetime
     limitations on changes in any per annum Mortgage Rate at the time of any
     adjustment; or
 
          (4) Balloon mortgage loans ("Balloon Loans"), which are fixed-rate
     mortgage loans having original terms to maturity of generally five or seven
     years as described in the related Prospectus Supplement, with level monthly
     payments of principal and interest based on a 30-year amortization
     schedule. The amount of the monthly payment will remain constant until the
     maturity date, upon which date the full outstanding principal balance on
     such Balloon Loan will be due and payable (such amount, the "Balloon
     Amount").
 
     Certain information, including information regarding loan-to-value ratios
(each, a "Loan-to-Value Ratio") at origination of the Mortgage Loans underlying
each Series of Certificates, will be supplied in the related Prospectus
Supplement. The Loan-to-Value Ratio at origination is defined generally as the
ratio, expressed as a percentage, of the principal amount of the Mortgage Loan
at origination to the lesser of (x) the appraised value determined in an
appraisal obtained at origination of such Mortgage Loan and (y) the sales price
for the related Mortgaged Property. The lesser of the items described in (x) and
(y) of the preceding sentence is hereinafter referred to as the "Appraised
Value."
 
- ---------------
 
* The index (the "Index") for a particular Mortgage Pool will be specified in
  the related Prospectus Supplement and may include one of the following
  indices: (i) the twelve-month average of monthly yields on actively traded
  U.S. Treasury securities adjusted to a constant maturity of one year, (ii) the
  weekly average yield on U.S. Treasury securities adjusted to a constant
  maturity of one year, (iii) the weekly average of the secondary market
  interest rates on six-month negotiable certificates of deposit, (iv) the
  average of interbank offered rates for six-month U.S. dollar-denominated
  deposits in the London market, or (v) the monthly weighted average cost of
  funds for member institutions of the Federal Home Loan Bank of San Francisco,
  each calculated as of a date prior to each scheduled interest rate adjustment
  date which will be specified in the related Prospectus Supplement.
                                        9
<PAGE>   67
 
     The Mortgage Loans may be "equity refinance" Mortgage Loans, as to which a
portion of the proceeds are used to refinance an existing mortgage loan, and the
remaining proceeds may be retained by the Mortgagor or used for purposes
unrelated to the Mortgaged Property. Alternatively, the Mortgage Loans may be
"rate and term refinance" Mortgage Loans, as to which substantially all of the
proceeds (net of related costs incurred by the borrower under the Mortgage Loan
(the "Mortgagor") are used to refinance an existing mortgage loan or loans
(which may include a junior lien) primarily in order to change the interest rate
or other terms thereof. The Mortgage Loans may be mortgage loans which have been
consolidated and/or have had various terms changed, mortgage loans which have
been converted from adjustable rate mortgage loans to fixed rate mortgage loans,
or construction loans which have been converted to permanent mortgage loans. The
Mortgagors may be required to or have the option to make payments by means of
automatic debits from their checking or savings accounts. In addition, a
Mortgaged Property may be subject to secondary financing at the time of
origination of the Mortgage Loan or thereafter.
 
     If provided for in the related Prospectus Supplement, a Mortgage Pool may
contain ARM Loans which allow the Mortgagors to convert the adjustable rates on
such Mortgage Loans to a fixed rate at some point during the life of such
Mortgage Loans (each such Mortgage Loan, a "Convertible Mortgage Loan"),
generally during the period from one to twelve years subsequent to the date of
origination, depending upon the length of the initial adjustment period. If
specified in the related Prospectus Supplement, upon any conversion, the
Depositor or the Master Servicer, Seller or a third party may have the
obligation or the option to purchase the converted Mortgage Loan as and to the
extent set forth in the related Prospectus Supplement. If specified in the
related Prospectus Supplement, the Depositor or the Master Servicer (or another
party specified therein) may agree to act as remarketing agent with respect to
such converted Mortgage Loans and, in such capacity, to use its best efforts to
arrange for the sale of converted Mortgage Loans in the event that such party
does not exercise its option to purchase such converted Mortgage Loans. Upon the
failure of any party to fulfill its obligation or exercise its option to
purchase any such converted Mortgage Loan or the inability of any remarketing
agent to arrange for the sale of the converted Mortgage Loan, the related
Mortgage Pool will thereafter include both fixed rate and adjustable rate
Mortgage Loans. In addition, the Prospectus Supplement relating to any Series of
Certificates may specify other arrangements relating to the Convertible Loans
upon their conversion.
 
     If provided for in the related Prospectus Supplement, certain of the
Mortgage Loans may be subject to temporary buydown plans ("Buydown Mortgage
Loans") pursuant to which the monthly payments made by the Mortgagor during the
early years of the Mortgage Loan (the "Buydown Period") will be less than the
scheduled monthly payments on the Mortgage Loan, the resulting difference to be
made up from (i) an amount (such amount, exclusive of investment earnings
thereon, being hereinafter referred to as "Buydown Funds") contributed by the
seller of the Mortgaged Property or another source and placed in a custodial
account (the "Buydown Account"), (ii) if the Buydown Funds are contributed on a
present value basis, investment earnings on such Buydown Funds or (iii)
additional buydown funds to be contributed over time by the Mortgagor's employer
or another source. The applicable Prospectus Supplement or Current Report on
Form 8-K will contain information with respect to any Buydown Mortgage Loans,
including information on the interest rate initially payable by the Mortgagor,
increases in the interest rate paid by the Mortgagor over the term of the
related Buydown Mortgage Loan and the length of the Buydown Period.
 
     The Prospectus Supplement for each Series of Certificates will contain
information as to the type of Mortgage Loans which will be included in the
related Mortgage Pool. Each Prospectus Supplement applicable to a Series of
Certificates will include certain information, generally as of the Cut-off Date
and to the extent then available to the Depositor, on an approximate basis, as
to (i) the aggregate principal balance of the Mortgage Loans, (ii) the type of
property securing the Mortgage Loans, (iii) the original terms to maturity of
the Mortgage Loans, (iv) the range of principal balances of the Mortgage Loans
at origination, (v) the earliest origination date and latest maturity date of
the Mortgage Loans, (vi) the Loan-to-Value Ratios of the Mortgage Loans, (vii)
the Mortgage Rate or range of Mortgage Rates borne by the Mortgage Loans, (viii)
if any of the Mortgage Loans are ARM Loans or Net 5 Loans, the applicable Index,
the range of Note Margins and the weighted average Note Margin, (ix) the
geographical distribution of the Mortgage Loans, (x) the
 
                                       10
<PAGE>   68
 
number and aggregate principal balance of Buydown Mortgage Loans, if applicable,
and (xi) the percent of ARM Loans which are convertible to fixed-rate mortgage
loans, if applicable.
 
     A Current Report on Form 8-K will be available to the Purchasers of the
related Series of Certificates at or before the initial issuance of such Series
of Certificates and will be filed, together with the related Pooling Agreement,
with the Securities and Exchange Commission within fifteen days after the
initial issuance of such Certificates. In the event that Mortgage Loans are
added to or deleted from the Trust Fund after the date of the related Prospectus
Supplement, such addition or deletion will be noted in the Current Report on
Form 8-K. In addition, specific information with respect to the Mortgage Loans
in a particular Mortgage Pool and any applicable credit enhancements which is
not included in the related Prospectus Supplement will generally be included in
such Current Report on Form 8-K.
 
     The Depositor will cause the Mortgage Loans constituting each Mortgage Pool
to be assigned to the Trustee named in the related Prospectus Supplement, for
the benefit of the holders of all of the Certificates of a Series. The Master
Servicer will service the Mortgage Loans pursuant to a Pooling Agreement and
will receive a fee for such services. See "MORTGAGE LOAN PROGRAM" and
"DESCRIPTION OF THE CERTIFICATES." Certain Mortgage Loans may be serviced for
the Master Servicer by other mortgage servicing institutions ("Subservicers"),
which may be affiliates of the Depositor and the Master Servicer. With respect
to those Mortgage Loans serviced by the Master Servicer through a Subservicer,
the Master Servicer will remain liable for its servicing obligations under the
related Pooling Agreement as if the Master Servicer alone were servicing such
Mortgage Loans.
 
     As specified in the related Prospectus Supplement, (i) the Depositor may
assign certain limited representations and warranties regarding the Mortgage
Loans, and (ii) the Depositor may have made certain limited representations and
warranties regarding the Mortgage Loans. The Depositor's assignment of the
Mortgage Loans to the Trustee will be without recourse. See "DESCRIPTION OF THE
CERTIFICATES -- Assignment of Mortgage Loans." The Master Servicer's obligations
with respect to the Mortgage Loans will consist principally of its contractual
servicing obligations under the related Pooling Agreement (including its
obligation to enforce certain purchase and other obligations of Sellers and
Subservicers, if any, as more fully described herein under "MORTGAGE LOAN
PROGRAM--Representations and Warranties by Sellers," and "DESCRIPTION OF THE
CERTIFICATES -- Assignment of Mortgage Loans," and its obligation to make
certain cash advances in the event of delinquencies in payments on or with
respect to the Mortgage Loans in amounts described herein under "DESCRIPTION OF
THE CERTIFICATES -- Advances"). The obligation of the Master Servicer to make
advances will be limited to amounts which the Master Servicer believes
ultimately would be reimbursable out of the proceeds of liquidation of the
Mortgage Loans or any applicable form of credit support. See "DESCRIPTION OF THE
CERTIFICATES -- Advances."
 
                                 THE DEPOSITOR
 
     The Depositor was incorporated in the State of Delaware on May 6, 1996 and
filed a Certificate of Amendment of Certificate of Incorporation changing its
name to "BA Mortgage Securities, Inc." on August 23, 1996. Bank of America, FSB
acquired, subject to regulatory approval, all of the outstanding stock of the
Depositor from its affiliate, Bank of America National Trust and Savings
Association ("Bank of America NT&SA"), on January 1, 1998. It is not expected
that the Depositor will have any business operations other than offering
Certificates and related similar activities.
 
     The principal executive offices of the Depositor are located at 345
Montgomery Street, Lower Level #2, Unit #8152, San Francisco, California 94104.
The Depositor's telephone number is (415) 622-3676.
 
                                       11
<PAGE>   69
 
                             MORTGAGE LOAN PROGRAM
 
     The Depositor will purchase the Mortgage Loans, either directly or
indirectly through its affiliates, from Sellers. The Mortgage Pools may consist
of Mortgage Loans purchased from Affiliated Sellers, Unaffiliated Sellers or
both Unaffiliated Sellers and Affiliated Sellers. A description of Bank of
America, FSB is given below under "-- Bank of America, FSB," and the Prospectus
Supplement related to any Series of Certificates for which the underlying
Mortgage Pool contains a substantial number of Mortgage Loans purchased from any
other Affiliated Seller will describe such Affiliated Seller. The Mortgage Loans
purchased from Affiliated Sellers will generally have been originated in
accordance with the underwriting standards of the Affiliated Sellers, as
described below under "-- Underwriting Standards."
 
     The Prospectus Supplement related to any Series of Certificates for which
the underlying Mortgage Pool contains a substantial number of Mortgage Loans
purchased from an Unaffiliated Seller will describe such Unaffiliated Seller.
The Mortgage Loans purchased from Unaffiliated Sellers may have been originated
in accordance with underwriting standards that vary substantially from those
used by Affiliated Sellers. See "-- Underwriting Standards" and
"-- Qualifications of Unaffiliated Sellers" below.
 
BANK OF AMERICA, FSB
 
     With more than $21.3 billion in assets as of September 30, 1998, Bank of
America, FSB, a subsidiary of BankAmerica Corporation, originates and services
home loans nationwide through retail, wholesale, and other specialized channels.
In addition, Bank of America, FSB's Community Development Division finances
affordable housing projects and offers government-guaranteed small business
loans in 11 states.
 
     Bank of America, FSB's deposits are insured by the Federal Deposit
Insurance Corporation (the "FDIC") to the extent provided by law. Bank of
America, FSB has been approved as a mortgagee and Seller/Servicer by the
Department of Housing and Urban Development, the Veterans Administration, the
Government National Mortgage Association ("GNMA"), the Federal National Mortgage
Association ("FNMA") and Federal Home Loan Mortgage Corporation ("FHLMC"). Bank
of America, FSB has been an active one- to four-family residential real estate
mortgage lender since 1992. It originates both fixed and adjustable rate loans
throughout the United States. See "-- Residential Mortgage Loan Servicing
Activities" and "-- Delinquency, Foreclosure and Loss Experience" for a
description of Bank of America, FSB's loan servicing operations and activities.
 
     Bank of America, FSB's headquarters is located in Portland, Oregon, and its
administrative offices are located at 555 California Street, San Francisco,
California 94104 (telephone 415-622-2220).
 
UNDERWRITING STANDARDS
 
     The Affiliated Sellers have written, and are continuously updating,
underwriting guides for the origination of one- to four-family residential first
mortgage loans (as modified from time to time, the "Guides"). The underwriting
standards as set forth in the Guides are continuously revised based on
prevailing conditions in the residential mortgage market, evolving credit
standards of the Affiliated Sellers and the investment market for residential
mortgage loans.
 
     The underwriting standards set forth in the Guides are intended to assess
the prospective borrower's ability and willingness to repay the debt and the
adequacy of the property as collateral for the loan requested. Credit policies
of the Affiliated Sellers require that loan underwriters be satisfied that the
value of the property being financed supports the outstanding loan balance with
sufficient value at loan origination to mitigate the effects of adverse shifts
in real estate values. The emphasis, however, remains on the borrowers' ability
to repay debt.
                                       12
<PAGE>   70
 
     The real estate lending processes of the Affiliated Sellers for one- to
four-family mortgage loans follow standard procedures, designed to comply with
applicable federal and state laws and regulations. Initially, a prospective
borrower is required to complete a detailed application designed to provide to
the underwriter pertinent information about the prospective borrower, the
property to be financed and the type of loan desired. Information regarding the
property to be financed may be provided by the prospective borrower after the
applicable Affiliated Seller has approved, subject to review of the property to
be financed, a loan to the prospective borrower. As part of the description of
the prospective borrower's financial condition, the Affiliated Sellers generally
require a description of assets and liabilities and income and expenses and
obtain a credit report which summarizes the prospective borrower's credit
history with merchants and lenders and any public records, such as bankruptcy.
In most cases, employment verification is obtained providing current and
historical income information. Such employment verification is obtained either
through the applicable Affiliated Seller's analysis of the prospective
borrower's W-2 forms for the most recent two years and year-to-date earnings
statement or most recent two years' tax returns or from the prospective
borrower's employer, wherein the employer reports the length of employment and
current salary with that organization. Self-employed prospective borrowers
generally are required to submit their federal tax returns for the past two
years plus year-to-date financial statements if the loan application is made 120
days or longer after the end of the most recent tax year for which a federal tax
return was provided. In general, an employment verification is obtained, and
with respect to certain loans, a telephonic employment confirmation is obtained
by the Affiliated Seller.
 
     Beginning in April 1994, the Affiliated Sellers began using an automated
process to assist in making credit decisions on certain residential real estate
loans. A prospective borrower's credit history is assigned a score based on
standard criteria designed to predict the possibility of a default by the
prospective borrower on a mortgage loan. An application from a prospective
borrower whose score indicates a high probability of default will receive
scrutiny from a senior underwriter who may override a decision based on the
credit score. An application from a prospective borrower whose score indicates a
low probability of default is eligible for the Affiliated Sellers' rapid
processing program (the "Rapid Processing Program"). Loans in the Rapid
Processing Program are subject to less stringent underwriting guidelines and
documentation standards to verify the information in the application.
 
     With respect to most mortgage loans originated by the Affiliated Sellers,
once the employment verification (or confirmation) and the credit report are
received by the underwriter considering the loan application, a determination is
made as to whether the prospective borrower has sufficient monthly income
available to meet the borrower's monthly obligations on the proposed loan and
other expenses related to the residence as well as to meet other financial
obligations and monthly living expenses. The Affiliated Sellers have established
as general lending guidelines that the mortgage payments plus applicable real
property taxes, condominium or homeowner association common charges, hazard
insurance premiums and premiums on any Primary Mortgage Insurance Policy (as
defined herein) generally should not exceed 33% of the borrower's gross income,
and that all monthly payments, including those mentioned above and other
obligations, such as car payments, generally should not exceed 38% of gross
income. However, other credit considerations may cause an underwriter to depart
from (or not consider) these guidelines. The Affiliated Sellers follow standard
exceptions procedures pursuant to which underwriters generally have delegated
authority to approve or recommend the approval of loan applications when certain
lending guidelines are not met, including when the ratios of the borrower's
housing and fixed expenses to gross income exceed 40%. Where there are two
individuals co-signing any mortgage note, the income and payment obligations of
both may be included in the computation. With respect to ARM Loans with Mortgage
Rates that adjust initially five or more years after their origination and Net 5
Loans, these ratios are calculated using the initial Mortgage Rates. With
respect to all other ARM Loans, these ratios are generally calculated using the
fully-indexed Mortgage Rate.
 
     Prior to final loan approval a prospective borrower generally is expected
to have liquid assets sufficient to cover the down-payment, closing costs and
cash reserves that could be used to pay future housing expenses in
 
                                       13
<PAGE>   71
 
a depository or related account of the borrower. However, the Affiliated Sellers
generally do not require prospective borrowers to have such liquid assets when
they originate refinance loans.
 
     An appraisal is made of each property to be financed. The appraisal is
conducted by either a staff appraiser of the applicable Affiliated Seller, or in
some instances, an independent fee appraiser licensed in the jurisdiction where
such property is located. Generally, as part of the loan origination process,
the appraiser personally visits the property and estimates its market value on
the basis of comparable properties and other factors.
 
     The Affiliated Sellers have generally not made one- to four-family mortgage
loans having Loan-to-Value Ratios above 80% unless they have obtained or caused
the borrowers to obtain Primary Mortgage Insurance Policies.
 
     The Mortgaged Properties may be located in states where, in general, a
lender providing credit on a single-family property may not seek a deficiency
judgment against the mortgagor but rather 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 underwriting standards contained in the Guides applicable to all states
(including anti-deficiency states) require that the value of the property being
financed, as indicated by the appraisal, currently supports and is anticipated
to support in the future the outstanding loan balance, although there can be no
assurance that such value will support the loan balance in the future.
 
     In addition, the Depositor will purchase Mortgage Loans which may not fully
conform to the underwriting standards set forth in the Guides. Certain of the
Mortgage Loans will be purchased either directly or through an affiliate of the
Depositor in negotiated transactions, and such negotiated transactions may be
governed by agreements ("Master Commitments") relating to ongoing purchases of
Mortgage Loans by the Depositor or such affiliate of the Depositor, from
Unaffiliated Sellers who will represent that the Mortgage Loans have been
originated in accordance with underwriting standards agreed to by the Depositor
or such affiliate of the Depositor. The Depositor or an affiliate of the
Depositor will generally review only a sample of the Mortgage Loans in any
delivery of such Mortgage Loans from the related Unaffiliated Seller for credit
quality.
 
     The underwriting standards utilized in negotiated transactions and Master
Commitments with Unaffiliated Sellers may vary substantially from the
underwriting standards set forth in the Guides. Such underwriting standards are
generally intended to provide an underwriter with 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 generally will not distinguish among the various
underwriting standards applicable to the Mortgage Loans nor describe any review
for compliance with applicable underwriting standards performed by the Depositor
or an affiliate of the Depositor. Moreover, there can be no assurance that every
Mortgage Loan was originated in conformity with the applicable 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.
 
QUALIFICATION OF UNAFFILIATED SELLERS
 
     Each Unaffiliated Seller must be an institution experienced in originating
and servicing Mortgage Loans of the type contained in the related Mortgage Pool
in accordance with practices and guidelines which are substantially similar to
the Guides, must maintain satisfactory facilities to originate and service those
 
                                       14
<PAGE>   72
 
Mortgage Loans, must be a seller/servicer approved by either FNMA or FHLMC and
must be a mortgagee approved by the Federal Housing Administration ("FHA") or an
institution the deposit accounts in which are insured by the FDIC. In addition,
the Depositor will evaluate the financial condition of each Unaffiliated Seller.
However, the Depositor makes no representation regarding the financial condition
of any such Unaffiliated Seller.
 
REPRESENTATIONS AND WARRANTIES BY SELLERS
 
     As specified in the related Prospectus Supplement, (i) each Seller may have
made representations and warranties in respect of the Mortgage Loans sold by
such Seller to the Depositor which the Depositor will assign to the related
Trust Fund on the date of initial issuance of the related Series of
Certificates, and (ii) the Depositor may have made representations and
warranties in respect of each Mortgage Loan on the date of initial issuance of
the related Series of Certificates. Such representations and warranties
generally include, among other things, that at the time of the sale by the
Depositor of each Mortgage Loan to the applicable Trust Fund: (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, title
insurance (or in the case of Mortgaged Properties located in areas where such
policies are generally not available, an attorney's certificate of title) and
any required hazard and primary mortgage insurance were effective at the
origination of each Mortgage Loan, and each policy (or certificate of title)
remains in full force and effect; (iii) the Seller has good title to each such
Mortgage Loan and such Mortgage Loan was subject to no offsets, defenses or
counterclaims except as may be provided under the Relief Act and except to the
extent that any buydown agreement exists for a Buydown Mortgage Loan; (iv)
except in the case of Cooperative Loans, each Mortgage is a valid first lien on
an unencumbered estate in fee simple or leasehold interest in the Mortgaged
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); (v) each Mortgaged Property
is free from material damage and in generally good repair, except for ordinary
wear and tear; (vi) there are no delinquent tax or assessment liens against the
Mortgaged Property; (vii) if a Primary Mortgage Insurance Policy is required
with respect to a Mortgage Loan, such Mortgage Loan is the subject of such a
policy; (viii) each Mortgage Loan was made in compliance with all applicable
local, state and federal laws in all material respects; and (ix) that the
Mortgage Note and documents relating to each Mortgage Loan are genuine and that
each is the legal, valid and binding obligation of the maker thereof, subject to
certain customary exceptions.
 
     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 MORTGAGE LOANS AND RELATED MATTERS -- Cooperative Loans."
 
     In the event of a breach of a Seller's representation or warranty that
materially adversely affects the interests of the Certificateholders in a
Mortgage Loan, the related Seller will be obligated to cure such breach or
repurchase or substitute another Mortgage Loan for such Mortgage Loan as
described below. Promptly upon becoming aware of any breach of a representation
or warranty which materially and adversely affects the interests of the
Certificateholders with respect to a Mortgage Loan or Mortgage Loans, the Master
Servicer shall be required to provide notice to the related Seller and request
that such Seller either cure such breach or repurchase or substitute another
Mortgage Loan for such Mortgage Loan. However, there can be no assurance
                                       15
<PAGE>   73
 
that a Seller will honor its obligation to cure such breach or repurchase or
substitute another Mortgage Loan for any Mortgage Loan as to which such a breach
of a representation or warranty arises.
 
     If a Seller cannot cure a breach of any representation or warranty made by
it in respect of a Mortgage Loan which materially and adversely affects the
interests of the Certificateholders in such Mortgage Loan within 90 days after
notice from the Master Servicer, such Seller will be obligated to purchase such
Mortgage Loan. The Purchase Price for any such Mortgage Loan will be equal to
the principal balance thereof as of the date of purchase plus accrued and unpaid
interest to the first day of the month following the month of repurchase at the
Pass-Through Rate. If specified in the related Prospectus Supplement, as to any
such Mortgage Loan required to be purchased by the related Seller as provided
above, rather than repurchase the Mortgage Loan, the related Seller may, at its
sole option, remove such Mortgage Loan (a "Deleted Mortgage Loan") from the
Trust Fund and substitute in its place another Mortgage Loan of like kind (a
"Qualified Substitute Mortgage Loan"); however, such substitution must be
effected within 120 days of the date of the initial issuance of the Certificates
with respect to a Trust Fund for which no REMIC election is to be made. With
respect to a Trust Fund for which a REMIC election is to be made, such
substitution of a defective Mortgage Loan must be effected within two years of
the date of the initial issuance of the Certificates, and may not be made if
such substitution would cause the Trust Fund to not qualify as a REMIC or result
in a prohibited transaction tax under the Internal Revenue Code of 1986 (the
"Code"). Any Qualified Substitute Mortgage Loan generally will, on the date of
substitution, (i) have an outstanding principal balance, after deduction of the
principal portion of the monthly payment due in the month of substitution, not
in excess of the outstanding principal balance of the Deleted Mortgage Loan (the
amount of any shortfall to be deposited in a custodial account (the "Custodial
Account") in the month of substitution for distribution to the
Certificateholders), (ii) have a Mortgage Rate and a Net Mortgage Rate not less
than (and not more than one percentage point greater than) the Mortgage Rate and
Net Mortgage Rate, respectively, of the Deleted Mortgage Loan as of the date of
substitution, (iii) have a Loan-to-Value Ratio at the time of substitution no
higher than that of the Deleted Mortgage Loan at the time of substitution, (iv)
have a remaining term to maturity not greater than (and not more than one year
less than) that of the Deleted Mortgage Loan, and (v) comply with all of the
representations and warranties set forth in the related mortgage loan purchase
agreement as of the date of substitution. (Section 2.04) The related Pooling
Agreement may include additional requirements relating to ARM Loans, Net 5 Loans
or other specific types of Mortgage Loans, or additional provisions relating to
meeting the foregoing requirements on an aggregate basis where a number of
substitutions occur contemporaneously. This substitution or repurchase
obligation constitutes the sole remedy available to the Certificateholders or
the Trustee for any such breach.
 
RESIDENTIAL MORTGAGE LOAN SERVICING ACTIVITIES
 
     Residential mortgage loans originated by the Affiliated Sellers, or
purchased from Unaffiliated Sellers, including the Mortgage Loans, are serviced
currently by Bank of America, FSB at either its servicing facility located in
Cypress, California (the "Cypress Center") or its servicing facility located in
Richmond, Virginia (the "Richmond Center"). Bank of America, FSB acquired the
Cypress Center from Bank of America NT&SA on January 1, 1998. On September 30,
1998, the Cypress Center was servicing approximately 413,579 mortgage loans with
an aggregate principal balance of $55,140,000,000 and the Richmond Center was
servicing approximately 456,081 mortgage loans with an aggregate principal
balance of $44,600,000,000.
 
     The Cypress Center and Richmond Center are responsible for answering
customers inquiries, receiving loan payments, reporting to investors,
maintaining hazard insurance or a blanket hazard policy, monitoring payment of
taxes, assessments and, when applicable, Primary Mortgage Insurance Policies,
and all mortgage accounting and record keeping. The Cypress Center and Richmond
Center also are responsible for collection efforts on delinquent residential
mortgage loans and foreclosures thereon. Separate units exist within affiliates
of BankAmerica to manage and dispose of other real estate owned.
 
                                       16
<PAGE>   74
 
     Because both Centers service loans for governmental and quasi-governmental
agencies of the U.S. Government, the Centers are regularly examined by Bank of
America, FSB's internal and external auditors and periodically by FNMA, FHLMC,
GNMA, the Office of Thrift Supervision ("OTS") and the Department of Housing and
Urban Development. Certain financial records of Bank of America, FSB relating to
its mortgage servicing activities are reviewed annually by its independent
public accountants.
 
DELINQUENCY, FORECLOSURE AND LOSS EXPERIENCE
 
     The delinquency, foreclosure and loss experience on the portfolios of one-
to four-family first mortgage loans owned by Bank of America, FSB and Bank of
America NT&SA and serviced or subserviced by Bank of America, FSB are set forth
in the following table.* The delinquency, foreclosure and loss experience
indicated excludes certain loans originated by private banking units of Bank of
America, FSB's affiliates. The portfolio of mortgage loans serviced or
subserviced by Bank of America, FSB includes both fixed and adjustable interest
rate mortgage loans, including Buydown Mortgage Loans, loans with stated
maturities of 15 to 40 years and other types of mortgage loans having a variety
of payment characteristics, and includes mortgage loans secured by mortgaged
properties in geographic locations that may not be representative of the
geographic distribution or concentration of the Mortgaged Properties securing
the Mortgage Loans. There can be no assurance that the delinquency, foreclosure
and loss experience set forth below with respect to the portfolio of one- to
four-family first mortgage loans owned by Bank of America, FSB and Bank of
America NT&SA and serviced or subserviced by Bank of America, FSB will be
similar to the results that may be experienced with respect to the Mortgage
Loans underlying any Series of Certificates.
 
- ---------------
 
* The delinquency, foreclosure and loss experience indicated includes the
  delinquency, foreclosure and loss experience on mortgage loans owned by Bank
  of America NT&SA and serviced by it prior to January 1, 1998. Bank of America,
  FSB acquired the Cypress Center on January 1, 1998. In addition, the
  delinquency, foreclosure and loss experience set forth for 1997 and for the
  six-month period ended June 30, 1998 includes certain mortgage loans, with an
  aggregate principal balance that does not exceed 15% of the total portfolio by
  dollar amount for any period indicated, that are owned by an affiliate of Bank
  of America, FSB (other than Bank of America NT&SA) and serviced or subserviced
  by Bank of America, FSB.
                                       17
<PAGE>   75
 
                  DELINQUENCY, FORECLOSURE AND LOSS EXPERIENCE
 
<TABLE>
<CAPTION>
                                               AT OR FOR THE YEAR ENDED DECEMBER 31,
                            ---------------------------------------------------------------------------        AT OR FOR THE
                                                                                                                 SIX-MONTH
                                                                                                               PERIOD ENDED
                                     1995                      1996                      1997                JUNE 30, 1998(7)
                            -----------------------   -----------------------   -----------------------   -----------------------
                                        BY DOLLAR                 BY DOLLAR                 BY DOLLAR                 BY DOLLAR
                              BY        AMOUNT OF       BY        AMOUNT OF       BY        AMOUNT OF       BY        AMOUNT OF
                            NO. OF        LOANS       NO. OF        LOANS       NO. OF        LOANS       NO. OF        LOANS
                             LOANS    (IN MILLIONS)    LOANS    (IN MILLIONS)    LOANS    (IN MILLIONS)    LOANS    (IN MILLIONS)
                            -------   -------------   -------   -------------   -------   -------------   -------   -------------
<S>                         <C>       <C>             <C>       <C>             <C>       <C>             <C>       <C>
Total Portfolio...........  174,863     $26,335.1     149,178     $27,832.2     150,688     $28,721.2     115,373     $25,004.9
Average Portfolio
  Balance(1)..............  178,221      26,308.5     160,712      27,105.7     178,809      32,381.2     129,917      26,184.3
Period of Delinquency
  31 to 59 days...........    2,728         367.5       2,613         366.2       3,180         415.8       2,757         379.7
  60 to 89 days...........      779         118.3         662          96.7         817         113.1         702          97.8
  90 days or more(2)......      877         161.7         613          98.3         780         107.0         574          79.8
                            -------     ---------     -------     ---------     -------     ---------     -------     ---------
Total Delinquent Loans....    4,384     $   647.5       3,888     $   561.2       4,777     $   635.9       4,033     $   557.3
Delinquency Ratio.........     2.51%         2.46%       2.61%         2.02%       3.17%         2.21%       3.50%         2.23%
Foreclosures Pending(3)...    1,101     $   216.0         904     $   160.4       1,082     $   178.0       1,036     $   158.6
Foreclosure Ratio.........     0.63%         0.82%       0.61%         0.58%       0.72%         0.62%       0.90%         0.63%
Losses(4).................    1,286     $   112.6       1,832     $    98.8       1,363     $    50.8         447     $    12.3
Loss Ratio(5).............     0.72%         0.43%       1.14%         0.36%       0.76%         0.16%       0.69          0.09%
Excess Recovery(6)........       13     $     0.2          54     $     0.5          67     $     0.8           7     $     0.1
</TABLE>
 
- ---------------
 
(1) Average Portfolio Balance for the period indicated is based on end of month
    balances divided by the number of months in the period indicated.
 
(2) Does not include Foreclosures Pending.
 
(3) Includes mortgage loans for which foreclosure proceedings had been
    instituted and title to which had not been acquired by Bank of America, FSB,
    Bank of America NT&SA, a third party or by an insurer at the date indicated.
 
(4) Losses are the sum of losses less net gains (Excess Recoveries) on all
    mortgage loans liquidated during the period indicated. Loss for any mortgage
    loan is equal to the difference between (a) the sum of the outstanding
    principal balance plus accrued interest, lost interest income accrued at
    Bank of America, FSB's internal reinvestment rate or Bank of America NT&SA's
    internal reinvestment rate, as applicable, from the date such mortgage loan
    became a REO mortgage loan until the date it was liquidated, Servicing
    Advances and all liquidation expenses related to such mortgage loan and (b)
    all amounts received in connection with the liquidation of the related
    mortgaged property. Losses are included in the year in which they were
    expensed or written down.
 
(5) Loss Ratios are computed by dividing the Losses during the period indicated
    by the Average Portfolio Balance during such period.
 
(6) Excess Recovery is calculated only with the respect to defaulted mortgage
    loans as to which the liquidation of the related mortgaged property resulted
    in recoveries in excess of the sum of the outstanding principal balance plus
    accrued interest thereon, Servicing Advances and all liquidation expenses
    related to such mortgage loan.
 
(7) Excess Recovery indicated is for the three-month period ended March 31,
    1998.
 
                                       18
<PAGE>   76
 
                        DESCRIPTION OF THE CERTIFICATES
 
GENERAL
 
     Each Series of Certificates will be issued pursuant to a Pooling Agreement,
similar to the form filed as an exhibit to the Registration Statement of which
this Prospectus is a part. Each Pooling Agreement will be filed with the
Securities and Exchange Commission as an exhibit to a Current Report on Form
8-K. The following summaries (together with additional summaries under "THE
POOLING AGREEMENT" below) describe certain provisions relating to the
Certificates common to each Pooling Agreement. References in this Prospectus to
the relevant articles, sections and exhibits of the applicable Pooling Agreement
appear in parenthesis. The summaries 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 Trust Fund and the related
Prospectus Supplement. Wherever particular sections or defined terms of the
Pooling Agreement are referred to herein, such sections or defined terms are
thereby incorporated herein by reference.
 
     Certificates of each Series covered by a particular Pooling Agreement will
evidence specified beneficial ownership interests in a separate Trust Fund
created pursuant to such Pooling Agreement. (Article I and Sections 5.01 and
5.02) A Trust Fund will consist of, to the extent provided in the Pooling
Agreement: (i) such Mortgage Loans (and the related mortgage documents) or
interests therein underlying a particular Series of Certificates as from time to
time are subject to the Pooling Agreement (exclusive of any Retained Yield
(described below)); (ii) such assets including, without limitation, all payments
and collections in respect of the Mortgage Loans due after the related Cut-off
Date, as from time to time are identified as deposited in respect thereof in the
Custodial Account and in the related Certificate Account; (iii) property
acquired by foreclosure of such Mortgage Loans or deed in lieu of foreclosure;
(iv) hazard insurance policies and Primary Mortgage Insurance Policies, if any,
and certain proceeds thereof; and (v) any combination, as and to the extent
specified in the related Prospectus Supplement, of a Letter of Credit, Mortgage
Pool Insurance Policy, Special Hazard Insurance Policy, Certificate Insurance
Policy, Bankruptcy Bond or other type of credit enhancement as described under
"DESCRIPTION OF CREDIT ENHANCEMENTS." To the extent that any Trust Fund includes
certificates of interest or participations in Mortgage Loans, the related
Prospectus Supplement will describe the material terms and conditions of such
certificates or participations. (Article I)
 
     Each Series of Certificates may consist of any one or a combination of the
following: (i) a single Class of Certificates; (ii) two or more Classes of
Certificates, one or more Classes of which will be senior ("Senior
Certificates") in right of payment to one or more of the other Classes
("Subordinate Certificates"), and as to which certain Classes of Senior (or
Subordinate) Certificates may be senior to other Classes of Senior (or
Subordinate) Certificates, as described in the respective Prospectus Supplement
(any such Series, a "Senior/Subordinate Series"); (iii) two or more Classes of
Certificates, one or more Classes ("Strip Certificates") of which will be
entitled to (a) principal distributions, with disproportionate, nominal or no
interest distributions or (b) interest distributions, with disproportionate,
nominal or no principal distributions; (iv) two or more Classes of Certificates
which differ as to the timing, sequential order, rate, pass-through rate or
amount of distributions of principal or interest or both, or as to which
distributions of principal or interest or both on any Class may be made upon the
occurrence of specified events, in accordance with a schedule or formula
(including "planned amortization Classes" and "targeted amortization Classes"),
or on the basis of collections from designated portions of the Mortgage Pool,
which Series may include one or more Classes of Certificates ("Accrual
Certificates") with respect to which certain accrued interest will not be
distributed but rather will be added to the principal balance thereof on each
Distribution Date for the period described in the related Prospectus Supplement;
or (v) other types of Classes of Certificates, as described in the related
Prospectus Supplement. Credit support for each Series of Certificates will be
provided by a Mortgage Pool Insurance Policy, Special Hazard Insurance Policy,
Certificate Insurance Policy, Bankruptcy Bond, Letter of Credit, Reserve Fund or
other credit enhancement as described under "DESCRIPTION OF CREDIT
ENHANCEMENTS," by the subordination of one or more Classes of Certificates as
described under "SUBORDINATION" or by any combination of the foregoing, as
specified in the Prospectus Supplement applicable for such Series.
 
                                       19
<PAGE>   77
 
     If so specified in the Prospectus Supplement relating to a Series of
Certificates, one or more elections may be made to treat the related Trust Fund,
or designated portion thereof, as a REMIC. If such an election is made with
respect to a Series of Certificates, one of the Classes of Certificates will be
designated as evidencing the sole Class of "residual interests" in each related
REMIC, as defined in the Code; alternatively, a separate Class of ownership
interests will evidence such residual interests. All other Classes of
Certificates in such Series will constitute "regular interests" in the related
REMIC, as defined in the Code and will be designated as such. As to each Series,
all Certificates offered hereby will be rated in one of the four highest rating
categories by one or more Rating Agencies. As to each Series of Certificates as
to which a REMIC election is to be made, the Depositor, or such other person
specified in the related Prospectus Supplement, will be obligated to take
certain specified actions required in order to comply with applicable laws and
regulations.
 
FORM OF CERTIFICATES
 
     If so specified in the related Prospectus Supplement, one or more Classes
of Certificates of a Series will be issued as physical certificates in fully
registered form only in the denominations specified in the related Prospectus
Supplement, and will be transferable and exchangeable at the corporate trust
office of the Certificate Registrar named in the related Prospectus Supplement.
(Section 5.02) No service charge will be made for any registration of exchange
or transfer of Certificates, but the Trustee may require payment of a sum
sufficient to cover any tax or other governmental charge. (Section 5.02) The
term "Certificateholder" or "Holder" as used herein refers to the entity whose
name appears on the records of the Certificate Registrar (or, if applicable, the
Transfer Agent) as the registered holder thereof.
 
     If so specified in the related Prospectus Supplement, one or more Classes
of Certificates of a Series ("Book-Entry Certificates") may be initially
represented by one or more certificates registered in the name of The Depository
Trust Company ("DTC") or other securities depository and be available only in
the form of book-entries. Any Book-Entry Certificates will initially be
registered in the name of Cede & Co., the nominee of DTC. Certificateholders may
also hold Certificates of a Series through CEDEL or Euroclear (in Europe), if
they are participants in such systems or indirectly through organizations that
are participants in such systems. CEDEL and Euroclear will hold omnibus
positions on behalf of their participants through customers' certificates
accounts in CEDEL's and Euroclear's names on the books of their respective
Depositaries which in turn will hold such positions in customers' certificates
accounts in the Depositaries' names on the books of DTC. Citibank, N.A.
("Citibank"), will act as depositary for CEDEL and Morgan Guaranty Trust Company
of New York ("Morgan") will act as depositary for Euroclear (in such capacities,
the "Depositaries").
 
     Transfers between DTC participants will occur in the ordinary way in
accordance with DTC rules. Transfers between CEDEL Participants and Euroclear
Participants will occur in the ordinary way in accordance with their applicable
rules and operating procedures.
 
     Cross-market transfers between persons holding directly or indirectly
through DTC, on the one hand, and directly or indirectly through CEDEL or
Euroclear Participants, on the other, will be effected in DTC in accordance with
DTC rules on behalf of the relevant European international clearing system by
its Depositary; however, such cross-market transactions will require delivery of
instructions to the relevant European international clearing system by the
counterparty in such system in accordance with its rules an procedures and
within its established deadlines (European time). The relevant European
international clearing system will, if the transaction meets its settlement
requirements, deliver instructions to its Depositary to take action to effect
final settlement on its behalf by delivering or receiving certificates in DTC,
and making or receiving payment in accordance with normal procedures for
same-day funds settlement applicable to DTC. CEDEL Participants and Euroclear
Participants may not deliver instructions directly to the Depositaries.
 
     Because of time-zone differences, credits of certificates received in CEDEL
or Euroclear as a result of a transaction with a DTC participant will be made
during subsequent certificates settlement processing and dated the business day
following the DTC settlement date. Such credits or any transactions in such
certificates settled during such processing will be reported to the relevant
Euroclear or CEDEL participant on such business day. Cash received in CEDEL or
Euroclear as a result of sales of certificates by or through a CEDEL Participant
or a Euroclear Participant to a DTC Participant will be received with value on
the DTC settlement
 
                                       20
<PAGE>   78
 
date but will be available in the relevant CEDEL or Euroclear cash account only
as of the business day following settlement in DTC. For information with respect
to tax documentation procedures relating to the Certificates, see "FEDERAL
INCOME TAX CONSEQUENCES -- Prohibited Transactions and Other Possible REMIC
Taxes -- Foreign Investors in REMIC Certificates" herein.
 
     DTC is a limited-purpose trust company organized under the laws of the
State of New York, 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 accepts securities for deposit
from its participating organizations ("Participants") and facilitates the
clearance and settlement of securities transactions between Participants in such
securities through electronic book-entry changes in accounts of Participants,
thereby eliminating the need for physical movement of certificates. Participants
include securities brokers and dealers, banks and trust companies and clearing
corporations and may include certain other organizations. Indirect access to the
DTC system is also available to others such as banks, brokers, dealers and trust
companies that clear through or maintain a custodial relationship with a
Participant, either directly or indirectly ("Indirect Participants").
 
     Beneficial owners ("Owners") that are not Participants but desire to
purchase, sell or otherwise transfer ownership of Book-Entry Certificates may do
so only through Participants (unless and until Definitive Certificates, as
defined below, are issued). In addition, Owners will receive all distributions
of principal of, and interest on, the Book-Entry Certificates from the Trustee
or any Trustee, as the case may be, through DTC and Participants. Owners will
not receive or be entitled to receive certificates representing their respective
interests in the Book-Entry Certificates, except under the limited circumstances
described below.
 
     Unless and until Definitive Certificates (as defined below) are issued, it
is anticipated that the only "holder" of Book-Entry Certificates of any Series
will be Cede & Co., as nominee of DTC. Owners will only be permitted to exercise
the rights of holders indirectly through Participants and DTC.
 
     While any Book-Entry Certificates of a Series are outstanding (except under
the circumstances described below), under the rules, regulations and procedures
creating and affecting DTC and its operations (the "Rules"), DTC is required to
make book-entry transfers among Participants on whose behalf it acts with
respect to the Book-Entry Certificates and is required to receive and transmit
distributions of principal of, and interest on, the Book-Entry Certificates.
Participants with whom Owners have accounts with respect to Book-Entry
Certificates are similarly required to make book-entry transfers and receive and
transmit such distributions on behalf of their respective Owners. Accordingly,
although Owners will not possess certificates, the Rules provide a mechanism by
which Owners will receive distributions and will be able to transfer their
interests.
 
     Unless and until Definitive Certificates are issued, Owners who are not
Participants may transfer ownership of Book-Entry Certificates of a Series only
through Participants by instructing such Participants to transfer Book-Entry
Certificates, by book-entry transfer, through DTC for the account of the
purchasers of such Book-Entry Certificates, which account is maintained with
their respective Participants. Under the Rules and in accordance with DTC's
normal procedures, transfers of ownership of Book-Entry Certificates will be
executed through DTC and the accounts of the respective Participants at DTC will
be debited and credited. Similarly, the respective Participants will make debits
or credits, as the case may be, on their records on behalf of the selling and
purchasing Owners.
 
     Book-Entry Certificates of a Series will be issued in registered form to
Owners, or their nominees, rather than to DTC (such Book-Entry Certificates
being referred to herein as "Definitive Certificates") only under the
circumstances provided in the related Pooling Agreement, which generally will
include, except if otherwise provided therein, if (i) the Depositor advises the
Trustee in writing that DTC is no longer willing or able to discharge properly
its responsibilities as nominee and depository with respect to the Book-Entry
Certificates of such Series and the Trustee and the Depositor are unable to
locate a qualified successor, (ii) the Depositor, at its sole option, elects to
terminate the book-entry system through DTC or (iii) after the occurrence of an
event of default under the Pooling Agreement, a majority of the aggregate
Percentage Interest of any Class of Certificates of such Series advises DTC in
writing that the continuation of a book-entry system through DTC
                                       21
<PAGE>   79
 
(or a successor thereto) to the exclusion of any physical certificates being
issued to Owners is no longer in the best interests of Owners of such Class of
Certificates. Upon issuance of Definitive Certificates of a Series to Owners,
such Book-Entry Certificates will be transferable directly (and not exclusively
on a book-entry basis) and registered holders will deal directly with the
Trustee with respect to transfers, notices and distributions.
 
     DTC has advised the Master Servicer and the Depositor that, unless and
until Definitive Certificates are issued, DTC will take any action permitted to
be taken by a holder only at the direction of one or more Participants to whose
DTC accounts the Certificates are credited. DTC has advised the Master Servicer
and the Depositor that DTC will take such action with respect to any Percentage
Interests of the Book-Entry Certificates of a Series only at the direction of
and on behalf of such Participants with respect to such Percentage Interests of
the Book-Entry Certificates. DTC may take actions, at the direction of the
related Participants, with respect to some Book-Entry Certificates which
conflict with actions taken with respect to other Book-Entry Certificates.
 
     Centrale de Livraison de Valeurs Mobilieres S.A. ("CEDEL") is incorporated
under the laws of Luxembourg as a professional depository. CEDEL holds
securities for its participating organizations ("CEDEL Participants") and
facilitates the clearance and settlement of securities transactions between
CEDEL Participants through electronic book-entry changes in accounts of CEDEL
Participants, thereby eliminating the need for physical movement of securities.
Transactions may be settled in CEDEL in any of 28 currencies, including United
States dollars. CEDEL provides to its Participants, among other things, services
for safekeeping, administration, clearance and settlement of internationally
traded securities and securities lending and borrowing. CEDEL interfaces with
domestic markets in several countries. As a professional depository, CEDEL is
subject to regulation by the Luxembourg Monetary Institute. CEDEL Participants
are recognized financial institutions around the world including underwriters,
securities brokers and dealers, banks, trust companies, clearing corporations
and certain other organizations and may include any underwriters, agents or
dealers with respect to a Series of Certificates offered hereby. Indirect access
to CEDEL is also available to others, such as banks, brokers, dealers and trust
companies that clear through or maintain a custodial relationship with a CEDEL
Participant, either directly or indirectly.
 
     The Euroclear System ("Euroclear") was created in 1968 to hold securities
for participants of the Euroclear System ("Euroclear Participants") and to clear
and settle transactions between Euroclear Participants through simultaneous
electronic book-entry delivery against payment, thereby eliminating the need for
physical movement of certificates and any risk from lack of simultaneous
transfers of securities and cash. Transactions may now be settled in any of 27
currencies, including United States dollars. The Euroclear System includes
various other services, including securities lending and borrowing, and
interfaces with domestic markets in several countries generally similar to the
arrangements for cross-market transfers with DTC described above. The Euroclear
System is operated by Morgan Guaranty Trust Company of New York, Brussels,
Belgium office (the "Euroclear Operator"), under contract with Euroclear
Clearance System S.C., a Belgian cooperative corporation (the "Euroclear
Cooperative"). All operations are conducted by the Euroclear Operator, and all
Euroclear securities clearance accounts and Euroclear cash accounts are accounts
with the Euroclear Operator, not the Euroclear Cooperative. The Euroclear
Cooperative establishes policy for Euroclear on behalf of Euroclear
Participants. Euroclear Participants include banks (including central banks),
securities brokers and dealers with respect to a Series of Certificates offered
hereby. Indirect access to Euroclear is also available to other firms that clear
through or maintain a custodial relationship with a Euroclear Participant,
either directly or indirectly.
 
     The Euroclear Operator is the Belgian branch of a New York banking
corporation that is a member bank of the Federal Reserve System. As such, it is
regulated and examined by the Board of Governors of the Federal Reserve System
and the New York State Banking Department, as well as the Belgian Banking
Commission.
 
     Certificates clearance accounts and cash accounts with the Euroclear
Operator are governed by the Terms and Conditions Governing Use of Euroclear and
the related Operating Procedures of Euroclear and applicable Belgian law
(collectively, the "Terms and Conditions"). The Terms and Conditions govern
transfers of securities and cash within Euroclear, withdrawals of securities and
cash from Euroclear and
 
                                       22
<PAGE>   80
 
receipts of payments with respect to securities in the Euroclear. All securities
in Euroclear are held on a fungible basis without attribution of specific
certificates to specific securities clearance accounts. The Euroclear Operator
acts under the Terms and Conditions only on behalf of Euroclear Participants,
and has no record of or relationship with persons holding through Euroclear
Participants.
 
     Distributions with respect to Certificates held through CEDEL or Euroclear
will be credited to the cash accounts of CEDEL Participants or Euroclear
Participants in accordance with the relevant systems' rules and procedures, to
the extent received by its Depositary. Such distributions will be subject to tax
reporting in accordance with relevant United States tax laws and regulations.
See "FEDERAL INCOME TAX CONSEQUENCES" herein. CEDEL or the Euroclear Operator,
as the case may be, will take any other action permitted to be taken by a
Certificateholder under the Pooling Agreement or the relevant Supplement on
behalf of a CEDEL Participant or Euroclear Participant only in accordance with
its relevant rules and procedures and subject to its Depositary's ability to
effect such actions on its behalf through DTC.
 
ASSIGNMENT OF MORTGAGE LOANS
 
     At the time of issuance of a Series of Certificates, the Depositor will
cause the Mortgage Loans being included in the related Trust Fund to be assigned
to the Trustee (or its nominee), together with all principal and interest
received on or with respect to such Mortgage Loans after the Cut-off Date, other
than principal and interest due on or before the Cut-off Date. If specified in
the related Prospectus Supplement, the Depositor or a Seller may retain the
Retained Yield, if any, for itself or transfer the same to others. (Sections
2.01 and 3.10) The Trustee will, concurrently with such assignment, deliver a
Series of Certificates to the Depositor in exchange for the Mortgage Loans.
(Section 2.05) Each Mortgage Loan will be identified in a schedule appearing as
an exhibit to the related Pooling Agreement. Such schedule will include, among
other things, information as to the principal balance of each Mortgage Loans as
of the Cut-off Date, as well as information respecting the Mortgage Rate, the
currently scheduled monthly payment of principal and interest, the maturity of
the Mortgage Note and the Loan-to-Value Ratio at origination (without regard to
any secondary financing). (Article I)
 
     In addition, the Depositor will, as to each Mortgage Loan, deliver to the
Trustee (or to the custodian described below) the Mortgage Note (and any
modification or amendment thereto) endorsed without recourse either in blank or
to the order of the Trustee (or its nominee), the Mortgage with evidence of
recording indicated thereon or, in the case of a Cooperative Loan, on the
related financing statement (except for any Mortgage not returned from the
public recording office) an assignment in recordable form of the Mortgage (or,
with respect to a Cooperative Loan, an assignment of the related proprietary
lease or occupancy agreement) and, if applicable, any riders or modifications to
such Mortgage Note and Mortgage, together with certain other documents at such
times as set forth in the related Pooling Agreement. Such assignments may be
blanket assignments covering Mortgages secured by Mortgaged Properties located
in the same county, if permitted by law. In the event that, with respect to any
Mortgage Loan, the Depositor cannot deliver the Mortgage or any assignment with
evidence of recording thereon concurrently with the execution and delivery of
the related Pooling Agreement because of a delay caused by the public recording
office, the Depositor will deliver or cause to be delivered to the Trustee or
the custodian a true and correct photocopy of such Mortgage or assignment. The
Depositor will deliver or cause to be delivered to the Trustee or the custodian
such Mortgage or assignment with evidence of recording indicated thereon after
receipt thereof from the public recording office or from the related Seller.
Assignments of the Mortgage Loans to the Trustee (or its nominee) will be
recorded in the appropriate public recording office, except in states where, in
the opinion of counsel acceptable to the Trustee, such recording is not required
to protect the Trustee's interests in the Mortgage Loan against the claim of any
subsequent transferee or any successor to or creditor of the Depositor or the
originator of such Mortgage Loan. (Section 2.01)
 
     The Trustee (or the custodian hereinafter referred to) will hold such
documents in trust for the benefit of the Certificateholders, and generally will
review such documents within 45 days after receipt thereof in the case of
documents delivered concurrently with the execution and delivery of the related
Pooling Agreement, and within the time period specified in the related Pooling
Agreement in the case of all other documents delivered. If any such document is
found to be missing or defective in any material respect, the Trustee (or
                                       23
<PAGE>   81
 
such custodian) shall promptly so notify the Master Servicer and the Depositor,
the former of which shall notify the related Seller. If the Seller does not cure
the omission or defect within 60 days after notice is given to the Master
Servicer, the Seller will be obligated to purchase within 90 days of such notice
the related Mortgage Loan from the Trustee at its Purchase Price (or, if so
specified in the related Prospectus Supplement, will be permitted to substitute
for such Mortgage Loan under the conditions specified herein and in the related
Prospectus Supplement). The Master Servicer will be obligated to enforce this
obligation of the Seller to the extent described above under "MORTGAGE LOAN
PROGRAM -- Representations and Warranties by Sellers" but subject to the
provisions described below under "-- Realization Upon Defaulted Mortgage Loans."
There can be no assurance that the applicable Seller will fulfill its obligation
to purchase any Mortgage Loan as described above. Neither the Master Servicer
nor the Depositor will be obligated to purchase or substitute for such Mortgage
Loan if the Seller defaults on its obligation to do so. This obligation to
purchase or substitute for any such Mortgage Loan constitutes the sole remedy
available to the Certificateholders or the Trustee for omission of, or a
material defect in, a constituent document. Any Mortgage Loan not so purchased
or substituted for shall remain in the related Trust Fund.
 
     The Trustee will be authorized at any time to appoint one or more
custodians pursuant to a custodial agreement to hold title to the Mortgage
Loans, to maintain possession of and, if applicable, to review the documents
relating to the Mortgage Loans as the agent of the Trustee. The identity of any
such custodian to be appointed on the date of initial issuance of the
Certificates will be set forth in the related Prospectus Supplement. Except as
specified in the following paragraph, such custodian may not be an affiliate of
the Depositor or the Master Servicer. (Section 8.11)
 
     If specified in the Prospectus Supplement related to a Series of
Certificates, during the period that any Class of Certificates of that Series
are outstanding and so long as the ratings of the long-term senior unsecured
debt of BankAmerica Corporation satisfy the rating conditions set forth in the
Prospectus Supplement, the Master Servicer identified in the Prospectus
Supplement will hold the original documentation relating to each Mortgage Loan,
including the related Mortgage Note and Mortgage (such original documentation,
the "Mortgage File"), as custodian and agent for the Trustee. If BankAmerica's
long-term senior unsecured debt rating does not satisfy the above-described
conditions, the Mortgage Files will be delivered to the Trustee or an
independent custodian on behalf of the Trustee within 90 days of the date such
conditions are not satisfied. Under the related Pooling Agreement, the Trustee
will be appointed attorney-in-fact for the Depositor with power to prepare,
execute and record assignments of the Mortgages in the event that the Depositor
fails to do so on a timely basis. See "RISK FACTORS -- Creditors' Rights and
Bankruptcy Considerations" in the applicable Prospectus Supplement for a
description of the risks to Certificateholders with respect to any such Series.
 
     Pursuant to each Pooling Agreement, the Master Servicer, either directly or
through Subservicers, will service and administer the Mortgage Loans assigned to
the Trustee as more fully set forth below.
 
RETAINED YIELD
 
     For certain Series of Certificates, the Depositor 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 Pass-Through Rate from the Mortgage
Rate. Any such Retained Yield and any earnings from reinvestments thereof will
not be part of the Trust Fund.
 
PAYMENTS ON MORTGAGE LOANS; DEPOSITS TO CERTIFICATE ACCOUNT
 
     The Master Servicer will deposit or will cause to be deposited into the
Custodial Account on a daily basis certain payments and collections received by
it subsequent to the Cut-off Date (other than payments due on or before the
Cut-off Date), as specifically set forth in the related Pooling Agreement, which
generally will include the following except as otherwise provided therein:
 
          (i) all payments on account of principal, including principal payments
     received in advance of the date on which the related monthly payment is due
     (the "Due Date") ("Principal Prepayments"), on the Mortgage Loans
     comprising a Trust Fund;
                                       24
<PAGE>   82
 
          (ii) all payments on account of interest on the Mortgage Loans
     comprising such Trust Fund, net of the portion of each payment thereof
     retained by the Master Servicer or any Subservicer, if any, as its
     servicing or other compensation;
 
          (iii) all amounts (net of unreimbursed liquidation expenses and
     insured expenses incurred, and unreimbursed Servicing Advances made, by any
     related Subservicer) received and retained in connection with the
     liquidation of any defaulted Mortgage Loan, by foreclosure or otherwise
     ("Liquidation Proceeds"), including all proceeds of any Special Hazard
     Insurance Policy, Bankruptcy Bond, Mortgage Pool Insurance Policy,
     Certificate Insurance Policy, Primary Mortgage Insurance Policy and any
     title, hazard or other insurance policy covering any Mortgage Loan in such
     Mortgage Pool (together with any payments under any Letter of Credit,
     "Insurance Proceeds") or proceeds from any alternative arrangements
     established in lieu of any such insurance and described in the applicable
     Prospectus Supplement, other than proceeds to be applied to the restoration
     of the related property or released to the Mortgagor in accordance with the
     Master Servicer's normal servicing procedures;
 
          (iv) any Buydown Funds (and, if applicable, investment earnings
     thereon) required to be paid to Certificateholders, as described below;
 
          (v) all proceeds of any Mortgage Loan in such Trust Fund purchased
     (or, in the case of a substitution, certain amounts representing a
     principal adjustment) by the Depositor, any Seller or any other person
     pursuant to the terms of the Pooling Agreement. See "MORTGAGE LOAN
     PROGRAM -- Representations and Warranties by Sellers" and "-- Assignment of
     Mortgage Loans" above;
 
          (vi) any amount required to be deposited by the Master Servicer in
     connection with losses realized on investments of funds held in the
     Custodial Account, as described below; and
 
          (vii) any amounts required to be transferred from the Certificate
     Account to the Custodial Account.
 
     In addition to the Custodial Account, the Master Servicer will establish
and maintain, in the name of the Trustee for the benefit of the holders of each
Series of Certificates, an account for the disbursement of payments on the
Mortgage Loans evidenced by each Series of Certificates (the "Certificate
Account"). Both the Custodial Account and the Certificate Account must be either
(i) maintained with a depository institution whose debt obligations at the time
of any deposit therein are rated by the Rating Agency or Agencies that rated one
or more Classes of Certificates of the related Series not less than a specified
level comparable to the rating category of such Certificates, (ii) an account or
accounts the deposits in which are fully insured to the limits established by
the FDIC, provided that any deposits not so insured shall be otherwise
maintained such that, as evidenced by an opinion of counsel, the
Certificateholders have a claim with respect to the funds in such accounts or a
perfected first priority security interest in any collateral securing such funds
that is superior to the claims of any other depositors or creditors of the
depository institution with which such accounts are maintained, (iii) in the
case of the Certificate Account, a trust account or accounts maintained at the
Trustee, or (iv) such other account or accounts acceptable to the Rating Agency
or Agencies that rated one or more Classes of Certificates of such Series (an
"Eligible Account"). The collateral that is eligible to secure amounts in an
Eligible Account is limited to certain permitted investments, which are
generally limited to United States government securities and other investments
that are rated, at the time of acquisition, in one of the categories permitted
by the related Pooling Agreement ("Permitted Investments"). (Article I and
Section 3.07) A Certificate Account may be maintained as an interest-bearing or
a non-interest-bearing account, or funds therein may be invested in Permitted
Investments as described below. The Custodial Account may contain funds relating
to more than one Series of Mortgage Pass-Through Certificates as well as
payments received on other mortgage loans serviced or master serviced by the
Master Servicer that have been deposited into the Custodial Account.
 
     Not later than the business day preceding each Distribution Date (the
"Certificate Account Deposit Date"), the Master Servicer will withdraw from the
Custodial Account and deposit into the applicable Certificate Account, in
immediately available funds, the amount to be distributed therefrom to
Certificateholders on such Distribution Date. The Master Servicer or the Trustee
will also deposit or cause to be
 
                                       25
<PAGE>   83
 
deposited into the Certificate Account the amount of any advances made by the
Master Servicer as described herein under "Advances," any payments under any
Letter of Credit, any amounts required to be transferred to the Certificate
Account from a Reserve Fund, as described under "Credit Enhancements" below, any
amounts required to be paid by the Master Servicer out of its own funds due to
the operation of a deductible clause in any blanket policy maintained by the
Master Servicer to cover hazard losses on the Mortgage Loans as described under
"PRIMARY MORTGAGE INSURANCE, HAZARD INSURANCE; CLAIMS THEREUNDER" below and any
other amounts as specifically set forth in the related Pooling Agreement.
 
     The portion of any payment received by the Master Servicer in respect of a
Mortgage Loan that is allocable to Retained Yield will generally be deposited
into the Custodial Account, but will not be deposited in the Certificate Account
for the related Series of Certificates and will be distributed as provided in
the related Pooling Agreement.
 
     Funds on deposit in the Custodial Account may be invested in Permitted
Investments maturing in general not later than the business day preceding the
next Distribution Date and funds on deposit in the related Certificate Account
may be invested in Permitted Investments maturing, in general, no later than the
Distribution Date. All income and gain realized from any such investment will be
for the account of the Master Servicer. The amount of any loss incurred in
connection with any such investment must be deposited in the Custodial Account
or in the Certificate Account, as the case may be, by the Master Servicer out of
its own funds upon realization of such loss. (Sections 3.07 and 4.01).
 
     With respect to each Buydown Mortgage Loan, the Master Servicer will
deposit the related Buydown Funds provided to it in a Buydown Account which will
comply with the requirements set forth herein with respect to a Custodial
Account. The terms of Buydown Mortgage Loans will provide for the contribution
of Buydown Funds in an amount equal to or exceeding either (i) the total
payments to be made from such funds pursuant to the related buydown plan or (ii)
if such Buydown Funds are to be deposited on a discounted basis, that amount of
Buydown Funds which, together with investment earnings thereon at a rate that
will support the scheduled level of payments due under the Buydown Mortgage
Loan. Neither the Master Servicer nor the Depositor will be obligated to add to
any such discounted Buydown Funds any of its own funds should investment
earnings prove insufficient to maintain the scheduled level of payments. To the
extent that any such insufficiency is not recoverable from the Mortgagor or, in
an appropriate case, from the Seller, distributions to Certificateholders may be
affected. With respect to each Buydown Mortgage Loan, the Master Servicer will
withdraw from the Buydown Account and remit to the Custodial Account on or
before the date specified in the Subservicing Agreement described above the
amount, if any, of the Buydown Funds (and, if applicable, investment earnings
thereon) for each Buydown Mortgage Loan that, when added to the amount due from
the Mortgagor on such Buydown Mortgage Loan, equals the full monthly payment
which would be due on the Buydown Mortgage Loan if it were not subject to the
buydown plan. The Buydown Funds will in no event be a part of the related Trust
Fund.
 
     If the Mortgagor on a Buydown Mortgage Loan prepays such Mortgage Loan in
its entirety during the Buydown Period, the Master Servicer will withdraw from
the Buydown Account and remit to the Mortgagor or such other designated party in
accordance with the related buydown plan any Buydown Funds remaining in the
Buydown Account. Generally, if a prepayment by a Mortgagor during the Buydown
Period together with Buydown Funds will result in full prepayment of a Buydown
Mortgage Loan, the Master Servicer will be required to withdraw from the Buydown
Account and deposit in the Custodial Account the Buydown Funds and investment
earnings thereon, if any, which together with such prepayment will result in a
prepayment in full. Any Buydown Funds so remitted to the Master Servicer in
connection with a prepayment described in the preceding sentence will be deemed
to reduce the amount that would be required to be paid by the Mortgagor to repay
fully the related Mortgage Loan if the Mortgage Loan were not subject to the
buydown plan. Any investment earnings remaining in the Buydown Account after
prepayment or after termination of the Buydown Period will be remitted to the
related Mortgagor or such other designated party pursuant to the agreement
relating to each Buydown Mortgage Loan (the "Buydown Agreement"). If the
Mortgagor defaults during the Buydown Period with respect to a Buydown Mortgage
Loan and the property securing such Buydown Mortgage Loan is sold in liquidation
(either by the Master Servicer, the Primary Mortgage Insurer, the insurer under
the Mortgage Pool Insurance Policy (the "Pool Insurer") or any other insurer),
the Master
                                       26
<PAGE>   84
 
Servicer will withdraw from the Buydown Account the Buydown Funds and all
investment earnings thereon, if any, and deposit the same in the Custodial
Account or pay the same to the Primary Mortgage Insurer or the Pool Insurer if
the Mortgaged Property is transferred to such insurer and such insurer pays all
of the loss incurred in respect of such default.
 
WITHDRAWALS FROM THE CUSTODIAL ACCOUNT
 
     The Master Servicer may, from time to time, make withdrawals from the
Custodial Account for certain purposes, as specifically set forth in the related
Pooling Agreement, which generally will include the following except as
otherwise provided therein:
 
          (i) to make deposits to the Certificate Account in the amounts and in
     the manner provided in the Pooling Agreement and described in "Payments on
     Mortgage Loans; Deposits to Certificate Account";
 
          (ii) to reimburse itself or any Subservicer for Advances, or for
     amounts advanced in respect of taxes, insurance premiums or similar
     expenses ("Servicing Advances") as to any Mortgaged Property, out of late
     payments or collections on the related Mortgage Loan with respect to which
     such Advances or Servicing Advances were made;
 
          (iii) to pay to itself or any Subservicer unpaid Servicing Fees and
     Subservicing Fees, out of payments or collections of interest on each
     Mortgage Loan;
 
          (iv) to pay to itself as additional servicing compensation any
     investment income on funds deposited in the Custodial Account, and, if so
     provided in the Pooling Agreement, any profits realized upon disposition of
     a Mortgaged Property acquired by deed in lieu of foreclosure or otherwise
     allowed under the Pooling Agreement;
 
          (v) to pay to the Seller all amounts received with respect to each
     Mortgage Loan repurchased pursuant to the terms of the Pooling Agreement
     and not required to be distributed as of the date on which the related
     Purchase Price is determined;
 
          (vi) to pay the Depositor or the Seller, as applicable, or its
     assignee all amounts constituting Retained Yield, if any, out of
     collections or payments which represent interest on each Mortgage Loan
     (including any Mortgage Loan as to which title to the underlying Mortgaged
     Property was acquired);
 
          (vii) to reimburse itself or any Subservicer for any Advance or
     Servicing Advance previously made which the Master Servicer has determined
     to not be ultimately recoverable from Liquidation Proceeds, Insurance
     Proceeds or otherwise (a "Nonrecoverable Advance"), subject, in the case of
     a Senior/Subordinate Series, to certain limitations set forth in the
     Pooling Agreement as described in the related Prospectus Supplement;
 
          (viii) to reimburse itself or the Depositor for certain other expenses
     incurred for which it or the Depositor is entitled to reimbursement or
     against which it or the Depositor is indemnified pursuant to the Pooling
     Agreement; and
 
          (ix) to clear the Custodial Account of amounts relating to the
     corresponding Mortgage Loans in connection with the termination of the
     Trust Fund pursuant to the Pooling Agreement, as described in "THE POOLING
     AGREEMENT -- Termination; Retirement of Certificates." (Section 3.10)
 
DISTRIBUTIONS
 
     Beginning on the Distribution Date in the month next succeeding the month
in which the Cut-off Date occurs (or such other date as may be set forth in the
related Prospectus Supplement) for a Series of Certificates, distributions of
principal and interest (or, where applicable, of principal only or interest
only) on each Class of Certificates entitled thereto will be made either by the
Trustee, the Master Servicer acting on behalf of the Trustee or a paying agent
appointed by the Trustee (the "Paying Agent"), to the persons who are registered
as the Holders of such Certificates at the close of business on the last
business day of the preceding month (the "Record Date") in proportion to their
respective Percentage Interests. If so specified in the
 
                                       27
<PAGE>   85
 
related Prospectus Supplement, interest which accrues and is not payable on a
Class of Certificates will be added to the principal balance of each Certificate
of such Class in proportion to its Percentage Interest. The undivided percentage
interest (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 balance of all the Certificates of such
Class. Distributions will be made in immediately available funds (by wire
transfer or otherwise) to the account of a Certificateholder at a bank or other
entity having appropriate facilities therefor, if such Certificateholder has so
notified the Trustee, the Master Servicer or the Paying Agent, as the case may
be, and the applicable Pooling Agreement provides for such form of payment, or
by check mailed to the address of the person entitled thereto as it appears on
the Certificate Register; provided, however, that the final distribution in
retirement of the Certificates will be made only upon presentation and surrender
of the Certificates at the office or agency of the Trustee specified in the
notice to Certificateholders of such final distribution. (Article I and Sections
4.01 and 9.01)
 
PRINCIPAL AND INTEREST ON THE CERTIFICATES
 
     The method of determining, and the amount of, distributions of principal
and interest (or, where applicable, of principal only or interest only) on a
particular Series of Certificates will be described in the related Prospectus
Supplement. Distributions of interest on each Class of Certificates will be made
prior to distributions of principal thereon. Each Class of Certificates (other
than certain Classes of Strip Certificates) may have a different specified
interest rate or rates (each, a "Pass-Through Rate") which may be a fixed,
variable or adjustable Pass-Through Rate, or any combination of two or more such
Pass-Through Rates. The related Prospectus Supplement will specify the
Pass-Through Rate or Rates for each Class, or the initial Pass-Through Rate or
Rates and the method for determining the Pass-Through Rate or Rates. If so
specified in the related Prospectus Supplement, interest on any Class of
Certificates for any Distribution Date may be limited to the extent of available
funds for such Distribution Date. Interest on the Certificates will be
calculated on the basis of a 360-day year consisting of twelve 30-day months.
 
     On each Distribution Date for a Series of Certificates, the Trustee or the
Master Servicer on behalf of the Trustee will distribute or cause the Paying
Agent to distribute, as the case may be, to each holder of record on the Record
Date of a Class of Certificates, an amount equal to the Percentage Interest
represented by the Certificate held by such holder multiplied by such Class's
Distribution Amount. The 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,
plus, if such Class is entitled to payments of interest on such Distribution
Date, one month's interest at the applicable Pass-Through Rate on the principal
balance (a "Certificate Principal Balance") or notional balance of such Class
specified in the applicable Prospectus Supplement, less certain interest
shortfalls, as specified in the Prospectus Supplement, which generally will
include (i) any Deferred Interest added to the principal balance of the Mortgage
Loans and/or the outstanding balance of one or more Classes of Certificates on
the related Due Date, (ii) any other interest shortfalls (including, without
limitation, shortfalls resulting from application of the Relief Act or similar
legislation or regulations as in effect from time to time) allocable to
Certificateholders which are not covered by advances or the applicable credit
enhancement and (iii) shortfalls (a "Prepayment Interest Shortfall") in
collections of interest on Mortgage Loans resulting from Mortgagor prepayments
during the month preceding the month of distribution to the extent such
Prepayment Interest Shortfall is not paid by the Master Servicer as Compensating
Interest (as defined in the related Prospectus Supplement), in each case in such
amount that is allocated to such Class on the basis set forth in the 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 (including distributions
among multiple Classes of Senior Certificates or Subordinate Certificates) of
each such Class shall be as set forth 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.
 
                                       28
<PAGE>   86
 
     Except as otherwise provided in the related Pooling Agreement, on or prior
to the 15th day (or if such day is not a business day, the next succeeding
business day) of the month of distribution (the "Determination Date"), the
Master Servicer will determine the amounts of principal and interest which will
be passed through to Certificateholders on the immediately succeeding
Distribution Date. Prior to the close of business on the business day next
succeeding each Determination Date, the Master Servicer will furnish a statement
to the Trustee (the information in such statement to be made available to
Certificateholders by the Master Servicer on request) setting forth, among other
things, the amount to be distributed on the next succeeding Distribution Date.
 
ADVANCES
 
     The Master Servicer will agree to advance (either out of its own funds,
funds advanced to it by Subservicers or funds being held in the Custodial
Account for future distribution to the holders of such Certificates), for the
benefit of the holders of the Certificates of the related Series, on or before
each Distribution Date, an amount equal to the aggregate of all scheduled
payments of principal (other than any Balloon Amount in the case of a Balloon
Loan) and interest at the applicable Pass-Through Rate or Net Mortgage Rate, as
the case may be (an "Advance"), which were delinquent as of the close of
business on the business day preceding the related Determination Date on the
Mortgage Loans in the related Mortgage Pool, but only to the extent that such
advances would, in the judgment of the Master Servicer, be recoverable out of
late payments by the Mortgagors, Liquidation Proceeds, Insurance Proceeds or
otherwise. (Article I and Sections 3.07 and 4.04)
 
     The Master Servicer will make such advances in order to maintain a regular
flow of scheduled interest and principal payments to holders of the relevant
Classes of Certificates; such advances do not represent an obligation of the
Master Servicer to guarantee or insure against losses. If advances have been
made by the Master Servicer from cash being held for future distribution to
Certificateholders, the Master Servicer will replace such funds on or before any
future Distribution Date to the extent that funds in the applicable Certificate
Account on such Distribution Date would be less than payments required to be
made to Certificateholders on such date. Any Master Servicer funds advanced as
described above will be reimbursable to the Master Servicer out of recoveries on
the related Mortgage Loans for which such amounts were advanced (e.g., late
payments made by the related Mortgagor, any related Liquidation Proceeds,
proceeds of any applicable form of credit enhancement, or proceeds of any
Mortgage Loan purchased by a Seller under the circumstances described above).
Such advances by the Master Servicer will also be reimbursable to the Master
Servicer (or Subservicer) from cash otherwise distributable to
Certificateholders to the extent that the Master Servicer shall determine that
any such advances previously made are not ultimately recoverable from proceeds
of the applicable Mortgage Loan. The Master Servicer will also be obligated to
make advances for the purpose of protecting any Mortgaged Property or the Trust
Fund's security interest therein, including certain taxes and insurance premiums
not paid by Mortgagors on a timely basis, but only to the extent that such
advances would, in the judgment of the Master Servicer, be recoverable out of
Liquidation Proceeds or other proceeds of the related Mortgage Loan. Funds so
advanced will also be reimbursable to the Master Servicer from cash otherwise
distributable to Certificateholders to the extent that the Master Servicer shall
determine that any such advances previously made are not ultimately recoverable
from proceeds of the applicable Mortgage Loan. Notwithstanding the foregoing, if
the Master Servicer exercises its option, if any, to purchase the assets of a
Trust Fund as described under "THE POOLING AGREEMENT -- Termination; Retirement
of Certificates" below, the Master Servicer will be deemed to have been
reimbursed for all related advances previously made by it and not theretofore
reimbursed to it. The Master Servicer's obligation to make advances may be
supported as described in the related Pooling Agreement. In the event that the
short-term or long-term obligations of the provider of such support are
downgraded by a Rating Agency rating the related Certificates or if any
collateral supporting such obligation is not performing or is removed pursuant
to the terms of any agreement described in the related Prospectus Supplement,
the Certificates may also be downgraded. (Article I and Sections 3.08, 3.10 and
4.04)
 
                                       29
<PAGE>   87
 
REPORTS TO CERTIFICATEHOLDERS
 
     With each distribution to Certificateholders of a particular Class, the
Trustee will forward or cause to be forwarded to each holder of record of such
Class of Certificates a statement or statements with respect to the related
Trust Fund setting forth the information specifically described in the related
Pooling Agreement, which generally will include the following as applicable
except as otherwise provided therein:
 
          (i) the amount, if any, of such distribution allocable to principal;
 
          (ii) the amount, if any, of such distribution allocable to interest,
     and, with respect to a Senior/Subordinate Series of Certificates, the
     amount, if any, of any shortfall in the amount of interest and principal
     distributed;
 
          (iii) the aggregate unpaid principal balance of the Mortgage Loans
     after giving effect to the distribution of principal on such Distribution
     Date;
 
          (iv) with respect to a Series consisting of two or more Classes the
     outstanding principal balance or notional amount of each Class after giving
     effect to the distribution of principal on such Distribution Date;
 
          (v) the number and aggregate principal balances of Mortgage Loans in
     the related Mortgage Pool that are delinquent (a) one month, (b) two months
     and (c) three months, and that are in foreclosure;
 
          (vi) the book value of any real estate acquired by such Trust Fund
     through foreclosure or grant of a deed in lieu of foreclosure;
 
          (vii) the balance of the Reserve Fund, if any, at the close of
     business on such Distribution Date;
 
          (viii) the Senior Percentages and Senior Accelerated Distribution
     Percentage, if applicable, after giving effect to the distributions on such
     Distribution Date;
 
          (ix) the amount of coverage under any Letter of Credit, Mortgage Pool
     Insurance Policy, Certificate Insurance Policy or other form of credit
     enhancement covering default risk as of the close of business on the
     applicable Determination Date and a description of any credit enhancement
     substituted therefor;
 
          (x) the Special Hazard Amount, Fraud Loss Amount and Bankruptcy Amount
     as of the close of business on the applicable Distribution Date and a
     description of any change in the calculation of such amounts; and
 
          (xi) in the case of Certificates benefiting from alternative credit
     enhancement arrangements described in a Prospectus Supplement, the amount
     of coverage under such alternative arrangements as of the close of business
     on the applicable Determination Date.
 
     Each amount set forth pursuant to clause (i) and (ii) above will be
expressed as a dollar amount per Single Certificate. As to a particular Class of
Certificates, a "Single Certificate" generally will evidence a Percentage
Interest obtained by dividing $1,000 by the initial principal balance or
notional balance of all the Certificates of such Class, except as otherwise
provided in the related Pooling Agreement. In addition to the information
described above, reports to Certificateholders will contain such other
information as is set forth in the applicable Pooling Agreement, which may
include, without limitation, information as to Advances, reimbursements to
Subservicers and the Master Servicer and losses borne by the related Trust Fund.
In addition, within a reasonable period of time after the end of each calendar
year, the Master Servicer will furnish a report to each holder of record of a
Class of Certificates at any time during such calendar year which, among other
things, will include information as to the aggregate of amounts reported
pursuant to clauses (i) and (ii) above for such calendar year or, in the event
such person was a holder of record of a Class of Certificates during a portion
of such calendar year, for the applicable portion of such a year. (Section 4.02
or 4.03)
 
                                       30
<PAGE>   88
 
COLLECTION AND OTHER SERVICING PROCEDURES
 
     The Master Servicer, directly or through Subservicers, as the case may be,
will make reasonable efforts to collect all payments required under the Mortgage
Loans and will, consistent with the Pooling Agreement and any Letter of Credit,
Mortgage Pool Insurance Policy, Certificate Insurance Policy, Primary Mortgage
Insurance Policy, Bankruptcy Bond or applicable alternative credit enhancement
arrangements, follow such collection procedures as it would employ in its good
faith business judgment and which are normal and usual in its general mortgage
servicing activities. Consistent with the foregoing, the Master Servicer may in
its discretion (i) waive payments of interest or principal, (ii) accept a deed
in lieu of foreclosure, (iii) waive any late payment charge or any prepayment
charge or penalty interest in connection with the prepayment of a Mortgage Loan
or (iv) extend the Due Date for payments due on a Mortgage Loan, provided,
however, that the Master Servicer shall first determine that any such action
will not impair the coverage of any related insurance policy or materially
adversely affect the lien of the related Mortgage.
 
     In any case in which property subject to a Mortgage Loan (other than an ARM
Loan described below) is being conveyed by the Mortgagor, the Master Servicer,
directly or through a Subservicer, shall in general be obligated, to the extent
it has knowledge of such conveyance, to exercise its rights to accelerate the
maturity of such Mortgage Loan under any due-on-sale clause applicable thereto,
but only if the exercise of such rights is permitted by applicable law and only
to the extent it would not adversely affect or jeopardize coverage under any
Primary Mortgage Insurance Policy or applicable credit enhancement arrangements.
The original Mortgagor may be released from liability on a Mortgage Loan if the
Master Servicer or Subservicer shall have determined in good faith that such
release will not adversely affect the collectability of the Mortgage Loan. An
ARM Loan may be assumed if such ARM Loan is by its terms assumable and if, in
the reasonable judgment of the Master Servicer or the Subservicer, the proposed
transferee of the related Mortgaged Property establishes its ability to repay
the loan and the security for such ARM Loan would not be impaired by the
assumption. If a Mortgagor transfers the Mortgaged Property subject to an ARM
Loan without consent, such ARM Loan may be declared due and payable. Any fee
collected by the Master Servicer or Subservicer for entering into an assumption
or substitution of liability agreement will be retained by the Master Servicer
or Subservicer as additional servicing compensation. See "CERTAIN LEGAL ASPECTS
OF MORTGAGE LOANS AND RELATED MATTERS -- Enforceability of Certain Provisions"
herein. In connection with any such assumption, the Mortgage Rate borne by the
related Mortgage Note may not be altered. Mortgagors may, from time to time,
request partial releases of the Mortgaged Properties, easements, consents to
alteration or demolition and other similar matters. The Master Servicer or the
related Subservicer may approve such a request if it has determined, exercising
its good faith business judgment in the same manner as it would if it were the
owner of the related Mortgage Loan, that such approval will not adversely affect
the security for, and the timely and full collectability of, the related
Mortgage Loan. Any fee collected by the Master Servicer or the Subservicer for
processing such request will be retained by the Master Servicer or Subservicer
as additional servicing compensation. (Section 3.13)
 
     The Master Servicer is required to maintain a fidelity bond and errors and
omissions policy with respect to its officers and employees and other persons
acting on behalf of the Master Servicer in connection with its activities under
the Pooling Agreement. (Section 3.12)
 
REALIZATION UPON DEFAULTED MORTGAGE LOANS
 
     In the event that title to any Mortgaged Property is acquired in
foreclosure or by deed in lieu of foreclosure, the deed or certificate of sale
will be issued to the Trustee or to its nominee on behalf of Certificateholders
of the related Series. Notwithstanding any such acquisition of title and
cancellation of the related Mortgage Loan, such Mortgage Loan (an "REO Mortgage
Loan") will be considered for most purposes to be an outstanding Mortgage Loan
held in the Trust Fund until such time as the Mortgaged Property is sold and all
recoverable Liquidation Proceeds and Insurance Proceeds have been received with
respect to such defaulted Mortgage Loan (a "Liquidated Mortgage Loan"). For
purposes of calculations of amounts distributable to Certificateholders in
respect of an REO Mortgage Loan, the amortization schedule in effect at the time
of any such acquisition of title (before any adjustment thereto by reason of any
bankruptcy or any similar proceeding or any moratorium or similar waiver or
grace period) will be deemed to have
                                       31
<PAGE>   89
 
continued in effect (and, in the case of an ARM Loan, such amortization schedule
will be deemed to have adjusted in accordance with any interest rate changes
occurring on any adjustment date therefor) so long as such REO Mortgage Loan is
considered to remain in the Trust Fund. Any Mortgaged Property so acquired by
the Trust Fund must be disposed of, if a REMIC election has been made, in
accordance with applicable federal income tax regulations and consistent with
the status of the Trust Fund as a REMIC. Any income (net of expenses and other
than gains described below) received by the Master Servicer or a Subservicer on
such Mortgaged Property prior to its disposition will be deposited in the
Custodial Account upon such disposition and will be available at such time to
the extent provided in the related Pooling Agreement, for making payments to
Certificateholders. (Section 3.14)
 
     With respect to a Mortgage Loan in default, the Master Servicer may pursue
foreclosure (or similar remedies) concurrently with pursuing any remedy for a
breach of a representation and warranty. However, the Master Servicer is not
required to continue to pursue both such remedies if it determines that one such
remedy is more likely to result in a greater recovery. Upon the first to occur
of final liquidation (by foreclosure or otherwise) and a repurchase or
substitution pursuant to a breach of a representation and warranty, such
Mortgage Loan will be removed from the related Trust Fund if it has not been
removed previously. The Master Servicer may elect to treat a defaulted Mortgage
Loan as having been finally liquidated if substantially all amounts expected to
be received in connection therewith have been received. Any additional
liquidation expenses relating to such Mortgage Loan thereafter incurred will be
reimbursable to the Master Servicer (or any Subservicer) from any amounts
otherwise distributable to holders of Certificates of the related Series, or may
be offset by any subsequent recovery related to such Mortgage Loan.
Alternatively, for purposes of determining the amount of related Liquidation
Proceeds to be distributed to Certificateholders, the amount of any Realized
Loss (as defined under "SUBORDINATION" herein) or the amount required to be
drawn under any applicable form of credit support, the Master Servicer may take
into account minimal amounts of additional receipts expected to be received, as
well as estimated additional liquidation expenses expected to be incurred in
connection with such defaulted Mortgage Loan. With respect to certain Series of
Certificates, if so provided in the related Prospectus Supplement, the
applicable form of credit enhancement may provide, to the extent of coverage
thereunder, that a defaulted Mortgage Loan or REO Mortgage Loan will be removed
from the Trust Fund prior to the final liquidation thereof. In the case of a
Senior/Subordinate Series, if a final liquidation of a Mortgage Loan resulted in
a Realized Loss and within two years thereafter the Master Servicer receives a
subsequent recovery specifically related to such Mortgage Loan (in connection
with a related breach of a representation or warranty or otherwise), such
subsequent recovery shall be distributed to current Certificateholders of the
Class or Classes to which such Realized Loss was allocated (with the amounts to
be distributed allocated among such Classes in the same proportions as such
Realized Loss was allocated), provided that no such distribution shall result in
distributions on the Certificates of any such Class in excess of the total
amounts of principal and interest that would have been distributable thereon if
such Mortgage Loan had been liquidated with no Realized Loss. In the case of a
Series of Certificates other than a Senior/Subordinate Series, if so provided in
the related Prospectus Supplement, the applicable form of credit enhancement may
provide for reinstatement subject to certain conditions in the event that,
following the final liquidation of a Mortgage Loan and a draw under such credit
enhancement, subsequent recoveries are received. If a defaulted Mortgage Loan or
REO 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 an
REO Mortgage Loan which is not required by law to be remitted to the related
Mortgagor, the Master Servicer will be entitled to retain such gain as
additional servicing compensation. For a description of the Master Servicer's
obligations to maintain and make claims under applicable forms of credit
enhancement and insurance relating to the Mortgage Loans, see "DESCRIPTION OF
CREDIT ENHANCEMENTS" and "PRIMARY MORTGAGE INSURANCE, HAZARD INSURANCE; CLAIMS
THEREUNDER."
 
                                       32
<PAGE>   90
 
                                 SUBORDINATION
 
     A Senior/Subordinate Series of Certificates will consist of one or more
Classes of Senior Certificates and one or more Classes of Subordinate
Certificates, as specified in the related Prospectus Supplement. Subordination
of the Subordinate Certificates of any Senior/Subordinate Series of Certificates
will be effected by the following method, unless an alternative method is
specified in the related Prospectus Supplement. In addition, certain Classes of
Senior (or Subordinated Certificates may be senior to other Classes of Senior
(or Subordinate) Certificates, as specified in the related Prospectus
Supplement, in which case the following discussion is qualified in its entirety
by reference to the related Prospectus Supplement with respect to the various
priorities and other rights as among the various Classes of Senior Certificates
or Subordinate Certificates, as the case may be.
 
     With respect to any Senior/Subordinate Series of Certificates, the total
amount available for distribution on each Distribution Date, as well as the
method for allocating such amount among the various Classes of Certificates
included in such Series, will be described in the related Prospectus Supplement.
Generally, the amount available for distribution will be allocated first to
interest on the Senior Certificates of such Series, and then to principal of the
Senior Certificates up to the amounts determined as specified in the related
Prospectus Supplement, prior to allocation to the Subordinate Certificates of
such Series.
 
     In the event of any Realized Losses on Mortgage Loans not in excess of the
limitations described below, other than Extraordinary Losses, the rights of the
Subordinate Certificateholders to receive distributions with respect to the
Mortgage Loans will be subordinate to the rights of the Senior
Certificateholders. With respect to any defaulted Mortgage Loan that is finally
liquidated, through foreclosure sale, disposition of the related Mortgaged
Property if acquired by deed in lieu of foreclosure, or otherwise, the amount of
loss realized, if any (as more fully described in the related Pooling Agreement,
a "Realized Loss"), will equal the portion of the Stated Principal Balance
remaining after application of all amounts recovered (net of amounts
reimbursable to the Master Servicer for related Advances and expenses) towards
interest and principal owing on the Mortgage Loan. With respect to a Mortgage
Loan the principal balance of which has been reduced in connection with
bankruptcy proceedings, the amount of such reduction will be treated as a
Realized Loss.
 
     Except as noted below, Realized Losses will be allocated to the Subordinate
Certificates of the related Series, until the Certificate Principal Balance (as
defined in the related Prospectus Supplement) of such Subordinate Certificates
thereof has been reduced to zero. Additional Realized Losses, if any, will be
allocated to the Senior Certificates (or, if such Series includes more than one
Class of Senior Certificates, either on a pro rata basis among all of the Senior
Certificates in proportion to their respective outstanding Certificate Principal
Balances or as otherwise provided in the related Prospectus Supplement).
 
     With respect to certain Realized Losses resulting from physical damage to
Mortgaged Properties which are generally of the same type as are covered under a
Special Hazard Insurance Policy, the amount thereof that may be allocated to the
Subordinate Certificates of the related Series may be limited to an amount (the
"Special Hazard Amount") specified in the related Prospectus Supplement. See
"DESCRIPTION OF CREDIT ENHANCEMENTS -- Special Hazard Insurance Policies." If
so, any Special Hazard Losses in excess of the Special Hazard Amount will be
allocated among all outstanding Classes of Certificates of the related Series,
either on a pro rata basis in proportion to their outstanding Certificate
Principal Balances, regardless of whether any Subordinate Certificates remain
outstanding, or as otherwise provided in the related Prospectus Supplement. The
respective amounts of other specified types of losses (including Fraud Losses
and Bankruptcy Losses) that may be borne solely by the Subordinate Certificates
may be similarly limited to an amount (with respect to Fraud Losses, the "Fraud
Loss Amount" and with respect to Bankruptcy Losses, the "Bankruptcy Amount"),
and the Subordinate Certificates may provide no coverage with respect to certain
other specified types of losses, as described in the related Prospectus
Supplement, in which case such losses would be allocated on a pro rata basis
among all outstanding Classes of Certificates. Each of the Special Hazard
Amount, Fraud Loss Amount and Bankruptcy Amount may be subject to periodic
reductions under provisions described in the related Prospectus Supplement. Each
such amount may be subject to further reduction or termination, without the
consent of the Certificateholders, upon the written confirmation from each
applicable Rating Agency that the then-current rating of the related Series of
Certificates will not be adversely affected thereby.
 
                                       33
<PAGE>   91
 
     Generally, any allocation of a Realized Loss (including a Special Hazard
Loss) to a Certificate in a Senior/Subordinate Series will be made by reducing
the Certificate Principal Balance thereof as of the Distribution Date following
the calendar month in which such Realized Loss was incurred. If so provided in
the related Prospectus Supplement, in the event of certain Realized Losses, the
Senior Certificateholders may be entitled to receive a distribution of
principal, to be paid from and to the extent of funds otherwise distributable to
the Subordinate Certificateholders, equal to the product of the then applicable
Senior Percentage (as defined below) and the amount, if any, by which (i) the
Stated Principal Balance of the related Mortgage Loan exceeds (ii) the total
amount of the related unscheduled recovery which is allocable to principal (as
more fully described in the related Pooling Agreement, the "Unrecovered Senior
Portion"). Payments to the Senior Certificateholders in respect of any
Unrecovered Senior Portion on any Distribution Date will only be made with
respect to Realized Losses incurred in connection with Mortgage Loans that were
finally liquidated during the preceding calendar month, and will not be made as
to any Special Hazard Losses in excess of the Special Hazard Amount, Fraud
Losses in excess of the Fraud Loss Amount or Bankruptcy Losses in excess of the
Bankruptcy Amount (or other specified types of losses in excess of any
applicable coverage limitations), if applicable. See "DESCRIPTION OF CREDIT
ENHANCEMENTS -- Special Hazard Insurance Policies." As with any other
distribution of principal, any payment to the holders of Senior Certificates
attributable to an Unrecovered Senior Portion will be applied to reduce the
Certificate Principal Balance thereof. At any given time, the percentage of the
Certificate Principal Balances of all of the Certificates evidenced by the
Senior Certificates is the "Senior Percentage," determined in the manner set
forth in the related Prospectus Supplement. The "Stated Principal Balance" of
any Mortgage Loan as of any date of determination is equal to the principal
balance thereof as of the Cut-off Date, after application of all scheduled
principal payments due on or before the Cut-off Date whether or not received,
reduced by all amounts allocable to principal that are distributed to
Certificateholders on or before the date of determination, and as further
reduced to the extent that any Realized Loss thereon has been allocated to one
or more Classes of Certificates on or before the date of determination.
 
     As set forth above, the rights of holders of the various Classes of
Certificates of any Series to receive distributions of principal and interest is
determined by the aggregate Certificate Principal Balance of each such Class
(or, if applicable, the related notional amount). The Certificate Principal
Balance of any Certificate will be reduced by all amounts previously distributed
on such Certificate in respect of principal, and by any Realized Losses
allocated thereto. If there are no Realized Losses or prepayments of principal
on any of the Mortgage Loans, the respective rights of the holders of
Certificates of any Series to future distributions generally would not change.
However, to the extent so provided in the related Prospectus Supplement, holders
of Senior Certificates may be entitled to receive a disproportionately larger
amount of prepayments received during certain specified periods, which will have
the effect (absent offsetting losses) of accelerating the amortization of the
Senior Certificates and increasing the respective percentage ownership interest
evidenced by the Subordinate Certificates in the related Trust Fund (with a
corresponding decrease in the Senior Percentage), thereby preserving the
availability of the subordination provided by the Subordinate Certificates. In
addition, as set forth above, certain Realized Losses generally will be
allocated first to Subordinate Certificates by reduction of the Certificate
Principal Balance thereof, which will have the effect of increasing the
respective ownership interest evidenced by the Senior Certificates in the
related Trust Fund.
 
     If so provided in the related Prospectus Supplement, certain amounts
otherwise payable on any Distribution Date to holders of Subordinate
Certificates may be deposited into a reserve fund. Amounts held in any reserve
fund may be applied as described under "DESCRIPTION OF CREDIT
ENHANCEMENTS -- Reserve Funds" and in the related Prospectus Supplement.
 
     In lieu of the foregoing provisions, subordination may be effected in the
following manner, or in any other manner as may be described in the related
Prospectus Supplement. The rights of the holders of Subordinate Certificates to
receive any or a specified portion of distributions with respect to the Mortgage
Loans may be subordinated to the extent of the amount set forth in the related
Prospectus Supplement (the "Subordinate Amount"). As specified in the related
Prospectus Supplement, the Subordinate Amount may be subject to reduction based
upon the amount of losses borne by the holders of the Subordinate Certificates
as a result of such subordination, a specified schedule or such other method of
reduction as such Prospectus Supplement
 
                                       34
<PAGE>   92
 
may specify. If so specified in the related Prospectus Supplement, additional
credit support for this form of subordination may be provided by the
establishment of a reserve fund for the benefit of the holders of the Senior
Certificates (which may, if such Prospectus Supplement so provides, initially be
funded by a cash deposit) into which certain distributions otherwise allocable
to the holders of the Subordinate Certificates may be placed; such funds would
thereafter be available to cure shortfalls in distributions to holders of the
Senior Certificates.
 
     With respect to any Senior/Subordinate Series of Certificates, the terms
and provisions of the subordination may vary from those described above; any
such variation and any related additional credit support will be described in
the related Prospectus Supplement.
 
                       DESCRIPTION OF CREDIT ENHANCEMENTS
 
     Credit support with respect to each Series of Certificates may be comprised
of one or more of the following components. Each component will have a dollar
limit and will provide coverage with respect to Realized 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 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 (as defined below) (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 by a bankruptcy court
of the principal balance of or the Mortgage Rate on a Mortgage Loan or an
extension of its maturity (any such loss, a "Bankruptcy Loss"); and (iv)
incurred on defaulted Mortgage Loans as to which there was fraud in the
origination of such Mortgage Loans (any such loss, a "Fraud Loss"). Defaulted
Mortgage Losses, Special Hazard Losses, Bankruptcy Losses and Fraud Losses in
excess of the amount of coverage provided therefor and losses occasioned by war,
civil insurrection, certain governmental actions, nuclear reaction and certain
other risks ("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, a Certificate Insurance Policy 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, a Certificate Insurance Policy 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, a
Certificate Insurance Policy or a Bankruptcy Bond and (iv) coverage with respect
to Fraud Losses may be provided by one or more of a Letter of Credit, a
Certificate Insurance Policy, Mortgage Pool Insurance Policy or mortgage
repurchase bond. 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 a Reserve Fund to cover
such losses, in the form of subordination of one or more Classes of Subordinate
Certificates to provide credit support to one or more Classes of Senior
Certificates as described under "SUBORDINATION," or in the form of the
applicable Seller's agreement to repurchase certain mortgage loans, which
obligation may be supported by a Letter of Credit, surety bonds or other types
of insurance policies, certain other secured or unsecured corporate guarantees
or in such other form as may be described in the related Prospectus Supplement,
or in the form of a combination of two or more of the foregoing. The credit
support may be provided by an assignment of the right to receive certain cash
amounts, a deposit of cash into a Reserve Fund or other pledged assets, or by
banks, insurance companies, guarantees or any combination thereof identified in
the applicable Prospectus Supplement.
 
     The amounts and type of credit enhancement arrangement as well as the
provider thereof (the "Credit Enhancer"), if applicable, with respect to each
Series of Certificates will be set forth in the related Prospectus Supplement.
The Pooling Agreement or other documents may be modified in connection with the
provisions of any credit enhancement arrangement to provide for reimbursement
rights, control rights or other provisions
 
                                       35
<PAGE>   93
 
that may be required by the Credit Enhancer. 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. See "DESCRIPTION OF CREDIT ENHANCEMENTS -- Reduction or
Substitution of Credit Enhancement." If specified in the applicable Prospectus
Supplement, credit support for a Series of Certificates may cover one or more
other Series of Certificates.
 
     The descriptions of any insurance policies or bonds described 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 such policies, copies of which will be filed as an exhibit to a
Current Report on Form 8-K within 15 days of issuance of the Certificates of
such 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 (the
"Letter of Credit Bank") will deliver to the Trustee an irrevocable Letter of
Credit. The Letter of Credit may also provide for the payment of advances which
the Master Servicer would be obligated to make with respect to delinquent
monthly mortgage payments. 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. A copy of any Letter of
Credit for a Series will be filed with the Commission as an exhibit to a Current
Report on Form 8-K within 15 days of the issuance of the Certificates of such
Series.
 
MORTGAGE POOL INSURANCE POLICIES
 
     If so specified in the related Prospectus Supplement, an insurance policy
covering Defaulted Mortgage Losses (a "Mortgage Pool Insurance Policy") will be
obtained for a particular Series of Certificates. Each Mortgage Pool Insurance
Policy will, subject to the limitations described in the applicable Prospectus
Supplement, cover Defaulted Mortgage Losses in an amount equal to a percentage
specified in the applicable Prospectus Supplement of the aggregate principal
balance of the Mortgage Loans on the Cut-off Date. As set forth under
"Maintenance of Credit Enhancement," the Master Servicer will use its best
reasonable efforts to maintain the Mortgage Pool Insurance Policy and to present
claims thereunder to the Pool Insurer on behalf of itself, the Trustee and the
Certificateholders. The Mortgage Pool Insurance Policies, however, are not
blanket policies against loss, since claims thereunder may only be made
respecting particular defaulted Mortgage Loans and only upon satisfaction of
certain conditions precedent, which typically include, among other things, that
(i) any required Primary Mortgage Insurance Policy is in effect for the
defaulted Mortgage Loan and a claim thereunder has been submitted and settled,
(ii) hazard insurance on the property securing any such Mortgage Loan has been
kept in force and real estate taxes and other protection and preservation
expenses have been paid by the Master Servicer, (iii) if there has been physical
loss or damage to the applicable Mortgaged Property, it has been restored to its
condition (reasonable wear and tear excepted) at the Cut-off Date and (iv) the
insured has acquired good and merchantable title to the applicable Mortgaged
Property free and clear of liens except certain permitted encumbrances, as more
fully described in the applicable Prospectus Supplement. The Mortgage Pool
Insurance Policies may not cover losses due to a failure to pay or denial of a
claim under a Primary Mortgage Insurance Policy, irrespective of the reason
therefor. A copy of any Mortgage Pool Insurance Policy for a Series will be
filed with the Commission as an exhibit to a Current Report on Form 8-K within
15 days of the issuance of the Certificates of such Series.
 
SPECIAL HAZARD INSURANCE POLICIES
 
     If so provided in the related Prospectus Supplement, an insurance policy
covering Special Hazard Losses (a "Special Hazard Insurance Policy") will be
obtained for a particular Series of Certificates. Each Special Hazard Insurance
Policy will, subject to limitations and satisfaction of certain conditions
precedent described in the applicable Prospectus Supplement, protect holders of
the related Series of Certificates from (i) losses
                                       36
<PAGE>   94
 
due to direct physical damage to a Mortgaged Property other than any loss of a
type covered by a hazard insurance policy or a flood insurance policy, if
applicable, and (ii) losses from partial damage caused by reason of the
application of the co-insurance clauses contained in hazard insurance policies
("Special Hazard Losses"). See "PRIMARY MORTGAGE INSURANCE, HAZARD INSURANCE;
CLAIMS THEREUNDER." A Special Hazard Insurance Policy will not cover losses
occasioned by war, civil insurrection, certain governmental actions, errors in
design, faulty workmanship or materials (except under certain circumstances),
nuclear reaction, chemical contamination, waste by the Mortgagor and certain
other risks. A copy of any Special Hazard Insurance Policy for a Series will be
filed with the Commission as an exhibit to a Current Report on Form 8-K within
15 days of the issuance of the Certificates of such Series.
 
     As indicated under "DESCRIPTION OF THE CERTIFICATES -- Assignment of
Mortgage Loans" above and to the extent set forth in the applicable Prospectus
Supplement, coverage in respect of Special Hazard Losses for a Series of
Certificates may be provided, in whole or in part, by a type of Special Hazard
Instrument other than a Special Hazard Insurance Policy.
 
BANKRUPTCY BONDS
 
     In the event of a personal bankruptcy of a Mortgagor, it is possible that
the bankruptcy court may establish the value of the Mortgaged Property of such
Mortgagor at an amount less than the then outstanding principal balance of the
Mortgage Loan secured by such Mortgaged Property (a "Deficient Valuation"). The
amount of the secured debt could then be reduced to such value, and, thus, the
holder of such Mortgage Loan would become an unsecured creditor to the extent
the outstanding principal balance of such Mortgage Loan exceeds the value
assigned to the Mortgaged Property by the bankruptcy court. In addition, certain
other modifications of the terms of a Mortgage Loan can result from a bankruptcy
proceeding, including a reduction in the amount of the Monthly Payment on the
related Mortgage Loan (a "Debt Service Reduction"; Debt Service Reductions and
Deficient Valuations, collectively referred to herein as "Bankruptcy Losses").
See "CERTAIN LEGAL ASPECTS OF MORTGAGE LOANS AND RELATED MATTERS -- Anti-
Deficiency Legislation and Other Limitations on Lenders." Any Bankruptcy Bond to
provide coverage for Bankruptcy Losses for proceedings under the federal
Bankruptcy Code obtained by the Depositor for a Trust Fund will be issued by an
insurer named in the applicable Prospectus Supplement. The level of coverage
under each Bankruptcy Bond will be set forth in the applicable Prospectus
Supplement. A copy of any Bankruptcy Bond for a Series will be filed with the
Commission as an exhibit to a Current Report on Form 8-K within 15 days of the
issuance of the Certificates of such Series.
 
CERTIFICATE INSURANCE POLICIES
 
     If so provided in the related Prospectus Supplement, one or more insurance
policies (each, a "Certificate Insurance Policy") will be obtained for a
particular Series of Certificates guaranteeing timely distributions of interest
and full distributions of principal on the basis of a schedule of principal
distributions set forth in or determined in the manner specified in the related
Prospectus Supplement for such Series or for one or more Classes of Certificates
of such Series. If so specified in the related Prospectus Supplement, a
Certificate Insurance Policy will also guarantee against any payment made to a
Certificateholder which is subsequently treated as a "voidable preference"
payment under the Bankruptcy Code. A copy of any Certificate Insurance Policy
for a Series will be filed with the Commission as an exhibit to a Current Report
on Form 8-K within 15 days of the issuance of the Certificates of such Series.
 
RESERVE FUNDS
 
     If so provided in the related Prospectus Supplement, the Depositor will
deposit or cause to be deposited in an account (a "Reserve Fund") any
combination of cash, one or more irrevocable letters of credit or one or more
Permitted Investments in specified amounts, or any other instrument satisfactory
to the Rating Agency or Agencies, 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 any related Subordinate
Certificates, from Retained Yield or otherwise. To the extent
                                       37
<PAGE>   95
 
that the funding of the Reserve Fund is dependent on amounts otherwise payable
on related Subordinate Certificates, Retained Yield or other cash flows
attributable to the related Mortgage Loans or on reinvestment income, the
Reserve Fund may provide less coverage than initially expected if the cash flows
or reinvestment income on which such funding is dependent are lower than
anticipated. In addition, with respect to any Series of Certificates as to which
credit enhancement includes a Letter of Credit, if so specified in the related
Prospectus Supplement, under certain circumstances the remaining amount of the
Letter of Credit may be drawn by the Trustee and deposited in a Reserve Fund.
Amounts in a Reserve Fund may be distributed to Certificateholders, or applied
to reimburse the 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. Any such Reserve Fund will not be deemed to be part of
the related Trust Fund. If set forth in the related Prospectus Supplement, a
Reserve Fund may provide coverage to more than one Series of Certificates.
 
     In connection with the establishment of any Reserve Fund, the Reserve Fund
will be structured so that the Trustee will have a perfected security interest
for the benefit of the Certificateholders in the assets in the Reserve Fund.
However, to the extent that the Depositor, any affiliate thereof or any other
entity has an interest in any Reserve Fund, in the event of the bankruptcy,
receivership or insolvency of such entity, there could be delays in withdrawals
from the Reserve Fund and corresponding payments to the Certificateholders which
could adversely affect the yield to investors on the related Certificates.
 
     Amounts deposited in any Reserve Fund for a Series will be invested in
Permitted Investments by, or at the direction of, and for the benefit of the
Master Servicer or any other person named in the related Prospectus Supplement.
 
MAINTENANCE OF CREDIT ENHANCEMENT
 
     If a Letter of Credit, Certificate Insurance Policy or alternate form of
credit enhancement has been obtained for a Series of Certificates, the Master
Servicer will be obligated under the applicable Pooling Agreement to exercise
its best reasonable efforts to keep or cause to be kept such Letter of Credit,
Certificate Insurance Policy or alternate form of credit support in full force
and effect throughout the term of such Pooling Agreement, unless coverage
thereunder has been exhausted through payment of claims or otherwise, or
substitution therefor is made as described below under "Reduction or
Substitution of Credit Enhancement." If a Letter of Credit obtained for a Series
of Certificates is scheduled to expire prior to the date the final distribution
on such Certificates is made and coverage under such Letter of Credit has not
been exhausted and no substitution has occurred, the Trustee will draw the
amount available under the Letter of Credit and maintain such amount in trust
for such Certificateholders.
 
     If a Mortgage Pool Insurance Policy has been obtained for a Series of
Certificates, the Master Servicer will be obligated under the applicable Pooling
Agreement to exercise its best reasonable efforts to keep each Mortgage Pool
Insurance Policy (or an alternate form of credit support) in full force and
effect throughout the term of such Pooling Agreement, unless coverage thereunder
has been exhausted through payment of claims or until such Mortgage Pool
Insurance Policy is replaced in accordance with the terms of such Pooling
Agreement. The Master Servicer or the Trustee, as specified in the related
Prospectus Supplement, will agree to pay from collections received on the
Mortgage Loans the premiums for each Mortgage Pool Insurance Policy on a timely
basis. In the event the Pool Insurer ceases to be a Qualified Insurer (such term
being defined to mean a private mortgage guaranty insurance company duly
qualified as such under the laws of the state of its incorporation and each
state having jurisdiction over the insurer in connection with the Mortgage Pool
Insurance Policy and approved as an insurer by FHLMC, FNMA or any successor
entity) because it ceases to be qualified under any such law to transact such
insurance business or coverage is terminated for any reason other than
exhaustion of such coverage, the Master Servicer will use its best reasonable
efforts to obtain from another Qualified Insurer a replacement insurance policy
comparable to the Mortgage Pool Insurance Policy with a total coverage equal to
the then outstanding coverage of such Mortgage Pool Insurance Policy, provided
that, if the cost of the replacement policy is greater than the cost of such
Mortgage Pool Insurance Policy, the coverage of the replacement policy will,
unless otherwise agreed to by the Depositor, be reduced to a level such that its
premium rate does not exceed the premium rate on such Mortgage Pool Insurance
Policy. In the event that the Pool Insurer ceases to be a Qualified Insurer
because it ceases to be approved as an
                                       38
<PAGE>   96
 
insurer by FHLMC, FNMA or any successor entity, the Master Servicer will agree
to review, not less often than annually, the financial condition of the Pool
Insurer and will monitor the credit ratings of the Pool Insurer, in each case
with a view toward determining whether recoveries under the Mortgage Pool
Insurance Policy are jeopardized for reasons related to the financial condition
of the Pool Insurer. If the Master Servicer determines that recoveries are so
jeopardized, it has agreed to exercise its best reasonable efforts to obtain
from another Qualified Insurer a replacement insurance policy as described
above, subject to the same cost limit. Any losses associated with any reduction
or withdrawal in rating by an applicable Rating Agency shall be borne by the
Certificateholders. (Article I and Section 3.11)
 
     In lieu of the Master Servicer's obligation to maintain a Letter of Credit,
Mortgage Pool Insurance Policy, Certificate Insurance Policy or other form of
credit enhancement as provided above, the Master Servicer may obtain a
substitute Letter of Credit, Mortgage Pool Insurance Policy, Certificate
Insurance Policy or an alternate form of credit enhancement. If the Master
Servicer obtains such a substitute Letter of Credit, Mortgage Pool Insurance
Policy, Certificate Insurance Policy or other form of credit enhancement, it
will maintain and keep such Letter of Credit, Mortgage Pool Insurance Policy,
Certificate Insurance Policy or alternate form of credit enhancement in full
force and effect as provided herein. Prior to its obtaining any substitute
Letter of Credit, Mortgage Pool Insurance Policy, Certificate Insurance Policy
or alternate form of credit enhancement, the Master Servicer will obtain written
confirmation from the Rating Agency or Agencies that rated the related Series of
Certificates that the substitution of such Mortgage Pool Insurance Policy,
Letter of Credit, Certificate Insurance Policy or alternate form of credit
enhancement for the existing credit enhancement will not adversely affect the
then-current ratings assigned to such Certificates by such Rating Agency or
Agencies.
 
     If a Special Hazard Instrument has been obtained for a Series of
Certificates, the Master Servicer will also be obligated under the applicable
Pooling Agreement to exercise its best reasonable efforts to maintain and keep
such Special Hazard Instrument in full force and effect throughout the term of
such Pooling Agreement, unless coverage thereunder has been exhausted through
payment of claims or otherwise or substitution therefor is made as described
below under "Reduction or Substitution of Credit Enhancement." If the Special
Hazard Instrument takes the form of a Special Hazard Insurance Policy, such
policy will provide coverage against risks of the type described herein under
"DESCRIPTION OF CREDIT ENHANCEMENTS -- Special Hazard Insurance Policies." The
Master Servicer may obtain a substitute Special Hazard Instrument for the
existing Special Hazard Instrument if prior to such substitution the Master
Servicer obtains written confirmation from the Rating Agency or Agencies that
rated the Certificates that such substitution shall not adversely affect the
then-current ratings assigned to the Certificates by such Rating Agency or
Agencies. (Sections 3.12 and 3.16)
 
     If a Bankruptcy Bond has been obtained for a Series of Certificates, the
Master Servicer will be obligated under the applicable Pooling Agreement to
exercise its best reasonable efforts to maintain and keep such Bankruptcy Bond
in full force and effect throughout the term of such Pooling Agreement, unless
coverage thereunder has been exhausted through payment of claims or substitution
therefor is made as described below under "Reduction or Substitution of Credit
Enhancement." The Master Servicer may obtain a substitute Bankruptcy Bond or
other credit enhancement for the existing Bankruptcy Bond if prior to such
substitution the Master Servicer obtains written confirmation from the Rating
Agency or Agencies that rated the Certificates that such substitution shall not
adversely affect the then-current ratings assigned to the Certificates by such
Rating Agency or Agencies. (Sections 3.16 and 3.21) See "DESCRIPTION OF CREDIT
ENHANCEMENTS -- Bankruptcy Bonds."
 
     The Master Servicer, on behalf of itself, the Trustee and
Certificateholders, will provide the Trustee information required for the
Trustee to draw under the Letter of Credit and will present claims to each Pool
Insurer, to the issuer of each Special Hazard Insurance Policy or other Special
Hazard Instrument, to the issuer of each Bankruptcy Bond and, in respect of
defaulted Mortgage Loans for which there is no Subservicer, to each Primary
Mortgage Insurer and take such reasonable steps as are necessary to permit
recovery under such Letter of Credit, Certificate Insurance Policies or other
insurance policies or comparable coverage respecting defaulted Mortgage Loans or
Mortgage Loans which are the subject of a bankruptcy proceeding. As set forth
above, all collections by the Master Servicer under any Mortgage Pool Insurance
                                       39
<PAGE>   97
 
Policy, any Primary Mortgage Insurance Policy or any Bankruptcy Bond and, where
the related property has not been restored, any Special Hazard Instrument, are
to be deposited initially in the Custodial Account and ultimately in the
Certificate Account, subject to withdrawal as described above. All draws under
any Letter of Credit or Certificate Insurance Policy will be initially deposited
in the Certificate Account. In those cases in which a Mortgage Loan is serviced
by a Subservicer, the Subservicer, on behalf of itself, the Trustee and the
Certificateholders will present claims to the Primary Mortgage Insurer, and all
collections thereunder shall initially be deposited in a segregated account
generally comparable to the Custodial Account. (Sections 3.11, 3.12, 3.21 and
4.01)
 
     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 Instrument are insufficient to restore the damaged property to a
condition sufficient to permit recovery under any Letter of Credit, Mortgage
Pool Insurance Policy or any related Primary Mortgage Insurance Policy, the
Master Servicer is not required to expend its own funds to restore the damaged
property unless it determines (i) that such restoration will increase the
proceeds to one or more Classes of Certificateholders on liquidation of the
Mortgage Loan after reimbursement of the Master Servicer for its expenses and
(ii) that such expenses will be recoverable by it through Liquidation Proceeds
or Insurance Proceeds. If recovery under any Letter of Credit, Mortgage Pool
Insurance Policy, other credit enhancement or any related Primary Mortgage
Insurance Policy is not available because the Master Servicer has been unable to
make the above determinations, has made such determinations incorrectly or
recovery is not available for any other reason, the Master Servicer is
nevertheless obligated to follow such normal practices and procedures (subject
to the preceding sentence) as it deems necessary or advisable to realize upon
the defaulted Mortgage Loan and in any such event is entitled to reimbursement
of its expenses in connection with such restoration prior to payments to
Certificateholders. (Section 3.14)
 
     The failure of the Master Servicer to maintain a Letter of Credit,
Certificate Insurance Policy, Mortgage Pool Insurance Policy, Special Hazard
Instrument, Bankruptcy Bond or other form of credit enhancement under any
applicable Pooling Agreement, as provided above, which continues unremedied for
30 days (15 days in the case of a failure to pay the required premium) after the
giving of written notice of such failure to the Master Servicer by the Trustee
or the Depositor, or to the Master Servicer, the Depositor and the Trustee by
the holders of any Class of Certificates of the related Series evidencing not
less than 25% of the aggregate Percentage Interest constituting such Class, will
constitute an Event of Default by the Master Servicer under such Pooling
Agreement. See "THE POOLING AGREEMENT -- Rights Upon Event of Default" for a
discussion of the rights of the Depositor, the Trustee and the Certificateholder
during an Event of Default.
 
REDUCTION OR SUBSTITUTION OF CREDIT ENHANCEMENT
 
     The amount of credit support provided pursuant to any of the credit
enhancements (including, without limitation, a Mortgage Pool Insurance Policy,
Special Hazard Insurance Policy, Certificate Insurance Policy, Bankruptcy Bond,
Letter of Credit, Reserve Fund, or any alternative form of credit enhancement)
may be reduced under certain specified circumstances. In most cases, the amount
available pursuant to any credit enhancement will be subject to periodic
reduction in accordance with a schedule or formula on a nondiscretionary basis
pursuant to the terms of the related Pooling Agreement. Additionally, in most
cases, such credit support (and any replacements therefor) may be replaced,
reduced or terminated, and the formula used in calculating the amount of
coverage with respect to Bankruptcy Losses, Special Hazard Losses or Fraud
Losses may be changed, without the consent of the Certificateholders, upon the
written assurance from each applicable Rating Agency that the then-current
rating of the related Series of Certificates will not be adversely affected.
Furthermore, in the event that the credit rating of any obligor under any
applicable credit enhancement is downgraded, the credit rating of the related
Certificates may be downgraded to a corresponding level, and the Master Servicer
will be obligated to obtain replacement credit support in order to restore the
rating of the Certificates only to the extent specified in the related
Prospectus Supplement. The Master Servicer will also be permitted to replace
such credit support with other credit enhancement instruments issued by obligors
whose credit ratings are equivalent to such downgraded level and in lower
amounts which would satisfy such downgraded level, provided that the
then-current rating of the related Series of Certificates is maintained. Where
the credit support is in the form of a Reserve Fund, a permitted reduction in
the amount
 
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<PAGE>   98
 
of credit enhancement will result in a release of all or a portion of the assets
in the Reserve Fund to the Depositor, the Master Servicer or such other person
that is entitled thereto. Any assets so released will not be available for
distributions in future periods.
 
        PRIMARY MORTGAGE INSURANCE, HAZARD INSURANCE; CLAIMS THEREUNDER
 
     Each Mortgage Loan (other than any Cooperative Loan) will be required to be
covered by a hazard insurance policy (as described below) and, if required as
described below, a Primary Mortgage Insurance Policy. Cooperative Loans
generally will not be covered by a hazard insurance policy insuring the
individual dwelling unit as the related Cooperative typically is responsible for
the maintenance of hazard insurance for property owned by such Cooperative. The
following is only a brief description of certain insurance policies and does not
purport to summarize or describe all of the provisions of these policies. Such
insurance is subject to underwriting and approval of individual Mortgage Loans
by the respective insurers, unless such underwriting and approval authority has
been delegated to the applicable lender. The descriptions of any insurance
policies described 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 such forms of policies, sample copies of which are
available upon request.
 
PRIMARY MORTGAGE INSURANCE POLICIES
 
     Each Mortgage Loan having a Loan-to-Value Ratio at origination of over 80%
is required by the Depositor to be covered by a primary mortgage guaranty
insurance policy (a "Primary Mortgage Insurance Policy") insuring against
default on such Mortgage Loan up to at least the minimum amount required to be
covered by FNMA and FHLMC, unless and until the principal balance of the
Mortgage Loan is reduced to a level that would produce a Loan-to-Value Ratio
equal to or less than 80%, and the applicable Seller will represent and warrant
that, to the best of such Seller's knowledge, such Mortgage Loans are so
covered. The Mortgagor with respect to each Mortgage Loan covered by a Primary
Mortgage Insurance Policy will be required to pay the premiums allocable to such
Mortgage Loan under any applicable Primary Mortgage Insurance Policy. However,
the foregoing standard may vary significantly depending on the characteristics
of the Mortgage Loans and the applicable underwriting standards. A Mortgage Loan
will not be considered to be an exception to the foregoing standard if no
Primary Mortgage Insurance Policy was obtained at origination but the Mortgage
Loan has amortized to below an 80% Loan-to-Value Ratio level as of the
applicable Cut-off Date. In addition, the Master Servicer will have the ability
to cancel any Primary Mortgage Insurance Policy if the Loan-to-Value Ratio of
the Mortgage Loan is reduced below a specified percentage, which typically will
be either 75% or 80%, either based on an appraisal of the Mortgaged Property
after the related Cut-off Date or as a result of principal payments that reduce
the principal balance of the Mortgage Loan after such Cut-off Date, or if
necessary to comply with applicable law.
 
     While the terms and conditions of the Primary Mortgage Insurance Policies
issued by one primary mortgage guaranty insurer (a "Primary Mortgage Insurer")
will differ from those in Primary Mortgage Insurance Policies issued by other
Primary Mortgage Insurers, each Primary Mortgage Insurance Policy will in
general provide substantially the following coverage. The amount of the loss as
calculated under a Primary Mortgage Insurance Policy covering a Mortgage Loan
(herein referred to as the "Loss") will generally consist of the unpaid
principal amount of such Mortgage Loan and accrued and unpaid interest thereon
and limited 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) amounts expended but not approved by the Primary Mortgage Insurer, (iv)
claim payments previously made on such Mortgage Loan and (v) unpaid premiums and
certain other amounts.
 
     The Primary Mortgage Insurer 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 Primary Mortgage Insurer of good and merchantable title to, and
possession of, the Mortgaged Property; or (iii) at the option of the Primary
 
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<PAGE>   99
 
Mortgage Insurer under certain Primary Mortgage 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
Mortgage 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
Primary Mortgage 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 Mortgage
Insurance Policy (ordinary wear and tear excepted); and, if requested by the
Primary Mortgage Insurer, (iii) tender to the Primary Mortgage Insurer good and
merchantable title to, and possession of, the Mortgaged Property. Because the
Master Servicer will not be required to make Servicing Advances deemed to be
nonrecoverable, conditions (i) and (ii) above may not be satisfied with respect
to some claims under the Primary Mortgage Insurance Policies. In any such event,
Losses that would otherwise have been recoverable under the applicable Primary
Mortgage Insurance Policy may not be paid under such policy and, as a result,
will be borne by the Certificateholders.
 
     For any Certificates offered hereunder, the Master Servicer will maintain
or cause any applicable Subservicer to maintain in full force and effect and to
the extent coverage is available a Primary Mortgage Insurance Policy with regard
to each Mortgage Loan for which such coverage is required under the standard
described above, provided that such Primary Mortgage Insurance Policy was in
place as of the Cut-off Date and the Master Servicer had knowledge of such
Primary Mortgage Insurance Policy. In the event that the Master Servicer gains
knowledge that as of the Closing Date, a Mortgage Loan had a Loan-to-Value Ratio
at origination in excess of 80% and was not the subject of a Primary Mortgage
Insurance Policy (and was not included in any exception to such standard
disclosed in the related Prospectus Supplement) and that such Mortgage Loan has
a then current Loan-to-Value Ratio in excess of 80%, then the Master Servicer is
required to use its reasonable efforts to obtain and maintain a Primary Mortgage
Insurance Policy to the extent that such a policy is obtainable at a reasonable
price. The Master Servicer will not cancel or refuse to renew any such Primary
Mortgage 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 the replacement Primary Mortgage Insurance Policy for
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. (Section 3.11) The premiums allocable to a Mortgage Loan covered
by any Primary Mortgage Insurance Policy, to the extent not paid by the related
Mortgagor, will be reimbursed to the Master Servicer from collections on the
Mortgage Pool. For further information regarding the extent of coverage under
any Mortgage Pool Insurance Policy or Primary Mortgage Insurance Policy, see
"DESCRIPTION OF CREDIT ENHANCEMENTS -- Mortgage Pool Insurance Policies."
 
HAZARD INSURANCE POLICIES
 
     The terms of the Mortgage Loans (other than Cooperative Loans and Mortgage
Loans secured by condominium apartments) require each Mortgagor to maintain a
hazard insurance policy with extended coverage customary in the state in which
the related Mortgaged Property is located for their Mortgage Loan. Additionally,
the Pooling Agreement for each Series of Certificates will require the Master
Servicer to cause to be maintained for each Mortgage Loan 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
property is located. Such coverage generally will be in an amount equal to the
lesser of the principal balance owing on such Mortgage Loan or 100% of the
insurable value of the improvements securing the Mortgage Loan except that, if
generally available, such coverage must not be less than the minimum amount
required under the terms thereof to fully compensate for any damage or loss on a
replacement cost basis. The ability of the
 
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<PAGE>   100
 
Master Servicer to ensure that hazard insurance proceeds are appropriately
applied may be dependent on its being named as an additional insured or loss
payee under any hazard insurance policy and under any flood insurance policy
referred to below, or upon the extent to which information in this regard is
furnished to the Master Servicer by Mortgagors or Subservicers.
 
     As set forth above, all amounts collected by the Master Servicer 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
Master Servicer's normal servicing procedures) will be deposited initially in
the Custodial Account and ultimately in the Certificate Account, subject to
permitted withdrawals. The Pooling Agreement provides that the Master Servicer
may satisfy its obligation to cause hazard policies to be maintained by
maintaining a blanket policy insuring against losses on the Mortgage Loans. If
such blanket policy contains a deductible clause, the Master Servicer will
deposit in the Custodial Account or the applicable Certificate Account all sums
which would have been deposited therein but for such clause.
 
     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, hail, riot, strike and civil commotion,
subject to the conditions and exclusions specified 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 mudflows),
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.
Where the improvements securing a Mortgage Loan are located in a federally
designated flood area in participating communities at the time of origination of
such Mortgage Loan, the Pooling Agreement requires the Master Servicer to cause
to be maintained for each such Mortgage Loan serviced, flood insurance (to the
extent available) in an amount equal in general to the lesser of the amount
required to compensate for any loss or damage on a replacement cost basis or the
maximum insurance available under the federal flood insurance program.
 
     The hazard insurance policies covering the Mortgaged Properties typically
contain a co-insurance 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 generally provides that the insurer's
liability in the event of partial loss does not exceed the greater of (i) the
replacement cost of the improvements damaged or destroyed less physical
depreciation or (ii) such proportion of the loss as the amount of insurance
carried bears to the specified percentage of the full replacement cost of such
improvements.
 
     Since the amount of hazard insurance that Mortgagors are required to
maintain on the improvements securing the Mortgage Loans may decline as the
principal balances owing thereon decrease, and since residential properties have
historically appreciated in value over time, hazard insurance proceeds could be
insufficient to restore fully the damaged property in the event of a partial
loss. See "SUBORDINATION" above for a description of when subordination is
provided, the protection (limited to the Special Hazard Amount as described in
the related Prospectus Supplement) afforded by such subordination, and
"DESCRIPTION OF CREDIT ENHANCEMENTS -- Special Hazard Insurance Policies" for a
description of the limited protection afforded by any Special Hazard Insurance
Policy against losses occasioned by hazards which are otherwise uninsured
against (including losses caused by the application of the co-insurance clause
described in the preceding paragraph).
 
     Under the terms of the Mortgage Loans, Mortgagors are generally required to
present claims to insurers under hazard insurance policies maintained on the
Mortgaged Properties. The Master Servicer, on behalf of the Trustee and
Certificateholders, is obligated to present claims under any Special Hazard
Insurance Policy or other Special Hazard Instrument and any blanket insurance
policy insuring against hazard losses on the
 
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<PAGE>   101
 
Mortgaged Properties. However, the ability of the Master Servicer to present
such claims is dependent upon the extent to which information in this regard is
furnished to the Master Servicer or the Subservicers by Mortgagors. (Section
3.12)
 
     Hazard insurance and flood insurance generally will not 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 the 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 Loan 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 a borrower who is the owner of 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.
 
                             THE POOLING AGREEMENT
 
     As described above under "DESCRIPTION OF THE CERTIFICATES -- General," each
Series of Certificates will be issued pursuant to a Pooling Agreement as
described in that section. The following summaries describe certain additional
provisions common to each Pooling Agreement.
 
SERVICING AND OTHER COMPENSATION AND PAYMENT OF EXPENSES; RETAINED YIELD
 
     The principal servicing compensation to be paid to the Master Servicer in
respect of its master servicing activities for each Series of Certificates will
be equal to the percentage per annum described in the related Prospectus
Supplement (which may vary under certain circumstances) of the outstanding
principal balance of each Mortgage Loan, and such compensation will be retained
by it from collections of interest on such Mortgage Loan in the related Trust
Fund (after provision has been made for the payment of interest at the
applicable Pass-Through Rate to Certificateholders and for the payment of any
Retained Yield) at the time such collections are deposited into the applicable
Custodial Account. As compensation for its servicing duties, a Subservicer or,
if there is no Subservicer, the Master Servicer will be entitled to a monthly
servicing fee as described in the related Prospectus Supplement, which may vary
under certain circumstances from the amounts described in the Prospectus
Supplement. Certain Subservicers, in their capacity as Sellers, may also be
entitled to Retained Yield as additional compensation for the sale of the
applicable Mortgage Loans.
 
     The Master Servicer will pay or cause to be paid certain ongoing expenses
associated with each Trust Fund and incurred by it in connection with its
responsibilities under the Pooling Agreement, including, without limitation,
payment of any fee or other amount payable in respect of any alternative credit
enhancement arrangements, payment of the fees and disbursements of the Trustee,
any custodian appointed by the Trustee, the Certificate Registrar and any Paying
Agent, and payment of expenses incurred in enforcing the obligations of
Subservicers and Sellers. The Master Servicer will be entitled to reimbursement
of expenses incurred in enforcing the obligations of Subservicers and Sellers
under certain limited circumstances. In addition, as described above under
"DESCRIPTION OF THE CERTIFICATES -- Advances," the Master Servicer will be
entitled to reimbursements for certain expenses incurred by it in connection
with Liquidated Mortgage Loans and in connection with the restoration of
Mortgaged Properties, such right of reimbursement being prior to the rights of
Certificateholders to receive any related Liquidation Proceeds (including
Insurance Proceeds).
 
     The Prospectus Supplement for a Series of Certificates will specify whether
there will be any Retained Yield. Any such Retained Yield will be a specified
portion of the interest payable on each Mortgage Loan in a
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<PAGE>   102
 
Mortgage Pool. Any such Retained Yield will be established on a loan-by-loan
basis and the amount thereof with respect to each Mortgage Loan in a Mortgage
Pool will be specified on an exhibit to the related Pooling Agreement. Any
Retained Yield in respect of a Mortgage Loan will represent a specified portion
of the interest payable thereon and will not be part of the related Trust Fund.
Any partial recovery of interest in respect of a Mortgage Loan will be allocated
between the owners of any Retained Yield and the holders of Classes of
Certificates entitled to payments of interest as provided in the Prospectus
Supplement and the applicable Pooling Agreement.
 
EVIDENCE AS TO COMPLIANCE
 
     Each Pooling Agreement will provide that on or before a specified date in
each year, beginning the first such date that is at least a specified number of
months after the Cut-off Date, a firm of independent public accountants will
furnish a statement to the Depositor and the Trustee to the effect that, on the
basis of an examination by such firm conducted substantially in compliance with
the Uniform Single Audit Program for Mortgage Bankers or the Audit Program for
Mortgages serviced for FHLMC, the servicing of mortgage loans under agreements
(including the related Pooling Agreement) substantially similar to each other
was conducted in compliance with such agreements except for such significant
exceptions or errors in records that, in the opinion of the firm, the Uniform
Single Audit Program for Mortgage Bankers or the Audit Program for Mortgages
serviced for FHLMC requires it to report. (Section 3.19)
 
     Each Pooling Agreement will also provide for delivery (on or before a
specified date in each year) to the Trustee of an annual statement signed by an
officer of the Master Servicer to the effect that the Master Servicer has
fulfilled in all material respects its obligations under the Pooling Agreement
throughout the preceding year or, if there has been a material default in the
fulfillment of any such obligation, such statement shall specify each such known
default and the nature and status thereof. Such statement may be provided as a
single form making the required statements as to more than one Pooling
Agreement. (Section 3.18)
 
     Copies of the annual statement of the Master Servicer may be obtained by
Certificateholders without charge upon written request to the Trustee.
 
CERTAIN MATTERS REGARDING THE MASTER SERVICER AND THE DEPOSITOR
 
     The Pooling Agreement for each Series of Certificates will provide that the
Master Servicer may not resign from its obligations and duties thereunder except
upon a determination that performance of such duties is no longer permissible
under applicable law or except in connection with a permitted transfer of
servicing. No such resignation will become effective until the Trustee or a
successor servicer has assumed the Master Servicer's obligations and duties
under the Pooling Agreement. (Section 6.04)
 
     Each Pooling Agreement will also provide that, except as set forth below,
neither the Master Servicer, the Depositor, nor any director, officer, employee
or agent of the Master Servicer or the Depositor will be under any liability to
the Trust Fund or the Certificateholders for any action taken or for refraining
from the taking of any action in good faith pursuant to the Pooling Agreement,
or for errors in judgment; provided, however, that neither the Master Servicer,
the Depositor, 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. Each Pooling Agreement will further provide
that the Master Servicer, the Depositor, and any director, officer, employee or
agent of the Master Servicer or the Depositor 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 related Series of 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,
each Pooling Agreement will provide that neither the Master Servicer nor the
Depositor will be under any obligation to appear in, prosecute or defend any
legal or administrative action that is not incidental to its respective duties
under the Pooling Agreement and which in
 
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<PAGE>   103
 
its opinion may involve it in any expense or liability. The Master Servicer or
the Depositor 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 Master Servicer or the Depositor, as the
case may be, will be entitled to be reimbursed therefor out of funds otherwise
distributable to Certificateholders. (Section 6.03)
 
     Any person into which the Master Servicer may be merged or consolidated,
any person resulting from any merger or consolidation to which the Master
Servicer is a party or any person succeeding to the business of the Master
Servicer will be the successor of the Master Servicer under the Pooling
Agreement, provided that (i) such person is qualified to service mortgage loans
on behalf of FNMA or FHLMC and (ii) such merger, consolidation or succession
does not adversely affect the then-current rating of the Classes of Certificates
of the related Series that have been rated. In addition, notwithstanding the
prohibition on its resignation, the Master Servicer may assign its rights under
a Pooling Agreement to any person to whom the Master Servicer is transferring a
substantial portion of its mortgage servicing portfolio, provided clauses (i)
and (ii) above are satisfied and such person is reasonably satisfactory to the
Depositor and the Trustee. In the case of any such assignment, the Master
Servicer will be released from its obligations under such Pooling Agreement,
exclusive of liabilities and obligations incurred by it prior to the time of
such assignment. (Section 6.02)
 
EVENTS OF DEFAULT
 
     Events of Default under the Pooling Agreement in respect of a Series of
Certificates will include, without limitation, (i) any failure by the Master
Servicer to make a required deposit to the Certificate Account or, if the Master
Servicer is the Paying Agent, to distribute to the holders of any Class of
Certificates of such Series any required payment which continues unremedied for
5 days after the giving of written notice of such failure to the Master Servicer
by the Trustee or the Depositor, or to the Master Servicer, the Depositor and
the Trustee by the holders of Certificates of such Class evidencing not less
than 25% of the aggregate Percentage Interests constituting such Class; (ii) any
failure by the Master Servicer duly to observe or perform in any material
respect any other of its covenants or agreements in the Pooling Agreement with
respect to such Series of Certificates which continues unremedied for 30 days
(15 days in the case of a failure to pay the premium for any insurance policy
which is required to be maintained under the Pooling Agreement) after the giving
of written notice of such failure to the Master Servicer by the Trustee or the
Depositor, or to the Master Servicer, the Depositor and the Trustee by the
holders of any Class of Certificates of such Series evidencing not less than 25%
of the aggregate Percentage Interests constituting such Class; and (iii) certain
events of insolvency, readjustment of debt, marshalling of assets and
liabilities or similar proceedings regarding the Master Servicer and certain
actions by the Master Servicer indicating its insolvency or inability to pay its
obligations. (Section 7.01)
 
RIGHTS UPON EVENT OF DEFAULT
 
     So long as an Event of Default remains unremedied, either the Depositor or
the Trustee may, and at the direction of the holders of Certificates evidencing
not less than 51% of the aggregate undivided interests (or, if so specified in
the related Prospectus Supplement, voting rights) in the related Trust Fund
(except as otherwise provided for in the related Pooling Agreement with respect
to the Credit Enhancer) the Trustee shall, by written notification to the Master
Servicer and to the Depositor or the Trustee, as applicable, terminate all of
the rights and obligations of the Master Servicer under the Pooling Agreement
covering such Trust Fund and in and to the Mortgage Loans and the proceeds
thereof, whereupon the Trustee or, upon notice to the Depositor and with the
Depositor's consent, its designee will succeed to all responsibilities, duties
and liabilities of the Master Servicer under such Pooling Agreement and will be
entitled to similar compensation arrangements. In the event that the Trustee
would be obligated to succeed the Master Servicer but is unwilling so to act, it
may appoint (or if it is unable so to act, it shall appoint) or petition a court
of competent jurisdiction for the appointment of, a FNMA- or FHLMC-approved
mortgage servicing institution with a net worth of at least $10,000,000 to act
as successor to the Master Servicer under the Pooling
 
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<PAGE>   104
 
Agreement. Pending such appointment, the Trustee is obligated to act in such
capacity. The Trustee and such successor may agree upon the servicing
compensation to be paid, which in no event may be greater than the compensation
to the initial Master Servicer under the Pooling Agreement. (Sections 7.01 and
7.02)
 
     No Certificateholder will have any right under a Pooling Agreement to
institute any proceeding with respect to such Pooling Agreement (except as
otherwise provided for in the related Pooling Agreement with respect to the
Credit Enhancer) unless such holder previously has given to the Trustee written
notice of default and the continuance thereof and unless the holders of
Certificates of any Class evidencing not less than 25% of the aggregate
Percentage Interests constituting such Class 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
after receipt of such request and indemnity has neglected or refused to
institute any such proceeding. (Section 11.03) However, the Trustee will be
under no obligation to exercise any of the trusts or powers vested in it by the
Pooling Agreement or to institute, conduct or defend any litigation thereunder
or in relation thereto at the request, order or direction of any of the holders
of Certificates covered by such Pooling Agreement, 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. (Section 8.02)
 
AMENDMENT
 
     Each Pooling Agreement may be amended by the Depositor, the Master Servicer
and the Trustee, without the consent of any of the holders of Certificates
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 or to correct any error, (iii) to change the timing and/or
nature of deposits in the Custodial Account or the Certificate Account or to
change the name in which the Custodial Account is maintained; provided that (a)
the Certificate Account Deposit Date would in no event be later than the related
Distribution Date, (b) such change would not adversely affect in any material
respect the interests of any Certificateholder, as evidenced by an opinion of
counsel, and (c) such change would not adversely affect the then-current rating
of any rated Classes of Certificates, as evidenced by a letter from each
applicable Rating Agency, (iv) if a REMIC election has been made with respect to
the related Trust Fund, to modify, eliminate or add to any of its provisions (A)
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, provided that the Trustee has received an Opinion of Counsel
to the effect that (a) such action is necessary or desirable to maintain such
qualification or to avoid or minimize such risk, and (b) such action will not
adversely affect in any material respect the interests of any holder of
Certificates covered by the Pooling Agreement, or (B) to restrict the transfer
of the REMIC Residual Certificates, provided that the Depositor has determined
that the then-current ratings of the Classes of the Certificates that have been
rated will not be adversely affected, as evidenced by a letter from each
applicable Rating Agency, and that any such amendment will not give rise to any
tax with respect to the transfer of the REMIC Residual Certificates to a
non-Permitted Transferee, (v) to make any other provisions with respect to
matters or questions arising under such Pooling Agreement which are not
materially inconsistent with the provisions thereof, provided that such action
will not adversely affect in any material respect the interests of any
Certificateholder, or (vi) to amend specified provisions that are not material
to holders of any Class of Certificates offered hereunder.
 
     The Pooling Agreement may also be amended by the Depositor, the Master
Servicer and the Trustee (except as otherwise provided for in the related
Pooling Agreement with respect to the Credit Enhancer) with the consent of the
holders of Certificates of each Class affected thereby evidencing, in each case,
not less than 66% of the aggregate Percentage Interests constituting such Class
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 covered by such Pooling
Agreement, except 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 on a Certificate of any Class without the consent of
the holder of such Certificate or (ii) reduce the aforesaid percentage of
Certificates of any Class the holders of
 
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<PAGE>   105
 
which are required to consent to any such amendment without the consent of the
holders of all Certificates of such Class covered by such Pooling Agreement then
outstanding.
 
     Notwithstanding the foregoing, if a REMIC election has been made with
respect to the related Trust Fund, the Trustee will not be entitled to consent
to any amendment to a Pooling Agreement without having first received an Opinion
of Counsel to the effect that such amendment or the exercise of any power
granted to the Master Servicer, the Depositor or the Trustee in accordance with
such amendment will not result in the imposition of a tax on the related Trust
Fund or cause such Trust Fund to fail to qualify as a REMIC. (Section 11.01)
 
TERMINATION; RETIREMENT OF CERTIFICATES
 
     The obligations created by the Pooling Agreement for each Series of
Certificates (other than certain limited payment and notice obligations of the
Trustee and the Depositor, respectively) will terminate upon the payment to
Certificateholders of that Series of all amounts held in the Certificate Account
or by the Master Servicer and required to be paid to them pursuant to such
Pooling Agreement following the earlier of (i) the final payment or other
liquidation or disposition (or any advance with respect thereto) of the last
Mortgage Loan subject thereto and all property acquired upon foreclosure or deed
in lieu of foreclosure of any such Mortgage Loan and (ii) the purchase by the
Master Servicer or the Depositor or, if specified in the related Prospectus
Supplement, by the holder of the REMIC Residual Certificates (see "FEDERAL
INCOME TAX CONSEQUENCES" below) from the Trust Fund for such Series of all
remaining Mortgage Loans and all property acquired in respect of such Mortgage
Loans. In no event, however, will the trust created by the Pooling Agreement
continue beyond the expiration of 21 years from the death of the survivor of
certain persons named in such Pooling Agreement. Written notice of termination
of the Pooling Agreement will be given to each Certificateholder, and the final
distribution will be made only upon surrender and cancellation of the
Certificates at an office or agency appointed by the Trustee which will be
specified in the notice of termination. (Section 9.01) If the Certificateholders
are permitted to terminate the trust under the applicable Pooling Agreement, a
penalty may be imposed upon the Certificateholders based upon the fee that would
be foregone by the Master Servicer because of such termination.
 
     Any such purchase of Mortgage Loans and property acquired in respect of
Mortgage Loans evidenced by a Series of Certificates shall be made at the option
of the Master Servicer or the Depositor or, if applicable, the holder of the
REMIC Residual Certificates at the price specified in the related Prospectus
Supplement. The exercise of such right will effect early retirement of the
Certificates of that Series, but the right of the Master Servicer or the
Depositor or, if applicable, such holder to so purchase is subject to the
aggregate principal balance of the Mortgage Loans for that Series as of the
Distribution Date on which the purchase proceeds are to be distributed to
Certificateholders being less than the percentage specified in the related
Prospectus Supplement of the aggregate principal balance of the Mortgage Loans
at the Cut-off Date for that Series. The Prospectus Supplement for each Series
of Certificates will set forth the amounts that the holders of such Certificates
will be entitled to receive upon such early retirement. Such early termination
may adversely affect the yield to holders of certain Classes of such
Certificates. If a REMIC election has been made, the termination of the related
Trust Fund will be effected in a manner consistent with applicable federal
income tax regulations and its status as a REMIC. (Sections 9.01 and 9.02)
 
THE TRUSTEE
 
     The Trustee under each Pooling Agreement will be named in the related
Prospectus Supplement. The commercial bank or trust company serving as Trustee
may have normal banking relationships with the Depositor and/or its affiliates,
including Bank of America, FSB.
 
     The Trustee may resign at any time, in which event the Depositor will be
obligated to appoint a successor Trustee. The Depositor may also remove the
Trustee if the Trustee ceases to be eligible to continue as such under the
Pooling Agreement or if the Trustee becomes insolvent. Upon becoming aware of
such circumstances, the Depositor will be obligated to appoint a successor
Trustee. The Trustee may also be removed at any time by the holders of
Certificates evidencing not less than 51% of the aggregate undivided interests
(or, if
 
                                       48
<PAGE>   106
 
so specified in the related Prospectus Supplement, voting rights) 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. (Section 8.07)
 
                              YIELD CONSIDERATIONS
 
     The yield to maturity of a Certificate will depend on the price paid by the
holder for such Certificate, the Pass-Through Rate on any such Certificate
entitled to payments of interest (which Pass-Through Rate may vary if so
specified in the related Prospectus Supplement) and the rate and timing of
principal payments (including prepayments, defaults, liquidations and
repurchases) on the Mortgage Loans and the allocation thereof to reduce the
principal balance of such Certificate (or notional amount thereof if applicable)
and other factors. See "RISK FACTORS -- Yield and Prepayment Uncertainty" above.
 
     Each monthly interest payment on a Mortgage Loan will be calculated as
one-twelfth of the applicable Mortgage Rate multiplied by the principal balance
of such Mortgage Loan outstanding as of the first day of the month prior to the
month in which the Distribution Date for the related Series of Certificates
occurs, after giving effect to the payment of principal due on such first day,
subject to any Deferred Interest. The amount of such payments with respect to
each Mortgage Loan distributed (or accrued in the case of Deferred Interest or
Accrual Certificates) monthly to holders of a Class of Certificates entitled to
payments of interest will be similarly calculated on the basis of such Class's
specified percentage of each such payment of interest (or accrual in the case of
Accrual Certificates) and will be expressed as a fixed, adjustable or variable
Pass-Through Rate payable on the outstanding principal balance or notional
amount of such Certificate, or any combination of such Pass-Through Rates,
calculated as described herein and in the related Prospectus Supplement. Holders
of Strip Certificates or a Class of Certificates having a Pass-Through Rate that
varies based on the weighted average Mortgage Rate of the underlying Mortgage
Loans will be affected by disproportionate prepayments and repurchases of
Mortgage Loans having higher Net Mortgage Rates or rates applicable to the Strip
Certificates, as applicable.
 
     The effective yield to maturity to each holder of Certificates entitled to
payments of interest will be below that otherwise produced by the applicable
Pass-Through Rate and purchase price of such Certificate because, while interest
will accrue on each Mortgage Loan from the first day of each month, the
distribution of such interest will be made on 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.
 
     A Class of Certificates may be entitled to payments of interest at a fixed
Pass-Through Rate, a variable Pass-Through Rate or adjustable Pass-Through Rate,
or any combination of such Pass-Through Rates, each as specified in the related
Prospectus Supplement. A variable Pass-Through Rate may be calculated based on
the weighted average of the Mortgage Rates (net of servicing fees and any
Retained Yield (each, a "Net Mortgage Rate")) of the related Mortgage Loans for
the month preceding the Distribution Date if so specified in the related
Prospectus Supplement. As will be described in the related Prospectus
Supplement, the aggregate payments of interest on a Class of Certificates, and
the yield to maturity thereon, will be affected by the rate of payment of
principal on the Certificates (or the rate of reduction in the notional balance
of Certificates entitled only to payments of interest) and, in the case of
Certificates evidencing interests in ARM Loans or Net 5 Loans, by changes in the
Net Mortgage Rates on the ARM Loans or Net 5 Loans, as applicable. See "MATURITY
AND PREPAYMENT CONSIDERATIONS" below. The yield on the Certificates will also be
affected by liquidations of Mortgage Loans following Mortgagor defaults and by
purchases of Mortgage Loans in the event of breaches of representations made in
respect of such Mortgage Loans by the Sellers, or conversions of ARM Loans to a
fixed interest rate. See "MORTGAGE LOAN PROGRAM -- Representations and
Warranties by Sellers" and "Descriptions of the Certificates -- Assignment of
Mortgage Loans" above.
 
     In general, if a Class of Certificates is purchased at initial issuance at
a premium and payments of principal on the related Mortgage Loans occur at a
rate faster than anticipated at the time of purchase, the purchaser's actual
yield to maturity will be lower than that assumed at the time of purchase.
Conversely, if a Class of Certificates is purchased at initial issuance at a
discount and payments of principal on the related
                                       49
<PAGE>   107
 
Mortgage Loans occur at a rate slower than that assumed at the time of purchase,
the purchaser's actual yield to maturity will be lower than that originally
anticipated. The effect of principal prepayments, liquidations and purchases on
yield will be particularly significant in the case of a Series of Certificates
having a Class entitled to payments of interest only or to payments of interest
that are disproportionately high relative to the principal payments to which
such Class is entitled. Such a Class will likely be sold at a substantial
premium to its principal balance and any faster than anticipated rate of
prepayments will adversely affect the yield to holders thereof. In certain
circumstances extremely rapid prepayments may result in the failure of such
holders to recoup their original investment. In addition, the yield to maturity
on certain other types of Classes of Certificates, including Accrual
Certificates, Certificates with a Pass-Through Rate which fluctuates inversely
with or at a multiple of an index or certain other Classes in a Series including
more than one Class of Certificates, may be relatively more sensitive to the
rate of prepayment on the related Mortgage Loans than other Classes of
Certificates. See "RISK FACTORS -- Yield and Prepayment Uncertainty" above.
 
     The timing of changes in the rate of principal payments on or repurchases
of the 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, the greater will be the effect on an investor's yield to maturity. As a
result, the effect on an investor's yield 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.
 
     When a full prepayment is made on a Mortgage Loan, the Mortgagor is charged
interest on the principal amount of the Mortgage Loan so prepaid for the number
of days in the month actually elapsed up to the date of the prepayment, at a
daily rate determined by dividing the Mortgage Rate by 365. Unless otherwise
specified in the related Prospectus Supplement, the effect of prepayments in
full will be to reduce the amount of interest paid in the following month to
holders of Certificates entitled to payments of interest because interest on the
principal amount of any Mortgage Loan so prepaid will be paid only to the date
of prepayment rather than for a full month. A partial prepayment of principal is
applied so as to reduce the outstanding principal balance of the related
Mortgage Loan as of the first day of the month in which such partial prepayment
is received. As a result, the effect of a partial prepayment on a Mortgage Loan
will be to reduce the amount of interest passed through to holders of
Certificates in the month following the receipt of such partial prepayment by an
amount equal to one month's interest at the applicable Pass-Through Rate or Net
Mortgage Rate, as the case may be, on the prepaid amount to the extent such
shortfalls in interest are not paid to the Certificateholders by the Master
Servicer as Compensating Interest (as defined in the related Prospectus
Supplement). If specified in the related Prospectus Supplement, such shortfalls
in collections of a full month's interest in connection with prepayments (a
"Prepayment Interest Shortfall") will be paid to the Certificateholders by the
Master Servicer as Compensating Interest to the extent described in such
Prospectus Supplement. See "DESCRIPTION OF THE CERTIFICATES -- Interest
Distributions" and "CERTAIN YIELD AND PREPAYMENT CONSIDERATIONS" in the related
Prospectus Supplement. Neither full nor partial principal prepayments are passed
through until the month following receipt. See "MATURITY AND PREPAYMENT
CONSIDERATIONS."
 
     The rate of defaults on the Mortgage Loans will also affect the rate and
timing of principal payments on the Mortgage Loans and thus the yield on the
Certificates. In general, defaults on mortgage loans are expected to occur with
greater frequency in their early years. The rate of default on Mortgage Loans
which are refinance mortgage loans, and on Mortgage Loans with high
Loan-to-Value Ratios, may be higher than for other types of Mortgage Loans.
Furthermore, the rate and timing of prepayments, defaults and liquidations on
the Mortgage Loans will be affected by the general economic condition of the
region of the country in which the related Mortgaged Properties are located. The
risk of delinquencies and loss is greater and prepayments are less likely in
regions where a weak or deteriorating economy exists, as may be evidenced by,
among other factors, increasing unemployment or falling property values.
 
     For each Mortgage Pool, if all necessary advances are made and if there is
no unrecoverable loss on any Mortgage Loan, the net effect of each distribution
respecting interest will be to pass-through to each holder of
                                       50
<PAGE>   108
 
a Class of Certificates entitled to payments of interest an amount which is
equal to one month's interest at the applicable Pass-Through Rate on such
Class's principal balance or notional balance, as adjusted downward to reflect
any decrease in interest caused by any principal prepayments and the addition of
any Deferred Interest to the principal balance of any Mortgage Loan. See
"DESCRIPTION OF THE CERTIFICATE -- Principal and Interest on the Certificates."
 
                     MATURITY AND PREPAYMENT CONSIDERATIONS
 
     As indicated above under "THE MORTGAGE POOLS," the original terms to
maturity of the Mortgage Loans in a given Mortgage Pool will vary depending upon
the type of Mortgage Loans included in such Mortgage Pool. The Prospectus
Supplement for a Series of Certificates will contain information with respect to
the types and maturities of the Mortgage Loans in the related Mortgage Pool. The
Mortgage Loans may be prepaid without penalty in full or in part at any time.
The prepayment experience of the Mortgage Loans in a Mortgage Pool will affect
the life and yield of the related Series of Certificates. For a discussion of
the prepayment risks associated with any Series of Certificates for which the
related Mortgage Pool contains Convertible Mortgage Loans, see "RISK
FACTORS -- Risks Presented by Convertible Mortgage Loans" and "DESCRIPTION OF
THE MORTGAGE POOL" in the related Prospectus Supplement.
 
     With respect to Balloon Loans, payment of the Balloon Amount (which, based
on the amortization schedule of such Mortgage Loans, is expected to be a
substantial amount) will generally depend on the Mortgagor's ability to obtain
refinancing of such Mortgage Loans or to sell the Mortgaged Property prior to
the maturity of the Balloon Loan. The ability to obtain refinancing will depend
on a number of factors prevailing at the time refinancing or sale is required,
including, without limitation, real estate values, the Mortgagor's financial
situation, prevailing mortgage loan interest rates, the Mortgagor's equity in
the related Mortgaged Property, tax laws and prevailing general economic
conditions. Neither the Seller or the Depositor, Bank of America, FSB nor any of
their affiliates will be obligated to refinance or repurchase any Mortgage Loan
or to sell the Mortgaged Property.
 
     A number of factors, including homeowner mobility, economic conditions,
enforceability of due-on-sale clauses, mortgage market interest rates,
solicitations and the availability of mortgage funds, affect prepayment
experience. The Mortgage Loans (other than ARM Loans) will contain due-on-sale
provisions permitting the mortgagee to accelerate the maturity of the Mortgage
Loan upon sale or certain transfers by the Mortgagor of the underlying Mortgaged
Property. The Master Servicer will generally enforce any due-on-sale clause to
the extent it has knowledge of the conveyance or proposed conveyance of the
underlying Mortgaged Property and it is entitled to do so under applicable law,
provided, however, that the Master Servicer will not take any action in relation
to the enforcement of any due-on-sale provision which would adversely affect or
jeopardize coverage under any applicable insurance policy. An ARM Loan is
assumable under certain conditions if the proposed transferee of the related
Mortgaged Property establishes its ability to repay the Mortgage Loan and, in
the reasonable judgment of the Master Servicer or any related Subservicer, the
security for the ARM Loan would not be impaired by the assumption. The extent to
which ARM Loans are assumed by purchasers of the Mortgaged Properties rather
than prepaid by the related Mortgagors in connection with the sales of the
Mortgaged Properties will affect the weighted average life of the related Series
of Certificates. See "DESCRIPTION OF THE CERTIFICATES -- Collection and Other
Servicing Procedures" and "Certain Legal Aspects of the Mortgage Loans and
Related Matters -- Enforceability of Certain Provisions" for a description of
certain provisions of the Pooling Agreement and certain legal developments that
may affect the prepayment experience on the Mortgage Loans.
 
     At the request of the Mortgagor, the Master Servicer may allow the
refinancing of a Mortgage Loan in any Trust Fund by accepting prepayments
thereon and permitting a new loan secured by a mortgage on the same property. In
the event of such a refinancing, the new loan would not be included in the
related Trust Fund and, therefore, such refinancing would have the same effect
as a prepayment in full of the related Mortgage Loan. The Master Servicer may,
from time to time, implement programs designed to encourage refinancing. Such
programs may include, without limitation, modifications of existing loans,
general or targeted solicitations, the offering of pre-approved applications,
reduced origination fees or closing costs, or
 
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<PAGE>   109
 
other financial incentives. In addition, the Master Servicer may encourage the
refinancing of Mortgage Loans, including defaulted Mortgage Loans, that would
permit creditworthy borrowers to assume the outstanding indebtedness of such
Mortgage Loans.
 
     All statistics known to the Depositor that have been compiled with respect
to prepayment experience on mortgage loans indicate that while some mortgage
loans may remain outstanding until their stated maturities, a substantial number
will be paid prior to their respective stated maturities.
 
     Although the Mortgage Rates on ARM Loans and Net 5 Loans will be subject to
periodic adjustments, such adjustments generally will, as specified in the
related Prospectus Supplement, (i) not increase or decrease such Mortgage Rates
by more than a stated percentage amount on each adjustment date, (ii) not
increase such Mortgage Rates over a fixed percentage amount during the life of
any ARM Loan and (iii) be based on an index (which may not rise and fall
consistently with mortgage interest rates) plus the related Note Margin (which
may be different from margins being used at the time for newly originated
adjustable rate mortgage loans). As a result, the Mortgage Rates on the ARM
Loans or Net 5 Loans, as applicable, in a Mortgage Pool at any time may not
equal the prevailing rates for similar, newly originated mortgage loans. In
certain rate environments, the prevailing rates on fixed-rate mortgage loans may
be sufficiently low in relation to the then-current Mortgage Rates on ARM Loans
or Net 5 Loans that the rate of prepayment may increase as a result of
refinancings. There can be no certainty as to the rate of prepayments on the
Mortgage Loans during any period or over the life of any Series of Certificates.
 
     Under certain circumstances, the Master Servicer or the Depositor or, if
specified in the related Prospectus Supplement, the holders of the REMIC
Residual Certificates may have the option to purchase the Mortgage Loans in a
Trust Fund. See "THE POOLING AGREEMENT -- Termination; Retirement of
Certificates."
 
          CERTAIN LEGAL ASPECTS OF MORTGAGE LOANS AND RELATED MATTERS
 
     The following discussion contains summaries of certain legal aspects of
mortgage loans that are general in nature. Because such legal aspects are
governed in part by state law (which laws may differ substantially from state to
state), the summaries do not purport to be complete, to reflect the laws of any
particular state or to encompass the laws of all states in which the Mortgaged
Properties may be situated. If the Mortgaged Properties relating to a Series of
Certificates are concentrated in a particular state or states, the related
Prospectus Supplement will contain a summary of relevant laws of such state or
states to the extent such laws are not addressed generally in the following
discussion. The summaries are qualified in their entirety by reference to the
applicable federal and state laws governing the Mortgage Loans.
 
GENERAL
 
     The Mortgage Loans (other than Cooperative Loans) will be secured by either
deeds of trust or mortgages, depending upon the prevailing practice in the state
in which the related Mortgaged Property is located. In some states, a mortgage
or deed of trust creates a lien upon the real property encumbered by the
mortgage. In other states, the mortgage or deed of trust conveys legal title to
the property to the mortgagee subject to a condition subsequent (i.e., the
payment of the indebtedness secured thereby). It is not prior to the lien for
real estate taxes and assessments and other charges imposed under governmental
police powers. Priority with respect to such instruments depends on their terms
and in some cases on the terms of separate subordination or inter-creditor
agreements, and generally on the order of recordation of the mortgage in the
appropriate recording office. There are two parties to a mortgage, the
mortgagor, who is 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. In the case of a land trust, there are three
parties because title to the property is held by a land trustee under a land
trust agreement of which the borrower is the beneficiary; at origination of a
mortgage loan, the borrower executes a separate undertaking to make payments on
the mortgage note. Although a deed of trust is similar to a mortgage, a deed of
trust has three parties: the trustor, who is the borrower/homeowner; the
beneficiary, who is the lender; and a third-party grantee called the trustee.
Under a deed of trust, the borrower grants the property, irrevocably until the
debt is paid, in trust,
                                       52
<PAGE>   110
 
generally with a power of sale, to the trustee to secure payment of the
obligation. The trustee's authority under a deed of trust and the mortgagee's
authority under a mortgage are governed by the law of the state in which the
real property is located, the express provisions of the deed of trust or
mortgage and, in certain deed of trust transactions, the directions of the
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 include Cooperative Loans. Each Cooperative
Note will be secured by a security interest in shares issued by the related
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.
 
     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 is 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 the Mortgage Loans, the collateral
securing the 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
 
                                       53
<PAGE>   111
 
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 related 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 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
Section 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 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
 
     Although a deed of trust may also be foreclosed by judicial action,
foreclosure of a deed of trust is generally accomplished by a nonjudicial
trustee's sale under a specific provision in the deed of trust which authorizes
the trustee to sell the property upon any default by the borrower under the
terms of the note or deed of trust. In addition to any notice requirements
contained in a deed of trust, in some states, the trustee must record a notice
of default and send a copy to the borrower/trustor and to any person who has
recorded a request for a copy of notice of default and notice of sale. In
addition, in some states, the trustee must provide notice to any other
individual having an interest of record in the real property, including any
junior lienholders. If the deed of trust is not reinstated within a specified
period, a notice of sale must be posted in a public place and, in most states,
published for a specific period of time in one or more newspapers. In addition,
some states' laws require that a copy of the notice of sale be posted on the
property and sent to all parties having an interest of record in the real
property.
 
     Foreclosure of a mortgage generally is accomplished by judicial action.
Generally, the action is initiated by the service of legal pleadings upon all
parties having an interest of record in the real property. Delays in completion
of the foreclosure may result from difficulties in locating and serving
necessary parties, including borrowers located outside the jurisdiction in which
the mortgaged property is located. If the mortgagee's right to foreclose is
contested, the legal proceedings necessary to resolve the issue can be
time-consuming.
 
     In some states, the borrower-trustor has the right to reinstate the loan at
any time following default until shortly before the trustee's sale. In general,
in such states, the borrower, 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.
 
                                       54
<PAGE>   112
 
     In the case of foreclosure under either a mortgage or a deed of trust, the
sale by the referee or other designated officer or by the trustee generally is a
public sale. However, because of the difficulty a potential buyer at the sale
would have in determining the exact status of title and because 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 a
foreclosure sale. Rather, it is common for the lender to purchase the property
from the trustee or referee for a credit bid less than or equal to the unpaid
principal amount of the mortgage or deed of trust, accrued and unpaid interest
and the expense of foreclosure. Generally, state law controls the amount of
foreclosure costs and expenses, including attorneys' fees, which may be
recovered by a lender. Thereafter, subject to the right of the borrower in some
states to remain in possession during the redemption period, the lender will
assume the burdens of ownership, including obtaining hazard insurance and making
such repairs at its own expense as are necessary to render the property suitable
for sale. Generally, the lender will 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 and, in some
states, the lender may be entitled to a deficiency judgment. Any loss may be
reduced by the receipt of any mortgage insurance proceeds or other forms of
credit enhancement for a Series of Certificates. See "DESCRIPTION OF CREDIT
ENHANCEMENTS."
 
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 or occupancy agreement, 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
agreements 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
 
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<PAGE>   113
 
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 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 a
mortgage, the borrower and foreclosed junior lienors or other parties are given
a statutory period (generally ranging from six months to two years) in which to
redeem the property from the foreclosure sale. In some states, redemption may
occur only upon payment of the entire principal balance of the loan, accrued
interest and expenses of foreclosure. In other states, redemption may be
authorized if the former borrower pays only a portion of the sums due. The
effect of a statutory right of redemption is to diminish the ability of the
lender to sell the foreclosed property. The rights of redemption would defeat
the title of any purchaser subsequent to foreclosure or sale under a deed of
trust. Consequently, the practical effect of the redemption right is to force
the lender to maintain the property and pay the expenses of ownership until the
redemption period has expired.
 
ANTI-DEFICIENCY LEGISLATION AND OTHER LIMITATIONS ON LENDERS
 
     Certain states have imposed statutory prohibitions which limit the remedies
of a beneficiary under a deed of trust or a mortgagee under a mortgage. In some
states (including California), statutes limit the right of the beneficiary or
mortgagee to obtain a deficiency judgment against the borrower following
foreclosure. A deficiency judgment is a personal judgment against the former
borrower 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. In
the case of a Mortgage Loan secured by a property owned by a trust where the
Mortgage Note is executed on behalf of the trust, a deficiency judgment against
the trust following foreclosure or sale under a deed of trust, even if
obtainable under applicable law, may be of little value to the mortgagee or
beneficiary if there are no trust assets against which such deficiency judgment
may be executed. Some state statutes require the beneficiary or mortgagee 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 borrower. In certain other states, the lender has the option of bringing a
personal action against the borrower on the debt without first exhausting such
security; however in some of these states, the lender, following judgment on
such personal action, may be deemed to have elected a remedy and may be
precluded from exercising remedies with respect to the security. Consequently,
the practical effect of the election requirement, in those states permitting
such
 
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<PAGE>   114
 
election, is that lenders will usually proceed against the security first rather
than bringing a personal action against the borrower.
 
     Finally, in certain other states, statutory provisions limit any deficiency
judgment against the borrower following a foreclosure to the excess of the
outstanding debt over the fair value of the property at the time of the public
sale. The purpose of these statutes is generally to prevent a beneficiary or
mortgagee from obtaining a large deficiency judgment against the former borrower
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 laws limiting or prohibiting deficiency judgments, numerous
other federal and state 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 realize upon its collateral and/or
enforce a deficiency judgment. For example, under the federal bankruptcy law,
all actions against the debtor, the debtor's property and any co-debtor are
automatically stayed upon the filing of a bankruptcy petition. Moreover, a court
having federal bankruptcy jurisdiction may permit a debtor through its Chapter
11 or Chapter 13 rehabilitative plan to cure a monetary default in respect of a
mortgage loan on a debtor'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 final judgment of
foreclosure had been entered in state court 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.
 
     Courts with federal bankruptcy jurisdiction have also indicated that the
terms of a mortgage loan secured by property which is not the principal
residence of the debtor may be modified. These courts have allowed modifications
that include reducing the amount of each monthly payment, changing the rate of
interest, altering the repayment schedule, forgiving all or a portion of the
debt and reducing the lender's security interest to the value of the residence,
thus leaving the lender 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. Generally, however, the terms of a mortgage loan secured only
by a mortgage on real property that is the debtor's principal residence may not
be modified pursuant to a plan confirmed pursuant to Chapter 11 or Chapter 13
except with respect to mortgage payment arrearages, which may be cured within a
reasonable time period.
 
     Certain tax liens arising under the Code may, in certain circumstances,
have priority over the lien of a mortgage or deed of trust. This may have the
effect of delaying or interfering with the enforcement of rights with respect to
a defaulted Mortgage Loan. In addition, substantive requirements are imposed
upon mortgage lenders in connection with the origination and the servicing of
mortgage loans by numerous federal and some state consumer protection laws.
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 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.
 
ENVIRONMENTAL LEGISLATION
 
     Real property pledged as security to a lender may be subject to unforeseen
environmental risks. Most environmental statutes create obligations for any
party that can be classified as the "owner" or "operator" of a "facility"
(referring to both operating facilities and to real property). Under the laws of
some states and under the federal Comprehensive Environmental Response,
Compensation and Liability Act of 1980, 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, if agents or
employees of the lender have become
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<PAGE>   115
 
sufficiently involved in the operations of the borrower or, subsequent to a
foreclosure, in the management of the property. Such liability may arise
regardless of whether the environmental damage or threat was caused by a prior
owner.
 
     Under federal and certain state laws, contamination of a property may give
rise to a lien on the property to assure the payment of clean-up costs. Under
federal law and in several states, such a lien has priority over the lien of an
existing mortgage against such property. If a lender is or becomes directly
liable for environmental remediation as an "owner" following a foreclosure, it
may be precluded from bringing an action for contribution against the owner or
operator who created the environmental hazard. Such clean-up costs may be
substantial. It is possible that such costs could become a liability of the
related Trust Fund and occasion a loss to Certificateholders in certain
circumstances described above if such remedial costs were incurred.
 
     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.
 
ENFORCEABILITY OF CERTAIN PROVISIONS
 
     The Mortgage Loans generally contain due-on sale clauses. These clauses
permit the lender to accelerate the maturity of the loan if the borrower sells,
transfers or conveys the property. The enforceability of these clauses has been
the subject of legislation or 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") preempts
state constitutional, statutory and case law that prohibit 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.
 
     The Garn-St Germain Act also sets forth nine specific instances in which a
mortgage lender covered by the Garn-St Germain Act may not exercise a
due-on-sale clause, notwithstanding the fact that a transfer of the mortgaged
property may have occurred. These include intra-family transfers, certain
transfers by operation of law, leases of fewer than three years and the creation
of a junior encumbrance. Regulations promulgated under the Garn-St Germain Act
also prohibit the imposition of a prepayment penalty upon the acceleration of a
loan pursuant to a due-on-sale clause.
 
     The inability to enforce a due-on-sale clause may result in a mortgage loan
bearing an interest rate below the current market rate being assumed by a new
home buyer rather than being paid off, 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.
 
     Upon foreclosure, courts have imposed general equitable principles. These
equitable principles are generally designed to relieve the borrower 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 expensive actions to determine the causes for the
borrower's default and the likelihood that the borrower will be able to
reinstate the loan. In some cases, courts have required that lenders reinstate
loans or recast payment schedules in order to accommodate borrowers who are
suffering from temporary financial disability. In other cases, courts have
limited the right of the lender to foreclose if the default under the mortgage
instrument is not monetary, such as the borrower failing to adequately maintain
the property or the borrower executing a second mortgage or deed of trust
affecting the property. Finally, 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 borrowers under deeds of trust or
mortgages 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 sale by a trustee under a deed of trust, or under a
mortgage having a power of sale, does not involve sufficient state action to
afford constitutional protections to the borrower.
 
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<PAGE>   116
 
APPLICABILITY OF USURY LAWS
 
     Title V of the Depository Institutions Deregulation and Monetary Control
Act of 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 Office
of Thrift Supervision is authorized to issue rules and regulations and to
publish interpretations governing implementation of Title V. The statute
authorized 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 by the law to adopt a provision limiting discount points or
other charges on mortgage loans covered by Title V. Certain states have taken
action to reimpose interest rate limits or to limit discount points or other
charges.
 
     As indicated above under "MORTGAGE LOAN PROGRAM -- Representations and
Warranties by Sellers," each Seller of a Mortgage Loan will have represented
that each Mortgage Loan sold by it was originated in compliance with then
applicable state laws, including usury laws, in all material respects. However,
the Mortgage Rates on the Mortgage Loans will be subject to applicable usury
laws as in effect from time to time.
 
ALTERNATIVE MORTGAGE INSTRUMENTS
 
     Alternative mortgage instruments, including adjustable rate mortgage loans
and early ownership 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, (i) 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, (ii) 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
(iii) all other non-federally chartered housing creditors, including
state-chartered savings and loan associations, state-chartered savings banks and
mutual savings banks and mortgage banking companies, may originate alternative
mortgage instruments in accordance with the regulations promulgated by the
Federal Home Loan Bank Board, predecessor to 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.
 
SOLDIERS' AND SAILORS' CIVIL RELIEF ACT OF 1940
 
     Under the terms of the Soldiers' and Sailors' Civil Relief Act of 1940, as
amended (the "Relief Act"), a borrower who enters military service after the
origination of such borrower's mortgage loan (including a borrower who was in
reserve status and is called to active duty after origination of the mortgage
loan), may not be charged interest (including fees and charges) above an annual
rate of 6% during the period of such borrower's active duty status, unless a
court orders otherwise upon application of the lender. The Relief Act applies to
borrower who are members of the Army, Navy, Air Force, Marines, National Guard,
Reserves, Coast Guard, and officers of the U.S. Public Health Service assigned
to duty with the military. Because the Relief Act applies to borrowers who enter
military service (including reservists who are called to active duty) after
origination of the related mortgage loan, no information can be provided as to
the number of mortgage loans that may be affected by the Relief Act. With
respect to Mortgage Loans included in a Trust Fund, application of the Relief
Act would adversely affect, for an indeterminate period of time, the ability of
the Master Servicer to collect full amounts of interest on certain of the
Mortgage Loans. Any shortfall in interest collections resulting from the
application of the Relief Act or similar legislation or regulations, which would
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<PAGE>   117
 
not be recoverable from the related Mortgage Loans, would result in a reduction
of the amounts distributable to the holders of the related Certificates, and
would not be covered by Advances or any form of credit enhancement provided in
connection with the related Series of Certificates. In addition, the Relief Act
imposes limitations that would impair the ability of the Master Servicer to
foreclose on an affected Mortgage Loan during the Mortgagor's period of active
duty status, and, under certain circumstances, during an additional three month
period thereafter. Thus, in the event that the Relief Act or similar legislation
or regulations applies to any Mortgage Loan which goes into default, there may
be delays in payment and losses on the related Certificates in connection
therewith. Any other interest shortfalls, deferrals or forgiveness of payments
on the Mortgage Loans resulting from similar legislation or regulations may
result in delays in payments or losses to Certificateholders of the related
Series.
 
                        FEDERAL INCOME TAX CONSEQUENCES
 
GENERAL
 
     The following is a general discussion of anticipated material federal
income tax consequences of the purchase, ownership and disposition of the
Certificates offered hereunder. This discussion is directed solely to
Certificateholders that hold the Certificates as "capital assets" within the
meaning of Section 1221 of the Code and does not purport to discuss all federal
income tax consequences that may be applicable to particular categories of
investors, some of which (such as banks, insurance companies and foreign
investors) may be subject to special rules. Section 1221 of the Code defines
"capital assets" generally as property other than (i) property held for sale to
customers or (ii) real, tangible personal, property used in a trade or business.
Further, the authorities on which this discussion, and the opinion referred to
below, are based are subject to change or differing interpretations, which could
apply retroactively. Taxpayers and preparers of tax returns (including those
filed by any REMIC or other issuer) should be aware that under applicable
Treasury regulations a provider of advice on specific issues of law is not
considered an income tax return preparer unless the advice (i) is given with
respect to events that have occurred at the time the advice is rendered and is
not given with respect to the consequences of contemplated actions, and (ii) is
directly relevant to the determination of an entry on a tax return. Accordingly,
taxpayers should consult their own tax advisors and tax return preparers
regarding the preparation of any item on a tax return, even where the
anticipated tax treatment has been discussed herein. In addition to the federal
income tax consequences described herein, potential investors should consider
the state and local tax consequences, if any, of the purchase, ownership and
disposition of the Certificates. See "STATE AND OTHER TAX CONSEQUENCES."
Certificateholders are advised to consult their own tax advisors concerning the
federal, state, local or other tax consequences to them of the purchase,
ownership and disposition of the Certificates offered hereunder. Additional
material income tax consequences may be set forth in the related Prospectus
Supplement.
 
     The following discussion addresses securities of two general types: (i)
certificates ("Grantor Trust Certificates") representing interests in a Trust
Fund ("Grantor Trust Fund") which the Master Servicer will covenant not to elect
to have treated as a real estate mortgage investment conduit ("REMIC"), and (ii)
certificates ("REMIC Certificates") representing interests in a Trust Fund, or a
portion thereof, which the Master Servicer will covenant to elect to have
treated as a REMIC under Sections 860A through 860G (the "REMIC Provisions") of
the Code. The Prospectus Supplement for each Series of Certificates will
indicate whether a REMIC election (or elections) will be made for the related
Trust Fund and, if such an election is to be made, will identify all "regular
interests" and "residual interests" in the REMIC. For purposes of this tax
discussion, references to a "Certificateholder" or a "holder" are to the
beneficial owner of a Certificate.
 
     The following discussion is based in part upon the rules governing original
issue discount that are set forth in Sections 1271-1273 and 1275 of the Code and
in the Treasury regulations issued thereunder (the "OID Regulations"), and in
part upon the REMIC Provisions and the Treasury regulations issued thereunder
(the "REMIC Regulations"). The OID Regulations, which are effective with respect
to debt instruments issued on or after April 4, 1994, do not adequately address
certain issues relevant to, and in some instances provide that they are not
applicable to, securities such as the Certificates.
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<PAGE>   118
 
GRANTOR TRUST FUNDS
 
     Classification of Grantor Trust Funds
 
     With respect to each Series of Grantor Trust Certificates, Orrick,
Herrington & Sutcliffe LLP, counsel to the Depositor ("Special Tax Counsel"), is
of the opinion that, assuming compliance with all provisions of the related
Pooling Agreement, the related Grantor Trust Fund will be Classified as a
grantor trust under subpart E, part I of subchapter J of the Code and not as a
partnership or an association taxable as a corporation. Accordingly, each holder
of a Grantor Trust Certificate generally will be treated as the owner of an
interest in the Mortgage Loans included in the Grantor Trust Fund. The following
general discussion of the anticipated federal income tax consequences of the
purchase, ownership and disposition of the Grantor Trust Certificates together
with the discussion, if any, under the heading "FEDERAL INCOME TAX CONSEQUENCES"
in the Prospectus Supplement represents the opinion of Special Tax Counsel,
subject to any qualifications set forth herein and therein. Special Tax Counsel
have prepared or reviewed the statements in this Prospectus under the heading
"FEDERAL INCOME TAX CONSEQUENCES" and in the Prospectus Supplement under the
heading "FEDERAL INCOME TAX CONSEQUENCES," if any, and are of the opinion that
such statements are correct in all material respects. A copy of the opinion of
Special Tax Counsel relating to such statements will be included in a Current
Report on Form 8-K filed prior to the Delivery Date with respect to any Series
of Grantor Trust Certificates. Such statements are intended as an explanatory
discussion of the possible effects of the classification of the Trust Fund as a
grantor trust for federal income tax purposes on investors generally and of
related tax matters affecting investors generally, but do not purport to furnish
information in the level of detail or with attention to an investor's specific
tax circumstances that would be provided by an investor's own tax advisor.
Accordingly, each investor is advised to consult its own tax advisors with
regard to the tax consequences to it of investing in the Grantor Trust
Certificates.
 
     For purposes of the following discussion, a Grantor Trust Certificate
representing an undivided equitable ownership interest in the principal of the
Mortgage Loans constituting the related Grantor Trust Fund, together with
interest thereon at a pass-through rate, will be referred to as a "Grantor Trust
Fractional Interest Certificate." A Grantor Trust Certificate representing
ownership of all or a portion of the difference between interest paid on the
Mortgage Loans constituting the related Grantor Trust Fund (net of normal
administration fees and any Retained Yield) and interest paid to the holders of
Grantor Trust Fractional Interest Certificates issued with respect to such
Grantor Trust Fund will be referred to as a "Grantor Trust Strip Certificate." A
Grantor Trust Strip Certificate may also evidence a nominal ownership interest
in the principal of the Mortgage Loans constituting the related Grantor Trust
Fund.
 
CHARACTERIZATION OF INVESTMENTS IN GRANTOR TRUST CERTIFICATES
 
     Grantor Trust Fractional Interest Certificates
 
     In the case of Grantor Trust Fractional Interest Certificates, if so
specified in the related Prospectus Supplement and subject to the discussion
below with respect to Buydown Mortgage Loans, Grantor Trust Fractional Interest
Certificates will represent interests in (i) "loans . . . secured by an interest
in real property" within the meaning of Section 7701(a)(19)(C)(v) of the Code;
(ii) "obligation[s] (including any participation or certificate of beneficial
ownership therein) which . . . [are] principally secured by an interest in real
property" within the meaning of Section 860G(a)(3)(A) of the Code; and (iii)
"real estate assets" within the meaning of Section 856(c)(4)(A) of the Code. In
addition, if so specified in the related Prospectus Supplement, interest on
Grantor Trust Fractional Interest Certificates will be considered "interest on
obligations secured by mortgages on real property or on interests in real
property" within the meaning of Section 856(c)(3)(B) of the Code. Special Tax
Counsel provides no assurances as to the treatment of Grantor Trust Fractional
Interest Certificates under the Code provisions described in this paragraph,
except to the extent specified in the related Prospectus Supplement.
 
     The assets constituting certain Grantor Trust Funds may include Buydown
Mortgage Loans. The characterization of an investment in Buydown Mortgage Loans
will depend upon the precise terms of the related Buydown Agreement, but to the
extent that such Buydown Mortgage Loans are secured by a bank account or other
personal property, they may not be treated in their entirety as assets described
in the
 
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<PAGE>   119
 
foregoing sections of the Code. No directly applicable precedents exist with
respect to the federal income tax treatment or the characterization of
investments in Buydown Mortgage Loans. Accordingly, holders of Grantor Trust
Certificates should consult their own tax advisors with respect to the
characterization of investments in Grantor Trust Certificates representing an
interest in a Grantor Trust Fund that includes Buydown Mortgage Loans.
 
     Grantor Trust Strip Certificates
 
     Even if Grantor Trust Strip Certificates evidence an interest in a Grantor
Trust Fund consisting of Mortgage Loans that are "real estate assets" within the
meaning of Section 856(c)(4)(A) of the Code, and the interest on which is
"interest on obligations secured by mortgages on real property" within the
meaning of Section 856(c)(3)(B) of the Code, it is unclear whether the Grantor
Trust Strip Certificates, and the income therefrom, will be so characterized.
However, the policies underlying such sections (namely, to encourage or require
investments in mortgage loans by thrift institutions and real estate investment
trusts) may suggest that such characterization is appropriate. Counsel to the
Depositor will not deliver any opinion on these questions. Prospective
purchasers to which such characterization of an investment in Grantor Trust
Strip Certificates is material should consult their tax advisors regarding
whether the Grantor Trust Strip Certificates, and the income therefrom, will be
so characterized.
 
     The Grantor Trust Strip Certificates will be "obligation[s] (including any
participation or certificate of beneficial ownership therein) which . . . [are]
principally secured by an interest in real property" within the meaning of
Section 860G(a)(3)(A) of the Code.
 
     Taxation of Owners of Grantor Trust Fractional Interest Certificates
 
     Holders of a particular Series of Grantor Trust Fractional Interest
Certificates generally will be required to report on their federal income tax
returns their shares of the entire income from the Mortgage Loans (including
amounts used to pay reasonable servicing fees and other expenses) and will be
entitled to deduct their shares of any such reasonable servicing fees and other
expenses. Because of stripped interests, market or original issue discount, or
premium, the amount includible in income on account of a Grantor Trust
Fractional Interest Certificate may differ significantly from the amount
distributable thereon representing interest on the Mortgage Loans. Under Section
67 of the Code, an individual, estate or trust holding a Grantor Trust
Fractional Interest Certificate directly or through certain pass-through
entities will be allowed a deduction for such reasonable servicing fees and
expenses only to the extent that the aggregate of such holder's miscellaneous
itemized deductions exceeds two percent of such holder's adjusted gross income.
In addition, Section 68 of the Code provides that the amount of itemized
deductions otherwise allowable for an individual whose adjusted gross income
exceeds a specified amount will be reduced by the lesser of (i) 3% of the excess
of the individual's adjusted gross income over such amount or (ii) 80% of the
amount of itemized deductions otherwise allowable for the taxable year. The
amount of additional taxable income reportable by holders of Grantor Trust
Fractional Interest Certificates who are subject to the limitations of either
Section 67 or Section 68 of the Code may be substantial. Further,
Certificateholders (other than corporations) subject to the alternative minimum
tax may not deduct miscellaneous itemized deductions in determining such
holder's alternative minimum taxable income. Although it is not entirely clear,
it appears that in transactions in which multiple Classes of Grantor Trust
Certificates (including Grantor Trust Strip Certificates) are issued, such fees
and expenses should be allocated among the Classes of Grantor Trust Certificates
using a method that recognizes that each such Class benefits from the related
services. In the absence of statutory or administrative clarification as to the
method to be used, it currently is intended to base information returns or
reports to the Internal Revenue Service (the "IRS") and Certificateholders on a
method that allocates such expenses among Classes of Grantor Trust Certificates
with respect to each period based on the distributions made to each such Class
during that period.
 
     The federal income tax treatment of Grantor Trust Fractional Interest
Certificates of any Series will depend on whether they are subject to the
"stripped bond" rules of Section 1286 of the Code. Grantor Trust Fractional
Interest Certificates may be subject to those rules if (i) a Class of Grantor
Trust Strip Certificates is issued as part of the same Series of Certificates or
(ii) the Depositor or any of its affiliates retains (for its
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<PAGE>   120
 
own account or for purposes of resale) a right to receive a specified portion of
the interest payable on the Mortgage Loans. Further, the IRS has ruled that an
unreasonably high servicing fee retained by a seller or servicer will be treated
as a retained ownership interest in mortgages that constitutes a stripped
coupon. For purposes of determining what constitutes reasonable servicing fees
for various types of mortgages the IRS has established certain "safe harbors."
The servicing fees paid with respect to the Mortgage Loans for certain Series of
Grantor Trust Certificates may be higher than the "safe harbors" and,
accordingly, may not constitute reasonable servicing compensation. The related
Prospectus Supplement will include information regarding servicing fees paid to
the Master Servicer, any subservicer or their respective affiliates necessary to
determine whether the preceding "safe harbor" rules apply.
 
     If Stripped Bond Rules Apply
 
     If the stripped bond rules apply, each Grantor Trust Fractional Interest
Certificate will be treated as having been issued with "original issue discount"
within the meaning of Section 1273(a) of the Code, subject, however, to the
discussion below regarding the treatment of certain stripped bonds as market
discount bonds and the discussion regarding de minimis market discount. See
"-- Taxation of Owners of Grantor Trust Fractional Interest
Certificates -- Market Discount." Under the stripped bond rules, the holder of a
Grantor Trust Fractional Interest Certificate (whether a cash or accrual method
taxpayer) will be required to report interest income from its Grantor Trust
Fractional Interest Certificate for each month in an amount equal to the income
that accrues on such Certificate in that month calculated under a constant yield
method, in accordance with the rules of the Code relating to original issue
discount.
 
     The original issue discount on a Grantor Trust Fractional Interest
Certificate will be the excess of such Certificate's stated redemption price
over its issue price. The issue price of a Grantor Trust Fractional Interest
Certificate as to any purchaser will be equal to the price paid by such
purchaser for the Grantor Trust Fractional Interest Certificate. The stated
redemption price of a Grantor Trust Fractional Interest Certificate will be the
sum of all payments to be made on such Certificate, as well as such
Certificate's share of reasonable servicing fees and other expenses, other than
payments of "qualified stated interest," if any. See "-- Taxation of Owners of
Grantor Trust Fractional Interest Certificates -- If Stripped Bond Rules Do Not
Apply" for a definition of "qualified stated interest." In general, the amount
of such income that accrues in any month would equal the product of such
holder's adjusted basis in such Grantor Trust Fractional Interest Certificate at
the beginning of such month (see "Sales of Grantor Trust Certificates") and the
yield of such Grantor Trust Fractional Interest Certificate to such holder. Such
yield would be computed at the rate (assuming compounding based on the regular
interval between payment dates) that, if used to discount the holder's share of
future payments on the Mortgage Loans, would cause the present value of those
future payments to equal the price at which the holder purchased such
Certificate. In computing yield under the stripped bond rules, a
Certificateholder's share of future payments on the Mortgage Loans will not
include any payments made in respect of any ownership interest in the Mortgage
Loans retained by the Depositor, the Master Servicer, any subservicer or their
respective affiliates, but will include such Certificateholder's share of any
reasonable servicing fees and other expenses.
 
     Section 1272(a)(6) of the Code requires (i) the use of a reasonable
prepayment assumption in accruing original issue discount and (ii) adjustments
in the accrual of original issue discount when prepayments do not conform to the
prepayment assumption with respect to the Grantor Trust Fractional Interest
Certificates. It is uncertain whether the assumed prepayment rate should be
determined based on conditions at the time of the first sale of the Grantor
Trust Fractional Interest Certificate or, with respect to any subsequent holder,
at the time of purchase of the Grantor Trust Fractional Interest Certificate by
that holder. Certificateholders are advised to consult their own tax advisors
concerning reporting original issue discount in general and, in particular, how
a prepayment assumption should be used in reporting original issue discount with
respect to Grantor Trust Fractional Interest Certificates.
 
     In the case of a Grantor Trust Fractional Interest Certificate acquired at
a price equal to the principal amount of the Mortgage Loans allocable to such
Certificate, the use of a prepayment assumption will not ordinarily have any
significant effect on the yield used in calculating accruals of interest income.
In the case, however, of a Grantor Trust Fractional Interest Certificate
acquired at a discount or premium (that is, at a
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<PAGE>   121
 
price less than or greater than such principal amount, respectively), the use of
a prepayment assumption will increase or decrease such yield, and thus
accelerate or decelerate, respectively, the reporting of income.
 
     When a Mortgage Loan prepays in full, it appears that the holder of a
Grantor Trust Fractional Interest Certificate acquired at a discount or a
premium generally will not recognize a separate item of income or loss. Instead,
a prepayment should be treated as a partial payment of the stated redemption
price of the Grantor Trust Fractional Interest Certificate and accounted for
under a method similar to that described for taking account of original issue
discount on REMIC Regular Certificates. See "-- REMICs -- Taxation of Owners of
REMIC Regular Certificates -- Original Issue Discount." It is unclear what
adjustments will be required to reflect differences between an assumed
prepayment rate and the actual rate of prepayments.
 
     In the absence of statutory or administrative clarification, it is
currently intended to base information reports or returns to the IRS and
Certificateholders in transactions subject to the stripped bond rules on a
prepayment assumption (the "Prepayment Assumption") that will be disclosed in
the related Prospectus Supplement and on a constant yield computed using a
representative initial offering price for each Class of Certificates. However,
neither the Depositor nor the Master Servicer will make any representation that
the Mortgage Loans will in fact prepay at a rate conforming to such Prepayment
Assumption or any other rate and Certificateholders should bear in mind that the
use of a representative initial offering price will mean that such information
returns or reports, even if otherwise accepted as accurate by the IRS, will in
any event be accurate only as to the initial Certificateholders of each Series
who bought at that price.
 
     Under Treasury regulation Section 1.1286-1T, certain stripped bonds are to
be treated as market discount bonds and, accordingly, any purchaser of such a
bond is to account for any discount on the bond as market discount rather than
original issue discount. This treatment only applies, however, if immediately
after the most recent disposition of the bond by a person stripping one or more
coupons from the bond and disposing of the bond or coupon (i) there is no
original issue discount (or only a de minimis amount of original issue discount)
or (ii) the annual stated rate of interest payable on the original bond is no
more than one percentage point lower than the gross interest rate payable on the
original mortgage loan (before subtracting any servicing fee or any stripped
coupon). If interest payable on a Grantor Trust Fractional Interest Certificate
is more than one percentage point lower than the gross interest rate payable on
the Mortgage Loans, the related Prospectus Supplement will disclose that fact.
If the original issue discount or market discount on a Grantor Trust Fractional
Interest Certificate determined under the stripped bond rules is less than 0.25%
of the stated redemption price multiplied by the weighted average maturity of
the Mortgage Loans, then such original issue discount or market discount will be
considered to be de minimis. Original issue discount or market discount of only
a de minimis amount will be included in income in the same manner as de minimis
original issue and market discount described in "-- Taxation of Owners of
Grantor Trust Fractional Interest Certificates -- If Stripped Bond Rules Do Not
Apply" and "-- Market Discount."
 
     If Stripped Bond Rules Do Not Apply
 
     Subject to the discussion below on original issue discount, if the stripped
bond rules do not apply to a Grantor Trust Fractional Interest Certificate, the
Certificateholder will be required to report its share of the interest income on
the Mortgage Loans in accordance with such Certificateholder's normal method of
accounting.
 
     Recently enacted amendments to Section 1272(a)(6) of the Code require the
use of a prepayment assumption in determining the existence and accrual of
original issue discount associated with pools of debt instruments whose yield
may be affected by prepayments. No regulations have been issued interpreting the
application of this provision to securities such as the Grantor Trust Fractional
Interest Certificates nor do the committee reports prepared by those
Congressional committees that examined such provision in the course of its
enactment provide guidance as to its intended application to such securities. In
the absence of such guidance, various interpretations are possible. For example,
the provision could be interpreted as requiring the pool of mortgage loans
underlying the Grantor Trust Fractional Interest Certificates to be segregated
into two subpools consisting respectively of those mortgage loans that had
original issue discount upon their origination (the "OID Pool") and those
mortgage loans that did not have original issue discount upon their origination
 
                                       64
<PAGE>   122
 
(the "Non-OID Pool"). A holder of a Grantor Trust Fractional Interest
Certificate would be required to report its share of the interest income on the
Mortgage Loans in the Non-OID Pool in accordance with such holder's normal
method of accounting and, to the extent that the portion of its purchase price
for such Certificates properly allocable to its interest in the Non-OID Pool
were less than its share of the aggregate principal amount of the Mortgage Loans
in the Non-OID Pool, would be subject to the Market Discount rules described
below under "Market Discount" or "REMICS -- Taxation of Owners of REMIC Regular
Certificates -- Market Discount." Such holder would be required to treat the
portion of its Certificate representing an interest in the OID Pool as a single
debt instrument issued on the Closing Date with original issue discount equal to
its pro-rata share of the aggregate of the unaccrued original issue discount on
the Mortgage Loans in the OID Pool as of such date and subject to the rules for
reporting original issue discount described under "REMICS -- Taxation of Owners
of REMIC Regular Certificates -- Original Issue Discount." To the extent that
the portion of such holder's purchase price for its Certificate properly
allocable to the OID Pool represented a discount greater than such holder's
pro-rata share of the aggregate original issue discount on the Mortgage Loans in
the OID Pool, such holder would be subject to the Market Discount Rules
described below under "REMICS -- Taxation of Owners of REMIC Regular
Certificates -- Market Discount."
 
     Alternatively, a Grantor Trust Fractional Interest Certificate could be
treated as a single debt instrument issued on the Closing Date and subject to
the rules described under "REMICS -- Taxation of Owners of REMIC Regular
Certificates -- Original Issue Discount" and "-- Market Discount." Other
interpretations of the application of the original issue discount rules to
Grantor Trust Fractional Interest Certificates are possible. Investors are urged
to consult their tax advisors concerning the application and effect of such
rules on their investment in such Certificates.
 
     The Trustee will provide to any holder of a Grantor Trust Fractional
Interest Certificate such information as such holder may reasonably request from
time to time with respect to original issue discount accruing on Grantor Trust
Fractional Interest Certificates. See "Grantor Trust Reporting" below.
 
     Market Discount
 
     If the stripped bond rules do not apply to the Grantor Trust Fractional
Interest Certificate, a Certificateholder may be subject to the market discount
rules of Sections 1276 through 1278 of the Code. The amendment to Section
1272(a)(6) of the Code described under "-- Stripped Bond Rules Do Not Apply,"
above, could be interpreted as requiring the use of a prepayment assumption in
connection with the determination, accrual and inclusion in income of market
discount. If such a requirement were applicable, a Grantor Trust Fractional
Interest Certificate would probably be treated as a single aggregate debt
instrument to which the rules described under "REMICS -- Taxation of Owners of
REMIC Regular Certificates -- Market Discount" would apply. Alternatively, if
the requirement of a prepayment assumption were not applicable, the rules
described in the succeeding paragraphs of this section would be applicable
either on a Mortgage-Loan-by-Mortgage-Loan basis or on such a basis with respect
to the Non-OID Pool and on an aggregate basis with respect to the OID Pool.
Other interpretations of the effect of the amendment to Section 1272(a)(6) on
the determination and accrual of market discount are possible. Investors are
advised to consult their tax advisors concerning the application of the market
discount rules to Grantor Trust Fractional Interest Certificates.
 
     If a prepayment assumption generally is not required in the application of
the market discount rules to pools of debt instruments, a Grantor Trust
Fractional Interest Certificate may be subject to the market discount rules to
the extent an interest in a Mortgage Loan is considered to have been purchased
at a "market discount," that is, in the case of a Mortgage Loan issued without
original issue discount, at a purchase price less than its remaining stated
redemption price (as defined above), or in the case of a Mortgage Loan issued
with original issue discount, at a purchase price less than its adjusted issue
price (as defined above). If market discount is in excess of a de minimis amount
(as described below), the holder generally will be required to include in income
in each month the amount of such discount that has accrued (under the rules
described in the next paragraph) through such month that has not previously been
included in income, but limited, in the case of the portion of such discount
that is allocable to any Mortgage Loan, to the payment of stated redemption
price on such Mortgage Loan that is received by (or, in the case of accrual
basis Certificate-
 
                                       65
<PAGE>   123
 
holders, due to) the Trust Fund in that month. A Certificateholder may elect to
include market discount in income currently as it accrues (under a constant
yield method based on the yield of the Certificate to such holder) 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 during or after the first taxable year to which such election
applies. In addition, the OID Regulations would 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 with respect to a Mortgage Loan with
market discount, the Certificateholder would be deemed to have made an election
to include market discount in income currently with respect to all other debt
instruments having market discount that such Certificateholder acquires during
the taxable year of the election and thereafter, and possibly previously
acquired instruments. Similarly, a Certificateholder that made this election for
a Certificate acquired at a premium would be deemed to have made an election to
amortize bond premium with respect to all debt instruments having amortizable
bond premium that such Certificateholder owns or acquires. See " --
REMICs -- Taxation of Owners of REMIC Regular Certificates -- Premium" below.
Each of these elections to accrue interest, discount and premium with respect to
a Certificate on a constant yield method or as interest is irrevocable.
 
     Section 1276(b)(3) of the Code specifically authorizes the Treasury
Department to issue regulations providing for the method for accruing market
discount 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 Conference Committee Report (the
"Committee Report") accompanying the Tax Reform Act of 1986 will apply. Under
those rules, in each accrual period market discount on the Mortgage Loans should
accrue, at the Certificateholder's option: (i) on the basis of a constant yield
method, (ii) in the case of a Mortgage Loan issued without original issue
discount, in an amount that bears the same ratio to the total remaining market
discount as the stated interest paid in the accrual period bears to the total
stated interest remaining to be paid on the Mortgage Loan as of the beginning of
the accrual period, or (iii) in the case of a Mortgage Loan issued with original
issue discount, in an amount that bears the same ratio to the total remaining
market discount as the original issue discount accrued in the accrual period
bears to the total original issue discount remaining at the beginning of the
accrual 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. The effect of using a prepayment assumption could be to
accelerate the reporting of such discount income. 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
Mortgage Loan purchased at a discount in the secondary market.
 
     Since the Mortgage Loans will provide for periodic payments of stated
redemption price, such discount may be required to be included in income at a
rate that is not significantly slower than the rate at which such discount would
be included in income if it were original issue discount.
 
     Market discount with respect to Mortgage Loans generally will be considered
to be de minimis if it is not greater than or equal to 0.25% of the stated
redemption price of the Mortgage Loans multiplied by the number of complete
years to maturity remaining after the date of its purchase. In interpreting a
similar 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 with respect to
market discount, presumably taking into account the prepayment assumption used,
if any. The effect of using a prepayment assumption could be to accelerate the
reporting of such discount income. If market discount is treated as de minimis
under the foregoing rule, it appears that actual discount would be treated in a
manner similar to original issue discount of a de minimis amount. See
"-- REMICS -- Taxation of Owners of REMIC Regular Certificates -- Original Issue
Discount."
 
     Further, under the rules described in "-- REMICs -- Taxation of Owners of
REMIC Regular Certificates -- Market Discount," below, any discount that is not
original issue discount and exceeds a de minimis amount may require the deferral
of interest expense deductions attributable to accrued market discount not yet
includible in income, unless an election has been made to report market discount
currently as it accrues.
 
                                       66
<PAGE>   124
 
     Premium
 
     If a Certificateholder is treated as acquiring the underlying Mortgage
Loans at a premium, that is, at a price in excess of their remaining stated
redemption price, such Certificateholder may elect under Section 171 of the Code
to amortize such premium using a constant yield method. Amortizable premium is
treated as an offset to interest income on the related Mortgage Loans rather
than as a separate interest deduction. Premium allocable to Mortgage Loans for
which an amortization election is not made should be allocated among the
payments on the Mortgage Loan representing stated redemption price and be
allowed as an ordinary deduction as such -- payments are made (or, for a
Certificateholder using the accrual method of accounting, when such payments are
due).
 
     It is unclear whether a prepayment assumption should be used in computing
amortization of premium allowable under Section 171 of the Code. If premium is
not subject to amortization using a prepayment assumption and a Mortgage Loan
prepays in full, the holder of a Grantor Trust Fractional Interest Certificate
acquired at a premium should recognize a loss, equal to the difference between
the portion of the prepaid principal amount of the Mortgage Loan that is
allocable to the Certificate and the portion of the adjusted basis of the
Certificate that is allocable to the Mortgage Loan. If a prepayment assumption
is used to amortize such premium, it appears that such a loss would be
unavailable. Instead, if a prepayment assumption is used, a prepayment should be
treated as a partial payment of the stated redemption price of the Grantor Trust
Fractional Interest Certificate and accounted for under a method similar to that
described for taking account of original issue discount on REMIC Regular
Certificates. See "-- REMICs -- Taxation of Owners of REMIC Regular
Certificates -- Original Issue Discount." It is unclear what adjustments would
be required to reflect differences between an assumed prepayment rate and the
actual rate of prepayments.
 
     Taxation of Owners of Grantor Trust Strip Certificates
 
     The "stripped coupon" rules of Section 1286 of the Code will apply to the
Grantor Trust Strip Certificates. Except as described above in "-- Taxation of
Owners of Grantor Trust Fractional Interest Certificates -- If Stripped Bond
Rules Apply," no regulations or published rulings under Section 1286 of the Code
have been issued and some uncertainty exists as to how it will be applied to
securities such as the Grantor Trust Strip Certificates. Accordingly, holders of
Grantor Trust Strip Certificates should consult their own tax advisors
concerning the method to be used in reporting income or loss with respect to
such Certificates.
 
     The OID Regulations do not apply to "stripped coupons," although they
provide general guidance as to how the original issue discount sections of the
Code will be applied. In addition, the discussion below is subject to the
discussion under "Possible Application of Proposed Contingent Payment Rules" and
assumes that the holder of a Grantor Trust Strip Certificate will not own any
Grantor Trust Fractional Interest Certificates.
 
     Under the stripped coupon rules, it appears that original issue discount
will be required to be accrued in each month on the Grantor Trust Strip
Certificates based on a constant yield method. In effect, each holder of Grantor
Trust Strip Certificates would include as interest income in each month an
amount equal to the product of such holder's adjusted basis in such Grantor
Trust Strip Certificate at the beginning of such month and the yield of such
Grantor Trust Strip Certificate to such holder. Such yield would be calculated
based on the price paid for that Grantor Trust Strip Certificate by its holder
and the payments remaining to be made thereon at the time of the purchase, plus
an allocable portion of the servicing fees and expenses to be paid with respect
to the Mortgage Loans. See "-- Taxation of Owners of Grantor Trust Fractional
Interest Certificates -- If Stripped Bond Rules Apply" above.
 
     Section 1272(a)(6) of the Code requires that a prepayment assumption be
used in computing the accrual of original issue discount with respect to the
Grantor Trust Strip Certificates, and that adjustments be made in the amount and
rate of accrual of such discount when prepayments do not conform to such
prepayment assumption. It is uncertain whether the assumed prepayment rate
should be determined based on conditions at the time of the first sale of the
Grantor Trust Strip Certificate or, with respect to any subsequent holder, at
the time of purchase of the Grantor Trust Strip Certificate by that holder.
 
                                       67
<PAGE>   125
 
     The accrual of income on the Grantor Trust Strip Certificates will be
significantly slower using a prepayment assumption than if yield were computed
assuming no prepayments. In the absence of statutory or administrative
clarification, it currently is intended to base information returns or reports
to the IRS and Certificateholders on the Prepayment Assumption disclosed in the
related Prospectus Supplement and on a constant yield computed using a
representative initial offering price for each Class of Certificates. However,
neither the Depositor nor the Master Servicer will make any representation that
the Mortgage Loans will in fact prepay at a rate conforming to the Prepayment
Assumption or at any other rate and Certificateholders should bear in mind that
the use of a representative initial offering price will mean that such
information returns or reports, even if otherwise accepted as accurate by the
IRS, will in any event be accurate only as to the initial Certificateholders of
each Series who bought at that price. Prospective purchasers of the Grantor
Trust Strip Certificates should consult their own tax advisors regarding the use
of the Prepayment Assumption.
 
     It is unclear under what circumstances, if any, the prepayment of a
Mortgage Loan will give rise to a loss to the holder of a Grantor Trust Strip
Certificate. If a Grantor Trust Strip Certificate is treated as a single
instrument (rather than an interest in discrete mortgage loans) and the effect
of prepayments is taken into account in computing yield with respect to such
Grantor Trust Strip Certificate, it appears that no loss may be available as a
result of any particular prepayment unless prepayments occur at a rate
sufficiently faster than the Prepayment Assumption to assure that the holder of
such Certificate will not recover its initial purchase price together with
previously accrued original issue discount. However, if a Grantor Trust Strip
Certificate is treated as an interest in discrete Mortgage Loans then when a
Mortgage Loan is prepaid, the holder of a Grantor Trust Strip Certificate should
be able to recognize a loss equal to the portion of the adjusted issue price of
the Grantor Trust Strip Certificate that is allocable to such Mortgage Loan.
 
     Possible Application of Contingent Payment Rules
 
     The coupon stripping rules' general treatment of stripped coupons is to
regard them as newly issued debt instruments in the hands of each purchaser. To
the extent that payments on the Grantor Trust Strip Certificates would cease if
the Mortgage Loans were prepaid in full, the Grantor Trust Strip Certificates
could be considered to be debt instruments providing for contingent payments.
Under the OID Regulations, debt instruments providing for contingent payments
are not subject to the same rules as debt instruments providing for
noncontingent payments. As in the case of the OID Regulations generally, the
regulations addressing contingent payment debt instruments do not specifically
address securities, such as the Grantor Trust Strip Certificates, that are
subject to the stripped bond rules of Section 1286 of the Code.
 
     If the contingent payment rules under the OID Regulations were to apply,
the holder of a Grantor Trust Strip Certificate would be required to apply a
"noncontingent bond method." Under that method, the issuer of a Grantor Trust
Strip Certificate would determine a projected payment schedule with respect to
such Grantor Trust Strip Certificate. Holders of Grantor Trust Strip
Certificates would be bound by the issuer's projected payment schedule, which
would consist of all noncontingent payments and a projected amount for each
contingent payment based on the projected yield (as described below) of the
Grantor Trust Strip Certificate. The projected amount of each payment would be
determined so that the projected payment schedule reflected the projected yield
reasonably expected to be received by the holder of a Grantor Trust Strip
Certificate. The projected yield referred to above would be a reasonable rate,
not less than the "applicable Federal rate" that, as of the issue date,
reflected general market conditions, the credit quality of the issuer, and the
terms and conditions of the Mortgage Loans. The holder of a Grantor Trust Strip
Certificate would be required to include as interest income in each month the
adjusted issue price of the Grantor Trust Strip Certificate at the beginning of
the period multiplied by the projected yield, and would add to, or subtract
from, such income any variation between the payment actually received in such
month and the payment originally projected to be made in such month.
 
     Certificateholders should consult their tax advisors concerning the
possible application of the contingent payment rules to the Grantor Trust Strip
Certificates.
 
                                       68
<PAGE>   126
 
     Sales of Grantor Trust Certificates
 
     Except as described below, any gain or loss recognized on the sale of a
Grantor Trust Certificate generally will be capital gain or loss, and will be
equal to the difference between the amount realized on the sale of a Grantor
Trust Certificate and its adjusted basis. The adjusted basis of a Grantor Trust
Certificate generally will equal its cost, increased by any income (including
original issue discount and market discount income) recognized by the seller and
reduced (but not below zero) by any previously reported losses, amortized
premium and distributions with respect to such Grantor Trust Certificate.
 
     Gain or loss from the sale of a Grantor Trust Certificate may be partially
or wholly ordinary and not capital in certain circumstances. Gain attributable
to accrued and unrecognized market discount will be treated as ordinary income,
as will gain or loss recognized by banks and other financial institutions
subject to Section 582(c) of the Code. Furthermore, a portion of any gain that
might otherwise be capital gain may be treated as ordinary income to the extent
that the Grantor Trust Certificate is held as part of a "conversion transaction"
within the meaning of Section 1258 of the Code. 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 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 appropriate "applicable Federal rate" (which rate
is computed and published monthly by the IRS) 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.
Finally, 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.
 
     Grantor Trust Reporting
 
     The Trustee will furnish to each holder of a Grantor Trust Certificate with
each distribution a statement setting forth the amount of such distribution
allocable to principal on the underlying Mortgage Loans and to interest thereon
at the related Pass-Through Rate. In addition, within a reasonable time after
the end of each calendar year, based on information provided by the Master
Servicer, the Trustee will furnish to each Certificateholder during such year
such customary factual information as the Trustee deems necessary or desirable
to enable holders of Grantor Trust Certificates to prepare their tax returns and
will furnish comparable information to the IRS as and when required by law to do
so. Because the rules for accruing discount and amortizing premium with respect
to the Grantor Trust Certificates are uncertain in various respects, there is no
assurance the IRS will agree with the Trustee's information reports of such
items of income and expense. Moreover, such information reports, even if
otherwise accepted as accurate by the IRS, will in any event be accurate only as
to the initial Certificateholders who bought their Certificates at the
representative initial offering price used in preparing such reports.
 
     Backup Withholding
 
     In general, the rules described in "-- REMICs -- Backup Withholding with
Respect to REMIC Certificates" and "-- REMICs -- New Withholding Regulations"
will also apply to Grantor Trust Certificates.
 
     Foreign Investors
 
     In general, the discussion with respect to REMIC Regular Certificates in
"-- REMICs -- Foreign Investors in REMIC Certificates -- REMIC Regular
Certificates" and "-- REMICs -- New Withholding Regulations" applies to Grantor
Trust Certificates.
 
     To the extent that interest on a Grantor Trust Certificate would be exempt
under Sections 871(h)(1) and 881(c) of the Code from United States withholding
tax, and the Grantor Trust Certificate is not held in
 
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connection with a Certificateholder's trade or business in the United States,
such Grantor Trust Certificate will not be subject to United States estate taxes
in the estate of a non-resident alien individual.
 
REMICS
 
     Classification of REMICs
 
     With respect to each Series of REMIC Certificates, Orrick, Herrington &
Sutcliffe, counsel to the Depositor ("Special Tax Counsel"), is of the opinion
that, assuming compliance with all provisions of the related Pooling Agreement,
the related Trust Fund (or each applicable portion thereof) will qualify as a
REMIC and the REMIC Certificates offered with respect thereto will be considered
to evidence ownership of "regular interests" ("REMIC Regular Certificates") or
"residual interests" ("REMIC Residual Certificates") in that REMIC within the
meaning of the REMIC Provisions. The following general discussion of the
anticipated federal income tax consequences of the purchase, ownership and
disposition of the REMIC Certificates together with the discussion, if any,
under the heading "FEDERAL INCOME TAX CONSEQUENCES" in the Prospectus Supplement
represents the opinion of Special Tax Counsel, subject to any qualifications set
forth herein and therein. Special Tax Counsel have prepared or reviewed the
statements in this prospectus under the heading "FEDERAL INCOME TAX
CONSEQUENCES" and in the Prospectus Supplement under the heading "FEDERAL INCOME
TAX CONSEQUENCES," if any, and are of the opinion that such statements are
correct in all material respects. A copy of the opinion of Special Tax Counsel
relating to such statements will be included in a Current Report on Form 8-K
filed prior to the Delivery Date with respect to any Series of REMIC
Certificates. Such statements are intended as an explanatory discussion of the
possible effects of the classification of the Trust Fund as a REMIC for federal
income tax purposes on investors generally and of related tax matters affecting
investors generally, but do not purport to furnish information in the level of
detail or with attention to an investor's specific tax circumstances that would
be provided by an investor's own tax advisor. Accordingly, each investor is
advised to consult its own tax advisors with regard to the tax consequences to
it of investing in the REMIC Certificates.
 
     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 such status during any taxable
year, the Code provides that the entity will not be treated as a REMIC for such
year and thereafter. In that event, such entity may be taxable as a separate
corporation under Treasury regulations, and the related REMIC Certificates may
not be accorded the status or given the tax treatment described below. Although
the Code authorizes the Treasury Department to issue regulations providing
relief in the event of an inadvertent termination of REMIC status, no such
regulations have been issued. Any such relief, moreover, may be accompanied by
sanctions, such as the imposition of a corporate tax on all or a portion of the
Trust Fund's income for the period in which the requirements for such status are
not satisfied. The Pooling Agreement with respect to each REMIC will include
provisions designed to maintain the Trust Fund's status as a REMIC under the
REMIC Provisions. It is not anticipated that the status of any Trust Fund as a
REMIC will be terminated.
 
     Characterization of Investments in REMIC Certificates
 
     In general, the REMIC Certificates will be "real estate assets" within the
meaning of Section 856(c)(5)(A) of the Code and assets described in Section
7701(a)(19)(C) of the Code in the same proportion that the assets of the REMIC
underlying such Certificates would be so treated. Moreover, if 95% or more of
the assets of the REMIC qualify for any of the foregoing treatments at all times
during a calendar year, the REMIC Certificates will qualify for the
corresponding status in their entirety for that calendar year. Interest
(including original issue discount) on the REMIC Regular Certificates and income
allocated to the Class of REMIC Residual Certificates will be interest described
in Section 856(c)(3)(B) of the Code to the extent that such Certificates are
treated as "real estate assets" within the meaning of Section 856(c)(4)(A) of
the Code. In addition, the REMIC Regular Certificates will be "qualified
mortgages" within the meaning of Section 860G(a)(3)(C) of the Code if
transferred to another REMIC on its startup day in exchange for regular or
residual interests therein. The determination as to the percentage of the
REMIC's assets that 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
 
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<PAGE>   128
 
REMIC during such calendar quarter. The Master Servicer will report those
determinations to Certificateholders in the manner and at the times required by
applicable Treasury regulations.
 
     The assets of the REMIC will include, in addition to Mortgage Loans,
payments on Mortgage Loans held pending distribution on the REMIC Certificates
and property acquired by foreclosure held pending sale, and may include amounts
in reserve accounts. It is unclear whether property acquired by foreclosure held
pending sale and amounts in reserve accounts would be considered to be part of
the Mortgage Loans, or whether such assets (to the extent not invested in assets
described in the foregoing sections) otherwise would receive the same treatment
as the Mortgage Loans for purposes of all of the foregoing sections. In
addition, in some instances Mortgage Loans may not be treated entirely as assets
described in the foregoing sections. If so, the related Prospectus Supplement
will describe the Mortgage Loans that may not be so treated. The REMIC
Regulations do provide, however, that payments on Mortgage Loans held pending
distribution are considered part of the Mortgage Loans for purposes of Section
856(c)(4)(A) of the Code.
 
     Tiered REMIC Structures
 
     For certain Series of REMIC Certificates, two or more separate elections
may be made to treat designated portions of the related Trust Fund as REMICs
("Tiered REMICs") for federal income tax purposes. Upon the issuance of any such
Series of REMIC Certificates, Orrick, Herrington & Sutcliffe LLP, counsel to the
Depositor, will deliver their opinion generally to the effect that, assuming
compliance with all provisions of the related Pooling Agreement, the Tiered
REMICs will each qualify as a REMIC and the REMIC Certificates issued by the
Tiered REMICs, respectively, will be considered to evidence ownership of REMIC
Regular Certificates or REMIC Residual Certificates in the related REMIC within
the meaning of the REMIC Provisions.
 
     Solely for purposes of determining whether the REMIC Certificates will be
"real estate assets" within the meaning of Section 856(c)(4)(A) of the Code and
"loans secured by an interest in real property" under Section 7701(a)(19)(C) of
the Code, and whether the income on such Certificates is interest described in
Section 856(c)(3)(B) of the Code, the Tiered REMICs will be treated as one
REMIC.
 
TAXATION OF OWNERS OF REMIC REGULAR CERTIFICATES
 
     General
 
     Except as otherwise stated in this discussion, REMIC Regular Certificates
will be treated for federal income tax purposes as debt instruments issued by
the REMIC and not as ownership interests in the REMIC or its assets. Moreover,
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.
 
     Original Issue Discount
 
     Certain REMIC Regular Certificates may be issued with "original issue
discount" within the meaning of Section 1273(a) of the Code. 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 the method described below, in advance of the receipt of the
cash attributable to such income. In addition, Section 1272(a)(6) of the Code
provides special rules applicable to REMIC Regular Certificates and certain
other debt instruments issued with original issue discount. Regulations have not
been issued under that section.
 
     The Code requires that a prepayment assumption be used with respect to
Mortgage Loans held by a REMIC in computing the accrual of original issue
discount on REMIC Regular Certificates issued by that REMIC, and that
adjustments be made in the amount and rate of accrual of such discount to
reflect differences between the actual prepayment rate and the prepayment
assumption. The prepayment assumption is to be determined in a manner prescribed
in Treasury regulations; as noted above, those regulations have not been issued.
The Committee Report indicates that the regulations will provide that the
prepayment
 
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<PAGE>   129
 
assumption used with respect to a REMIC Regular Certificate must be the same as
that used in pricing the initial offering of such REMIC Regular Certificate. The
prepayment assumption used by the Master Servicer in reporting original issue
discount for each Series of REMIC Regular Certificates (the "Prepayment
Assumption") will be consistent with this standard and will be disclosed in the
related Prospectus Supplement. However, neither the Depositor nor the Master
Servicer will make any representation that the Mortgage Loans will in fact
prepay at a rate conforming to the Prepayment Assumption or at any other rate.
 
     The original issue discount, if any, on a REMIC Regular Certificate will be
the excess of its stated redemption price at maturity over its issue price. The
issue price of a particular Class of REMIC Regular Certificates will be the
first cash price at which a substantial amount of REMIC Regular Certificates of
that Class is sold (excluding sales to bond houses, brokers and underwriters).
If less than a substantial amount of a particular Class of REMIC Regular
Certificates is sold for cash on or prior to the date of their initial issuance
(the "Closing Date"), the issue price for such Class will be treated as the fair
market value of such Class on the Closing Date. Under the OID Regulations, the
stated redemption price of a REMIC Regular Certificate is equal to the total of
all payments to be made on such Certificate other than "qualified stated
interest." "Qualified stated interest" includes interest that is unconditionally
payable at least annually at a single fixed rate, or in the case of a variable
rate debt instrument, at a "qualified floating rate," an "objective rate," a
combination of a single fixed rate and one or more "qualified floating rates" or
one "qualified inverse floating rate," or a combination of "qualified floating
rates" that generally does not operate in a manner that accelerates or defers
interest payments on such REMIC Regular Certificate.
 
     In the case of REMIC Regular Certificates bearing adjustable interest
rates, the determination of the total amount of original issue discount and the
timing of the inclusion thereof will vary according to the characteristics of
such REMIC Regular Certificates. If the original issue discount rules apply to
such Certificates, the related Prospectus Supplement will describe the manner in
which such rules will be applied by the Master Servicer with respect to those
Certificates in preparing information returns to the Certificateholders and the
IRS.
 
     Certain Classes of the REMIC Regular Certificates may provide for the first
interest payment with respect to such Certificates to be made more than one
month after the date of issuance, a period which is longer than the subsequent
monthly intervals between interest payments. Assuming the "accrual period" (as
defined below) for original issue discount is each monthly period that ends on a
Distribution Date, in some cases, as a consequence of this "long first accrual
period," some or all interest payments may be required to be included in the
stated redemption price of the REMIC Regular Certificate and accounted for as
original issue discount. Because interest on REMIC Regular Certificates must in
any event be accounted for under an accrual method, applying this analysis would
result in only a slight difference in the timing of the inclusion in income of
the yield on the REMIC Regular Certificates.
 
     In addition, if the accrued interest to be paid on the first Distribution
Date is computed with respect to a period that begins prior to the Closing Date,
a portion of the purchase price paid for a REMIC Regular Certificate will
reflect such accrued interest. In such cases, information returns to the
Certificateholders and the IRS will be based on the position that the portion of
the purchase price paid for the interest accrued with respect to periods prior
to the Closing Date is treated as part of the overall cost of such REMIC Regular
Certificate (and not as a separate asset the cost of which is recovered entirely
out of interest received on the next Distribution Date) and that portion of the
interest paid on the first Distribution Date in excess of interest accrued for a
number of days corresponding to the number of days from the Closing Date to the
first Distribution Date should be included in the stated redemption price of
such REMIC Regular Certificate. However, the OID Regulations state that all or
some portion of such accrued interest may be treated as a separate asset the
cost of which is recovered entirely out of interest paid on the first
Distribution Date. It is unclear how an election to do so would be made under
the OID Regulations and whether such an election could be made unilaterally by a
Certificateholder.
 
     Notwithstanding the general definition of original issue discount, original
issue discount on a REMIC Regular Certificate will be considered to be de
minimis if it is less than 0.25% of the stated redemption price of the REMIC
Regular Certificate multiplied by its weighted average maturity. For this
purpose, the weighted
 
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<PAGE>   130
 
average maturity of the REMIC Regular Certificate is computed as the sum of the
amounts determined, as to each payment included in the stated redemption price
of such REMIC Regular Certificate, by multiplying (i) the number of complete
years (rounding down for partial years) from the issue date until such payment
is expected to be made (presumably taking into account the Prepayment
Assumption) by (ii) a fraction, the numerator of which is the amount of the
payment, and the denominator of which is the stated redemption price at maturity
of such REMIC Regular Certificate. Under the OID Regulations, original issue
discount of only a de minimis amount (other than de minimis original issue
discount attributable to a so-called "teaser" interest rate or an initial
interest holiday) will be included in income as each payment of stated principal
is made, based on the product of the total amount of such de minimis original
issue discount and a fraction, the numerator of which is the amount of such
principal payment and the denominator of which is the outstanding 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" for a description of
such election under the OID Regulations.
 
     If original issue discount on a REMIC Regular Certificate is in excess of a
de minimis amount, the holder of such Certificate must include in ordinary gross
income the sum of the "daily portions" of original issue discount for each day
during its taxable year on which it held such REMIC Regular Certificate,
including the purchase date but excluding the disposition date. In the case of
an original holder of a REMIC Regular Certificate, the daily portions of
original issue discount will be determined as follows.
 
     As to each "accrual period," which in general is the period corresponding
to the period between Distribution Dates or other interest compounding period, a
calculation will be made of the portion of the original issue discount that
accrued during such accrual period. The portion of original issue discount that
accrues in any accrual period will equal the excess, if any, of (i) the sum of
(A) the present value, as of the end of the accrual period, of all of the
distributions remaining to be made on the REMIC Regular Certificate, if any, in
future periods and (B) the distributions made on such REMIC Regular Certificate
during the accrual period of amounts included in the stated redemption price,
over (ii) the adjusted issue price of such REMIC Regular Certificate at the
beginning of the accrual period. The present value of the remaining
distributions referred to in the preceding sentence will be calculated (i)
assuming that distributions on the REMIC Regular Certificate will be received in
future periods based on the Mortgage Loans being prepaid at a rate equal to the
Prepayment Assumption and (ii) using a discount rate equal to the original yield
to maturity of the Certificate. For these purposes, the original yield to
maturity of the Certificate will be calculated based on its issue price and
assuming that distributions on the Certificate will be made in all accrual
periods based on the Mortgage Loans being prepaid at a rate equal to 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 that
accrued with respect to such Certificate 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 its stated redemption price. The
original issue discount accruing during any accrual period, computed as
described above, will be allocated ratably to each day during the accrual period
to determine the daily portion of original issue discount for such day.
 
     A subsequent purchaser of a REMIC Regular Certificate that purchases such
Certificate at a price (excluding any portion of such price attributable to
accrued qualified stated interest) less than its remaining stated redemption
price will also be required to include in gross income the daily portions of any
original issue discount with respect to such Certificate. However, each such
daily portion will be reduced, if such cost is in excess of its "adjusted issue
price," in proportion to the ratio such excess bears to the aggregate original
issue discount remaining to be accrued on such REMIC Regular Certificate. The
adjusted issue price of a REMIC Regular Certificate on any given day equals the
sum of (i) the adjusted issue price (or, in the case of the first accrual
period, the issue price) of such Certificate at the beginning of the accrual
period which includes such day and (ii) the daily portions of original issue
discount for all days during such accrual period prior to such day.
 
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<PAGE>   131
 
     Market Discount
 
     A Certificateholder that purchases a REMIC Regular Certificate at a market
discount, that is, in the case of a REMIC Regular Certificate issued without
original issue discount, at a purchase price less than its remaining stated
principal amount, or in the case of a REMIC Regular Certificate issued with
original issue discount, at a purchase price less than its adjusted issue price
will recognize income upon receipt of each distribution representing stated
redemption price. In particular, under Section 1276 of the Code such a
Certificateholder generally will be required to allocate the portion of each
such distribution representing stated redemption price first to accrued market
discount not previously included in income, and to recognize ordinary income to
that extent. 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
with respect to a REMIC Regular Certificate with market discount, the
Certificateholder would be deemed to have made an election to include market
discount in income currently with respect to all other debt instruments having
market discount that such Certificateholder acquires during the taxable year of
the election or thereafter, and possibly previously acquired instruments.
Similarly, a Certificateholder that made this election for a Certificate that is
acquired at a premium would be deemed to have made an election to amortize bond
premium with respect to all debt instruments having amortizable bond premium
that such Certificateholder owns or acquires. See "Taxation of Owners of REMIC
Regular Certificates -- Premium." Each of these elections to accrue interest,
discount and premium with respect to a Certificate on a constant yield method or
as interest would be irrevocable.
 
     However, market discount with respect to a REMIC Regular Certificate will
be considered to be de minimis for purposes of Section 1276 of the Code if such
market discount is less than 0.25% of the remaining stated redemption price 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
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 with respect to
market discount, presumably taking into account the Prepayment Assumption. If
market discount is treated as de minimis under this rule, it appears that the
actual discount would be treated in a manner similar to original issue discount
of a de minimis amount. See "Taxation of Owners 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 in income using the method described above.
 
     Section 1276(b)(3) of the Code specifically authorizes the Treasury
Department to issue regulations providing for the method for accruing market
discount on debt instruments, the principal of which is payable in more than one
installment. Until regulations are issued by the Treasury Department, certain
rules described in the Committee Report apply. The Committee Report indicates
that in each accrual period market discount on REMIC Regular Certificates should
accrue, at the Certificateholder's option: (i) on the basis of a constant yield
method, (ii) in the case of a REMIC Regular Certificate issued without original
issue discount, in an amount that bears the same ratio to the total remaining
market discount as the stated interest paid in the accrual period bears to the
total amount of stated interest remaining to be paid on the REMIC Regular
Certificate as of the beginning of the accrual period, or (iii) in the case of a
REMIC Regular Certificate issued with original issue discount, in an amount that
bears the same ratio to the total remaining market discount as the original
issue discount accrued in the accrual period bears to the total original issue
discount remaining on the REMIC Regular Certificate at the beginning of the
accrual period. Moreover, the Prepayment Assumption used in evaluating the
accrual of original issue discount is to be used in calculating the accrual of
market discount. 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.
 
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<PAGE>   132
 
     To the extent that REMIC Regular Certificates provide for monthly or other
periodic distributions throughout their term, the effect of these rules may be
to require market discount to be includible in income at a rate that is not
significantly slower than the rate at which such discount would accrue if it
were original issue discount. Moreover, in any event a holder of a REMIC Regular
Certificate generally will be required to treat a portion of any gain on the
sale or exchange of such 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.
 
     Further, under Section 1277 of the Code a holder of a REMIC Regular
Certificate 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 a REMIC Regular Certificate purchased with market discount.
For these purposes, the de minimis rule referred to above applies. Any such
deferred interest expense would not exceed the market discount that accrues
during such taxable year and is, in general, allowed as a deduction not later
than the year in which such market discount is includible in income. 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.
 
     Premium
 
     A REMIC Regular Certificate purchased at a cost (excluding any portion of
such cost attributable to accrued qualified stated interest) greater than its
remaining stated redemption price will be considered to be purchased at a
premium. The holder of such a REMIC Regular Certificate may elect under Section
171 of the Code to amortize such premium under the constant yield method over
the life of the Certificate. If made, such an election will apply to all debt
instruments having amortizable bond premium that the holder owns or subsequently
acquires. Amortizable premium will be treated as an offset to interest income on
the related REMIC Regular Certificate, rather than as a separate interest
deduction. 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. See "Taxation of Owners of REMIC Regular
Certificates -- Market Discount." The Committee Report states that the same
rules that apply to accrual of market discount (which rules will require use of
a Prepayment Assumption in accruing market discount with respect to REMIC
Regular Certificates without regard to whether such Certificates have original
issue discount) will also apply in amortizing bond premium under Section 171 of
the Code.
 
     Realized Losses
 
     Under Section 166 of the Code, both corporate holders of the REMIC Regular
Certificates and noncorporate holders of the 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 the
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
Section 166 of the Code 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
giving effect to any reductions in distributions attributable to defaults or
delinquencies on the Mortgage Loans or the Underlying Certificates 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 the 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.
 
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<PAGE>   133
 
TAXATION OF OWNERS OF REMIC RESIDUAL CERTIFICATES
 
     General
 
     As residual interests, the REMIC Residual Certificates will be subject to
tax rules that differ significantly from those that would apply if the REMIC
Residual Certificates were treated for federal income tax purposes as direct
ownership interests in the Mortgage Loans or as debt instruments issued by the
REMIC.
 
     A holder of a REMIC Residual Certificate generally will be required to
report its daily portion of the taxable income or, subject to the limitations
noted in this discussion, the net loss of the REMIC for each day during a
calendar quarter that such holder owned such REMIC Residual Certificate. For
this purpose, the taxable income or net loss of the REMIC will be allocated to
each day in the calendar quarter ratably using a "30 days per month/90 days per
quarter/360 days per year" convention. The daily amounts will then be allocated
among the REMIC Residual Certificateholders in proportion to their respective
ownership interests on such day. Any amount included in the gross income or
allowed as a loss of any REMIC Residual Certificateholder by virtue of this
allocation will be treated as ordinary income or loss. The taxable income of the
REMIC will be determined under the rules described below in "Taxable Income of
the REMIC" and will be taxable to the REMIC Residual Certificateholders without
regard to the timing or amount of cash distributions by the REMIC until the
REMIC terminates. Ordinary income derived from REMIC Residual Certificates will
be "portfolio income" for purposes of the taxation of taxpayers subject to
limitations under Section 469 of the Code on the deductibility of "passive
losses."
 
     A holder of a REMIC Residual Certificate that purchased such Certificate
from a prior holder of such Certificate also will be required to report on its
federal income tax return amounts representing its daily portion of the taxable
income (or net loss) of the REMIC for each day that it holds such REMIC Residual
Certificate. These daily portions generally will equal the amounts of taxable
income or net loss determined as described above. The Committee Report indicates
that certain modifications of the general rules may be made, by regulations,
legislation or otherwise, to reduce (or increase) the income or loss of a holder
of a REMIC Residual Certificateholder that purchased such REMIC Residual
Certificate from a prior holder of such Certificate at a price greater than (or
less than) the adjusted basis (as defined below) such REMIC Residual Certificate
would have had in the hands of an original holder of such Certificate. The REMIC
Regulations, however, do not provide for any such modifications.
 
     Any payments received by a holder of a REMIC Residual Certificate in
connection with the acquisition of such REMIC Residual 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.
 
     The amount of income REMIC Residual Certificateholders will be required to
report (or the tax liability associated with such income) may exceed the amount
of cash distributions received from the REMIC for the corresponding period.
Consequently, REMIC Residual Certificateholders should have other sources of
funds sufficient to pay any federal income taxes due as a result of their
ownership of REMIC Residual Certificates or unrelated deductions against which
income may be offset, subject to the rules relating to "excess inclusions,"
residual interests without "significant value" and "noneconomic" residual
interests discussed below. The fact that the tax liability associated with the
income allocated to REMIC Residual Certificateholders may exceed the cash
distributions received by such REMIC Residual Certificateholders for the
corresponding period may significantly adversely affect such REMIC Residual
Certificateholders' after-tax rate of return.
 
     Taxable Income of the REMIC
 
     The taxable income of the REMIC will equal the income from the Mortgage
Loans and other assets of the REMIC plus any cancellation of indebtedness income
due to the allocation of realized losses to REMIC
 
                                       76
<PAGE>   134
 
Regular Certificates, less the deductions allowed to the REMIC for interest
(including original issue discount and reduced by the amortization of any
premium received on issuance) on the REMIC Regular Certificates (and any other
Class of REMIC Certificates constituting "regular interests" in the REMIC not
offered hereby), amortization of any premium on the Mortgage Loans, bad debt
deductions with respect to the Mortgage Loans and, except as described below,
for servicing, administrative and other expenses.
 
     For purposes of determining its taxable income, the REMIC will have an
initial aggregate basis in its assets equal to their fair market value
immediately after their transfer to the REMIC. For this purpose, the Master
Servicer 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. Such aggregate basis will be allocated among the Mortgage
Loans collectively and the other assets of the REMIC in proportion to their
respective fair market values. The issue price of any REMIC Certificates offered
hereby will be determined in the manner described above under "-- Taxation of
Owners of REMIC Regular Certificates -- Original Issue Discount." Accordingly,
if one or more Classes of REMIC Certificates are retained initially rather than
sold, the Master Servicer may be required to estimate the fair market value of
such interests in order to determine the basis of the REMIC in the Mortgage
Loans and other property held by the REMIC.
 
     Subject to the possible application of the de minimis rules, the method of
accrual by the REMIC of original issue discount income and market discount
income with respect to Mortgage Loans that it holds will be equivalent to the
method of accruing original issue discount income for REMIC Regular
Certificateholders (that is, under the constant yield method taking into account
the Prepayment Assumption). However, a REMIC that acquires loans at a market
discount must include such discount in income currently, as it accrues, on a
constant interest basis. See "-- Taxation of Owners of REMIC Regular
Certificates" above, which describes a method of accruing discount income that
is analogous to that required to be used by a REMIC as to Mortgage Loans with
market discount that it holds.
 
     A Mortgage Loan will be deemed to have been acquired with discount (or
premium) to the extent that the REMIC's basis therein, determined as described
in the preceding paragraph, is less than (or greater than) its stated redemption
price. Any such discount will be includible in the income of the REMIC as it
accrues, in advance of receipt of the cash attributable to such income, under a
method similar to the method described above for accruing original issue
discount on the REMIC Regular Certificates. It is anticipated that each REMIC
will elect under Section 171 of the Code to amortize any premium on the Mortgage
Loans. Premium on any Mortgage Loan to which such election applies may be
amortized under a constant yield method, presumably taking into account a
Prepayment Assumption.
 
     The REMIC will be allowed deductions for interest (including original issue
discount) on the REMIC Regular Certificates (including any other Class of REMIC
Certificates constituting "regular interests" in the REMIC not offered hereby)
equal to the deductions that would be allowed if the REMIC Regular Certificates
(including any other Class of REMIC Certificates constituting "regular
interests" in the REMIC not offered hereby) were indebtedness of the REMIC.
Original issue discount will be considered to accrue for this purpose as
described above under "-- Taxation of Owners of REMIC Regular
Certificates -- Original Issue Discount," except that the de minimis rule and
the adjustments for subsequent holders of REMIC Regular Certificates (including
any other Class of Certificates constituting "regular interests" in the REMIC
not offered hereby) described therein will not apply.
 
     If a Class of REMIC Regular Certificates is issued at a price in excess of
the stated redemption price of such Class (such excess, "Issue Premium"), the
net amount of interest deductions that are allowed the REMIC in each taxable
year with respect to the REMIC Regular Certificates of such Class will be
reduced by an amount equal to the portion of the Issue Premium that is
considered to be amortized or repaid in that year. Although the matter is not
entirely certain, it is likely that Issue Premium would be amortized under a
constant yield method in a manner analogous to the method of accruing original
issue discount described above under "-- Taxation of Owners of REMIC Regular
Certificates -- Original Issue Discount."
 
     As a general rule, the taxable income of the REMIC is required to be
determined in the same manner as if the REMIC were an individual having the
calendar year as its taxable year and using the accrual method of accounting.
However, no item of income, gain, loss or deduction allocable to a prohibited
transaction will be
                                       77
<PAGE>   135
 
taken into account. See "-- Prohibited Transactions and Other Possible REMIC
Taxes" below. Further, the limitation on miscellaneous itemized deductions
imposed on individuals by Section 67 of the Code (which allows such deductions
only to the extent they exceed in the aggregate two percent of the taxpayer's
adjusted gross income) will not be applied at the REMIC level so that the REMIC
will be allowed deductions for servicing, administrative and other non-interest
expenses in determining its taxable income. All such expenses will be allocated
as a separate item to the holders of REMIC Certificates, subject to the
limitation of Section 67 of the Code. See "-- Possible Pass-Through of
Miscellaneous Itemized Deductions." If the deductions allowed to the REMIC
exceed its gross income for a calendar quarter, such excess will be the net loss
for the REMIC for that calendar quarter.
 
     Basis Rules, Net Losses and Distributions
 
     The adjusted basis of a REMIC Residual Certificate will be equal to the
amount paid for such REMIC Residual Certificate, increased by amounts included
in the income of the REMIC Residual Certificateholder and decreased (but not
below zero) by distributions made, and by net losses allocated, to such REMIC
Residual Certificateholder.
 
     A REMIC Residual Certificateholder is not allowed to take into account any
net loss for any calendar quarter to the extent such net loss exceeds such REMIC
Residual Certificateholder'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 that is not currently deductible 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 ability of REMIC Residual Certificateholders to deduct net
losses may be subject to additional limitations under the Code, as to which
REMIC Residual Certificateholders should consult their tax advisors.
 
     Any distribution on a REMIC Residual Certificate will be treated as a
non-taxable return of capital to the extent it does not exceed the holder's
adjusted basis in such REMIC Residual Certificate. To the extent a distribution
on a REMIC Residual Certificate exceeds such adjusted basis, it will be treated
as gain from the sale of such REMIC Residual Certificate. Holders of certain
REMIC Residual Certificates may be entitled to distributions early in the term
of the related REMIC under circumstances in which their bases in such REMIC
Residual Certificates will not be sufficiently large that such distributions
will be treated as nontaxable returns of capital. Their bases in such REMIC
Residual Certificates will initially equal the amount paid for such REMIC
Residual Certificates and will be increased by their allocable shares of taxable
income of the Trust Fund. However, such basis increases may not occur until the
end of the calendar quarter, or perhaps the end of the calendar year, with
respect to which such REMIC taxable income is allocated to the REMIC Residual
Certificateholders. To the extent such REMIC Residual Certificateholders'
initial bases are less than the distributions to such REMIC Residual
Certificateholders, and increases in such initial bases either occur after such
distributions or (together with their initial bases) are less than the amount of
such distributions, gain will be recognized to such REMIC Residual
Certificateholders on such distributions and will be treated as gain from the
sale of their REMIC Residual Certificates.
 
     The effect of these rules is that a Residual Certificateholder may not
amortize its basis in a REMIC Residual Certificate, but may only recover its
basis through distributions, through the deduction of its share of any net
losses of the REMIC or upon the sale of its REMIC Residual Certificate. See
"-- Sales of REMIC Certificates." For a discussion of possible modifications of
these rules that may require adjustments to income of a holder of a REMIC
Residual Certificate other than an original holder in order to reflect any
difference between the cost of such REMIC Residual Certificate to such holder
and the adjusted basis such REMIC Residual Certificate would have had in the
hands of the original holder, see "-- Taxation of Owners of REMIC Residual
Certificates -- General."
 
     Excess Inclusions
 
     Any "excess inclusions" with respect to a REMIC Residual Certificate will
be subject to federal income tax in all events.
 
                                       78
<PAGE>   136
 
     In general, the "excess inclusions" with respect to a REMIC Residual
Certificate for any calendar quarter will be the excess, if any, of (i) the sum
of the daily portions of REMIC taxable income allocable to such REMIC Residual
Certificate over (ii) the sum of the "daily accruals" (as defined below) for
each day during such quarter that such REMIC Residual Certificate was held by
such REMIC Residual Certificateholder. The daily accruals of a REMIC Residual
Certificateholder will be 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% of
the "long-term Federal rate" in effect on the Closing Date. For this purpose,
the adjusted issue price of a REMIC Residual Certificate as of the beginning of
any calendar quarter will be equal to the issue price of the REMIC Residual
Certificate, increased by the sum of the daily accruals for all prior quarters
and decreased (but not below zero) 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. The "long-term Federal rate" is an
average of current yields on Treasury securities with a remaining term of
greater than nine years, computed and published monthly by the IRS.
 
     For REMIC Residual Certificateholders, an excess inclusion (i) will not be
permitted to be offset by deductions, losses or loss carryovers from other
activities, (ii) will be treated as "unrelated business taxable income" to an
otherwise tax-exempt organization and (iii) will not be eligible for any rate
reduction or exemption under any applicable tax treaty with respect to the 30%
United States withholding tax imposed on distributions to REMIC Residual
Certificateholders that are foreign investors. See, however, "-- Foreign
Investors in REMIC Certificates," below. In addition, excess inclusions are not
permitted to be offset by the alternative tax net operating loss deduction and
alternative minimum taxable income may not be less than the taxpayer's excess
inclusions.
 
     Although it has not done so, the Treasury has authority to issue
regulations that would treat the entire amount of income accruing on a REMIC
Residual Certificate as an excess inclusion if the REMIC Residual Certificates
are considered not to have "significant value." The REMIC Regulations provide
that in order to be treated as having significant value, the REMIC Residual
Certificates must have an aggregate issue price at least equal to two percent of
the aggregate issue prices of all of the related REMIC's Regular and Residual
Certificates. In addition, based on the Prepayment Assumption, 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 qualified liquidation provided for in the REMIC's organizational
documents. If the Treasury issues regulations pursuant to its authority, the
related Prospectus Supplement will disclose whether offered REMIC Residual
Certificates may be considered to have "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 Depositor will make no representation that a REMIC Residual
Certificate will have "significant value" for purposes of the above-described
rules.
 
     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 Section 857(b)(2) of the
Code, 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. Treasury regulations yet to be issued could apply a similar rule to
regulated investment companies, common trust funds and certain cooperatives; the
REMIC Regulations currently do not address this subject.
 
     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"
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<PAGE>   137
 
REMIC Residual Certificate. The REMIC Regulations provide that a REMIC Residual
Certificate is noneconomic unless, based on the Prepayment Assumption and on any
required or permitted clean up calls, or required qualified liquidation provided
for in the REMIC's organizational documents, (1) the present value of the
expected future distributions (discounted using the "applicable Federal rate"
for obligations whose term ends on the close of the last quarter in which excess
inclusions are expected to accrue with respect to the REMIC Residual
Certificate, which rate is computed and published monthly by the IRS) on the
REMIC Residual Certificate 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 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, as
to which the transferor also is required to make a reasonable investigation to
determine such transferee's historic payment of its debts and ability to
continue to pay its debts as they come due in the future. 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 related 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 not be considered "noneconomic" will be based upon
certain assumptions, and the Depositor will make no representation that a REMIC
Residual Certificate will not be considered "noneconomic" for purposes of the
above-described rules. See "-- Foreign Investors in REMIC Certificates -- REMIC
Residual Certificates" below for additional restrictions applicable to transfers
of certain REMIC Residual Certificates to foreign persons.
 
     Mark-to-Market Rules
 
     On December 24, 1996, the IRS released final regulations (the
"Mark-to-Market Regulations") relating to the requirement that a securities
dealer mark to market securities held for sale to customers. This mark-to-
market requirement applies to all securities owned by a dealer, except to the
extent that the dealer has specifically identified a security as held for
investment. The Mark-to-Market Regulations provide that for purposes of this
mark-to-market requirement, a REMIC Residual Certificate acquired on or after
January 4, 1995 is not treated as a security and thus may not be marked to
market. Prospective purchasers of a REMIC Residual Certificate should consult
their tax advisors regarding the possible application of the mark-to-market
requirement to REMIC Residual Certificates.
 
     Possible Pass-Through of Miscellaneous Itemized Deductions
 
     Fees and expenses of a REMIC generally will be allocated to the holders of
the related REMIC Residual Certificates. The applicable Treasury regulations
indicate, however, that in the case of a REMIC that is similar to a single class
grantor trust, all or a portion of such fees and expenses should be allocated to
the holders of the related REMIC Regular Certificates. The related Prospectus
Supplement will so indicate if a related Trust Fund constitutes such a "single
class REMIC," in which case such fees and expenses will be allocated to holders
of the related REMIC Regular Certificates.
 
     With respect to REMIC Residual Certificates or REMIC Regular Certificates
the holders of which receive an allocation of fees and expenses in accordance
with the preceding discussion, if any holder thereof is an individual, estate or
trust, or a "pass-through entity" beneficially owned by one or more individuals,
estates or trusts, (i) an amount equal to such individual's, estate's or trust's
share of such fees and expenses will be added to the gross income of such holder
and (ii) such individual's, estate's or trust's share of such fees and expenses
will be treated as a miscellaneous itemized deduction allowable subject to the
limitation of
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<PAGE>   138
 
Section 67 of the Code, which permits such deductions only to the extent they
exceed in the aggregate two percent of a taxpayer's adjusted gross income. In
addition, Section 68 of the Code provides that the amount of itemized deductions
otherwise allowable for an individual whose adjusted gross income exceeds a
specified amount will be reduced by the lesser of (i) 3% of the excess of the
individual's adjusted gross income over such amount or (ii) 80% of the amount of
itemized deductions otherwise allowable for the taxable year. The amount of
additional taxable income reportable by REMIC Certificateholders that are
subject to the limitations of either Section 67 or Section 68 of the Code may be
substantial. Furthermore, in determining the alternative minimum taxable income
of such a holder of a REMIC Certificate that is an individual, estate or trust,
or a "pass-through entity" beneficially owned by one or more individuals,
estates or trusts, no deduction will be allowed for such holder's allocable
portion of servicing fees and other miscellaneous itemized deductions of the
REMIC, even though an amount equal to the amount of such fees and other
deductions will be included in such holder's gross income. Accordingly, such
REMIC Certificates may not be appropriate investments for individuals, estates,
or trusts, or pass-through entities beneficially owned by one or more
individuals, estates or trusts. Such prospective investors should consult
carefully with their tax advisors prior to making an investment in such
Certificates.
 
     Sales of REMIC Certificates
 
     If a REMIC Certificate is sold, the selling Certificateholder 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 such Certificateholder, increased by income reported by such
Certificateholder with respect to such REMIC Regular Certificate (including
original issue discount and market discount income) and reduced (but not below
zero) by distributions on such REMIC Regular Certificate received by such
Certificateholder and by any amortized premium. The adjusted basis of a REMIC
Residual Certificate will be determined as described under "-- Taxation of
Owners of REMIC Residual Certificates -- Basis Rules, Net Losses and
Distributions." Except as described below, any such gain or loss generally will
be capital gain or loss.
 
     Gain from the sale of a REMIC Regular Certificate that might otherwise be
capital gain will be treated as ordinary income to the extent such gain does not
exceed the excess, if any, of (i) the amount that would have been includible in
the seller's income with respect to such REMIC Regular Certificate had income
accrued thereon at a rate equal to 110% of the "applicable Federal rate"
(generally, a rate based on an average of current yields on Treasury securities
having a maturity comparable to that of the Certificate, which rate is computed
and published monthly by the IRS), determined as of the date of purchase of such
REMIC Regular Certificate, over (ii) the amount of ordinary income actually
includible in the seller's income prior to such sale. In addition, gain
recognized on the sale of a REMIC Regular Certificate by a seller who purchased
such REMIC Regular Certificate at a market discount will be taxable as ordinary
income to the extent of any accrued and previously unrecognized market discount
that accrued during the period the Certificate was held. See "-- Taxation of
Owners of REMIC Regular Certificates -- Market Discount."
 
     REMIC Certificates will be "evidences of indebtedness" within the meaning
of Section 582(c)(1) of the Code, so that gain or loss recognized from the sale
of a REMIC Certificate by a bank or thrift institution to which such section
applies will be ordinary income or loss.
 
     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 Section 1258 of the Code. 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 appropriate "applicable Federal rate" (which rate is computed and
published monthly by the IRS) 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.
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<PAGE>   139
 
     Finally, 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 the 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.
 
     Except as may be provided in Treasury regulations yet to be issued, if the
seller of a REMIC Residual Certificate reacquires the Certificate, any other
residual interest in a REMIC or any similar interest in a "taxable mortgage
pool" (as defined in Section 7701(i) of the Code) within six months of the date
of such sale, the sale will be subject to the "wash sale" rules of Section 1091
of the Code. In that event, any loss realized by the REMIC Residual
Certificateholder on the sale will not be deductible, but instead will be added
to such REMIC Residual Certificateholder's adjusted basis in the newly-acquired
asset.
 
PROHIBITED TRANSACTIONS AND OTHER POSSIBLE REMIC TAXES
 
     The Code imposes a tax on REMICs equal to 100% of the net income derived
from "prohibited transactions" (a "Prohibited Transactions Tax"). In general,
subject to certain specified exceptions a prohibited transaction means the
disposition of a Mortgage Loan, the receipt of income from a 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. It is not anticipated that any REMIC
will engage in any prohibited transactions in which it would recognize a
material amount of net income.
 
     In addition, certain contributions to a REMIC made after the day on which
the REMIC issues all of its interests could result in the imposition of a tax on
the REMIC equal to 100% of the value of the contributed property (a
"Contributions Tax"). Each Pooling Agreement will include provisions designed to
prevent the acceptance of any contributions that would be subject to such tax.
 
     REMICs also are subject to federal income tax at the highest corporate rate
on "net income from foreclosure property," determined by reference to the rules
applicable to real estate investment trusts. "Net income from foreclosure
property" generally means gain from the sale of a foreclosure property that is
inventory property and gross income from foreclosure property other than
qualifying rents and other qualifying income for a real estate investment trust.
It is not anticipated that any REMIC will recognize "net income from foreclosure
property" subject to any material federal income tax.
 
     To the extent permitted by then applicable laws, any Prohibited
Transactions Tax, Contributions Tax, tax on "net income from foreclosure
property" or state or local income or franchise tax that may be imposed on the
REMIC will be borne by the Master Servicer or Trustee in either case out of its
own funds, provided that the Master Servicer or the Trustee, as the case may be,
has sufficient assets to do so, and provided further that such tax arises out of
a breach of the Master Servicer's or the Trustee's obligations, as the case may
be, under the related Pooling Agreement and in respect of compliance with
applicable laws and regulations. Any such tax not borne by the Master Servicer
or the Trustee will be payable out of the related Trust Fund resulting in a
reduction in amounts payable to holders of the related REMIC Certificates.
 
     Tax and Restrictions on Transfers of REMIC Residual Certificates to Certain
Organizations
 
     If a REMIC Residual Certificate is transferred to a "disqualified
organization" (as defined below), a tax would be imposed in an amount
(determined under the REMIC Regulations) equal to the product of (i) the present
value (discounted using the "applicable Federal rate" for obligations whose term
ends on the close of the last quarter in which excess inclusions are expected to
accrue with respect to the Certificate, which rate is computed and published
monthly by the IRS) of the total anticipated excess inclusions with respect to
such REMIC Residual Certificate for periods after the transfer and (ii) the
highest marginal federal income tax rate applicable to corporations. 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. Such a tax generally would be imposed on the
transferor of the REMIC Residual Certificate, except that where such transfer is
through an agent for a
                                       82
<PAGE>   140
 
disqualified organization, the tax would instead be imposed on such agent.
However, a transferor of a REMIC Residual Certificate would in no event be
liable for such tax with respect to a transfer if the transferee furnishes to
the transferor an affidavit that the transferee is not a disqualified
organization and, as of the time of the transfer, the transferor does not have
actual knowledge that such affidavit is false. Moreover, an entity will not
qualify as a REMIC unless there are reasonable arrangements designed to ensure
that (i) residual interests in such entity are not held by disqualified
organizations and (ii) information necessary for the application of the tax
described herein will be made available. Restrictions on the transfer of REMIC
Residual Certificates and certain other provisions that are intended to meet
this requirement will be included in the Pooling Agreement, including provisions
(i) requiring any transferee of a REMIC Residual Certificate to provide an
affidavit representing that it is not a "disqualified organization" and is not
acquiring the REMIC Residual Certificate on behalf of a "disqualified
organization," undertaking to maintain such status and agreeing to obtain a
similar affidavit from any person to whom it shall transfer the REMIC Residual
Certificate, (ii) providing that any transfer of a REMIC Residual Certificate to
a "disqualified person" shall be null and void and (iii) granting to the Master
Servicer the right, without notice to the holder or any prior holder, to sell to
a purchaser of its choice any REMIC Residual Certificate that shall become owned
by a "disqualified organization" despite (i) and (ii) above.
 
     In addition, if a "pass-through entity" (as defined below) 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
each record holder of an interest in such pass-through entity furnishes to such
pass-through 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 penalties of perjury that such record
holder is not a disqualified organization.
 
     For these purposes, a "disqualified organization" means (i) the United
States, any State or political subdivision thereof, any foreign government, any
international organization, or any agency or instrumentality of the foregoing
(but would not include instrumentalities described in Section 168(h)(2)(D) of
the Code or the Federal Home Loan Mortgage Corporation), (ii) any organization
(other than a cooperative described in Section 521 of the Code) that is exempt
from federal income tax, unless it is subject to the tax imposed by Section 511
of the Code or (iii) any organization described in Section 1381(a)(2)(C) of the
Code. 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
will, with respect to such interest, be treated as a pass-through entity.
 
     Termination
 
     A REMIC will terminate immediately after the Distribution Date following
receipt by the REMIC of the final payment in respect of the Mortgage Loans or
upon a sale of the REMIC's assets following the adoption by the REMIC of a plan
of complete liquidation. The last distribution on a REMIC Regular Certificate
will be treated as a payment in retirement of a debt instrument. In the case of
a REMIC Residual Certificate, if the last distribution on such REMIC Residual
Certificate is less than the REMIC Residual Certificateholder's adjusted basis
in such Certificate, such REMIC Residual Certificateholder should be treated as
realizing a loss equal to the amount of such difference, and such loss may be
treated as a capital loss.
 
     Reporting and Other Administrative Matters
 
     Solely for purposes of the administrative provisions of the Code, the REMIC
will be treated as a partnership and Residual Certificateholders will be treated
as partners. The Master Servicer will file REMIC federal income tax returns on
behalf of the related REMIC, will be designated as and will act as the "tax
 
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<PAGE>   141
 
matters person" with respect to the REMIC in all respects, and generally will
hold at least a nominal amount of REMIC Residual Certificates.
 
     As the tax matters person, the Master Servicer will, subject to certain
notice requirements and various restrictions and limitations, generally have the
authority to act on behalf of the REMIC and the REMIC Residual
Certificateholders in connection with the administrative and judicial review of
items of income, deduction, gain or loss of the REMIC, as well as the REMIC's
Classification. REMIC Residual Certificateholders will generally be required to
report such REMIC items consistently with their treatment on the related REMIC's
tax return and may in some circumstances be bound by a settlement agreement
between the Master Servicer, as tax matters person, and the IRS concerning any
such REMIC item. Adjustments made to the REMIC tax return may require a REMIC
Residual Certificateholder to make corresponding adjustments on its return, and
an audit of the REMIC's tax return, or the adjustments resulting from such an
audit, could result in an audit of a REMIC Residual Certificateholder's return.
No REMIC will be registered as a tax shelter pursuant to Section 6111 of the
Code because it is not anticipated that any REMIC will have a net loss for any
of the first five taxable years of its existence. Any person that holds a REMIC
Residual Certificate as a nominee for another person may be required to furnish
to the related REMIC, in a manner to be provided in Treasury regulations, the
name and address of such person and other information.
 
     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. These information reports generally
are required to be sent to individual holders of REMIC Regular Interests and the
IRS; holders of REMIC Regular Certificates that are corporations, trusts,
securities dealers and certain other non-individuals 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
applicable 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 must also comply with rules
requiring a REMIC Regular Certificate issued with original issue discount to
disclose on its face certain information including the amount of original issue
discount and the issue date, and requiring such information to be reported to
the IRS. Reporting with respect to the REMIC Residual Certificates, including
income, excess inclusions, investment expenses and relevant information
regarding qualification of the REMIC's assets will be made as required under the
Treasury regulations, generally on a quarterly basis.
 
     As applicable, the REMIC Regular Certificate information reports will
include a statement of the adjusted issue price of the REMIC Regular Certificate
at the beginning of each accrual period. In addition, the reports will include
information required by regulations with respect to computing the accrual of any
market discount. Because exact computation of the accrual of market discount on
a constant yield method requires information relating to the holder's purchase
price that the Master Servicer will not have, such regulations only require that
information pertaining to the appropriate proportionate method of accruing
market discount be provided. See "Taxation of Owners of REMIC Regular
Certificates -- Market Discount."
 
     The responsibility for complying with the foregoing reporting rules will be
borne by the Master Servicer. The Prospectus Supplement related to any Series of
Certificates will specify the manner in which Certificateholders may request any
information with respect to the returns described in Section 1.6049-7(e)(2) of
the Treasury regulations.
 
     Backup Withholding With Respect to REMIC Certificates
 
     Payments of interest and principal, 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% 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.
 
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<PAGE>   142
 
     Foreign Investors in REMIC Certificates
 
     A REMIC Regular Certificateholder that is not a "United States person" (as
defined below) and is not subject to federal income tax as a result of any
direct or indirect connection to the United States in addition to its ownership
of a REMIC Regular Certificate will not be subject to United States federal
income or withholding tax in respect of a distribution on a REMIC Regular
Certificate, provided that the holder complies to the extent necessary with
certain identification requirements (including delivery of a statement, signed
by the Certificateholder under penalties of perjury, certifying that such
Certificateholder is not a United States person and providing the name and
address of such Certificateholder). For these purposes, "United States person"
means a citizen or resident of the United States, a corporation, partnership or
other entity created or organized in, or under the laws of, the United States or
any political subdivision thereof, or an estate or trust whose income from
sources without the United States is includible in gross income for United
States federal income tax purposes regardless of its connection with the conduct
of a trade or business within the United States. It is possible that the IRS may
assert that the foregoing tax exemption should not apply with respect to a REMIC
Regular Certificate held by a REMIC Residual Certificateholder that owns
directly or indirectly a 10% or greater interest in the REMIC Residual
Certificates. 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 tax rate of 30%, subject to reduction under
any applicable tax treaty.
 
     In addition, 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 income received by such
controlled foreign corporation.
 
     Further, it appears that a REMIC Regular Certificate would not be included
in the estate of a nonresident alien individual and would not be subject to
United States estate taxes. However, Certificateholders who are non-resident
alien individuals should consult their tax advisors concerning this question.
 
     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,
1999, subject to certain transition rules. Prospective investors are urged to
consult their own tax advisors regarding the New Regulations.
 
                        STATE AND OTHER TAX CONSEQUENCES
 
     In addition to the federal income tax consequences described in "FEDERAL
INCOME TAX CONSEQUENCES", potential investors should consider the state and
local tax consequences of the acquisition, ownership, and disposition of the
Certificates offered hereunder. State tax law may differ substantially from the
corresponding federal tax law, and the discussion above does not purport to
describe any aspect of the tax laws of any state or other jurisdiction.
Therefore, prospective investors should consult their own tax advisors with
respect to the various tax consequences of investments in the certificates
offered hereunder.
 
                              ERISA CONSIDERATIONS
 
     The Employee Retirement Income Security Act of 1974, as amended ("ERISA"),
imposes certain fiduciary and prohibited transaction restrictions on employee
pension and welfare benefit plans subject to ERISA ("ERISA Plans"). Section 4975
of the Code imposes similar prohibited transaction restrictions on tax-qualified
retirement plans described in Section 401(a) of the Code ("Qualified Retirement
Plans") and on Individual Retirement Accounts ("IRAs") described in Section 408
of the Code (collectively, "Tax-Favored Plans"). 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
 
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<PAGE>   143
 
instruments governing the Plan, consistent with the Plan's overall investment
policy and appropriate in view of the composition of its investment portfolio.
 
     Certain employee benefit plans, such as 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 ERISA requirements discussed herein. Accordingly,
assets of such plans may be invested in Certificates without regard to the ERISA
considerations described below, subject to the provisions of applicable federal
and state law. Any such plan that is a Qualified Retirement Plan and exempt from
taxation under Sections 401(a) and 501(a) of the Code, however, is subject to
the prohibited transaction rules set forth in Section 503 of the Code.
 
     Section 406 of ERISA and Section 4975 of the Code prohibit a broad range of
transactions involving "plan assets" of ERISA Plans and Tax-Favored Plans
(collectively, "Plans") and persons ("parties in interest" under ERISA or
"disqualified persons" under the Code (collectively, "Parties in Interest")) who
have certain specified relationships to the Plans, unless a statutory or
administrative exemption is available. Certain Parties in Interest who
participate in a prohibited transaction may be subject to a penalty or an excise
tax imposed pursuant to Section 502(i) of ERISA or Section 4975 of the Code,
unless a statutory or administrative exemption is available.
 
PLAN ASSET REGULATIONS
 
     Investments of Plan Assets (as defined below) in Certificates may cause the
underlying Mortgage Loans included in a Trust Fund to be deemed "plan assets" of
investing Plans. The U.S. Department of Labor (the "DOL") has promulgated
regulations (the "DOL Regulations") concerning whether or not the assets of a
Plan would be deemed to include an interest in the underlying assets of an
entity (such as a Trust Fund), for purposes of applying the general fiduciary
responsibility provisions of ERISA and the prohibited transaction provisions of
ERISA and Section 4975 of the Code, when a Plan acquires an "equity interest"
(such as a Certificate) in such entity. Because of the factual nature of certain
of the rules set forth in the DOL Regulations, Plan Assets either may be deemed
to include an interest in the assets of a Trust Fund or may be deemed merely to
include its interest in the Certificates. Therefore, neither Plans nor such
entities should acquire or hold Certificates in reliance upon the availability
of any exception under the DOL Regulations. For purposes of this Section "ERISA
CONSIDERATIONS," the term "Plan Assets" or "assets of a Plan" has the meaning
specified in the DOL Regulations and includes an undivided interest in the
underlying assets of certain entities in which a Plan invests.
 
     The prohibited transaction provisions of Section 406 of ERISA and Section
4975 of the Code may apply to a Trust Fund and cause the Depositor, the Master
Servicer, any Subservicer, the Trustee, the obligor under any credit enhancement
mechanism or certain affiliates thereof, to be considered or become Parties in
Interest with respect to an investing Plan or a Plan holding an interest in an
investing entity whose assets include Plan Assets (a "Plan Asset Investor"). If
so, the acquisition or holding of Certificates by, on behalf of or with Plan
Assets of any Plan could also give rise to a prohibited transaction under ERISA
and/or Section 4975 of the Code, unless some statutory or administrative
exemption is available. Certificates acquired by a Plan would constitute assets
of that Plan. Under the DOL Regulations, the Trust Fund, including the Mortgage
Loans and the other assets held in the Trust Fund, may also be deemed to be
assets of each Plan that acquires Certificates. Special caution should be
exercised before Plan Assets are used to acquire a Certificate in such
circumstances, especially if, with respect to such assets, the Depositor, the
Master Servicer, any Subservicer, the Trustee, the obligor under any credit
enhancement mechanism or an affiliate thereof either (i) has investment
discretion with respect to the investment of such Plan Assets or (ii) has
authority or responsibility to give (or regularly gives) investment advice with
respect to such Plan Assets for a fee pursuant to an agreement or understanding
that such advice will serve as a primary basis for investment decisions with
respect to such Plan Assets.
 
     Any person who has discretionary authority or control respecting the
management or disposition of Plan Assets, and any person who provides investment
advice with respect to such assets for a fee (in the manner described above), is
a fiduciary of the investing Plan. If the Mortgage Loans were to constitute Plan
Assets, then any party exercising management or discretionary control regarding
those assets may be deemed to be a
 
                                       86
<PAGE>   144
 
Plan "fiduciary," and thus subject to the fiduciary requirements of ERISA and
the prohibited transaction provisions of ERISA and Section 4975 of the Code with
respect to any investing Plan. In addition, if the Mortgage Loans were to
constitute Plan Assets, then the acquisition or holding of Certificates by, on
behalf of or with Plan Assets, as well as the operation of the Trust Fund, may
constitute or result in a prohibited transaction under ERISA and/or Section 4975
of the Code.
 
PROHIBITED TRANSACTION CLASS EXEMPTION 83-1
 
     Prohibited Transaction Class Exemption ("PTCE") 83-1 (Class Exemption for
Certain Transactions Involving Mortgage Pool Investment Trusts) 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 under the DOL Regulations 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 and Sections 4975(c)(1)(A)-(D) of the Code (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 and Sections
4975(c)(1)(E) and (F) of the Code (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 Depositor 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 Depositor, the Trustee and the obligor under any
credit enhancement mechanism, 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.
 
     The Trustee for each Series will be unaffiliated with the Depositor, and
the first general condition of PTCE 83-1 will be satisfied for each such Series.
With respect to the second general condition of PTCE 83-1, the Depositor 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 Senior
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 Depositor intends to use its best efforts to
establish for each Series a compensation method which will produce for the
Depositor total compensation which will not exceed adequate consideration for
forming the Mortgage Pool, selling the Certificates and fulfilling any duties
owed the Mortgage Pool by the Depositor under the applicable Pooling Agreement.
However, the Depositor 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
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<PAGE>   145
 
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 Depositor, the Trustee, the
obligor under any credit enhancement mechanism, as applicable, 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 a Trust Fund that includes 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 the 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 or 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 or 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 Supplement, may accord a Plan or a Plan Asset Investor protection
from violations of the prohibited transaction rules of ERISA and Section 4975 of
the Code if the Plan or Plan Asset Investor satisfies the conditions described
in the applicable Prospectus Supplement.
 
TAX EXEMPT INVESTORS
 
     A Plan that is exempt from federal income taxation pursuant to Section 501
of the Code (a "Tax Exempt Investor") nonetheless will be subject to federal
income taxation to the extent that its income is "unrelated business taxable
income" ("UBTI") within the meaning of Section 512 of the Code. All "excess
inclusions" of a REMIC allocated to a REMIC Residual Certificate held by a
Tax-Exempt Investor will be considered UBTI and thus will be subject to federal
income tax. See "FEDERAL INCOME TAX CONSEQUENCES -- Taxation of Owners of REMIC
Residual Certificates -- Excess Inclusions."
 
CONSULTATION WITH COUNSEL
 
     Any fiduciary or other Plan Asset Investor that proposes to acquire or hold
Certificates on behalf of or with Plan Assets of any Plan should consult with
its counsel with respect to the potential applicability of the fiduciary
responsibility provisions of ERISA and the prohibited transaction provisions of
ERISA and
 
                                       88
<PAGE>   146
 
Section 4975 of the Code to the proposed investment and the availability of PTCE
83-1 or any other prohibited transaction exemption.
 
                            LEGAL INVESTMENT MATTERS
 
     Each Class of Certificates offered by means of this Prospectus and the
related Prospectus Supplement will be rated at the date of issuance in one of
the four highest rating categories by at least one Rating Agency. If so
specified in the related Prospectus Supplement each such Class that is rated in
one of the two highest rating categories by at least one Rating Agency 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 on or prior to October 3, 1991
specifically limiting the legal investment authority of any such entities with
respect to "mortgage related securities," such securities will constitute legal
investments for entities subject to such legislation only to the extent provided
therein. Certain States have enacted legislation which overrides the preemption
provisions of SMMEA. SMMEA provides, however, that in no event will the
enactment of any such legislation affect the validity of any contractual
commitment to purchase, hold or invest in "mortgage related securities," or
require the sale or other disposition of such securities, so long as such
contractual commitment was made or such securities acquired prior to the
enactment of such legislation.
 
     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 "mortgage
related securities" without limitation as to the percentage of their assets
represented thereby, federal credit unions may invest in such securities, and
national banks may purchase such securities for their own account without regard
to the limitations generally applicable to investment securities set forth in 12
U.S.C. 24 (Seventh), subject in each case to such regulations as the applicable
federal regulatory authority may prescribe.
 
     The Federal Financial Institutions Examination Council has issued a
supervisory policy statement (the "Policy Statement") applicable to all
depository institutions, setting forth guidelines for and significant
restrictions on investments in "high-risk mortgage securities." The Policy
Statement has been adopted by the Federal Reserve Board, the Office of the
Comptroller of the Currency, the FDIC and the OTS with an effective date of
February 10, 1992. The Policy Statement generally indicates that a mortgage
derivative product will be deemed to be high risk if it exhibits greater price
volatility than a standard fixed rate 30-year mortgage security. According to
the Policy Statement, prior to purchase, a depository institution will be
required to determine whether a mortgage derivative product that it is
considering acquiring is high-risk, and if so that the proposed acquisition
would reduce the institution's overall interest rate risk. Reliance on analysis
and documentation obtained from a securities dealer or other outside party
without internal analysis by the institution would be unacceptable. There can be
no assurance as to which Classes of Certificates will be treated as high-risk
under the Policy Statement.
 
     The predecessor to the OTS issued a bulletin, entitled "Mortgage Derivative
Products and Mortgage Swaps," which is applicable to thrift institutions
regulated by the OTS. The bulletin established guidelines for the investment by
savings institutions in certain "high-risk" mortgage derivative securities and
limitations on the use of such securities by insolvent, undercapitalized or
otherwise "troubled" institutions. According to the bulletin, such "high-risk"
mortgage derivative securities include securities having certain specified
characteristics, which may include certain Classes of Certificates. In addition,
the National Credit Union Administration has issued regulations governing
federal credit union investments which prohibit investment in certain
 
                                       89
<PAGE>   147
 
specified types of securities, which may include certain Classes of
Certificates. Similar policy statements have been issued by regulators having
jurisdiction over other types of depository institutions.
 
     Certain Classes of Certificates offered hereby, including any Class that is
not rated in one of the two highest rating categories by at least one Rating
Agency, will not constitute "mortgage related securities" for purposes of SMMEA.
Any such Class of Certificates will be identified in the related Prospectus
Supplement. Prospective investors in such Classes of Certificates, in
particular, should consider the matters discussed in the following paragraph.
 
     There may be other restrictions on the ability of certain investors either
to purchase certain Classes of Certificates or to purchase any Class of
Certificates representing more than a specified percentage of the investors'
assets. The Depositor will make no representations as to the proper
characterization of any Class of Certificates for legal investment or other
purposes, or as to the ability of particular investors to purchase any Class of
Certificates under applicable legal investment restrictions. These uncertainties
may adversely affect the liquidity of any Class of Certificates. Accordingly,
all investors whose investment activities are subject to legal investment laws
and regulations, regulatory capital requirements or review by regulatory
authorities should consult with their own legal advisors in determining whether
and to what extent the Certificates of any Class constitute legal investments or
are subject to investment, capital or other restrictions, and, if applicable,
whether SMMEA has been overridden in any jurisdiction relevant to such investor.
 
                                USE OF PROCEEDS
 
     Substantially all of the net proceeds to be received from the sale of
Certificates will be applied by the Depositor to finance the purchase of, or to
repay short-term loans incurred to finance the purchase of, the Mortgage Loans
underlying the Certificates or will be used by the Depositor for general
corporate purposes. The Depositor expects that it will make additional sales of
securities similar to the Certificates from time to time, but the timing and
amount of any such additional offerings will be dependent upon a number of
factors, including the volume of mortgage loans purchased by the Depositor,
prevailing interest rates, availability of funds and general market conditions.
 
                            METHODS OF DISTRIBUTION
 
     The Certificates offered hereby and by the related Prospectus Supplements
will be offered in Series through one or more of the methods described below.
The Prospectus Supplement prepared for each Series will describe the method of
offering being utilized for that Series and will state the net proceeds to the
Depositor from such sale.
 
     The Depositor intends that Certificates will be offered through the
following methods from time to time and that offerings may be made concurrently
through more than one of these methods or that an offering of a particular
Series of Certificates may be made through a combination of two or more of these
methods. Such methods are as follows:
 
          1. By negotiated firm commitment or best efforts underwriting and
     public re-offering by underwriters;
 
          2. By placements by the Depositor with institutional investors through
     dealers; and
 
          3. By direct placements by the Depositor with institutional investors.
 
     If underwriters are used in a sale of any Certificates (other than in
connection with an underwriting on a best efforts basis), such Certificates will
be acquired by the underwriters for their own account and may be resold from
time to time in one or more transactions, including negotiated transactions, at
fixed public offering prices or at varying prices to be determined at the time
of sale or at the time of commitment therefor. The managing underwriter or
underwriters with respect to the offer and sale of a particular Series of
Certificates will be set forth on the cover of the Prospectus Supplement
relating to such Series and the members of the underwriting syndicate, if any,
will be named in such Prospectus Supplement. NationsBanc Montgomery
 
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<PAGE>   148
 
Securities LLC an affiliate of the Depositor and the Master Servicer, may
participate as an underwriter in the offering of the Certificates.
 
     In connection with the sale of the Certificates, underwriters may receive
compensation from the Depositor or from purchasers of the Certificates in the
form of discounts, concessions or commissions. Underwriters and dealers
participating in the distribution of the Certificates may be deemed to be
underwriters in connection with such Certificates, and any discounts or
commissions received by them from the Depositor and any profit on the resale of
Certificates by them may be deemed to be underwriting discounts and commissions
under the Securities Act of 1933, as amended.
 
     This Prospectus and the related Prospectus Supplement may be used by
NationsBanc Montgomery Securities LLC in connection with offers and sales
related to secondary market transactions in any Series of Certificates.
NationsBanc Montgomery Securities LLC 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.
 
     It is anticipated that the underwriting agreement pertaining to the sale of
any Series of Certificates will provide that the obligations of the underwriters
will be subject to certain conditions precedent, that the underwriters will be
obligated to purchase all such Certificates if any are purchased (other than in
connection with an underwriting on a best efforts basis) and that, in limited
circumstances, the Depositor will indemnify the several underwriters and the
underwriters will indemnify the Depositor against certain civil liabilities,
including liabilities under the Securities Act of 1933, as amended, or will
contribute to payments required to be made in respect thereof.
 
     The Prospectus Supplement with respect to any Series offered by placements
through dealers will contain information regarding the nature of such offering
and any agreements to be entered into between the Depositor and purchasers of
Certificates of such Series.
 
     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 Securities Act of 1933, as amended, in connection with reoffers
and sales by them of Certificates. Holders of Certificates should consult with
their legal advisors in this regard prior to any such reoffer or sale.
 
                                     RATING
 
     It is a condition to the issuance of the Certificates of each Series
offered hereby and by the related Prospectus Supplement that they shall have
been rated in one of the four highest rating categories by one or more
nationally recognized statistical rating agencies (each, a "Rating Agency")
specified in the related Prospectus Supplement.
 
     Ratings on mortgage pass-through certificates address the likelihood of
receipt by certificateholders of all distributions on the underlying mortgage
loans. These ratings address the structural, legal and issuer-related aspects
associated with such certificates, the nature of the underlying mortgage loans
and the credit quality of the guarantor, if any. Ratings on mortgage
pass-through certificates do not represent any assessment of the likelihood of
principal prepayments by mortgagors or of the degree by which such prepayments
might differ from those originally anticipated. As a result, certificateholders
might suffer a lower than anticipated yield, and, in addition, holders of
stripped pass-through certificates in extreme cases might fail to recoup their
initial investments.
 
     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
organization. Each security rating should be evaluated independently of any
other security rating.
 
                                 LEGAL MATTERS
 
     Certain legal matters will be passed upon for the Depositor by Orrick,
Herrington & Sutcliffe LLP, San Francisco, California.
 
                                       91
<PAGE>   149
 
                             FINANCIAL INFORMATION
 
     The Depositor has determined that its financial statements are not material
to the offering made hereby.
 
                             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., and 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. In addition, such
Registration Statement, the exhibits thereto and any reports or other
information filed with the Commission through its Electronic Data Gathering,
Analysis, and Retrieval System are publicly available through the Commission's
Web site (http://www.sec.gov).
 
                                       92
<PAGE>   150
 
                         INDEX OF PRINCIPAL DEFINITIONS
 
<TABLE>
<CAPTION>
                                       PAGE
                                       ----
<S>                                    <C>
Accrual Certificates.................    19
Advance..............................    29
Affiliated Seller....................     8
Appraised Value......................     9
ARM Loans............................     8
Balloon Amount.......................     9
Baloon Loans.........................     9
Bank of America NT&SA................    11
Bankruptcy Amount....................    33
Bankruptcy Loss......................    35
Book-Entry Certificates..............    20
Buydown Account......................    10
Buydown Agreement....................    26
Buydown Funds........................    10
Buydown Mortgage Loans...............    10
Buydown Period.......................    10
CEDEL................................    22
CEDEL Participants...................    22
Certificate Account..................    25
Certificate Account Deposit Date.....    25
Certificate Insurance Policy.........    37
Certificate Principal Balance........    28
Certificateholders...................     3
Certificates.........................     8
Citibank.............................    20
Class................................     8
Closing Date.........................    72
Code.................................    16
Commission...........................     3
Committee Report.....................    66
Contributions Tax....................    82
Convertible Mortgage Loan............    10
Cooperative..........................     8
Cooperative Loans....................     8
Cooperative Notes....................     8
Credit Enhancer......................    35
Custodial Account....................    16
Cypress Center.......................    16
Debt Service Reduction...............    37
Defaulted Mortgage Loss..............    35
Deficient Valuation..................    37
Definitive Certificates..............    21
Deleted Mortgage Loan................    15
Depositaries.........................    20
</TABLE>
 
<TABLE>
<CAPTION>
                                       PAGE
                                       ----
<S>                                    <C>
Depositor............................     8
Determination Date...................    29
DOL..................................    86
DOL Regulations......................    86
DTC..................................    20
Due Date.............................    24
Eligible Account.....................    25
ERISA................................    85
ERISA Plans..........................    85
Euroclear............................    22
Euroclear Cooperative................    22
Euroclear Operator...................    22
Euroclear Participants...............    22
Extraordinary Losses.................    35
FDIC.................................    12
FHA..................................    14
FHLMC................................    12
FNMA.................................    12
Form of Pooling Agreement............     4
Fraud Loss...........................    35
Fraud Loss Amount....................    37
Garn-St Germain Act..................    58
GNMA.................................    12
Grantor Trust Certificates...........    60
Grantor Trust Fractional Interest
  Certificate........................    61
Grantor Trust Fund...................    60
Grantor Trust Strip Certificate......    61
Guides...............................    12
Holder...............................    20
Index................................     9
Indirect Participants................    21
Insurance Proceeds...................    25
IRAs.................................    85
IRS..................................    62
Issue Premium........................    77
Letter of Credit.....................    36
Letter of Credit Bank................    36
Liquidated Mortgage Loan.............    31
Liquidation Proceeds.................    25
Loan-to-Value Ratio..................     9
Loss.................................    41
Mark-to-Market Regulations...........    80
Master Commitments...................    14
Master Servicer......................     8
Morgan...............................    20
</TABLE>
 
                                       93
<PAGE>   151
 
<TABLE>
<CAPTION>
                                       PAGE
                                       ----
<S>                                    <C>
Mortgage File........................    25
Mortgage Loans.......................     8
Mortgage Notes.......................     8
Mortgage Pool........................     8
Mortgage Pool Insurance Policy.......    36
Mortgage Rate........................     8
Mortgaged Properties.................     8
Mortgages............................     8
Mortgagor............................     9
Net 5 Loans..........................     9
Net Mortgage Rate....................    54
New Regulations......................    85
Non-OID Pool.........................    65
Nonrecoverable Advance...............    27
Note Margin..........................     8
OID Pool.............................    64
OID Regulations......................    60
OTS..................................    16
Owners...............................    21
Participants.........................    21
Parties in Interest..................    86
Pass-Through Rate....................    28
Paying Agent.........................    27
Percentage Interest..................    28
Permitted Investments................    25
Plan Asset Investor..................    86
Plan Assets..........................    91
Plans................................    86
Policy Statement.....................    89
Pool Insurer.........................    30
Pooling Agreement....................     4
Prepayment Assumption................    64
Prepayment Interest Shortfall........    28
Primary Mortgage Insurance Policy....    41
Primary Mortgage Insurer.............    41
Principal Prepayments................    24
Prohibited Transactions Tax..........    82
PTCE.................................    87
Qualified Retirement Plans...........    85
Qualified Stated Interest............    72
Qualified Substitute Mortgage Loan...    15
Rapid Processing Program.............    13
Rating Agency........................    91
Realized Loss........................    33
</TABLE>
 
<TABLE>
<CAPTION>
                                       PAGE
                                       ----
<S>                                    <C>
Record Date..........................    27
Relief Act...........................    59
REMIC................................    60
REMIC Certificates...................    60
REMIC Provisions.....................    60
REMIC Regular Certificates...........    70
REMIC Regulations....................    60
REMIC Residual Certificates..........    70
REO Mortgage Loan....................    31
Reserve Fund.........................    37
Retained Yield.......................    24
Richmond Center......................    16
Rules................................    21
Sellers..............................     8
Senior Certificates..................    19
Senior Percentage....................    34
Senior/Subordinate Series............    19
Series...............................     8
Servicing Advances...................    27
Single Certificate...................    30
SMMEA................................    89
Special Hazard Amount................    33
Special Hazard Instrument............    35
Special Hazard Insurance Policy......    36
Special Hazard Loss..................    35
Special Tax Counsel..................    61
Stated Principal Balance.............    34
Strip Certificates...................    19
Subordinate Amount...................    34
Subordinate Certificates.............    19
Subservicers.........................    11
Tax Exempt Investor..................    88
Tax-Favored Plans....................    85
Terms and Conditions.................    22
Tiered REMICs........................    71
Title V..............................    59
Title VIII...........................    59
Trust Fund...........................     8
Trustee..............................     3
UBTI.................................    88
UCC..................................    56
Unaffiliated Sellers.................     8
Unrecovered Senior Portion...........    34
</TABLE>
 
                                       94
<PAGE>   152
 
                          BA MORTGAGE SECURITIES, INC.
                                   Depositor
 
                              BANK OF AMERICA, FSB
                                Master Servicer
 
                       MORTGAGE PASS-THROUGH CERTIFICATES
 
                                 SERIES 1998-6
 
                                  $397,395,732
                                 (APPROXIMATE)
 
                            ------------------------
 
                             PROSPECTUS SUPPLEMENT
 
                            ------------------------
 
                                  Underwriter
 
                          DONALDSON, LUFKIN & JENRETTE
                                   SECURITIES
                      CORPORATION
 
YOU SHOULD RELY ONLY ON THE INFORMATION CONTAINED OR INCORPORATED BY REFERENCE
IN THIS PROSPECTUS SUPPLEMENT AND THE ACCOMPANYING PROSPECTUS. WE HAVE NOT
AUTHORIZED ANYONE TO PROVIDE YOU WITH DIFFERENT INFORMATION.
 
WE ARE NOT OFFERING THE OFFERED CERTIFICATES IN ANY STATE WHERE THE OFFER IS NOT
PERMITTED.
 
WE DO NOT CLAIM THE ACCURACY OF THE INFORMATION IN THIS PROSPECTUS SUPPLEMENT
AND THE ACCOMPANYING PROSPECTUS AS OF ANY DATE OTHER THAN THE DATES STATED ON
THEIR RESPECTIVE COVERS.
 
DEALERS WILL DELIVER A PROSPECTUS SUPPLEMENT AND PROSPECTUS WHEN ACTING AS
UNDERWRITERS OF THE OFFERED CERTIFICATES AND WITH RESPECT TO THEIR UNSOLD
ALLOTMENTS OR SUBSCRIPTIONS. IN ADDITION, ALL DEALERS SELLING THE OFFERED
CERTIFICATES WILL DELIVER A PROSPECTUS SUPPLEMENT AND PROSPECTUS UNTIL FEBRUARY
16, 1999.


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