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SUPPLEMENT TO THE PROSPECTUS OF
DEAN WITTER FEDERAL SECURITIES TRUST Dated December 27, 1993
The following disclosure supplements the "Investment Objective and Policies"
section and replaces the ninth paragraph of that section appearing at page 6 of
the Prospectus:
The Fund will invest in mortgage pass-through securities representing
participation interests in pools of residential mortgage loans originated by
United States governmental or private lenders such as banks, broker-dealers and
financing corporations and guaranteed, to the extent provided in such
securities, by the United States Government or one of its agencies or
instrumentalities. Such securities, which are ownership interests in the
underlying mortgage loans, differ from conventional debt securities, which
provide for periodic payment of interest in fixed amounts (usually
semi-annually) and principal payments at maturity or on specified call dates.
Mortgage pass-through securities provide for monthly payments that are a
"pass-through" of the monthly interest and principal payments (including any
prepayments) made by the individual borrowers on the pooled mortgage loans, net
of any fees paid to the guarantor of such securities and the servicer of the
underlying mortgage loans.
The guaranteed mortgage pass-through securities in which the Fund may invest
include those issued or guaranteed by GNMA, FNMA and FHLMC. GNMA certificates
are direct obligations of the U.S. Government and, as such, are backed by the
"full faith and credit" of the United States. FNMA is a federally chartered,
privately owned corporation and FHLMC is a corporate instrumentality of the
United States. FNMA and FHLMC certificates are not backed by the full faith and
credit of the United States, but the issuing agency or instrumentality has the
right to borrow, to meet its obligations, from an existing line of credit with
the U.S. Treasury. The U.S. Treasury has no legal obligation to provide such
line of credit and may choose not to do so.
Certificates for mortgage-backed securities evidence an interest in a
specific pool of mortgages. These certificates are, in most cases, "modified
pass-through" instruments, wherein the issuing agency guarantees the payment of
principal and interest on mortgages underlying the certificates, whether or not
such amounts are collected by the issuer on the underlying mortgages.
ADJUSTABLE RATE MORTGAGE SECURITIES. The Fund may also invest in adjustable
rate mortgage securities ("ARMs"), which are pass-through mortgage securities
collateralized by mortgages with adjustable rather than fixed rates. ARMs
eligible for inclusion in a mortgage pool generally provide for a fixed initial
mortgage interest rate for either the first three, six, twelve or thirteen
scheduled monthly payments. Thereafter, the interest rates are subject to
periodic adjustment based on charges to a designated benchmark index.
ARMs contain maximum and minimum rates beyond which the mortgage interest
rate may not vary over the lifetime of the security. In addition, certain ARMs
provide for additional limitations on the maximum amount by which the mortgage
interest rate may adjust for any single adjustment period. Alternatively,
certain ARMs contain limitations on changes in the required monthly payment. In
the event that a monthly payment is not sufficient to pay the interest accruing
on an ARM, any such excess interest is added to the principal balance of the
mortgage loan, which is repaid through future monthly payments. If the monthly
payment for such an instrument exceeds the sum of the interest accrued at the
applicable mortgage interest rate and the principal payment required at such
point to amortize the outstanding principal balance over the remaining term of
the loan, the excess is utilized to reduce the then outstanding principal
balance of the ARM.
PRIVATE MORTGAGE PASS-THROUGH SECURITIES. Private mortgage pass-through
securities are structured similarly to the GNMA, FNMA and FHLMC mortgage
pass-through securities and are issued by originators of and investors in
mortgage loans, including savings and loan associations, mortgage banks,
commercial banks, investment banks and special purpose subsidiaries of the
foregoing. These securities usually are backed by a pool of conventional fixed
rate or adjustable rate mortgage loans. Since private mortgage pass-through
securities typically are not guaranteed by an entity having the credit status of
GNMA, FNMA and FHLMC, such securities generally are structured with one or more
types of credit enhancement.
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COLLATERALIZED MORTGAGE OBLIGATIONS AND MULTICLASS PASS-THROUGH
SECURITIES. Collateralized mortgage obligations or "CMOs" are debt obligations
collateralized by mortgage loans or mortgage pass-through securities. Typically,
CMOs are collateralized by GNMA, FNMA or FHLMC Certificates, but also may be
collateralized by whole loans or private mortgage pass-through securities (such
collateral collectively hereinafter referred to as "Mortgage Assets").
Multiclass pass-through securities are equity interests in a trust composed of
Mortgage Assets. Payments of principal of and interest on the Mortgage Assets,
and any reinvestment income thereon, provide the funds to pay debt service on
the CMOs or make scheduled distributions on the multiclass pass-through
securities. CMOs may be issued by agencies or instrumentalities of the United
States government, or by private originators of, or investors in, mortgage
loans, including savings and loan associations, mortgage banks, commercial
banks, investment banks and special purpose subsidiaries of the foregoing. The
issuer of a series of CMOs may elect to be treated as a Real Estate Mortgage
Investment Conduit ("REMIC"). REMICs include governmental and/or private
entities that issue a fixed pool of mortgages secured by an interest in real
property. REMICs are similar to CMOs in that they issue multiple classes of
securities, but unlike CMOs, which are required to be structured as debt
securities, REMICs may be structured as indirect ownership interests in the
underlying assets of the REMICs themselves. However, there are no effects on the
Fund from investing in CMOs issued by entities that have elected to be treated
as REMICs, and all future references to CMOs shall also be deemed to include
REMICs. The Fund may invest without limitation in CMOs.
In a CMO, a series of bonds or certificates is issued in multiple classes.
Each class of CMOs, often referred to as a "tranche", is issued at a specific
fixed or floating coupon rate and has a stated maturity or final distribution
date. Principal prepayments on the Mortgage Assets may cause the CMOs to be
retired substantially earlier than their stated maturities or final distribution
dates. Interest is paid or accrues on all classes of the CMOs on a monthly,
quarterly or semi-annual basis. Certain CMOs may have variable or floating
interest rates and others may be stripped (securities which provide only the
principal or interest feature of the underlying security).
The principal of and interest on the Mortgage Assets may be allocated among
the several classes of a CMO series in a number of different ways. Generally,
the purpose of the allocation of the cash flow of a CMO to the various classes
is to obtain a more predictable cash flow to the individual tranches than exists
with the underlying collateral of the CMO. As a general rule, the more
predictable the cash flow is on a CMO tranche, the lower the anticipated yield
will be on that tranche at the time of issuance relative to prevailing market
yields on mortgage-backed securities. As part of the process of creating more
predictable cash flows on most of the tranches in a series of CMOs, one or more
tranches generally must be created that absorb most of the volatility in the
cash flows on the underlying mortgage loans. The yields on these tranches are
generally higher than prevailing market yields on mortgage-backed securities
with similar maturities. As a result of the uncertainty of the cash flows of
these tranches, the market prices of and yield on these tranches generally are
more volatile.
The Fund also may invest in, among other things, parallel pay CMOs and
Planned Amortization Class CMOs ("PAC Bonds"). Parallel pay CMOs are structured
to provide payments of principal on each payment date to more than one class.
These simultaneous payments are taken into account in calculating the stated
maturity date or final distribution date of each class, which, as with other CMO
structures, must be retired by its stated maturity date or final distribution
date but may be retired earlier. PAC Bonds generally require payments of a
specified amount of principal on each payment date. PAC Bonds always are
parallel pay CMOs with the required principal payment on such securities having
the highest priority after interest has been paid to all classes.
January 28, 1994
