MORGAN STANLEY DEAN WITTER S&P 500 INDEX FUND
497, 1999-11-04
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<PAGE>

                                               Filed Pursuant to Rule 497(c)
                                               Registration File No.: 333-29721


                                                 PROSPECTUS - OCTOBER 29, 1999


MORGAN STANLEY DEAN WITTER


              ----------------------------------------------------------------


                                                            S&P 500 INDEX FUND




                               [GRAPHIC OMITTED]




A MUTUAL FUND THAT SEEKS TO PROVIDE INVESTMENT RESULTS THAT, BEFORE EXPENSES,
CORRESPOND TO THE TOTAL RETURN (I.E., THE COMBINATION OF CAPITAL CHANGES AND
INCOME) OF THE STANDARD & POOR'S (REGISTERED TRADEMARK) 500 COMPOSITE STOCK
PRICE INDEX





  The Securities and Exchange Commission has not approved or disapproved these
         securities or passed upon the adequacy of this Prospectus. Any
             representation to the contrary is a criminal offense.


<PAGE>


CONTENTS

<TABLE>
<CAPTION>
<S>                         <C>                                                           <C>
The Fund                    Investment Objective ..........................................  1
                            Principal Investment Strategies ...............................  1
                            Principal Risks ...............................................  2
                            Past Performance ..............................................  3
                            Fees and Expenses .............................................  4
                            Additional Investment Strategy Information ....................  5
                            Additional Risk Information ...................................  6
                            Fund Management ...............................................  7

Shareholder Information     Pricing Fund Shares ...........................................  9
                            How to Buy Shares .............................................  9
                            How to Exchange Shares ........................................ 11
                            How to Sell Shares ............................................ 13
                            Distributions ................................................. 15
                            Tax Consequences .............................................. 15
                            Share Class Arrangements ...................................... 16

Financial Highlights         .............................................................. 24

Our Family of Funds          ............................................... Inside Back Cover
</TABLE>


         This Prospectus contains important information about the Fund.
           Please read it carefully and keep it for future reference.


<PAGE>


THE FUND


[GRAPHIC OMITTED]


INVESTMENT OBJECTIVE
- --------------------
Morgan Stanley Dean Witter S&P 500 Index Fund seeks to provide investment
results that, before expenses, correspond to the total return (i.e., the
combination of capital changes and income) of the Standard & Poor's (Registered
Trademark) 500 Composite Stock Price Index.


[GRAPHIC OMITTED]


PRINCIPAL INVESTMENT STRATEGIES
- -------------------------------
The Fund will normally invest at least 80% of its total assets in common stocks
of companies included in the S&P 500 Index. The "Investment Manager," Morgan
Stanley Dean Witter Advisors Inc., "passively" manages the Fund's assets by
investing in stocks in approximately the same proportion as they are represented
in the Index. For example, if the common stock of a specific company represents
five percent of the Index, the Investment Manager typically will invest the same
percentage of the Fund's assets in that stock. The S&P 500 Index is a well-known
stock market index that includes common stocks of 500 companies representing a
significant portion of the market value of all common stocks publicly traded in
the United States. The Fund may invest in foreign companies that are included in
the S&P 500 Index.


[sidebar]
TOTAL RETURN
An investment objective having the goal of selecting securities with the
potential to rise in price and pay out income.
[end sidebar]


The Investment Manager seeks a correlation between the performance of the Fund,
before expenses, and that of the S&P 500 Index of 95% or better. A figure of
100% would indicate perfect correlation.

Common stock is a share ownership or equity interest in a corporation. It may or
may not pay dividends, as some companies reinvest all of their profits back into
their businesses, while others pay out some of their profits to shareholders as
dividends.

In addition, the Fund may invest in stock index futures on the S&P 500 Index,
and Standard & Poor's Depository Receipts ("SPDRs").


                                ----------------

"Standard & Poor's (Registered Trademark) ," "S&P (Registered Trademark) ," "S&P
500 (Registered Trademark) ," "Standard & Poor's 500," and "500" are trademarks
of The McGraw-Hill Companies, Inc. and have been licensed for use by the Fund.
The Fund is not sponsored, endorsed, sold or promoted by S&P, and S&P makes no
representation regarding the advisability of investing in the Fund.


                                                                               1


<PAGE>


[GRAPHIC OMITTED]


PRINCIPAL RISKS
- ---------------
There is no assurance that the Fund will achieve its investment objective. The
Fund's share price will fluctuate with changes in the market value of the Fund's
portfolio securities. When you sell Fund shares, they may be worth less than
what you paid for them and, accordingly, you can lose money investing in this
Fund.

A principal risk of investing in the Fund is associated with its common stock
investments. In general, stock values fluctuate in response to activities
specific to the issuer, as well as general market, economic and political
conditions. Stock prices can fluctuate widely in response to these factors.

Another risk of investing in the Fund arises from its operation as a "passively"
managed index fund. As such, the adverse performance of a particular stock
ordinarily will not result in the elimination of the stock from the Fund's
portfolio. The Fund will remain invested in common stocks even when stock prices
are generally falling. Ordinarily, the Investment Manager will not sell the
Fund's portfolio securities except to reflect additions or deletions of the
stocks that comprise the S&P 500 Index, or as may be necessary to raise cash to
pay Fund shareholders who sell Fund shares.

The performance of the S&P 500 Index is a hypothetical number which does not
take into account brokerage commissions and other transaction costs, custody and
other costs which will be borne by the Fund (e.g., management fee, transfer
agency and accounting costs).


The Fund's ability to correlate its performance, before expenses, with the S&P
500 Index may be affected by, among other things, changes in securities markets,
the manner in which the S&P 500 Index is calculated and the timing of purchases
and sales. The Fund's ability to correlate its performance to the Index also
depends to some extent on the size of the Fund's portfolio, the size of cash
flows into and out of the Fund and differences between how and when the Fund and
the Index are valued. The Investment Manager regularly monitors the correlation
and, in the event the desired correlation is not achieved, the Investment
Manager will determine what additional investment changes may need to be made.


The performance of the Fund also will depend on whether the Investment Manager
is successful in pursuing the Fund's investment strategy, including the
Investment Manager's ability to manage cash flows (primarily from purchases and
sales, and distributions from the Fund's investments). The Fund is also subject
to other risks from its other permissible investments including risks associated
with stock index futures, SPDRs and foreign securities. For more information
about these risks, see the "Additional Risk Information" section.

Shares of the Fund are not bank deposits and are not guaranteed or insured by
the FDIC or any other government agency.


2


<PAGE>


[GRAPHIC OMITTED]


PAST PERFORMANCE
- ----------------
The bar chart and table below provide some indication of the risks of investing
in the Fund. The Fund's past performance does not indicate how the Fund will
perform in the future.


[sidebar]
ANNUAL TOTAL RETURNS
This chart shows the performance of the Fund's Class B shares over the past
calendar year.
[end sidebar]



ANNUAL TOTAL RETURN -- CALENDAR YEAR

1998 ................................. 26.84%

The bar chart reflects the performance of Class B shares; the performance of the
other Classes will differ because the Classes have different ongoing fees. The
performance information in the bar chart does not reflect the deduction of sales
charges; if these amounts were reflected, returns would be less than shown.
Year-to-date total return as of September 30, 1999 was 4.07%.


During the periods shown in the bar chart, the highest return for a calendar
quarter was 21.06% (quarter ended December 31, 1998), and the lowest return for
a calendar quarter was -10.26% (quarter ended September 30, 1998).


[sidebar]
AVERAGE ANNUAL TOTAL RETURNS
This table compares the Fund's average annual returns with those of a broad
measure of market performance over time as well as with an index of funds with
similar investment objectives. The Fund's returns include the maximum
applicable sales charge for each Class and assume you sold your shares at the
end of each period.
[end sidebar]



AVERAGE ANNUAL TOTAL RETURNS (AS OF DECEMBER 31, 1998)
- ------------------------------------------------------

<TABLE>
<CAPTION>
                                             LIFE OF FUND
                             PAST 1 YEAR   (SINCE 9/26/97)
- ----------------------------------------------------------
<S>                          <C>           <C>
Class A                        21.19%          19.17%
- ----------------------------------------------------------
Class B                        21.84%          20.37%
- ----------------------------------------------------------
Class C                        25.86%          23.38%
- ----------------------------------------------------------
Class D                        28.18%          24.63%
- ----------------------------------------------------------
S&P Index(1)                   28.58%          25.04%
- ----------------------------------------------------------
Lipper S&P 500 Fund Index(2)   28.34%          24.84%
- ----------------------------------------------------------
</TABLE>

(1)   The Standard & Poor's (Registered Trademark) 500 Stock Price Index is a
      broad-based index, the performance of which is based on the average
      performance of 500 widely held common stocks. The performance of the Index
      does not include any expenses, fees or charges. The Index is unmanaged and
      should not be considered an investment.

(2)   The Lipper S&P 500 Fund Index is an equally-weighted performance index of
      the largest qualifying funds (based on net assets) in the Lipper S&P 500
      Index Funds objective. The Index, which is adjusted for capital gains
      distributions and income dividends, is unmanaged and should not be
      considered an investment. There are currently 10 funds represented in this
      Index.


                                                                               3


<PAGE>


[GRAPHIC OMITTED]


FEES AND EXPENSES
- -----------------
The table below briefly describes the fees and expenses that you may pay if you
buy and hold shares of the Fund. The Fund offers four classes of shares: Classes
A, B, C and D. Each Class has a different combination of fees, expenses and
other features. The Fund does not charge account or exchange fees. See the
"Share Class Arrangements" section for further fee and expense information.


[sidebar]
SHAREHOLDER FEES
These fees are paid directly from your investment.
[end sidebar]


[sidebar]
ANNUAL FUND OPERATING EXPENSES
These expenses are deducted from the Fund's assets and are based on expenses
paid for the fiscal year ended August 31, 1999.
[end sidebar]


<TABLE>
<CAPTION>
                                                  CLASS A       CLASS B       CLASS C      CLASS D
- --------------------------------------------------------------------------------------------------
<S>                                              <C>           <C>           <C>           <C>
SHAREHOLDER FEES
- --------------------------------------------------------------------------------------------------
Maximum sales charge (load) imposed on
purchases (as a percentage of offering price)     5.25%(1)       None          None         None
- --------------------------------------------------------------------------------------------------
Maximum deferred sales charge (load) (as a
percentage based on the lesser of the offering
price or net asset value at redemption)           None(2)        5.00%(3)      1.00%(4)     None
- --------------------------------------------------------------------------------------------------
ANNUAL FUND OPERATING EXPENSES
- --------------------------------------------------------------------------------------------------
Management fee                                    0.31%          0.31%         0.31%        0.31%
- --------------------------------------------------------------------------------------------------
Distribution and service (12b-1) fees             0.23%          1.00%         1.00%        None
- --------------------------------------------------------------------------------------------------
Other expenses                                    0.19%          0.19%         0.19%        0.19%
- --------------------------------------------------------------------------------------------------
Total annual Fund operating expenses(5)           0.73%          1.50%         1.50%        0.50%
- --------------------------------------------------------------------------------------------------
</TABLE>

(1)   Reduced for purchases of $25,000 and over.

(2)   Investments that are not subject to any sales charge at the time of
      purchase are subject to a contingent deferred sales charge ("CDSC") of
      1.00% that will be imposed if you sell your shares within one year after
      purchase, except for certain specific circumstances.

(3)   The CDSC is scaled down to 1.00% during the sixth year, reaching zero
      thereafter. See "Share Class Arrangements" for a complete discussion of
      the CDSC.

(4)   Only applicable if you sell your shares within one year after purchase.

(5)   The Investment Manager has agreed to assume all expenses (except for
      brokerage and 12b-1 fees) and to waive the compensation provided for in
      its Investment Management Agreement to the extent that such expenses and
      compensation on an annualized basis exceed 0.50% of the daily net assets
      of the Fund and will continue to do so on a permanent basis. The fees and
      expenses disclosed above reflect the assumption of such expenses and
      waiver of compensation by the Investment Manager to the extent that such
      expenses and compensation on an annualized basis exceed 0.50% of the daily
      net assets of the Fund.


4


<PAGE>


EXAMPLE

This example is intended to help you compare the cost of investing in the Fund
with the cost of investing in other mutual funds.

The example assumes that you invest $10,000 in the Fund, your investment has a
5% return each year, and the Fund's operating expenses remain the same. Although
your actual costs may be higher or lower, the tables below show your costs at
the end of each period based on these assumptions depending upon whether or not
you sell your shares at the end of each period.

<TABLE>
<CAPTION>
                 IF YOU SOLD YOUR SHARES:           IF YOU HELD YOUR SHARES:
- ------------------------------------------------    ----------------------------------------
<S>         <C>      <C>       <C>        <C>         <C>       <C>        <C>        <C>
          1 YEAR   3 YEARS   5 YEARS    10 YEARS    1 YEAR    3 YEARS    5 YEARS    10 YEARS
- ------------------------------------------------    ----------------------------------------
CLASS A    $596     $746      $910       $1,384      $596      $746       $910       $1,384
- ------------------------------------------------    ----------------------------------------
CLASS B    $653     $774      $1,018     $1,791      $153      $474       $818       $1,791
- ------------------------------------------------    ----------------------------------------
CLASS C    $253     $474      $818       $1,791      $153      $474       $818       $1,791
- ------------------------------------------------    ----------------------------------------
CLASS D    $51      $160      $280       $628        $51       $160       $280       $628
- ------------------------------------------------    ----------------------------------------
</TABLE>


Long-term shareholders of Class B and Class C may pay more in sales charges,
including distribution fees, than the economic equivalent of the maximum
front-end sales charges permitted by the NASD.



[GRAPHIC OMITTED]


ADDITIONAL INVESTMENT STRATEGY INFORMATION
- ------------------------------------------
This section provides additional information relating to the Fund's principal
strategies.


Stock Index Futures. The Fund may invest in stock index futures with respect to
the S&P 500 Index. Stock index futures may be used to simulate investment in the
S&P 500 Index while retaining a cash balance for fund management purposes, to
facilitate trading, to reduce transaction costs or to seek higher investment
returns.


SPDRs. The Fund may invest in securities referred to as SPDRs (known as
"spiders") that are designed to track the S&P 500 Index. SPDRs represent an
ownership interest in the SPDR Trust, which holds a portfolio of common stocks
that closely tracks the price performance and dividend yield of the S&P 500
Index. SPDRs trade on the American Stock Exchange like shares of common stock.

The percentage limitations relating to the composition of the Fund's portfolio
apply at the time the Fund acquires an investment and refer to the Fund's net
assets, unless otherwise noted. Subsequent percentage changes that result from
market fluctuations will not require the Fund to sell any portfolio security.
The Fund may change its principal investment strategies without shareholder
approval; however, you would be notified of any changes.


                                                                               5


<PAGE>


[GRAPHIC OMITTED]


ADDITIONAL RISK INFORMATION
- ---------------------------
This section provides additional information relating to the principal risks of
investing in the Fund.


Foreign Securities. The Fund's investments in the common stocks of foreign
corporations (including American Depository Receipts) may involve risks in
addition to the risks associated with domestic securities. Foreign securities
are affected by changes in currency rates. Foreign securities also have risks
related to political and economic developments abroad. Foreign companies, in
general, are not subject to the regulatory requirements of U.S. companies and,
as such, there may be less publicly available information about these companies.
Moreover, foreign accounting, auditing and financial reporting standards
generally are different from those applicable to U.S. companies.


Futures. If the Fund invests in futures, its participation in these markets
would subject the Fund's portfolio to certain risks. The Investment Manager's
predictions of movements in the direction of the stock market may be inaccurate,
and the adverse consequences to the Fund (e.g., a reduction in the Fund's net
asset value or a reduction in the amount of income available for distribution)
may leave the Fund in a worse position than if these strategies were not used.
Other risks inherent in the use of futures include, for example, the possible
imperfect correlation between the price of futures contracts and movements in
the prices of the securities.

SPDRs. SPDRs, which the Fund may hold, have many of the same risks as direct
investments in common stocks. The market value of SPDRs is expected to rise and
fall as the S&P 500 Index rises and falls. If the Fund invests in SPDRs, it
would, in addition to its own expenses, indirectly bear its ratable share of the
SPDR's expenses.

Year 2000. The Fund could be adversely affected if the computer systems
necessary for the efficient operation of the Investment Manager, the Fund's
other service providers and the markets and corporate and governmental issuers
in which the Fund invests do not properly process and calculate date-related
information from and after January 1, 2000. While year 2000-related computer
problems could have a negative effect on the Fund, the Investment Manager and
its affiliates are working hard to avoid any problems and to obtain assurances
from their service providers, market participants and individual governmental
issuers that they are taking similar steps.


In addition, it is possible that the markets for securities in which the Fund
invests may be detrimentally affected by computer failures throughout the
financial services industry beginning January 1, 2000. Improperly functioning
trading systems may result in settlement problems and liquidity issues.
Corporate and governmental data processing errors may result in production
problems for individual companies and overall economic uncertainties. Earnings
of individual issuers will be affected by



6


<PAGE>


remediation costs, which may be substantial and may be reported inconsistently
in U.S. and foreign financial statements. Accordingly, the Fund's investments
may be adversely affected.


[GRAPHIC OMITTED]


FUND MANAGEMENT
- ----------------
The Fund has retained the Investment Manager -- Morgan Stanley Dean Witter
Advisors Inc. -- to provide administrative services, manage its business affairs
and invest its assets, including the placing of orders for the purchase and sale
of portfolio securities. The Investment Manager is a wholly-owned subsidiary of
Morgan Stanley Dean Witter & Co., a preeminent global financial services firm
that maintains leading market positions in each of its three primary businesses:
securities, asset management and credit services. Its main business office is
located at Two World Trade Center, New York, NY 10048.


[sidebar]
MORGAN STANLEY DEAN WITTER ADVISORS INC.
The Investment Manager is widely recognized as a leader in the mutual fund
industry and together with Morgan Stanley Dean Witter Services Company Inc., its
wholly-owned subsidiary, has more than $134 billion in assets under management
or administration as of September 30, 1999.
[end sidebar]


The Fund's portfolio is managed within the Investment Manager's Growth and
Income Group. Guy G. Rutherfurd, Jr., Senior Vice President of the Investment
Manager, is the primary portfolio manager of the Fund. Mr. Rutherfurd has been a
portfolio manager with the Investment Manager since February 1997. Prior to
joining the Investment Manager, Mr. Rutherfurd was Executive Vice President and
Chief Investment Officer of Nomura Asset Management (U.S.A.). Mr. Rutherfurd is
assisted by Kevin Jung, a Vice President of the Investment Manager since
September 1997. Prior to joining the Investment Manager, Mr. Jung was a
portfolio manager with UBS Asset Management Inc.


The Fund pays the Investment Manager a monthly management fee as full
compensation for the services and facilities furnished to the Fund, and for Fund
expenses assumed by the Investment Manager calculated daily by applying the
annual rate of 0.40% to the Fund's average daily net assets. The fee is based on
the Fund's average daily net assets. The Investment Manager has agreed, on a
permanent basis, to assume the Fund's operating expenses (except for brokerage
and 12b-1 fees) to the extent such operating expenses exceed on an annualized
basis 0.50% of the average daily net assets of the Fund, which may reduce the
investment management fee below 0.40% of the Fund's average daily net assets.
For example, if "other expenses" are 0.40% of the Fund's average daily net
assets, then the investment management fee rate paid by the Fund would equal
0.10% of the Fund's average daily net assets. Alternatively, if "other expenses"



                                                                               7


<PAGE>


were to decline to 0.30% of the Fund's average daily net assets, the investment
management fee paid by the Fund would equal 0.20% of the Fund's average daily
net assets. For the fiscal year ended August 31, 1999, the Fund accrued total
compensation to the Investment Manager amounting to 0.31% of the Fund's average
daily net assets.






8


<PAGE>


SHAREHOLDER INFORMATION


[GRAPHIC OMITTED]


PRICING FUND SHARES
- -------------------
The price of Fund shares (excluding sales charges), called "net asset value," is
based on the value of the Fund's portfolio securities. While the assets of each
Class are invested in a single portfolio of securities, the net asset value of
each Class will differ because the Classes have different ongoing distribution
fees.


The net asset value per share of the Fund is determined once daily at 4:00 p.m.
Eastern time on each day that the New York Stock Exchange is open (or, on days
when the New York Stock Exchange closes prior to 4:00 p.m., at such earlier
time). Shares will not be priced on days that the New York Stock Exchange is
closed.


The value of the Fund's portfolio securities is based on the securities' market
price when available. When a market price is not readily available, including
circumstances under which the Investment Manager determines that a security's
market price is not accurate, a portfolio security is valued at its fair value,
as determined under procedures established by the Fund's Board of Trustees. In
these cases, the Fund's net asset value will reflect certain portfolio
securities' fair value rather than their market price.

An exception to the Fund's general policy of using market prices concerns its
short-term debt portfolio securities. Debt securities with remaining maturities
of sixty days or less at the time of purchase are valued at amortized cost.
However, if the cost does not reflect the securities' market value, these
securities will be valued at their fair value.


[GRAPHIC OMITTED]


HOW TO BUY SHARES
- -----------------
You may open a new account to buy Fund shares or buy additional Fund shares for
an existing account by contacting your Morgan Stanley Dean Witter Financial
Advisor or other authorized financial representative. Your Financial Advisor
will assist you, step-by-step, with the procedures to invest in the Fund. You
may also purchase shares directly by calling the Fund's transfer agent and
requesting an application.


[sidebar]
CONTACTING A FINANCIAL ADVISOR
If you are new to the Morgan Stanley Dean Witter Family of Funds and would like
to contact a Financial Advisor, call (800) THE-DEAN for the telephone number of
the Morgan Stanley Dean Witter office nearest you. You may also access our
office locator on our Internet site at: www.msdw.com/individual/funds
[end sidebar]


Because every investor has different immediate financial needs and long-term
investment goals, the Fund offers investors four Classes of shares: Classes A,
B, C and D. Class D shares are only offered to a limited group of investors.
Each Class of shares offers a distinct structure of sales charges, distribution
and service fees, and other features that are designed to address a variety of
needs. Your Financial Advisor or other authorized financial representative can
help you decide which Class may be most appropriate for you. When purchasing
Fund shares, you must specify which Class of shares you wish to purchase.


                                                                               9


<PAGE>



When you buy Fund shares, the shares are purchased at the next share price
calculated (less any applicable front-end sales charge for Class A shares) after
we receive your purchase order. Your payment is due on the third business day
after you place your purchase order. We reserve the right to reject any order
for the purchase of Fund shares.



[sidebar]
EASYINVEST(SM)
A purchase plan that allows you to transfer money automatically from your
checking or savings account or from a Money Market Fund on a semi-monthly,
monthly or quarterly basis. Contact your Morgan Stanley Dean Witter Financial
Advisor for further information about this service.
[end sidebar]


<TABLE>
<CAPTION>
MINIMUM INVESTMENT AMOUNTS
- --------------------------------------------------------------------------------------------------------
                                                                                   MINIMUM INVESTMENT
                                                                               -------------------------
INVESTMENT OPTIONS                                                              INITIAL       ADDITIONAL
- --------------------------------------------------------------------------------------------------------
<S>                                                        <C>                <C>           <C>
Regular Accounts                                                                $1,000          $100
- --------------------------------------------------------------------------------------------------------
Individual Retirement Accounts:                             Regular IRAs        $1,000          $100
                                                            Education IRAs      $500            $100
- --------------------------------------------------------------------------------------------------------
EasyInvest(SM)
(Automatically from your checking or savings account or
Money Market Fund)                                                              $100*           $100*
- --------------------------------------------------------------------------------------------------------
</TABLE>

* Provided your schedule of investments totals $1,000 in twelve months.


There is no minimum investment amount if you purchase Fund shares through: (1)
the Investment Manager's mutual fund asset allocation plan, (2) a program,
approved by the Fund's distributor, in which you pay an asset-based fee for
advisory, administrative and/or brokerage services, or (3) employer-sponsored
employee benefit plan accounts.

Investment Options for Certain Institutional and Other Investors/Class D Shares.
To be eligible to purchase Class D shares, you must qualify under one of the
investor categories specified in the "Share Class Arrangements" section of this
Prospectus.

Subsequent Investments Sent Directly to the Fund. In addition to buying
additional Fund shares for an existing account by contacting your Morgan Stanley
Dean Witter Financial Advisor, you may send a check directly to the Fund. To buy
additional shares in this manner:


o Write a "letter of instruction" to the Fund specifying the name(s) on the
  account, the account number, the social security or tax identification number,
  the Class of shares you wish to purchase and the investment amount (which
  would include any applicable front-end sales charge). The letter must be
  signed by the account owner(s).


o Make out a check for the total amount payable to: Morgan Stanley Dean Witter
  S&P 500 Index Fund.

o Mail the letter and check to Morgan Stanley Dean Witter Trust FSB at P.O.
  Box 1040, Jersey City, NJ 07303.


10


<PAGE>


[GRAPHIC OMITTED]


HOW TO EXCHANGE SHARES
- ----------------------

Permissible Fund Exchanges. You may exchange shares of any Class of the Fund for
the same Class of any other continuously offered Multi-Class Fund, or for shares
of a No-Load Fund, a Money Market Fund, North American Government Income Trust
or Short-Term U.S. Treasury Trust, without the imposition of an exchange fee.
See the inside back cover of this Prospectus for each Morgan Stanley Dean Witter
Fund's designation as a Multi-Class Fund, No-Load Fund or Money Market Fund. If
a Morgan Stanley Dean Witter Fund is not listed, consult the inside back cover
of that Fund's Prospectus for its designation. For purposes of exchanges, shares
of FSC Funds (subject to a front-end sales charge) are treated as Class A shares
of a Multi-Class Fund.

Exchanges may be made after shares of the Fund acquired by purchase have been
held for thirty days. There is no waiting period for exchanges of shares
acquired by exchange or dividend reinvestment. The current Prospectus for each
fund describes its investment objective(s), policies and investment minimum, and
should be read before investment. Since exchanges are available only into
continuously offered Morgan Stanley Dean Witter Funds, exchanges are not
available into any new Morgan Stanley Dean Witter Fund during its initial
offering period, or when shares of a particular Morgan Stanley Dean Witter Fund
are not being offered for purchase.


Exchange Procedures. You can process an exchange by contacting your Morgan
Stanley Dean Witter Financial Advisor or other authorized financial
representative. Otherwise, you must forward an exchange privilege authorization
form to the Fund's transfer agent -- Morgan Stanley Dean Witter Trust FSB -- and
then write the transfer agent or call (800) 869-NEWS to place an exchange order.
You can obtain an exchange privilege authorization form by contacting your
Financial Advisor or other authorized financial representative or by calling
(800) 869-NEWS. If you hold share certificates, no exchanges may be processed
until we have received all applicable share certificates.

An exchange to any Morgan Stanley Dean Witter Fund (except a Money Market Fund)
is made on the basis of the next calculated net asset values of the Funds
involved after the exchange instructions are accepted. When exchanging into a
Money Market Fund, the Fund's shares are sold at their next calculated net asset
value and the Money Market Fund's shares are purchased at their net asset value
on the following business day.

The Fund may terminate or revise the exchange privilege upon required notice.
The check writing privilege is not available for Money Market Fund shares you
acquire in an exchange.

Telephone Exchanges. For your protection when calling Morgan Stanley Dean Witter
Trust FSB, we will employ reasonable procedures to confirm that exchange
instructions communicated over the telephone are genuine. These procedures may
include


                                                                              11


<PAGE>


requiring various forms of personal identification such as name, mailing
address, social security or other tax identification number. Telephone
instructions also may be recorded.


Telephone instructions will be accepted if received by the Fund's transfer agent
between 9:00 a.m. and 4:00 p.m. Eastern time on any day the New York Stock
Exchange is open for business. During periods of drastic economic or market
changes, it is possible that the telephone exchange procedures may be difficult
to implement, although this has not been the case with the Fund in the past.


Margin Accounts. If you have pledged your Fund shares in a margin account,
contact your Morgan Stanley Dean Witter Financial Advisor or other authorized
financial representative regarding restrictions on the exchange of such shares.

Tax Considerations of Exchanges. If you exchange shares of the Fund for shares
of another Morgan Stanley Dean Witter Fund there are important tax
considerations. For tax purposes, the exchange out of the Fund is considered a
sale of the Fund's shares -- and the exchange into the other Fund is considered
a purchase. As a result, you may realize a capital gain or loss.

You should review the "Tax Consequences" section and consult your own tax
professional about the tax consequences of an exchange.

Frequent Exchanges. A pattern of frequent exchanges may result in the Fund
limiting or prohibiting, at its discretion, additional purchases and/or
exchanges. The Fund will notify you in advance of limiting your exchange
privileges.

CDSC Calculations on Exchanges. See the "Share Class Arrangements" section of
this Prospectus for a discussion of how applicable contingent deferred sales
charges (CDSCs) are calculated for shares of one Morgan Stanley Dean Witter Fund
that are exchanged for shares of another.

For further information regarding exchange privileges, you should contact your
Morgan Stanley Dean Witter Financial Advisor or call (800) 869-NEWS.


12


<PAGE>


[GRAPHIC OMITTED]


HOW TO SELL SHARES
- ------------------
You can sell some or all of your Fund shares at any time. If you sell Class A,
Class B or Class C shares, your net sale proceeds are reduced by the amount of
any applicable CDSC. Your shares will be sold at the next price calculated after
we receive your order to sell as described below.

<TABLE>
<CAPTION>
OPTIONS               PROCEDURES
- ------------------------------------------------------------------------------------------------------------------
<S>                   <C>
Contact Your          To sell your shares, simply call your Morgan Stanley Dean Witter Financial Advisor or
Financial Advisor     other authorized financial representative.
                      --------------------------------------------------------------------------------------------
[GRAPHIC OMITTED]     Payment will be sent to the address to which the account is registered or deposited in
                      your brokerage account.
- ------------------------------------------------------------------------------------------------------------------
By Letter             You can also sell your shares by writing a "letter of instruction" that includes:
                      o  your account number;
[GRAPHIC OMITTED]     o  the dollar amount or the number of shares you wish to sell;
                      o  the Class of shares you wish to sell; and
                      o  the signature of each owner as it appears on the account.
                      --------------------------------------------------------------------------------------------
                      If you are requesting payment to anyone other than the registered owner(s) or that
                      payment be sent to any address other than the address of the registered owner(s) or
                      pre-designated bank account, you will need a signature guarantee. You can obtain a
                      signature guarantee from an eligible guarantor acceptable to Morgan Stanley Dean
                      Witter Trust FSB. (You should contact Morgan Stanley Dean Witter Trust FSB at (800)
                      869-NEWS for a determination as to whether a particular institution is an eligible
                      guarantor.) A notary public cannot provide a signature guarantee. Additional
                      documentation may be required for shares held by a corporation, partnership, trustee
                      or executor.
                      --------------------------------------------------------------------------------------------
                      Mail the letter to Morgan Stanley Dean Witter Trust FSB at P.O. Box 983, Jersey City, NJ
                      07303. If you hold share certificates, you must return the certificates, along with the
                      letter and any required additional documentation.
                      --------------------------------------------------------------------------------------------
                      A check will be mailed to the name(s) and address in which the account is registered, or
                      otherwise according to your instructions.
- ------------------------------------------------------------------------------------------------------------------
Systematic            If your investment in all of the Morgan Stanley Dean Witter Family of Funds has a total
Withdrawal Plan       market value of at least $10,000, you may elect to withdraw amounts of $25 or more,
                      or in any whole percentage of a Fund's balance (provided the amount is at least $25), on
[GRAPHIC OMITTED]     a monthly, quarterly, semi-annual or annual basis, from any Fund with a balance of at least
                      $1,000. Each time you add a Fund to the plan, you must meet the plan requirements.
                      --------------------------------------------------------------------------------------------
                      Amounts withdrawn are subject to any applicable CDSC. A CDSC may be waived under
                      certain circumstances. See the Class B waiver categories listed in the "Share Class
                      Arrangements" section of this Prospectus.
                      --------------------------------------------------------------------------------------------
                      To sign up for the Systematic Withdrawal Plan, contact your Morgan Stanley Dean
                      Witter Financial Advisor or call (800) 869-NEWS. You may terminate or suspend your
                      plan at any time. Please remember that withdrawals from the plan are sales of shares,
                      not Fund "distributions," and ultimately may exhaust your account balance. The Fund
                      may terminate or revise the plan at any time.
- ------------------------------------------------------------------------------------------------------------------
</TABLE>


                                                                              13


<PAGE>


Payment for Sold Shares. After we receive your complete instructions to sell as
described above, a check will be mailed to you within seven days, although we
will attempt to make payment within one business day. Payment may also be sent
to your brokerage account.

Payment may be postponed or the right to sell your shares suspended under
unusual circumstances. If you request to sell shares that were recently
purchased by check, your sales will not be effected until it has been verified
that the check has been honored.

Tax Considerations. Normally, your sale of Fund shares is subject to federal and
state income tax. You should review the "Tax Consequences" section of this
Prospectus and consult your own tax professional about the tax consequences of a
sale.

Reinstatement Privilege. If you sell Fund shares and have not previously
exercised the reinstatement privilege, you may, within 35 days after the date of
sale, invest any portion of the proceeds in the same Class of Fund shares at
their net asset value and receive a pro rata credit for any CDSC paid in
connection with the sale.

Involuntary Sales. The Fund reserves the right, on sixty days' notice, to sell
the shares of any shareholder (other than shares held in an IRA or 403(b)
Custodial Account) whose shares, due to sales by the shareholder, have a value
below $100, or in the case of an account opened through EasyInvest(SM), if after
12 months the shareholder has invested less than $1,000 in the account.

However, before the Fund sells your shares in this manner, we will notify you
and allow you sixty days to make an additional investment in an amount that will
increase the value of your account to at least the required amount before the
sale is processed. No CDSC will be imposed on any involuntary sale.

Margin Accounts. If you have pledged your Fund shares in a margin account,
contact your Morgan Stanley Dean Witter Financial Advisor or other authorized
financial representative regarding restrictions on the sale of such shares.


14


<PAGE>


[GRAPHIC OMITTED]


DISTRIBUTIONS
- -------------
The Fund passes substantially all of its earnings from income and capital gains
along to its investors as "distributions." The Fund earns income from stocks and
interest from fixed-income investments. These amounts are passed along to Fund
shareholders as "income dividend distributions." The Fund realizes capital gains
whenever it sells securities for a higher price than it paid for them. These
amounts may be passed along as "capital gain distributions."


[sidebar]
TARGETED DIVIDENDS(SM)
You may select to have your Fund distributions automatically invested in other
Classes of Fund shares or Classes of another Morgan Stanley Dean Witter Fund
that you own. Contact your Morgan Stanley Dean Witter Financial Advisor for
further information about this service.
[end sidebar]


The Fund declares income dividends separately for each Class. Distributions paid
on Class A and Class D shares will be higher than for Class B and Class C
because distribution fees that Class B and Class C pay are higher. Normally,
income dividends are distributed to shareholders annually. Capital gains, if
any, are usually distributed in December. The Fund, however, may retain and
reinvest any long-term capital gains. The Fund may at times make payments from
sources other than income or capital gains that represent a return of a portion
of your investment.

Distributions are reinvested automatically in additional shares of the same
Class and automatically credited to your account, unless you request in writing
that all distributions be paid in cash. If you elect the cash option, the Fund
will mail a check to you no later than seven business days after the
distribution is declared. No interest will accrue on uncashed checks. If you
wish to change how your distributions are paid, your request should be received
by the Fund's transfer agent, Morgan Stanley Dean Witter Trust FSB, at least
five business days prior to the record date of the distributions.


[GRAPHIC OMITTED]


TAX CONSEQUENCES
- ----------------
As with any investment, you should consider how your Fund investment will be
taxed. The tax information in this Prospectus is provided as general
information. You should consult your own tax professional about the tax
consequences of an investment in the Fund.

Unless your investment in the Fund is through a tax-deferred retirement account,
such as a 401(k) plan or IRA, you need to be aware of the possible tax
consequences when:

o The Fund makes distributions; and

o You sell Fund shares, including an exchange to another Morgan Stanley Dean
  Witter Fund.

Taxes on Distributions. Your distributions are normally subject to federal and
state income tax when they are paid, whether you take them in cash or reinvest
them in Fund shares. A distribution also may be subject to local income tax. Any
income dividend distributions and any short-term capital gain distributions are
taxable to you as


                                                                              15


<PAGE>


ordinary income. Any long-term capital gain distributions are taxable as
long-term capital gains, no matter how long you have owned shares in the Fund.

Every January, you will be sent a statement (IRS Form 1099-DIV) showing the
taxable distributions paid to you in the previous year. The statement provides
full information on your dividends and capital gains for tax purposes.

Taxes on Sales. Your sale of Fund shares normally is subject to federal and
state income tax and may result in a taxable gain or loss to you. A sale also
may be subject to local income tax. Your exchange of Fund shares for shares of
another Morgan Stanley Dean Witter Fund is treated for tax purposes like a sale
of your original shares and a purchase of your new shares. Thus, the exchange
may, like a sale, result in a taxable gain or loss to you and will give you a
new tax basis for your new shares.

When you open your Fund account, you should provide your Social Security or tax
identification number on your investment application. By providing this
information, you will avoid being subject to a federal backup withholding tax of
31% on taxable distributions and redemption proceeds. Any withheld amount would
be sent to the IRS as an advance tax payment.


[GRAPHIC OMITTED]


SHARE CLASS ARRANGEMENTS
- ------------------------
The Fund offers several Classes of shares having different distribution
arrangements designed to provide you with different purchase options according
to your investment needs. Your Morgan Stanley Dean Witter Financial Advisor or
other authorized financial representative can help you decide which Class may be
appropriate for you.

The general public is offered three Classes: Class A shares, Class B shares and
Class C shares, which differ principally in terms of sales charges and ongoing
expenses. A fourth Class, Class D shares, is offered only to a limited category
of investors. Shares that you acquire through reinvested distributions will not
be subject to any front-end sales charge or CDSC -- contingent deferred sales
charge. Sales personnel may receive different compensation for selling each
Class of shares. The sales charges applicable to each Class provide for the
distribution financing of shares of that Class.


16


<PAGE>


The chart below compares the sales charge and the maximum annual 12b-1 fees
applicable to each Class:


<TABLE>
<CAPTION>
                                                                                                 MAXIMUM
CLASS     SALES CHARGE                                                                       ANNUAL 12B-1 FEE
- -------------------------------------------------------------------------------------------------------------
<S>       <C>                                                                               <C>
  A       Maximum 5.25% initial sales charge reduced for purchase of $25,000 or more;
          shares sold without an initial sales charge are generally subject to a 1.0% CDSC
          during first year.                                                                      0.25%
- -------------------------------------------------------------------------------------------------------------
  B       Maximum 5.0% CDSC during the first year decreasing to 0% after six years.               1.0%
- -------------------------------------------------------------------------------------------------------------
  C       1.0% CDSC during first year                                                             1.0%
- -------------------------------------------------------------------------------------------------------------
  D       None                                                                                    None
- -------------------------------------------------------------------------------------------------------------
</TABLE>


CLASS A SHARES  Class A shares are sold at net asset value plus an initial sales
charge of up to 5.25%. The initial sales charge is reduced for purchases of
$25,000 or more according to the schedule below. Investments of $1 million or
more are not subject to an initial sales charge, but are generally subject to a
contingent deferred sales charge, or CDSC, of 1.0% on sales made within one year
after the last day of the month of purchase. The CDSC will be assessed in the
same manner and with the same CDSC waivers as with Class B shares. Class A
shares are also subject to a distribution (12b-1) fee of up to 0.25% of the
average daily net assets of the Class.

The offering price of Class A shares includes a sales charge (expressed as a
percentage of the offering price) on a single transaction as shown in the
following table:


[sidebar]
FRONT-END SALES CHARGE OR FSC
An initial sales charge you pay when purchasing Class A shares that is based on
a percentage of the offering price. The percentage declines based upon the
dollar value of Class A shares you purchase. We offer three ways to reduce your
Class A sales charges -- the Combined Purchase Privilege, Right of Accumulation
and Letter of Intent.
[end sidebar]


<TABLE>
<CAPTION>
                                                   FRONT-END SALES CHARGE
                                      -----------------------------------------------
                                           PERCENTAGE OF       APPROXIMATE PERCENTAGE
AMOUNT OF SINGLE TRANSACTION           PUBLIC OFFERING PRICE   OF NET AMOUNT INVESTED
- -------------------------------------------------------------------------------------
<S>                                   <C>                     <C>
Less than $25,000                             5.25%                   5.54%
- -------------------------------------------------------------------------------------
$25,000 but less than $50,000                 4.75%                   4.99%
- -------------------------------------------------------------------------------------
$50,000 but less than $100,000                4.00%                   4.17%
- -------------------------------------------------------------------------------------
$100,000 but less than $250,000               3.00%                   3.09%
- -------------------------------------------------------------------------------------
$250,000 but less than $1 million             2.00%                   2.04%
- -------------------------------------------------------------------------------------
$1 million and over                             0                       0
- -------------------------------------------------------------------------------------
</TABLE>


                                                                              17


<PAGE>


The reduced sales charge schedule is applicable to purchases of Class A shares
in a single transaction by:

o A single account (including an individual, trust or fiduciary account).

o Family member accounts (limited to husband, wife and children under the age of
  21).

o Pension, profit sharing or other employee benefit plans of companies and their
  affiliates.

o Tax-exempt organizations.

o Groups organized for a purpose other than to buy mutual fund shares.

Combined Purchase Privilege. You also will have the benefit of reduced sales
charges by combining purchases of Class A shares of the Fund in a single
transaction with purchases of Class A shares of other Multi-Class Funds and
shares of FSC Funds.


Right of Accumulation. You also may benefit from a reduction of sales charges if
the cumulative net asset value of Class A shares of the Fund purchased in a
single transaction, together with shares of other Funds you currently own which
were previously purchased at a price including a front-end sales charge
(including shares acquired through reinvestment of distributions), amounts to
$25,000 or more. Also, if you have a cumulative net asset value of all your
Class A and Class D shares equal to at least $5 million (or $25 million for
certain employee benefit plans), you are eligible to purchase Class D shares of
any Fund subject to the Fund's minimum initial investment requirement.

You must notify your Morgan Stanley Dean Witter Financial Advisor or other
authorized financial representative (or Morgan Stanley Dean Witter Trust FSB if
you purchase directly through the Fund) at the time a purchase order is placed,
that the purchase qualifies for the reduced charge under the Right of
Accumulation. Similar notification must be made in writing when an order is
placed by mail. The reduced sales charge will not be granted if: (i)
notification is not furnished at the time of the order; or (ii) a review of the
records of Dean Witter Reynolds or other authorized dealer of Fund shares or the
Fund's transfer agent does not confirm your represented holdings.


Letter of Intent. The schedule of reduced sales charges for larger purchases
also will be available to you if you enter into a written "letter of intent." A
letter of intent provides for the purchase of Class A shares of the Fund or
other Multi-Class Funds or shares of FSC Funds within a thirteen-month period.
The initial purchase under a letter of intent must be at least 5% of the stated
investment goal. To determine the applicable sales charge reduction, you may
also include: (1) the cost of shares of other Morgan Stanley Dean Witter Funds
which were previously purchased at a price including a front-end sales charge
during the 90-day period prior to the distributor receiving the letter of
intent, and (2) the cost of shares of other Funds you currently own acquired in
exchange for shares of Funds purchased during that period at a price including a
front-end sales charge. You can obtain a letter of intent by contacting your
Morgan


18


<PAGE>


Stanley Dean Witter Financial Advisor or other authorized financial
representative, or by calling (800) 869-NEWS. If you do not achieve the stated
investment goal within the thirteen-month period, you are required to pay the
difference between the sales charges otherwise applicable and sales charges
actually paid, which may be deducted from your investment.

Other Sales Charge Waivers. In addition to investments of $1 million or more,
your purchase of Class A shares is not subject to a front-end sales charge (or a
CDSC upon sale) if your account qualifies under one of the following categories:

o A trust for which Morgan Stanley Dean Witter Trust FSB provides discretionary
  trustee services.

o Persons participating in a fee-based investment program (subject to all of its
  terms and conditions, including termination fees, mandatory sale or transfer
  restrictions on termination) approved by the Fund's distributor pursuant to
  which they pay an asset based fee for investment advisory, administrative
  and/or brokerage services.

o Employer-sponsored employee benefit plans, whether or not qualified under the
  Internal Revenue Code, for which Morgan Stanley Dean Witter Trust FSB serves
  as trustee or Dean Witter Reynolds' Retirement Plan Services serves as
  recordkeeper under a written Recordkeeping Services Agreement ("MSDW Eligible
  Plans") which have at least 200 eligible employees.

o A MSDW Eligible Plan whose Class B shares have converted to Class A shares,
  regardless of the plan's asset size or number of eligible employees.

o A client of a Morgan Stanley Dean Witter Financial Advisor who joined us from
  another investment firm within six months prior to the date of purchase of
  Fund shares, and you used the proceeds from the sale of shares of a
  proprietary mutual fund of that Financial Advisor's previous firm that imposed
  either a front-end or deferred sales charge to purchase Class A shares,
  provided that: (1) you sold the shares not more than 60 days prior to
  purchase, and (2) the sale proceeds were maintained in the interim in cash or
  a money market fund.

o Current or retired Directors/Trustees of the Morgan Stanley Dean Witter Funds,
  such persons' spouses and children under the age of 21, and trust accounts for
  which any of such persons is a beneficiary.

o Current or retired directors, officers and employees of Morgan Stanley Dean
  Witter & Co. and any of its subsidiaries, such persons' spouses and children
  under the age of 21, and trust accounts for which any of such persons is a
  beneficiary.


                                                                              19


<PAGE>


CLASS B SHARES  Class B shares are offered at net asset value with no initial
sales charge but are subject to a contingent deferred sales charge, or CDSC, as
set forth in the table below. For the purpose of calculating the CDSC, shares
are deemed to have been purchased on the last day of the month during which they
were purchased.


[sidebar]
CONTINGENT DEFERRED SALES CHARGE OR CDSC
A fee you pay when you sell shares of certain Morgan Stanley Dean Witter Funds
purchased without an initial sales charge. This fee declines the longer you hold
your shares as set forth in the table.
[end sidebar]


<TABLE>
<CAPTION>
                                      CDSC AS A PERCENTAGE OF
YEAR SINCE PURCHASE PAYMENT MADE          AMOUNT REDEEMED
- -------------------------------------------------------------
<S>                                  <C>
First                                          5.0%
- -------------------------------------------------------------
Second                                         4.0%
- -------------------------------------------------------------
Third                                          3.0%
- -------------------------------------------------------------
Fourth                                         2.0%
- -------------------------------------------------------------
Fifth                                          2.0%
- -------------------------------------------------------------
Sixth                                          1.0%
- -------------------------------------------------------------
Seventh and thereafter                         None
- -------------------------------------------------------------
</TABLE>

Each time you place an order to sell or exchange shares, shares with no CDSC
will be sold or exchanged first, then shares with the lowest CDSC will be sold
or exchanged next. For any shares subject to a CDSC, the CDSC will be assessed
on an amount equal to the lesser of the current market value or the cost of the
shares being sold.

CDSC Waivers. A CDSC, if otherwise applicable, will be waived in the case of:

o Sales of shares held at the time you die or become disabled (within the
  definition in Section 72(m)(7) of the Internal Revenue Code which relates to
  the ability to engage in gainful employment), if the shares are:
  (i) registered either in your name (not a trust) or in the names of you and
  your spouse as joint tenants with right of survivorship; or (ii) held in a
  qualified corporate or self-employed retirement plan, IRA or 403(b) Custodial
  Account, provided in either case that the sale is requested within one year of
  your death or initial determination of disability.


o Sales in connection with the following retirement plan "distributions:" (i)
  lump-sum or other distributions from a qualified corporate or self-employed
  retirement plan following retirement (or, in the case of a "key employee" of a
  "top heavy" plan, following attainment of age 59 1/2); (ii) distributions from
  an IRA or 403(b) Custodial Account following attainment of age 59 1/2; or
  (iii) a tax-free return of an excess IRA contribution (a "distribution" does
  not include a direct transfer of IRA, 403(b) Custodial Account or retirement
  plan assets to a successor custodian or trustee).


o Sales of shares held for you as a participant in a MSDW Eligible Plan.

o Sales of shares in connection with the Systematic Withdrawal Plan of up to 12%
  annually of the value of each Fund from which plan sales are made. The
  percentage is determined on the date you establish the Systematic Withdrawal
  Plan and based on the next calculated share price. You may have this CDSC
  waiver applied in amounts up to 1% per month, 3% per quarter, 6% semi-annually
  or 12% annually. Shares with no CDSC will be sold first, followed by those
  with the lowest CDSC. As such, the waiver


20


<PAGE>


  benefit will be reduced by the amount of your shares that are not subject to a
  CDSC. If you suspend your participation in the plan, you may later resume plan
  payments without requiring a new determination of the account value for the
  12% CDSC waiver.


o Sales of shares if you simultaneously invest the proceeds in the Investment
  Manager's mutual fund asset allocation program, pursuant to which investors
  pay an asset-based fee. Any shares you acquire in connection with the
  Investment Manager's mutual fund asset allocation program are subject to all
  of the terms and conditions of that program, including termination fees,
  mandatory sale or transfer restrictions on termination.


All waivers will be granted only following the Fund's Distributor receiving
confirmation of your entitlement. If you believe you are eligible for a CDSC
waiver, please contact your Financial Advisor or call (800) 869-NEWS.

Distribution Fee. Class B shares are also subject to an annual distribution
(12b-1) fee of 1.0% of the average daily net assets of Class B shares.

Conversion Feature. After ten (10) years, Class B shares will convert
automatically to Class A shares of the Fund with no initial sales charge. The
ten year period runs from the last day of the month in which the shares were
purchased, or in the case of Class B shares acquired through an exchange, from
the last day of the month in which the original Class B shares were purchased;
the shares will convert to Class A shares based on their relative net asset
values in the month following the ten year period. At the same time, an equal
proportion of Class B shares acquired through automatically reinvested
distributions will convert to Class A shares on the same basis. (Class B shares
acquired in exchange for shares of another Morgan Stanley Dean Witter Fund
originally purchased before May 1, 1997, however, will convert to Class A shares
in May 2007.)

In the case of Class B shares held in a MSDW Eligible Plan, the plan is treated
as a single investor and all Class B shares will convert to Class A shares on
the conversion date of the Class B shares of a Morgan Stanley Dean Witter Fund
purchased by that plan.

Currently, the Class B share conversion is not a taxable event; the conversion
feature may be cancelled if it is deemed a taxable event in the future by the
Internal Revenue Service.

If you exchange your Class B shares for shares of a Money Market Fund, a No-Load
Fund, North American Government Income Trust or Short-Term U.S. Treasury Trust,
the holding period for conversion is frozen as of the last day of the month of
the exchange and resumes on the last day of the month you exchange back into
Class B shares.

Exchanging Shares Subject to a CDSC. There are special considerations when you
exchange Fund shares that are subject to a CDSC. When determining the length of
time


                                                                              21


<PAGE>


you held the shares and the corresponding CDSC rate, any period (starting at the
end of the month) during which you held shares of a fund that does not charge a
CDSC will not be counted. Thus, in effect the "holding period" for purposes of
calculating the CDSC is frozen upon exchanging into a fund that does not charge
a CDSC.

For example, if you held Class B shares of the Fund for one year, exchanged to
Class B of another Morgan Stanley Dean Witter Multi-Class Fund for another year,
then sold your shares, a CDSC rate of 4% would be imposed on the shares based on
a two year holding period -- one year for each Fund. However, if you had
exchanged the shares of the Fund for a Money Market Fund (which does not charge
a CDSC) instead of the Multi-Class Fund, then sold your shares, a CDSC rate of
5% would be imposed on the shares based on a one year holding period. The one
year in the Money Market Fund would not be counted. Nevertheless, if shares
subject to a CDSC are exchanged for a fund that does not charge a CDSC, you will
receive a credit when you sell the shares equal to the distribution (12b-1) fees
you paid on those shares while in that Fund up to the amount of any applicable
CDSC.

In addition, shares that are exchanged into or from a Morgan Stanley Dean Witter
Fund subject to a higher CDSC rate will be subject to the higher rate, even if
the shares are re-exchanged into a Fund with a lower CDSC rate.


CLASS C SHARES  Class C shares are sold at net asset value with no initial sales
charge but are subject to a CDSC of 1.0% on sales made within one year after the
last day of the month of purchase. The CDSC will be assessed in the same manner
and with the same CDSC waivers as with Class B shares.

Distribution Fee. Class C shares are subject to an annual distribution (12b-1)
fee of up to 1.0% of the average daily net assets of that Class. The Class C
shares' distribution fee may cause that Class to have higher expenses and pay
lower dividends than Class A or Class D shares. Unlike Class B shares, Class C
shares have no conversion feature and, accordingly, an investor that purchases
Class C shares may be subject to distribution (12b-1) fees applicable to Class C
shares for an indefinite period.


CLASS D SHARES  Class D shares are offered without any sales charge on purchases
or sales and without any distribution (12b-1) fee. Class D shares are offered
only to investors meeting an initial investment minimum of $5 million ($25
million for MSDW Eligible Plans) and the following categories of investors:


o Investors participating in the Investment Manager's mutual fund asset
  allocation program (subject to all of its terms and conditions, including
  termination fees, mandatory sale or transfer restrictions on termination)
  pursuant to which they pay an asset-based fee.

o Persons participating in a fee-based investment program (subject to all of its
  terms and conditions, including termination fees, mandatory sale or transfer
  restrictions on



22


<PAGE>


  termination) approved by the Fund's distributor pursuant to which they pay an
  asset based fee for investment advisory, administrative and/or brokerage
  services.

o Employee benefit plans maintained by Morgan Stanley Dean Witter & Co. or any
  of its subsidiaries for the benefit of certain employees of Morgan Stanley
  Dean Witter & Co. and its subsidiaries.

o Certain unit investment trusts sponsored by Dean Witter Reynolds.

o Certain other open-end investment companies whose shares are distributed by
  the Fund's distributor.

o Investors who were shareholders of the Dean Witter Retirement Series on
  September 11, 1998 for additional purchases for their former Dean Witter
  Retirement Series accounts.

Meeting Class D Eligibility Minimums. To meet the $5 million ($25 million for
MSDW Eligible Plans) initial investment to qualify to purchase Class D shares
you may combine: (1) purchases in a single transaction of Class D shares of the
Fund and other Morgan Stanley Dean Witter Multi-Class Funds and/or (2) previous
purchases of Class A and Class D shares of Multi-Class Funds and shares of FSC
Funds you currently own, along with shares of Morgan Stanley Dean Witter Funds
you currently own that you acquired in exchange for those shares.


NO SALES CHARGES FOR REINVESTED CASH DISTRIBUTIONS  If you receive a cash
payment representing an income dividend or capital gain and you reinvest that
amount in the applicable Class of shares by returning the check within 30 days
of the payment date, the purchased shares would not be subject to an initial
sales charge or CDSC.


PLAN OF DISTRIBUTION (RULE 12B-1 FEES)  The Fund has adopted a Plan of
Distribution in accordance with Rule 12b-1 under the Investment Company Act of
1940 with respect to the distribution of Class A, Class B and Class C shares.
The Plan allows the Fund to pay distribution fees for the sale and distribution
of these shares. It also allows the Fund to pay for services to shareholders of
Class A, Class B and Class C shares. Because these fees are paid out of the
Fund's assets on an ongoing basis, over time these fees will increase the cost
of your investment in these Classes and may cost you more than paying other
types of sales charges.


                                                                              23


<PAGE>


FINANCIAL HIGHLIGHTS

The financial highlights table is intended to help you understand the Fund's
financial performance over the life of the Fund. Certain information reflects
financial results for a single Fund share. The total returns in the table
represent the rate an investor would have earned or lost on an investment in
the Fund (assuming reinvestment of all dividends and distributions).


This information has been audited by PricewaterhouseCoopers LLP, independent
accountants, whose report, along with the Fund's financial statements, is
included in the annual report, which is available upon request.

<TABLE>
<CAPTION>
                                            FOR THE YEAR ENDED    FOR THE PERIOD SEPTEMBER 26, 1997*
                                              AUGUST 31, 1999          THROUGH AUGUST 31, 1998
- ----------------------------------------------------------------------------------------------------
<S>                                        <C>                    <C>
CLASS A SHARES++
- ----------------------------------------------------------------------------------------------------
SELECTED PER SHARE DATA:
- ----------------------------------------------------------------------------------------------------
Net asset value, beginning of period             $10.18                      $10.00
- ----------------------------------------------------------------------------------------------------
Income from investment operations:
 Net investment income                             0.10                        0.10
 Net realized and unrealized gain                  3.85                        0.11
                                                 ------                      ------
Total income from investment operations            3.95                        0.21
- ----------------------------------------------------------------------------------------------------
Less dividends and distributions from:
 Net investment income                            (0.07)                      (0.03)
 Net realized gain                                (0.01)                         --
                                                 ------                      ------
Total dividends and distributions                 (0.08)                      (0.03)
- ----------------------------------------------------------------------------------------------------
Net asset value, end of period                   $14.05                      $10.18
- ----------------------------------------------------------------------------------------------------
TOTAL RETURN+                                     38.82%                       2.05%(1)
- ----------------------------------------------------------------------------------------------------
RATIOS TO AVERAGE NET ASSETS:
- ----------------------------------------------------------------------------------------------------
Expenses                                           0.73%(3)(4)                 0.75%(2)(3)
- ----------------------------------------------------------------------------------------------------
Net investment income                              0.72%(3)(4)                 0.91%(2)(3)
- ----------------------------------------------------------------------------------------------------
SUPPLEMENTAL DATA:
- ----------------------------------------------------------------------------------------------------
Net assets, end of period, in thousands         $99,140                     $28,719
- ----------------------------------------------------------------------------------------------------
Portfolio turnover rate                               5%                          1%
- ----------------------------------------------------------------------------------------------------
</TABLE>

*   Commencement of operations.

++  The per share amounts were computed using an average number of shares
    outstanding.

+   Does not reflect the deduction of sales charge. Calculated based on the
    net asset value as of the last business day of the period.

(1) Not annualized.

(2) Annualized.

(3) If the Fund had borne all of its expenses that were reimbursed or waived
    by the Investment Manager, the annualized expense and net investment
    income ratios would have been 0.81% and 0.64%, respectively, for the year
    ended August 31, 1999 and 0.89% and 0.77%, respectively, for period ended
    August 31, 1998.

(4) Reflects overall Fund ratios for investment income and non-class specific
    expenses.


24


<PAGE>


<TABLE>
<CAPTION>
                                               FOR THE YEAR ENDED     FOR THE PERIOD SEPTEMBER 26, 1997*
                                                 AUGUST 31, 1999           THROUGH AUGUST 31, 1998
- --------------------------------------------------------------------------------------------------------
<S>                                         <C>                      <C>
CLASS B SHARES++
- --------------------------------------------------------------------------------------------------------
SELECTED PER SHARE DATA:
- --------------------------------------------------------------------------------------------------------
Net asset value, beginning of period                 $10.13                      $10.00
- --------------------------------------------------------------------------------------------------------
Income (loss) from investment operations:
 Net investment income (loss)                         (0.01)                       0.02
 Net realized and unrealized gain                      3.83                        0.12
                                                     ------                      ------
Total income from investment operations                3.82                        0.14
- --------------------------------------------------------------------------------------------------------
Less dividends and distributions from:
 Net investment income                                (0.01)                      (0.01)
 Net realized gain                                    (0.01)                         --
                                                     ------                      ------
Total dividends and distributions                     (0.02)                      (0.01)
- --------------------------------------------------------------------------------------------------------
Net asset value, end of period                       $13.93                      $10.13
- --------------------------------------------------------------------------------------------------------
TOTAL RETURN+                                         37.68%                       1.38%(1)
- --------------------------------------------------------------------------------------------------------
RATIOS TO AVERAGE NET ASSETS:
- --------------------------------------------------------------------------------------------------------
Expenses                                               1.50%(3)(4)                 1.50%(2)(3)
- --------------------------------------------------------------------------------------------------------
Net investment income (loss)                          (0.05)%(3)(4)                0.16%(2)(3)
- --------------------------------------------------------------------------------------------------------
SUPPLEMENTAL DATA:
- --------------------------------------------------------------------------------------------------------
Net assets, end of period, in thousands          $1,587,661                    $536,349
- --------------------------------------------------------------------------------------------------------
Portfolio turnover rate                                   5%                          1%
- --------------------------------------------------------------------------------------------------------
</TABLE>

*     Commencement of operations.

++    The per share amounts were computed using an average number of shares
      outstanding.

+     Does not reflect the deduction of sales charge. Calculated based on the
      net asset value as of the last business day of the period.

(1)   Not annualized.

(2)   Annualized.

(3)   If the Fund had borne all of its expenses that were reimbursed or waived
      by the Investment Manager, the annualized expense and net investment
      income ratios would have been 1.58% and (0.13)%, respectively, for the
      year ended August 31, 1999 and 1.64% and 0.02%, respectively, for the
      period ended August 31, 1998.

(4)   Reflects overall Fund ratios for investment income and non-class specific
      expenses.


                                                                              25


<PAGE>


<TABLE>
<CAPTION>
                                               FOR THE YEAR ENDED     FOR THE PERIOD SEPTEMBER 26, 1997*
                                                 AUGUST 31, 1999           THROUGH AUGUST 31, 1998
- --------------------------------------------------------------------------------------------------------
<S>                                         <C>                      <C>
CLASS C SHARES++
- --------------------------------------------------------------------------------------------------------
SELECTED PER SHARE DATA:
- --------------------------------------------------------------------------------------------------------
Net asset value, beginning of period                $10.13                       $10.00
- --------------------------------------------------------------------------------------------------------
Income (loss) from investment operations:
 Net investment income (loss)                        (0.01)                        0.02
 Net realized and unrealized gain                     3.83                         0.12
                                                    ------                       ------
Total income from investment operations               3.82                         0.14
- --------------------------------------------------------------------------------------------------------
Less dividends and distributions from:
 Net investment income                               (0.01)                       (0.01)
 Net realized gain                                   (0.01)                          --
                                                    ------                       ------
Total dividends and distributions                    (0.02)                       (0.01)
- --------------------------------------------------------------------------------------------------------
Net asset value, end of period                      $13.93                       $10.13
- --------------------------------------------------------------------------------------------------------
TOTAL RETURN+                                        37.70%                        1.37%(1)
- --------------------------------------------------------------------------------------------------------
RATIOS TO AVERAGE NET ASSETS:
- --------------------------------------------------------------------------------------------------------
Expenses                                              1.50%(3)(4)                  1.50%(2)(3)
- --------------------------------------------------------------------------------------------------------
Net investment income (loss)                         (0.05)%(3)(4)                 0.16%(2)(3)
- --------------------------------------------------------------------------------------------------------
SUPPLEMENTAL DATA:
- --------------------------------------------------------------------------------------------------------
Net assets, end of period, in thousands           $143,092                      $40,730
- --------------------------------------------------------------------------------------------------------
Portfolio turnover rate                                  5%                           1%
- --------------------------------------------------------------------------------------------------------
</TABLE>

*     Commencement of operations.

++    The per share amounts were computed using an average number of shares
      outstanding.

+     Does not reflect the deduction of sales charge. Calculated based on the
      net asset value as of the last business day of the period.

(1)   Not annualized.

(2)   Annualized.

(3)   If the Fund had borne all of its expenses that were reimbursed or waived
      by the Investment Manager, the annualized expense and net investment
      income ratios would have been 1.58% and (0.13)%, respectively, for year
      ended August 31, 1999 and 1.64% and 0.02%, respectively, for the period
      ended August 31, 1998.

(4)   Reflects overall Fund ratios for investment income and non-class specific
      expenses.


26


<PAGE>


<TABLE>
<CAPTION>
                                             FOR THE YEAR ENDED    FOR THE PERIOD SEPTEMBER 26, 1997*
                                               AUGUST 31, 1999          THROUGH AUGUST 31, 1998
- -----------------------------------------------------------------------------------------------------
<S>                                        <C>                    <C>
CLASS D SHARES++
- -----------------------------------------------------------------------------------------------------
SELECTED PER SHARE DATA:
- -----------------------------------------------------------------------------------------------------
Net asset value, beginning of period              $10.20                     $10.00
- -----------------------------------------------------------------------------------------------------
Income from investment operations:
 Net investment income                              0.13                       0.12
 Net realized and unrealized gain                   3.85                       0.11
                                                  ------                     ------
Total income from investment operations             3.98                       0.23
- -----------------------------------------------------------------------------------------------------
Less dividends and distributions from:
 Net investment income                             (0.08)                     (0.03)
 Net realized gain                                 (0.01)                        --
                                                  ------                     ------
Total dividends and distributions                  (0.09)                     (0.03)
- -----------------------------------------------------------------------------------------------------
Net asset value, end of period                    $14.09                     $10.20
- -----------------------------------------------------------------------------------------------------
TOTAL RETURN+                                      39.13%                      2.30%(1)
- -----------------------------------------------------------------------------------------------------
RATIOS TO AVERAGE NET ASSETS:
- -----------------------------------------------------------------------------------------------------
Expenses                                            0.50%(3)(4)                0.50%(2)(3)
- -----------------------------------------------------------------------------------------------------
Net investment income                               0.95%(3)(4)                1.16%(2)(3)
- -----------------------------------------------------------------------------------------------------
SUPPLEMENTAL DATA:
- -----------------------------------------------------------------------------------------------------
Net assets, end of period, in thousands          $16,538                    $14,186
- -----------------------------------------------------------------------------------------------------
Portfolio turnover rate                                5%                         1%
- -----------------------------------------------------------------------------------------------------
</TABLE>

*     Commencement of operations.

++    The per share amounts were computed using an average number of shares
      outstanding.

+     Calculated based on the net asset value as of the last business day of
      the period.

(1)   Not annualized.

(2)   Annualized.

(3)   If the Fund had borne all of its expenses that were reimbursed or waived
      by the Investment Manager, the annualized expense and net investment
      income ratios would have been 0.58% and 0.87%, respectively, for the year
      ended August 31, 1999 and 0.64% and 1.02%, respectively, for the period
      ended August 31, 1998.

(4)   Reflects overall Fund ratios for investment income and non-class specific
      expenses.


                                                                              27


<PAGE>


NOTES


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28


<PAGE>


MORGAN STANLEY DEAN WITTER
FAMILY OF FUNDS

                          The Morgan Stanley Dean Witter Family of Funds offers
                          investors a wide range of investment choices. Come on
                          in and meet the family!
- --------------------------------------------------------------------------------

GROWTH FUNDS

GROWTH FUNDS
Aggressive Equity Fund
American Opportunities Fund
Capital Growth Securities
Developing Growth Securities
Growth Fund
Market Leader Trust
Mid-Cap Equity Trust
Next Generation Trust
Small Cap Growth Fund
Special Value Fund

THEME FUNDS
Financial Services Trust
Health Sciences Trust
Information Fund
Natural Resource Development Securities
Precious Metals and Minerals Trust

GLOBAL/INTERNATIONAL FUNDS
Competitive Edge Fund - "Best Ideas"  Portfolio
European Growth Fund
Fund of Funds - International Portfolio
International Fund
International SmallCap Fund
Japan Fund
Latin American Growth Fund
Pacific Growth Fund

- --------------------------------------------------------------------------------

GROWTH & INCOME FUNDS

Balanced Growth Fund
Balanced Income Fund
Convertible Securities Trust
Dividend Growth Securities
Equity Fund
Fund of Funds - Domestic Portfolio
Income Builder Fund
Mid-Cap Dividend Growth Securities
S&P 500 Index Fund
S&P 500 Select Fund
Strategist Fund
Total Market Index Fund
Total Return Trust
Value-Added Market Series/Equity Portfolio
Value Fund

THEME FUNDS
Global Utilities Fund
Real Estate Fund
Utilities Fund

GLOBAL FUNDS
Global Dividend Growth Securities

- --------------------------------------------------------------------------------

INCOME FUNDS

GOVERNMENT INCOME FUNDS
Federal Securities Trust
Short-Term U.S. Treasury Trust
U.S. Government Securities Trust

DIVERSIFIED INCOME FUNDS
Diversified Income Trust

CORPORATE INCOME FUNDS
High Yield Securities
Intermediate Income Securities
Short-Term Bond Fund(NL)

GLOBAL INCOME FUNDS

North American Government Income Trust
World Wide Income Trust

TAX-FREE INCOME FUNDS
California Tax-Free Income Fund
Hawaii Municipal Trust(FSC)
Limited Term Municipal Trust(NL)
Multi-State Municipal Series Trust(FSC)
New York Tax-Free Income Fund
Tax-Exempt Securities Trust

- --------------------------------------------------------------------------------

MONEY MARKET FUNDS

TAXABLE MONEY MARKET FUNDS
Liquid Asset Fund(MM)
U.S. Government Money Market Trust(MM)

TAX-FREE MONEY MARKET FUNDS
California Tax-Free Daily Income Trust(MM)
New York Municipal Money Market Trust(MM)
Tax-Free Daily Income Trust(MM)




There may be Funds created after this Prospectus was published. Please consult
the inside back cover of a new Fund's prospectus for its designations, e.g.,
Multi-Class Fund or Money Market Fund.

Unless otherwise noted, each listed Morgan Stanley Dean Witter Fund, except for
North American Government Income Trust and Short-Term U.S. Treasury Trust, is a
Multi-Class Fund. A Multi-Class Fund is a mutual fund offering multiple Classes
of shares. The other types of Funds are: NL -- No-Load (Mutual) Fund; MM --
Money Market Fund; FSC -- A mutual fund sold with a front-end sales charge and a
distribution (12b-1) fee.




<PAGE>


                                                  PROSPECTUS - OCTOBER 29, 1999


Additional information about the Fund's investments is available in the Fund's
Annual and Semi-Annual Reports to Shareholders. In the Fund's Annual Report, you
will find a discussion of the market conditions and investment strategies that
significantly affected the Fund's performance during its last fiscal year. The
Fund's Statement of Additional Information also provides additional information
about the Fund. The Statement of Additional Information is incorporated herein
by reference (legally is part of this Prospectus). For a free copy of any of
these documents, to request other information about the Fund, or to make
shareholder inquiries, please call:


                                 (800) 869-NEWS


You also may obtain information about the Fund by calling your Morgan Stanley
Dean Witter Financial Advisor or by visiting our Internet site at:


                          WWW.MSDW.COM/INDIVIDUAL/FUNDS


Information about the Fund (including the Statement of Additional Information)
can be viewed and copied at the Securities and Exchange Commission's Public
Reference Room in Washington, DC. Information about the Reference Room's
operations may be obtained by calling the SEC at (800) SEC-0330. Reports and
other information about the Fund are available on the SEC's Internet site
(www.sec.gov), and copies of this information may be obtained, upon payment of
a duplicating fee, by writing the Public Reference Section of the SEC,
Washington, DC 20549-6009.


TICKER SYMBOLS:

  Class A:            SPIAX
- -----------------------------
  Class B:            SPIBX
- -----------------------------
  Class C:            SPICX
- -----------------------------
  Class D:            SPIDX
- -----------------------------


(THE FUND'S INVESTMENT COMPANY ACT FILE NO. IS 811-8265)





                                                     MORGAN STANLEY DEAN WITTER


                                                             S&P 500 INDEX FUND




                                                            [GRAPHIC OMITTED]





A MUTUAL FUND THAT SEEKS TO PROVIDE INVESTMENT RESULTS THAT, BEFORE EXPENSES,
CORRESPOND TO THE TOTAL RETURN (I.E., THE COMBINATION OF CAPITAL CHANGES AND
INCOME) OF THE STANDARD & POOR'S (REGISTERED TRADEMARK) 500 COMPOSITE STOCK
PRICE INDEX




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