MORGAN STANLEY DEAN WITTER PRECIOUS METALS & MINERALS TRUS
497, 1999-02-26
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<PAGE>
                                                 PROSPECTUS -  FEBRUARY 22, 1999
 
Morgan Stanley Dean Witter
                                              PRECIOUS METALS AND MINERALS TRUST
 
[COVER PHOTO]
 
                         A MUTUAL FUND THAT SEEKS LONG-TERM CAPITAL APPRECIATION
 
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>
<S>                       <C>                                                           <C>
The Fund                  Investment Objective........................................                   1
                          Principal Investment Strategies.............................                   1
                          Principal Risks.............................................                   1
                          Past Performance............................................                   3
                          Fees and Expenses...........................................                   4
                          Additional Investment Strategy Information..................                   4
                          Additional Risk Information.................................                   5
                          Fund Management.............................................                   6
 
Shareholder Information   Pricing Fund Shares.........................................                   7
                          How to Buy Shares...........................................                   7
                          How to Exchange Shares......................................                   9
                          How to Sell Shares..........................................                  11
                          Distributions...............................................                  12
                          Tax Consequences............................................                  13
                          Share Class Arrangements....................................                  14
 
Financial Highlights      ............................................................                  20
 
Our Family of Funds       ............................................................   Inside Back Cover
 
                          THIS PROSPECTUS CONTAINS IMPORTANT INFORMATION ABOUT THE FUND.
                          PLEASE READ IT CAREFULLY AND KEEP IT FOR FUTURE REFERENCE.
</TABLE>
 
           FUND CATEGORY
           ---------------------------
       /X/  GROWTH
       / /  Growth and Income
       / /  Income
       / /  Money Market
<PAGE>
(Sidebar)
CAPITAL GROWTH
An investment objective having the goal of selecting securities with the
potential to rise in value rather than pay out income.
(End Sidebar)
 
THE FUND
 
ICON                INVESTMENT OBJECTIVE
- --------------------------------------------------------------------------------
                    Morgan Stanley Dean Witter Precious Metals and Minerals
                    Trust (the "Fund") is a mutual fund that seeks long-term
                    capital appreciation. There is no guarantee that the Fund
                    will achieve this objective.
 
ICON                PRINCIPAL INVESTMENT STRATEGIES
- --------------------------------------------------------------------------------
                    The Fund will normally invest at least 65% of its assets in
                    the common stock and other securities of foreign and
                    domestic companies principally engaged in the precious
                    metals and minerals business. The companies may engage in
                    the exploration, mining, fabrication, processing,
                    distribution or trading of precious metals and minerals --
                    or in financing, managing or operating companies engaged in
                    these activities. A company is considered to be principally
                    engaged in these activities if it derives a majority of its
                    income from, or devotes a majority of its assets to, the
                    activities. The Fund's "Investment Manager," Morgan Stanley
                    Dean Witter Advisors Inc., invests in companies that it
                    believes have growth potential based on a wide variety of
                    factors.
 
                    Because most of the world's gold production is outside of
                    the United States, a majority of the Fund's assets may be
                    invested in the securities of foreign companies.
 
                    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.
 
                    The Fund also may invest a portion of its assets in gold,
                    silver, platinum and palladium bullion and coins (or
                    certificates, receipts or contracts representing ownership
                    interests in these precious metals).
 
                    In pursuing the Fund's investment objective, the Investment
                    Manager has considerable leeway in deciding which
                    investments it buys, holds or sells on a day-to-day basis --
                    and which trading strategies it uses. For example, the
                    Investment Manager in its discretion may determine to use
                    some permitted trading strategies while not using others. In
                    addition to the investments discussed above, the Fund may
                    invest in common stocks of companies that are not primarily
                    engaged in the precious metals or minerals business,
                    long-term U.S. Government Securities and money market
                    instruments.
 
ICON                PRINCIPAL RISKS
- --------------------------------------------------------------------------------
                    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.
 
                    PRECIOUS METALS AND MINERALS. The Fund's investments related
                    to gold and other precious metals and minerals are
                    considered speculative and are impacted by a host of
                    world-wide economic, financial and political factors. Prices
                    of gold and other
 
                                                                               1
<PAGE>
                    precious metals may fluctuate widely over short periods of
                    time due to changes in inflation or expectations regarding
                    inflation in various countries, the availability of supplies
                    of these precious metals, changes in industrial and
                    commercial demand, and metal sales by governments, central
                    banks or international agencies. Prices also may fluctuate
                    widely due to investment speculation, monetary and other
                    economic policies of various governments and governmental
                    restrictions on the private ownership of certain precious
                    metals and minerals. Additionally, the precious metals and
                    minerals securities in which the Fund may invest may not
                    necessarily move in tandem with the prices of actual
                    precious metals and minerals.
 
                    At the present time, there are five major producers of gold
                    bullion. In order of magnitude they are: the Republic of
                    South Africa, the successor states of the former Soviet
                    Union, Canada, the United States and Australia. Political
                    and economic conditions in these countries may have a direct
                    effect on the mining, distribution and price of gold and
                    sales of central bank gold holdings.
 
                    CONCENTRATION POLICY. Unlike most industry diversified
                    mutual funds, the Fund is subject to the risks associated
                    with concentrating its assets in a particular industry --
                    precious metals and minerals. Thus, the Fund's overall
                    portfolio may decline in value due to developments specific
                    to this industry. Given the Fund's concentration policy,
                    Fund shares should not be considered a complete investment
                    program.
 
                    COMMON STOCK. In general, stock values fluctuate in response
                    to activities specific to the company as well as general
                    market, economic and political conditions. Stock prices can
                    fluctuate widely in response to these factors.
 
                    FOREIGN SECURITIES. The Fund's investments in foreign
                    securities (including depository receipts) involve risks
                    that are in addition to the risks associated with domestic
                    securities. One additional risk is currency risk. While the
                    price of Fund shares is quoted in U.S. dollars, the Fund
                    generally converts U.S. dollars to a foreign market's local
                    currency to purchase a security in that market. If the value
                    of that local currency falls relative to the U.S. dollar,
                    the U.S. dollar value of the foreign security will decrease.
                    This is true even if the foreign security's local price
                    remains unchanged.
 
                    Foreign securities also have risks related to economic and
                    political developments abroad, including expropriations,
                    confiscatory taxation, exchange control regulation,
                    limitations on the use or transfer of Fund assets and any
                    effects of foreign social, economic or political
                    instability. 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. Finally, in the event of
                    a default of any foreign debt obligations, it may be more
                    difficult for the Fund to obtain or enforce a judgment
                    against the issuers of the securities.
 
                    Securities of foreign issuers may be less liquid than
                    comparable securities of U.S. issuers and, as such, their
                    price changes may be more volatile. Furthermore, foreign
                    exchanges and broker-dealers are generally subject to less
                    government and exchange scrutiny and regulation than their
                    U.S. counterparts.
 
                    Many European countries have adopted or are in the process
                    of adopting a single European currency, referred to as the
                    "euro." The consequences of the euro conversion for foreign
                    exchange rates, interest rates and the value of European
 
2
<PAGE>
                    securities the Fund may purchase are presently unclear. The
                    consequences may adversely affect the value and/or increase
                    the volatility of securities held by the Fund.
(Sidebar)
ANNUAL TOTAL RETURNS
This chart shows how the performance of the Fund's Class B shares has varied
from year to year during the life of the Fund.
 
AVERAGE ANNUAL
TOTAL RETURNS
This table compares the Fund's average annual returns with those of a broad
measure of market performance over time. 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)
 
                    OTHER RISKS. The performance of the Fund also will depend on
                    whether or not the Investment Manager is successful in
                    pursuing the Fund's investment strategy. The Fund is also
                    subject to other risks from its permissible investments
                    including the risks associated with fixed-income 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 any bank, governmental entity, or
                    the FDIC.
 
ICON                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.
 
                    ANNUAL TOTAL RETURNS - CALENDAR YEARS
 
                    EDGAR REPRESENTATION OF DATA POINTS USED IN PRINTED GRAPHIC
 
<TABLE>
<S>        <C>
1990*        -10.42%
91            -4.41%
92            -9.95%
93            55.90%
94           -11.54%
95             4.97%
96             1.62%
97           -43.13%
98           -14.39%
</TABLE>
 
   
                    * For the period August 6, 1990 through December 31, 1990.
    
                    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.
 
                    During the periods shown in the bar chart, the highest
                    return for a calendar quarter was 24.77% (quarter ended June
                    30, 1993) and the lowest return for a calendar quarter was
                    -31.76% (quarter ended December 31, 1997).
 
   
<TABLE>
<CAPTION>
AVERAGE ANNUAL TOTAL RETURNS (FOR THE PERIODS ENDED THE 1998 CALENDAR YEAR)
- --------------------------------------------------------------------------------
                                     PAST 1 YEAR   PAST 5 YEARS    LIFE OF FUND
                                                                  (SINCE 8/6/90)
<S>                                  <C>           <C>            <C>
- --------------------------------------------------------------------------------
 Class A                               -18.33%          --                 --
- --------------------------------------------------------------------------------
 Class B(1)                            -18.67%       -14.71%            -6.82%
- --------------------------------------------------------------------------------
 Class C                               -15.24%          --                 --
- --------------------------------------------------------------------------------
 Class D                               -14.51%          --                 --
- --------------------------------------------------------------------------------
 S&P 500(2)                            28.58%         24.05%            19.77%
- --------------------------------------------------------------------------------
 Lipper Gold-Oriented Funds
 Index(3)                              -12.80%       -14.29%            -5.68%(4)
- --------------------------------------------------------------------------------
</TABLE>
    
 
1    Prior to July 28, 1997, the Fund only issued Class B shares.
2    The S&P 500-Registered Trademark- is Standard &
     Poor's-Registered Trademark- 500 Composite Stock Price Index, a widely
     recognized, unmanaged index of common stock prices. The Index is unmanaged,
     and should not be considered an investment.
3    The Lipper Gold-Oriented Funds Index is an equally-weighted performance
     index of the largest qualifying funds (based on net assets) in the Lipper
     Gold-Oriented 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.
4    For the Period August 31, 1990 to December 31, 1998.
 
                                                                               3
<PAGE>
(Sidebar)
SHAREHOLDER FEES
These fees are paid directly from your investment.
 
ANNUAL FUND
OPERATING EXPENSES
These expenses are deducted from the Fund's assets and are based on expenses
paid for the fiscal year ended October 31, 1998.
(End Sidebar)
 
ICON                FEES AND EXPENSES
- --------------------------------------------------------------------------------
                    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 table below briefly describes the
                    fees and expenses that you may pay if you buy and hold
                    shares of the Fund. The Fund does not charge account or
                    exchange fees. See the "Share Class Arrangements" section
                    for further fee and expense information.
 
<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                                                0.80%     0.80%     0.80%     0.80%
- ---------------------------------------------------------------------------------------------------
 Distribution and service (12b-1) fees                         0.23%     1.00%     1.00%     None
- ---------------------------------------------------------------------------------------------------
 Other expenses                                                0.98%     0.98%     0.98%     0.98%
- ---------------------------------------------------------------------------------------------------
 Total annual Fund operating expenses                          2.01%     2.78%     2.78%     1.78%
- ---------------------------------------------------------------------------------------------------
</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 on sales made 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 to sales made within one year after purchase.
 
                    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
                 -----------------------------------------   -----------------------------------------
                 1 YEAR    3 YEARS    5 YEARS    10 YEARS    1 YEAR    3 YEARS    5 YEARS    10 YEARS
<S>              <C>       <C>        <C>        <C>         <C>       <C>        <C>        <C>
- ----------------------------------------------------------   -----------------------------------------
 CLASS A           $718      $1122      $1551      $2740       $718      $1122      $1551      $2740
- ----------------------------------------------------------   -----------------------------------------
 CLASS B           $781      $1162      $1669      $3109       $281      $ 862      $1469      $3109
- ----------------------------------------------------------   -----------------------------------------
 CLASS C           $381      $ 862      $1469      $3109       $281      $ 862      $1469      $3109
- ----------------------------------------------------------   -----------------------------------------
 CLASS D           $181      $ 560      $ 964      $2095       $181      $ 560      $ 964      $2095
- ----------------------------------------------------------   -----------------------------------------
</TABLE>
 
ICON                ADDITIONAL INVESTMENT STRATEGY INFORMATION
- --------------------------------------------------------------------------------
                    This section provides additional information concerning the
                    Fund's principal strategies.
 
                    COMMON STOCKS AND OTHER SECURITIES. As discussed in the
                    "Principal Investment Strategies" section, the Fund will
                    normally invest at least 65% of its assets in the common
                    stocks and other securities of companies engaged in the
                    precious metals and minerals business. The other securities
                    in which the Fund may invest include securities convertible
                    into common stocks, preferred stocks and debt securities
 
4
<PAGE>
                    (including zero coupon bonds). The Fund's policy to
                    concentrate its investments in the precious metals and
                    minerals business, except during temporary "defensive"
                    periods discussed below, is a fundamental policy. A
                    fundamental policy may not be changed without shareholder
                    approval.
 
                    OTHER INVESTMENTS. The Fund also may invest up to 35% of its
                    assets, under normal market conditions, in common stocks of
                    companies that are not primarily engaged in the precious
                    metals or minerals business, long-term U.S. Government
                    securities and money market instruments.
 
                    DEFENSIVE INVESTING. The Fund may take temporary "defensive"
                    positions in attempting to respond to adverse market
                    conditions. The Fund may invest any amount of its assets in
                    cash or money market instruments in a defensive posture when
                    the Investment Manager believes it is advisable to do so.
                    Although taking a defensive posture is designed to protect
                    the Fund from an anticipated market downturn, it could have
                    the effect of reducing the benefit from any upswing in the
                    market.
 
                    The percentage limitations relating to the composition of
                    the Fund's portfolio apply at the time the Fund acquires an
                    investment. Subsequent percentage changes that result from
                    market fluctuations or changes in assets will not require
                    the Fund to sell any portfolio security. The Fund may change
                    its principal investment strategies (except for its
                    concentration policy for 65% of its assets) without
                    shareholder approval; however, you would be notified of any
                    changes.
 
ICON                ADDITIONAL RISK INFORMATION
- --------------------------------------------------------------------------------
                    This section provides information regarding the principal
                    risks of investing in the Fund in addition to those
                    discussed in the "Principal Risks" section.
 
                    OTHER SECURITIES AND INVESTMENTS. In addition to common
                    stocks, the Fund may invest in fixed-income securities, such
                    as preferred stock, corporate debt securities and U.S.
                    Government securities. All fixed-income securities are
                    subject to two types of risk: credit risk and interest rate
                    risk. Credit risk refers to the possibility that the issuer
                    of a security will be unable to make interest payments and
                    repay the principal on its debt.
 
                    Interest rate risk refers to fluctuations in the value of a
                    fixed-income security resulting from changes in the general
                    level of interest rates. When the general level of interest
                    rates goes up, the price of most fixed-income securities
                    goes down. When the general level of interest rates goes
                    down, the price of most fixed-income securities goes up.
                    (Zero coupon securities are typically subject to greater
                    price fluctuations than comparable securities that pay
                    interest.) Preferred stock also has risk characteristics
                    similar to those of common stocks.
 
                    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 individual 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
                    affiliates are working hard to avoid any problems and to
                    obtain assurances from their service providers that they are
                    taking similar steps.
 
                                                                               5
<PAGE>
(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 $127 billion in assets under management
or administration as of January 31, 1999.
(End Sidebar)
 
ICON                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.
 
   
                    The Fund's portfolio is managed within Investment Manager's
                    Growth Group. Robert Rossetti, a Vice President of the
                    Investment Manager, and a member of Investment Manager's
                    Growth Group, has been the primary portfolio manager of the
                    Fund since December of 1996. Prior to joining Investment
                    Manager in May of 1995, Mr. Rossetti was a Vice President at
                    Merrill Lynch & Co. Inc. (November 1994-April 1995) and
                    prior thereto was a Vice President at Prudential Securities
                    for six years.
    
 
6
<PAGE>
(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.deanwitter.com/funds
(End Sidebar)
 
SHAREHOLDER INFORMATION
 
                    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. The fee is based on the Fund's average
                    daily net assets. For the fiscal year ended October 31, 1998
                    the Fund accrued total compensation to the Investment
                    Manager amounting to 0.80% of the Fund's average daily net
                    assets.
 
                    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. In
                    addition, if the Fund holds securities primarily listed on
                    foreign exchanges, the value of the Fund's portfolio
                    securities may change on days when you will not be able to
                    purchase or sell your shares.
 
                    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.
 
                    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.
 
                    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.
 
                                                                               7
<PAGE>
(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)
 
                    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
                    investment order in proper form. We reserve the right to
                    reject any order for the purchase of Fund shares.
 
   
<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.
 
   
                    THREE DAY SETTLEMENT. Fund shares are sold through the
                    Fund's distributor, Morgan Stanley Dean Witter Distributors
                    Inc., on a normal three business day basis; that is, your
                    payment for Fund shares is due on the third business day
                    (settlement day) after you place a purchase order.
    
 
                    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 or other authorized financial
                    representative, you may send a check directly to the Fund.
                    To buy additional shares in this manner:
 
                    - 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).
 
                    - Make out a check for the total amount payable to: Morgan
                      Stanley Dean Witter Precious Metals and Minerals Trust.
 
                    - Mail the letter and check to Morgan Stanley Dean Witter
                      Trust FSB at P.O. Box 1040, Jersey City, NJ 07303.
 
8
<PAGE>
                    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, Money Market Fund 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 minimums, and should be read before investment.
 
                    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. Certain services normally available to
                    shareholders of Money Market Funds, including the check
                    writing privilege, are 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 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.
    
 
                                                                               9
<PAGE>
                    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 Fund 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 further
                    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 OTHER AUTHORIZED FINANCIAL REPRESENTATIVE, OR
                    CALL (800) 869-NEWS.
 
10
<PAGE>
(Sidebar)
SYSTEMATIC WITHDRAWAL PLAN
This plan
allows you to withdraw money automatically from your Fund account at regular
intervals. Contact your Morgan Stanley Dean Witter Financial Advisor for more
details.
(End Sidebar)
 
ICON                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
 Financial Advisor  Witter Financial Advisor or other authorized financial
                    representative.
                    ------------------------------------------------------------
 ICON               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:
                    ICON
                    - your account number;
                    - the dollar amount or the number of shares you wish to
                      sell;
                    - the Class of shares you wish to sell; and
                    - 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
 Withdrawal Plan    Family of Funds has a total 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 a monthly, quarterly,
                    semi-annual or annual basis, from any Fund with a balance of
                    $1,000. Each time you add a Fund to the plan, you must meet
                    the plan requirements.
                    ------------------------------------------------------------
 ICON               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 other
                    authorized financial representative, 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>
    
 
                    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, payment
                    of the sale proceeds may be delayed for the minimum time
                    needed to verify that the check has been honored (not more
                    than fifteen days from the time we receive the check).
    
 
                                                                              11
<PAGE>
(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)
 
                    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. Certain restrictions may apply to Fund
                    shares pledged in margin accounts with Dean Witter Reynolds
                    or another authorized broker-dealer of Fund shares. If you
                    hold Fund shares in this manner, please contact your Morgan
                    Stanley Dean Witter Financial Advisor or other authorized
                    financial representative for more details.
 
                    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."
    
 
   
                    The Fund declares income dividends separately for each
                    Class. Distributions paid on Class A and Class D shares
                    usually 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 and capital gains are distributed
                    annually 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.
 
12
<PAGE>
                    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:
 
                    - The Fund makes distributions; and
 
                    - 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 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.
 
                                                                              13
<PAGE>
(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)
 
                    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.
 
                    The chart below compares the sales charge and annual 12b-1
                    fee applicable to each Class:
 
   
<TABLE>
<CAPTION>
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 the 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 the 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:
 
   
<TABLE>
<CAPTION>
                                                      FRONT-END SALES CHARGE
                                          ----------------------------------------------
                                              PERCENTAGE OF       APPROXIMATE PERCENTAGE
 AMOUNT OF SINGLE TRANSACTION             PUBLIC OFFERING PRICE     OF 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>
    
 
14
<PAGE>
                    The reduced sales charge schedule is applicable to purchases
                    of Class A shares in a single transaction by:
 
                    - A single account (including an individual, trust or
                      fiduciary account).
 
                    - Family member accounts (limited to husband, wife and
                      children under the age of 21).
 
                    - Pension, profit sharing or other employee benefit plans of
                      companies and their affiliates.
 
                    - Tax-exempt organizations.
 
                    - 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
                    Stanley Dean Witter Financial Advisor or other authorized
                    financial representative, or by calling (800) 869-NEWS. If
                    you do not
 
                                                                              15
<PAGE>
(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)
 
                    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.
 
                    OTHER FRONT-END 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:
 
                    - A trust for which Morgan Stanley Dean Witter Trust FSB
                      provides discretionary trustee services.
 
                    - Persons participating in a fee-based investment program
                      (subject to all of its terms and conditions, including
                      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.
 
                    - 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.
 
                    - 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.
 
- - 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 the
  purchase of Fund shares, and (2) the sale proceeds were maintained in the
  interim in cash or a money market fund.
 
 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.
 
<TABLE>
<CAPTION>
 YEAR SINCE PURCHASE PAYMENT MADE              CDSC AS A PERCENTAGE OF 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.
 
16
<PAGE>
CDSC WAIVERS. A CDSC, if otherwise applicable, will be waived in the case of:
 
- - 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.
 
- - 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).
 
- - Sales of shares held for you as a participant in a MSDW Eligible Plan.
 
- - 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 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.
 
All waivers will be granted only following the 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 subject to an annual 12b-1 fee of 1.0% of
the lesser of: (a) the average daily aggregate gross purchases by all
shareholders of the Fund's Class B shares since the inception of the Fund (not
including reinvestments of dividends or capital gains distributions), less the
average daily aggregate net asset value of the Fund's Class B shares sold by all
shareholders since the Fund's inception upon which a CDSC has been imposed or
waived, or (b) the average daily net assets of Class B.
 
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
 
                                                                              17
<PAGE>
through automatically reinvested distributions will convert to Class A shares on
the same basis. (Class B shares held 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, No-Load
Fund 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 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, if any, 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 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.
 
18
<PAGE>
 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 investor categories:
 
- - Investors participating in the Investment Manager's mutual fund asset
  allocation program (subject to all of its terms and conditions, including
  mandatory sale or transfer restrictions on termination) pursuant to which they
  pay an asset-based fee.
 
- - Persons participating in a fee-based investment program (subject to all of its
  terms and conditions, including 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.
 
- - 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.
 
- - Certain unit investment trusts sponsored by Dean Witter Reynolds.
 
- - Certain other open-end investment companies whose shares are distributed by
  the Fund's distributor.
 
- - 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.
 
                                                                              19
<PAGE>
FINANCIAL HIGHLIGHTS
 
        The financial highlights table is intended to help you understand the
        Fund's financial performance for the past 5 fiscal years 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, whose
        report, along with the Fund's financial statements, is included in the
        annual report, which is available upon request.
    
 
<TABLE>
<CAPTION>
CLASS B SHARES
- ----------------------------------------------------------------------------------------------------------------------------
 FOR THE YEAR ENDED OCTOBER 31                                   1998++      1997*++       1996         1995        1994
<S>                                                              <C>         <C>         <C>          <C>        <C>
- ----------------------------------------------------------------------------------------------------------------------------
 
 SELECTED PER SHARE DATA:
- ----------------------------------------------------------------------------------------------------------------------------
 Net asset value, beginning of period                            $  6.85     $ 11.14     $   9.77     $  11.45     $   10.80
- ----------------------------------------------------------------------------------------------------------------------------
 INCOME (LOSS) FROM INVESTMENT OPERATIONS:
    Net investment loss                                            (0.09)      (0.10)       (0.10)       (0.08)        (0.06)
    Net realized and unrealized gain (loss)                        (1.75)      (3.35)        1.66        (1.38)         0.73
                                                                 -------     -------     --------     --------   -----------
 Total income (loss) from investment operations                    (1.84)      (3.45)        1.56        (1.46)         0.67
- ----------------------------------------------------------------------------------------------------------------------------
 LESS DIVIDENDS AND DISTRIBUTIONS FROM:
    Net investment income                                             --       (0.13)          --           --            --
    Net realized gain                                                 --       (0.71)       (0.19)       (0.22)        (0.02)
                                                                 -------     -------     --------     --------   -----------
 Total dividends and distributions                                    --       (0.84)       (0.19)       (0.22)        (0.02)
- ----------------------------------------------------------------------------------------------------------------------------
 Net asset value, end of period                                  $  5.01     $  6.85     $  11.14     $   9.77     $   11.45
- ----------------------------------------------------------------------------------------------------------------------------
 
 TOTAL RETURN+                                                    (26.86)%    (33.29)%      15.93%      (12.78)%        6.18%
- ----------------------------------------------------------------------------------------------------------------------------
 
 RATIOS TO AVERAGE NET ASSETS:
- ----------------------------------------------------------------------------------------------------------------------------
 Expenses                                                           2.78%(1)    2.36%        2.27%        2.29%         2.28%
- ----------------------------------------------------------------------------------------------------------------------------
 Net investment loss                                               (1.55)%(1)   (1.13)%     (0.84)%      (0.70)%       (0.87)%
- ----------------------------------------------------------------------------------------------------------------------------
 
 SUPPLEMENTAL DATA:
- ----------------------------------------------------------------------------------------------------------------------------
 Net assets, end of period, in thousands                         $30,005     $37,964     $ 60,841     $ 55,448     $  73,444
- ----------------------------------------------------------------------------------------------------------------------------
 Portfolio turnover rate                                              36%         53%          46%          23%           46%
- ----------------------------------------------------------------------------------------------------------------------------
</TABLE>
 
* Prior to July 28, 1997, the Fund issued one class of shares. All shares of the
  Fund held prior to that date have been designated Class B shares.
++ The per share amounts were computed using an average number of shares
   outstanding during the period.
+ Does not reflect the deduction of sales charges. Calculated based on the net
  asset value as of the last business day of the period.
(1) Reflects overall Fund ratios for investment income and non-class specific
    expenses.
 
20
<PAGE>
 
<TABLE>
<CAPTION>
CLASS A SHARES++
- ---------------------------------------------------------------------------------------------
                                         FOR THE YEAR ENDED    FOR THE PERIOD JULY 28, 1997*
                                          OCTOBER 31, 1998        THROUGH OCTOBER 31, 1997
<S>                                      <C>                   <C>
- ---------------------------------------------------------------------------------------------
 
 SELECTED PER SHARE DATA:
- ---------------------------------------------------------------------------------------------
 Net asset value, beginning of period          $  6.86                     $ 7.95
- ---------------------------------------------------------------------------------------------
 LOSS FROM INVESTMENT OPERATIONS:
    Net investment loss                          (0.05)                        --
    Net realized and unrealized loss             (1.76)                     (1.09)
                                              --------                    -------
 Total loss from investment operations           (1.81)                     (1.09)
- ---------------------------------------------------------------------------------------------
 Net asset value, end of period                $  5.05                     $ 6.86
- ---------------------------------------------------------------------------------------------
 
 TOTAL RETURN+                                  (26.38)%                   (13.71)%(1)
- ---------------------------------------------------------------------------------------------
 
 RATIOS TO AVERAGE NET ASSETS:
- ---------------------------------------------------------------------------------------------
 Expenses                                         2.01%(3)                   1.61%(2)
- ---------------------------------------------------------------------------------------------
 Net investment loss                             (0.78)%(3)                 (0.08)%(2)
- ---------------------------------------------------------------------------------------------
 
 SUPPLEMENTAL DATA:
- ---------------------------------------------------------------------------------------------
 Net assets, end of period, in
 thousands                                     $    91                     $   32
- ---------------------------------------------------------------------------------------------
 Portfolio turnover rate                            36%                        53%
- ---------------------------------------------------------------------------------------------
</TABLE>
 
<TABLE>
<CAPTION>
 CLASS C SHARES++
<S>                                      <C>                   <C>
- ---------------------------------------------------------------------------------------------
 
 SELECTED PER SHARE DATA:
- ---------------------------------------------------------------------------------------------
 Net asset value, beginning of period          $  6.84                     $  7.95
- ---------------------------------------------------------------------------------------------
 LOSS FROM INVESTMENT OPERATIONS:
    Net investment loss                          (0.09)                      (0.02)
    Net realized and unrealized loss             (1.74)                      (1.09)
                                              --------                    --------
 Total loss from investment operations           (1.83)                      (1.11)
- ---------------------------------------------------------------------------------------------
 Net asset value, end of period                $  5.01                     $  6.84
- ---------------------------------------------------------------------------------------------
 
 TOTAL RETURN+                                  (26.75)%                    (13.96)%(1)
- ---------------------------------------------------------------------------------------------
 
 RATIOS TO AVERAGE NET ASSETS:
- ---------------------------------------------------------------------------------------------
 Expenses                                         2.78%(3)                    2.37%(2)
- ---------------------------------------------------------------------------------------------
 Net investment loss                             (1.55)%(3)                  (0.79)%(2)
- ---------------------------------------------------------------------------------------------
 
 SUPPLEMENTAL DATA:
- ---------------------------------------------------------------------------------------------
 Net assets, end of period, in
 thousands                                     $ 1,046                     $   475
- ---------------------------------------------------------------------------------------------
 Portfolio turnover rate                            36%                         53%
- ---------------------------------------------------------------------------------------------
</TABLE>
 
* The date shares were first issued.
++ The per share amounts were computed using an average number of shares
outstanding during the period.
+ Does not reflect the deduction of sales charges. Calculated based on the net
asset value as of the last business day of the period.
(1) Not annualized.
(2) Annualized.
(3) Reflects overall Fund ratios for investment income and non-class specific
expenses.
 
                                                                              21
<PAGE>
 
<TABLE>
<CAPTION>
CLASS D SHARES++
- ---------------------------------------------------------------------------------------------
                                         FOR THE YEAR ENDED    FOR THE PERIOD JULY 28, 1997*
                                          OCTOBER 31, 1998        THROUGH OCTOBER 31, 1997
<S>                                      <C>                   <C>
- ---------------------------------------------------------------------------------------------
 
 SELECTED PER SHARE DATA:
- ---------------------------------------------------------------------------------------------
 Net asset value, beginning of period           $ 6.86                     $ 7.95
- ---------------------------------------------------------------------------------------------
 INCOME (LOSS) FROM INVESTMENT
OPERATIONS:
    Net investment income                         0.02                         --
    Net realized and unrealized loss             (1.85)                     (1.09)
                                               -------                    -------
 Total loss from investment operations           (1.83)                     (1.09)
- ---------------------------------------------------------------------------------------------
 Net asset value, end of period                 $ 5.03                     $ 6.86
- ---------------------------------------------------------------------------------------------
 TOTAL RETURN+                                  (26.68)%                   (13.71)%(1)
- ---------------------------------------------------------------------------------------------
 
 RATIOS TO AVERAGE NET ASSETS:
- ---------------------------------------------------------------------------------------------
 Expenses                                         1.78%(3)                   1.35%(2)
- ---------------------------------------------------------------------------------------------
 Net investment income (loss)                    (0.55)%(3)                  0.22%(2)
- ---------------------------------------------------------------------------------------------
 
 SUPPLEMENTAL DATA:
- ---------------------------------------------------------------------------------------------
 Net assets, end of period, in
 thousands                                      $  327                     $    9
- ---------------------------------------------------------------------------------------------
 Portfolio turnover rate                            36%                        53%
- ---------------------------------------------------------------------------------------------
</TABLE>
 
* The date shares were first issued.
++ The per share amounts were computed using an average number of shares
   outstanding during the period.
+ Calculated based on the net asset value as of the last business day of the
  period.
(1) Not annualized.
(2) Annualized.
(3) Reflects overall Fund ratios for investment income and non-class specific
    expenses.
 
22
<PAGE>
NOTES
 
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                                                                              23
<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 Value Fund
Capital Growth Securities
Developing Growth Securities
Equity Fund
Growth Fund
Market Leader Trust
Mid-Cap Growth Fund
Special Value Fund
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
   
Global Dividend Growth Securities
    
International SmallCap Fund
Japan Fund
Pacific Growth Fund
 
- --------------------------------------------------------------------------------
 GROWTH AND INCOME FUNDS
- --------------------------------
Balanced Growth Fund
Balanced Income Fund
Convertible Securities Trust
Dividend Growth Securities
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
Value-Added Market Series/Equity Portfolio
 
   
THEME FUNDS
    
   
Utilities Fund
    
   
Global Utilities Fund
    
 
- --------------------------------------------------------------------------------
 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
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)
N.Y. 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 front cover of a new Fund's PROSPECTUS for its designation, e.g.,
Multi-Class Fund or Money Market Fund.
   
Unless otherwise noted, each listed Morgan Stanley Dean Witter Fund, except for
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>
MORGAN STANLEY DEAN WITTER
PRECIOUS METALS AND MINERALS TRUST
 
(Sidebar)
TICKER SYMBOLS:
 
CLASS A:  METAX
- -------------------
CLASS B:  METBX
- -------------------
CLASS C:  METCX
- -------------------
CLASS D:  METDX
- -------------------
(End Sidebar)
 
                    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.DEANWITTER.COM/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.
 
   
(MORGAN STANLEY DEAN WITTER PRECIOUS METALS AND MINERALS TRUST;
                 INVESTMENT COMPANY ACT FILE NO. 811-5988)
    
<PAGE>
 
   
STATEMENT OF ADDITIONAL INFORMATION                                 MORGAN
FEBRUARY 22, 1999                                                   STANLEY
                                                                    DEAN WITTER
                                                                    PRECIOUS
                                                                    METALS AND
                                                                    MINERALS
                                                                    TRUST
 
- --------------------------------------------------------------------------------
    
 
    This STATEMENT OF ADDITIONAL INFORMATION is not a PROSPECTUS. The PROSPECTUS
(dated February 22, 1999) for the Morgan Stanley Dean Witter Precious Metals and
Minerals Trust may be obtained without charge from the Fund at its address or
telephone number listed below or from Dean Witter Reynolds at any of its branch
offices.
 
Morgan Stanley Dean Witter
Precious Metals and Minerals Trust
Two World Trade Center
New York, New York 10048
(800) 869-NEWS
<PAGE>
TABLE OF CONTENTS
- --------------------------------------------------------------------------------
 
<TABLE>
<S>                                                                                      <C>
I. Fund History........................................................................          4
 
II. Description of the Fund and Its Investments and Risks..............................          4
 
  A. Classification....................................................................          4
 
  B. Investment Strategies and Risks...................................................          4
 
  C. Fund Policies/Investment Restrictions.............................................         13
 
III. Management of the Fund............................................................         14
 
  A. Board of Trustees.................................................................         14
 
  B. Management Information............................................................         15
 
  C. Compensation......................................................................         19
 
IV. Control Persons and Principal Holders of Securities................................         21
 
V. Investment Management and Other Services............................................         21
 
  A. Investment Manager................................................................         21
 
  B. Principal Underwriter.............................................................         22
 
  C. Services Provided by the Investment Manager and Fund Expenses Paid by Third
   Parties.............................................................................         22
 
  D. Dealer Reallowances...............................................................         23
 
  E. Rule 12b-1 Plan...................................................................         23
 
  F. Other Service Providers...........................................................         27
 
VI. Brokerage Allocation and Other Practices...........................................         27
 
  A. Brokerage Transactions............................................................         27
 
  B. Commissions.......................................................................         28
 
  C. Brokerage Selection...............................................................         29
 
  D. Directed Brokerage................................................................         29
 
  E. Regular Broker-Dealers............................................................         29
 
VII. Capital Stock and Other Securities................................................         30
 
VIII. Purchase, Redemption and Pricing of Shares.......................................         30
 
  A. Purchase/Redemption of Shares.....................................................         30
 
  B. Offering Price....................................................................         31
 
IX. Taxation of the Fund and Shareholders..............................................         32
 
X. Underwriters........................................................................         34
 
XI. Calculation of Performance Data....................................................         34
 
XII. Financial Statements..............................................................         35
</TABLE>
 
                                       2
<PAGE>
GLOSSARY OF SELECTED DEFINED TERMS
- --------------------------------------------------------------------------------
 
    The terms defined in this glossary are frequently used in this STATEMENT OF
ADDITIONAL INFORMATION (other terms used occasionally are defined in the text of
the document).
 
"CUSTODIAN"--The Bank of New York.
 
"DEAN WITTER REYNOLDS"--Dean Witter Reynolds Inc., a wholly-owned broker-dealer
subsidiary of MSDW.
 
"DISTRIBUTOR"--Morgan Stanley Dean Witter Distributors Inc., a wholly-owned
broker-dealer subsidiary of MSDW.
 
"FINANCIAL ADVISORS"--Morgan Stanley Dean Witter authorized financial services
representatives.
 
"FUND"--Morgan Stanley Dean Witter Precious Metals and Minerals Trust, a
registered open-end investment company.
 
"INVESTMENT MANAGER"--Morgan Stanley Dean Witter Advisors Inc., a wholly-owned
investment advisor subsidiary of MSDW.
 
"INDEPENDENT TRUSTEES"--Trustees who are not "interested persons" (as defined by
the Investment Company Act) of the Fund.
 
"MORGAN STANLEY & CO."--Morgan Stanley & Co. Incorporated, a wholly-owned
broker-dealer subsidiary of MSDW.
 
"MORGAN STANLEY DEAN WITTER FUNDS"--Registered investment companies (i) for
which the Investment Manager serves as the investment advisor and (ii) that hold
themselves out to investors as related companies for investment and investor
services.
 
"MSDW"--Morgan Stanley Dean Witter & Co., a preeminent global financial services
firm.
 
"MSDW SERVICES COMPANY"--Morgan Stanley Dean Witter Services Company Inc., a
wholly-owned fund services subsidiary of the Investment Manager.
 
"TRANSFER AGENT"--Morgan Stanley Dean Witter Trust FSB, a wholly-owned transfer
agent subsidiary of MSDW.
 
"TRUSTEES"--The Board of Trustees of the Fund.
 
                                       3
<PAGE>
I. FUND HISTORY
- --------------------------------------------------------------------------------
 
    The Fund was organized as a Massachusetts business trust, under a
Declaration of Trust, on December 28, 1989, with the name Dean Witter Precious
Metals and Minerals Trust. Effective June 22, 1998, the Fund's name was changed
to Morgan Stanley Dean Witter Precious Metals and Minerals Trust.
 
II. DESCRIPTION OF THE FUND AND ITS INVESTMENTS AND RISKS
- --------------------------------------------------------------------------------
 
A. CLASSIFICATION
 
    The Fund is an open-end, diversified management investment company whose
investment objective is long-term capital appreciation.
 
B. INVESTMENT STRATEGIES AND RISKS
 
    The following discussion of the Fund's investment strategies and risks
should be read with the sections of the Fund's PROSPECTUS titled "Principal
Investment Strategies," "Principal Risks," "Additional Investment Strategy
Information," and "Additional Risk Information."
 
    OTHER PRECIOUS METALS RELATED INVESTMENTS.  The Fund may invest in other
precious metals related investments including precious metals indexed debt
securities.
 
    FORWARD FOREIGN CURRENCY EXCHANGE CONTRACTS.  The Fund may enter into
forward foreign currency exchange contracts ("forward contracts") as a hedge
against fluctuations in future foreign exchange rates. The Fund may conduct its
foreign currency exchange transactions either on a spot (i.e., cash) basis at
the spot rate prevailing in the foreign currency exchange market, or through
entering into forward contracts to purchase or sell foreign currencies. A
forward contract involves an obligation to purchase or sell a specific currency
at a future date, which may be any fixed number of days from the date of the
contract agreed upon by the parties, at a price set at the time of the contract.
These contracts are traded in the interbank market conducted directly between
currency traders (usually large, commercial and investment banks) and their
customers. Forward contracts only will be entered into with United States banks
and their foreign branches, insurance companies and other dealers or foreign
banks whose assets total $1 billion or more. A forward contract generally has no
deposit requirement, and no commissions are charged at any stage for trades.
 
    The Fund may enter into forward contracts under various circumstances. The
typical use of a forward contract is to "lock in" the price of a security in
U.S. dollars or some other foreign currency which the Fund is holding in its
portfolio. By entering into a forward contract for the purchase or sale, for a
fixed amount of dollars or other currency, of the amount of foreign currency
involved in the underlying security transactions, the Fund may be able to
protect itself against a possible loss resulting from an adverse change in the
relationship between the U.S. dollar or other currency which is being used for
the security purchase and the foreign currency in which the security is
denominated during the period between the date on which the security is
purchased or sold and the date on which payment is made or received.
 
    The Investment Manager also may from time to time utilize forward contracts
for other purposes. For example, they may be used to hedge a foreign security
held in the portfolio or a security which pays out principal tied to an exchange
rate between the U.S. dollar and a foreign currency, against a decline in value
of the applicable foreign currency. They also may be used to lock in the current
exchange rate of the currency in which those securities anticipated to be
purchased are denominated. At times, the Fund may enter into "cross-currency"
hedging transactions involving currencies other than those in which securities
are held or proposed to be purchased are denominated.
 
    The Fund will not enter into forward currency contracts or maintain a net
exposure to these contracts where the consummation of the contracts would
obligate the Fund to deliver an amount of foreign currency in excess of the
value of the Fund's portfolio securities.
 
    Although the Fund values its assets daily in terms of U.S. dollars, it does
not intend to convert its holdings of foreign currencies into U.S. dollars on a
daily basis. It will, however, do so from time to time,
 
                                       4
<PAGE>
and investors should be aware of the costs of currency conversion. Although
foreign exchange dealers do not charge a fee for conversion, they do realize a
profit based on the spread between the prices at which they are buying and
selling various currencies. Thus, a dealer may offer to sell a foreign currency
to the Fund at one rate, while offering a lesser rate of exchange should the
Fund desire to resell that currency to the dealer.
 
    The Fund may be limited in its ability to enter into hedging transactions
involving forward contracts by the Internal Revenue Code requirements relating
to qualification as a regulated investment company.
 
    Forward currency contracts may limit gains on portfolio securities that
could otherwise be realized had they not been utilized and could result in
losses. The contracts also may increase the Fund's volatility and may involve a
significant amount of risk relative to the investment of cash.
 
    OPTIONS AND FUTURES TRANSACTIONS.  The Fund may engage in transactions in
listed and OTC options. Listed options are issued or guaranteed by the exchange
on which they are traded or by a clearing corporation such as the Options
Clearing Corporation ("OCC"). Ownership of a listed call option gives the Fund
the right to buy from the OCC (in the U.S.) or other clearing corporation or
exchange, the underlying security or currency covered by the option at the
stated exercise price (the price per unit of the underlying security) by filing
an exercise notice prior to the expiration date of the option. The writer
(seller) of the option would then have the obligation to sell to the OCC (in the
U.S.) or other clearing corporation or exchange, the underlying security or
currency at that exercise price prior to the expiration date of the option,
regardless of its then current market price. Ownership of a listed put option
would give the Fund the right to sell the underlying security or currency to the
OCC (in the U.S.) or other clearing corporation or exchange, at the stated
exercise price. Upon notice of exercise of the put option, the writer of the put
would have the obligation to purchase the underlying security or currency from
the OCC (in the U.S.) or other clearing corporation or exchange, at the exercise
price.
 
    COVERED CALL WRITING.  The Fund is permitted to write covered call options
on portfolio securities and on the U.S. dollar and foreign currencies in which
they are denominated, without limit.
 
    The Fund will receive from the purchaser, in return for a call it has
written, a "premium;" i.e., the price of the option. Receipt of these premiums
may better enable the Fund to earn a higher level of current income than it
would earn from holding the underlying securities (or currencies) alone.
Moreover, the premium received will offset a portion of the potential loss
incurred by the Fund if the securities (or currencies) underlying the option
decline in value.
 
    The Fund may be required, at any time during the option period, to deliver
the underlying security (or currency) against payment of the exercise price on
any calls it has written. This obligation is terminated upon the expiration of
the option period or at such earlier time when the writer effects a closing
purchase transaction. A closing purchase transaction is accomplished by
purchasing an option of the same series as the option previously written.
However, once the Fund has been assigned an exercise notice, the Fund will be
unable to effect a closing purchase transaction.
 
    Options written by the Fund normally have expiration dates of from up to
eighteen months from the date written. The exercise price of a call option may
be below, equal to or above the current market value of the underlying security
at the time the option is written.
 
    COVERED PUT WRITING.  As a writer of a covered put option, the Fund incurs
an obligation to buy the security underlying the option from the purchaser of
the put, at the option's exercise price at any time during the option period, at
the purchaser's election. Through the writing of a put option, the Fund would
receive income from the premium paid by purchasers. The potential gain on a
covered put option is limited to the premium received on the option (less the
commissions paid on the transaction). During the option period, the Fund may be
required, at any time, to make payment of the exercise price against delivery of
the underlying security (or currency). The aggregate value of the obligations
underlying puts may not exceed 50% of the Fund's assets. The operation of and
limitations on covered put options in other respects are substantially identical
to those of call options.
 
                                       5
<PAGE>
    PURCHASING CALL AND PUT OPTIONS.  The Fund may purchase listed and OTC call
and put options in amounts equaling up to 10% of its total assets. The purchase
of a call option would enable the Fund, in return for the premium paid to lock
in a purchase price for a security or currency during the term of the option.
The purchase of a put option would enable the Fund, in return for a premium
paid, to lock in a price at which it may sell a security or currency during the
term of the option.
 
    OPTIONS ON FOREIGN CURRENCIES.  The Fund may purchase and write options on
foreign currencies for purposes similar to those involved with investing in
forward foreign currency exchange contracts.
 
    OTC OPTIONS.  OTC options are purchased from or sold (written) to dealers or
financial institutions which have entered into direct agreements with the Fund.
With OTC options, such variables as expiration date, exercise price and premium
will be agreed upon between the Fund and the transacting dealer, without the
intermediation of a third party such as the OCC. The Fund will engage in OTC
option transactions only with member banks of the Federal Reserve Bank System or
primary dealers in U.S. Government securities or with affiliates of such banks
or dealers.
 
    RISKS OF OPTIONS TRANSACTIONS.  The successful use of options depends on the
ability of the Investment Manager to forecast correctly interest rates, currency
exchange rates and/or market movements. If the market value of the portfolio
securities (or the currencies in which they are denominated) upon which call
options have been written increases, the Fund may receive a lower total return
from the portion of its portfolio upon which calls have been written than it
would have had such calls not been written. During the option period, the
covered call writer has, in return for the premium on the option, given up the
opportunity for capital appreciation above the exercise price should the market
price of the underlying security (or the value of its denominated currency)
increase, but has retained the risk of loss should the price of the underlying
security (or the value of its denominated currency) decline. The covered put
writer also retains the risk of loss should the market value of the underlying
security decline below the exercise price of the option less the premium
received on the sale of the option. In both cases, the writer has no control
over the time when it may be required to fulfill its obligation as a writer of
the option. Prior to exercise or expiration, an option position can only be
terminated by entering into a closing purchase or sale transaction. Once an
option writer has received an exercise notice, it cannot effect a closing
purchase transaction in order to terminate its obligation under the option and
must deliver or receive the underlying securities at the exercise price.
 
    The Fund's ability to close out its position as a writer of an option is
dependent upon the existence of a liquid secondary market on option exchanges.
There is no assurance that such a market will exist, particularly in the case of
OTC options.
 
    In the event of the bankruptcy of a broker through which the Fund engages in
transactions in options, the Fund could experience delays and/or losses in
liquidating open positions purchased or sold through the broker and/or incur a
loss of all or part of its margin deposits with the broker. In the case of OTC
options, if the transacting dealer fails to make or take delivery of the
securities underlying an option it has written, in accordance with the terms of
that option, due to insolvency or otherwise, the Fund would lose the premium
paid for the option as well as any anticipated benefit of the transaction.
 
    Each of the exchanges has established limitations governing the maximum
number of call or put options on the same underlying security which may be
written by a single investor, whether acting alone or in concert with others
(regardless of whether such options are written on the same or different
exchanges or are held or written on one or more accounts or through one or more
brokers). An exchange may order the liquidation of positions found to be in
violation of these limits and it may impose other sanctions or restrictions.
These position limits may restrict the number of listed options which the Fund
may write.
 
    The hours of trading for options may not conform to the hours during which
the underlying securities are traded. To the extent that the option markets
close before the markets for the underlying securities, significant price and
rate movements can take place in the underlying markets that cannot be reflected
in the option markets.
 
                                       6
<PAGE>
    The markets in foreign currency options are relatively new and the Fund's
ability to establish and close out positions on such options is subject to the
maintenance of a liquid secondary market.
 
    There can be no assurance that a liquid secondary market will exist for a
particular option at any specific time.
 
    The value of a foreign currency option depends upon the value of the
underlying currency relative to the U.S. dollar. As a result, the price of the
option position may vary with changes in the value of either or both currencies
and have no relationship to the investment merits of a foreign security. Because
foreign currency transactions occurring in the interbank market involve
substantially larger amounts than those that may be involved in the use of
foreign currency options, investors may be disadvantaged by having to deal in an
odd lot market (generally consisting of transactions of less than $1 million)
for the underlying foreign currencies at prices that are less favorable than for
round lots.
 
    There is no systematic reporting of last sale information for foreign
currencies or any regulatory requirement that quotations available through
dealers or other market sources be firm or revised on a timely basis. Quotation
information available is generally representative of very large transactions in
the interbank market and thus may not reflect relatively smaller transactions
(i.e., less than $1 million) where rates may be less favorable. The interbank
market in foreign currencies is a global, around-the-clock market. To the extent
that the U.S. options markets are closed while the markets for the underlying
currencies remain open, significant price and rate movements may take place in
the underlying markets that are not reflected in the options market.
 
    STOCK INDEX OPTIONS.  The Fund may invest in options on broadly based
indexes. Options on stock indexes are similar to options on stock except that,
rather than the right to take or make delivery of stock at a specified price, an
option on a stock index gives the holder the right to receive, upon exercise of
the option, an amount of cash if the closing level of the stock index upon which
the option is based is greater than, in the case of a call, or less than, in the
case of a put, the exercise price of the option. This amount of cash is equal to
such difference between the closing price of the index and the exercise price of
the option expressed in dollars times a specified multiple. The writer of the
option is obligated, in return for the premium received, to make delivery of
this amount.
 
    RISKS OF OPTIONS ON INDEXES.  Because exercises of stock index options are
settled in cash, the Fund could not, if it wrote a call option, provide in
advance for its potential settlement obligations by acquiring and holding the
underlying securities. A call writer can offset some of the risk of its writing
position by holding a diversified portfolio of stocks similar to those on which
the underlying index is based. However, most investors cannot, as a practical
matter, acquire and hold a portfolio containing exactly the same stocks as the
underlying index, and, as a result, bear a risk that the value of the securities
held will vary from the value of the index. Even if an index call writer could
assemble a stock portfolio that exactly reproduced the composition of the
underlying index, the writer still would not be fully covered from a risk
standpoint because of the "timing risk" inherent in writing index options.
 
    When an index option is exercised, the amount of cash that the holder is
entitled to receive is determined by the difference between the exercise price
and the closing index level on the date when the option is exercised. As with
other kinds of options, the writer will not learn that it had been assigned
until the next business day, at the earliest. The time lag between exercise and
notice of assignment poses no risk for the writer of a covered call on a
specific underlying security, such as a common stock, because there the writer's
obligation is to deliver the underlying security, not to pay its value as of a
fixed time in the past. So long as the writer already owns the underlying
security, it can satisfy its settlement obligations by simply delivering it, and
the risk that its value may have declined since the exercise date is borne by
the exercising holder. In contrast, even if the writer of an index call holds
stocks that exactly match the composition of the underlying index, it will not
be able to satisfy its assignment obligations by delivering those stocks against
payment of the exercise price. Instead, it will be required to pay cash in an
amount based on the closing index value on the exercise date; and by the time it
learns that it has
 
                                       7
<PAGE>
been assigned, the index may have declined, with a corresponding decrease in the
value of its stock portfolio. This "timing risk" is an inherent limitation on
the ability of index call writers to cover their risk exposure by holding stock
positions.
 
    A holder of an index option who exercises it before the closing index value
for that day is available runs the risk that the level of the underlying index
may subsequently change. If a change causes the exercised option to fall
out-of-the-money, the exercising holder will be required to pay the difference
between the closing index value and the exercise price of the option (times the
applicable multiplier) to the assigned writer.
 
    If dissemination of the current level of an underlying index is interrupted,
or if trading is interrupted in stocks accounting for a substantial portion of
the value of an index, the trading of options on that index will ordinarily be
halted. If the trading of options on an underlying index is halted, an exchange
may impose restrictions prohibiting the exercise of such options.
 
    FUTURES CONTRACTS.  The Fund may purchase and sell interest rate, currency
and index futures contracts that are traded on U.S. and foreign commodity
exchanges on such underlying securities as U.S. Treasury bonds, notes, bills and
GNMA Certificates and/or any foreign government fixed-income security, on
various currencies and on such indexes of U.S. and foreign securities as may
exist or come into existence.
 
    A futures contract purchaser incurs an obligation to take delivery of a
specified amount of the obligation underlying the contract at a specified time
in the future for a specified price. A seller of a futures contract incurs an
obligation to deliver the specified amount of the underlying obligation at a
specified time in return for an agreed upon price. The purchase of a futures
contract enables the Fund, during the term of the contract, to lock in a price
at which it may purchase a security or currency and protect against a rise in
prices pending purchase of portfolio securities. The sale of a futures contract
enables the Fund to lock in a price at which it may sell a security or currency
and protect against declines in the value of portfolio securities.
 
    Although most futures contracts call for actual delivery or acceptance of
securities, the contracts usually are closed out before the settlement date
without the making or taking of delivery. Index futures contracts provide for
the delivery of an amount of cash equal to a specified dollar amount times the
difference between the index value at the open or close of the last trading day
of the contract and the futures contract price. A futures contract sale is
closed out by effecting a futures contract purchase for the same aggregate
amount of the specific type of security (currency) and the same delivery date.
If the sale price exceeds the offsetting purchase price, the seller would be
paid the difference and would realize a gain. If the offsetting purchase price
exceeds the sale price, the seller would pay the difference and would realize a
loss. Similarly, a futures contract purchase is closed out by effecting a
futures contract sale for the same aggregate amount of the specific type of
security (currency) and the same delivery date. If the offsetting sale price
exceeds the purchase price, the purchaser would realize a gain, whereas if the
purchase price exceeds the offsetting sale price, the purchaser would realize a
loss. There is no assurance that the Fund will be able to enter into a closing
transaction.
 
    MARGIN.  If the Fund enters into a futures contract, it is initially
required to deposit an "initial margin" of cash or U.S. Government securities or
other liquid portfolio securities ranging from approximately 2% to 5% of the
contract amount. Initial margin requirements are established by the exchanges on
which futures contracts trade and may, from time to time, change. In addition,
brokers may establish margin deposit requirements in excess of those required by
the exchanges.
 
    Initial margin in futures transactions is different from margin in
securities transactions in that initial margin does not involve the borrowing of
funds by a broker's client but is, rather, a good faith deposit on the futures
contract which will be returned to the Fund upon the proper termination of the
futures contract. The margin deposits made are marked to market daily and the
Fund may be required to make subsequent deposits of cash or U.S. Government
securities, called "variation margin," which are reflective of price
fluctuations in the futures contract.
 
                                       8
<PAGE>
    OPTIONS ON FUTURES CONTRACTS.  The Fund may purchase and write call and put
options on futures contracts and enter into closing transactions with respect to
such options to terminate an existing position. An option on a futures contract
gives the purchaser the right (in return for the premium paid), and the writer
the obligation, to assume a position in a futures contract (a long position if
the option is a call and a short position if the option is a put) at a specified
exercise price at any time during the term of the option. Upon exercise of the
option, the delivery of the futures position by the writer of the option to the
holder of the option is accompanied by delivery of the accumulated balance in
the writer's futures margin account, which represents the amount by which the
market price of the futures contract at the time of exercise exceeds, in the
case of a call, or is less than, in the case of a put, the exercise price of the
option on the futures contract.
 
    The writer of an option on a futures contract is required to deposit initial
and variation margin pursuant to requirements similar to those applicable to
futures contracts. Premiums received from the writing of an option on a futures
contract are included in initial margin deposits.
 
    LIMITATIONS ON FUTURES CONTRACTS AND OPTIONS ON FUTURES.  The Fund may not
enter into futures contracts or purchase related options thereon if, immediately
thereafter, the amount committed to margin plus the amount paid for premiums for
unexpired options on futures contracts exceeds 5% of the value of the Fund's
total assets, after taking into account unrealized gains and unrealized losses
on such contracts it has entered into, provided, however, that in the case of an
option that is in-the-money (the exercise price of the call (put) option is less
(more) than the market price of the underlying security) at the time of
purchase, the in-the-money amount may be excluded in calculating the 5%.
However, there is no overall limitation on the percentage of the Fund's net
assets which may be subject to a hedge position.
 
    RISKS OF TRANSACTIONS IN FUTURES CONTRACTS AND RELATED OPTIONS.  The prices
of securities and indexes subject to futures contracts (and thereby the futures
contract prices) may correlate imperfectly with the behavior of the cash prices
of the Fund's portfolio securities (and the currencies in which they are
denominated). Also, prices of futures contracts may not move in tandem with the
changes in prevailing interest rates, market movements and/or currency exchange
rates against which the Fund seeks a hedge. A correlation may also be distorted
(a) temporarily, by short-term traders' seeking to profit from the difference
between a contract or security price objective and their cost of borrowed funds;
(b) by investors in futures contracts electing to close out their contracts
through offsetting transactions rather than meet margin deposit requirements;
(c) by investors in futures contracts opting to make or take delivery of
underlying securities rather than engage in closing transactions, thereby
reducing liquidity of the futures market; and (d) temporarily, by speculators
who view the deposit requirements in the futures markets as less onerous than
margin requirements in the cash market. Due to the possibility of price
distortion in the futures market and because of the possible imperfect
correlation between movements in the prices of securities and movements in the
prices of futures contracts, a correct forecast of interest rate, currency
exchange rate and/or market movement trends by the Investment Manager may still
not result in a successful hedging transaction.
 
    There is no assurance that a liquid secondary market will exist for futures
contracts and related options in which the Fund may invest. In the event a
liquid market does not exist, it may not be possible to close out a futures
position and, in the event of adverse price movements, the Fund would continue
to be required to make daily cash payments of variation margin. In addition,
limitations imposed by an exchange or board of trade on which futures contracts
are traded may compel or prevent the Fund from closing out a contract which may
result in reduced gain or increased loss to the Fund. The absence of a liquid
market in futures contracts might cause the Fund to make or take delivery of the
underlying securities (currencies) at a time when it may be disadvantageous to
do so.
 
    Exchanges limit the amount by which the price of a futures contract may move
on any day. If the price moves equal the daily limit on successive days, then it
may prove impossible to liquidate a futures position until the daily limit moves
have ceased. In the event of adverse price movements, the Fund would continue to
be required to make daily cash payments of variation margin on open futures
positions. In these situations, if the Fund has insufficient cash, it may have
to sell portfolio securities to
 
                                       9
<PAGE>
meet daily variation margin requirements at a time when it may be
disadvantageous to do so. In addition, the Fund may be required to take or make
delivery of the instruments underlying interest rate futures contracts it holds
at a time when it is disadvantageous to do so. The inability to close out
options and futures positions could also have an adverse impact on the Fund's
ability to effectively hedge its portfolio.
 
    Futures contracts and options thereon which are purchased or sold on foreign
commodities exchanges may have greater price volatility than their U.S.
counterparts. Furthermore, foreign commodities exchanges may be less regulated
and under less governmental scrutiny than U.S. exchanges. Brokerage commissions,
clearing costs and other transaction costs may be higher on foreign exchanges.
Greater margin requirements may limit the Fund's ability to enter into certain
commodity transactions on foreign exchanges. Moreover, differences in clearance
and delivery requirements on foreign exchanges may occasion delays in the
settlement of the Fund's transactions effected on foreign exchanges.
 
    In the event of the bankruptcy of a broker through which the Fund engages in
transactions in futures or options thereon, the Fund could experience delays
and/or losses in liquidating open positions purchased or sold through the broker
and/or incur a loss of all or part of its margin deposits with the broker.
 
    MONEY MARKET SECURITIES.  The Fund may invest in various money market
securities for cash management purposes or when assuming a temporary defensive
position, which among others may include commercial paper, bank acceptances,
bank obligations, corporate debt securities, certificates of deposit, U.S.
Government securities, obligations of savings institutions, and repurchase
agreements. Such securities are limited to:
 
    U.S. GOVERNMENT SECURITIES.  Obligations issued or guaranteed as to
principal and interest by the United States or its agencies (such as the
Export-Import Bank of the United States, Federal Housing Administration and
Government National Mortgage Association) or its instrumentalities (such as the
Federal Home Loan Bank), including Treasury bills, notes and bonds;
 
    BANK OBLIGATIONS.  Obligations (including certificates of deposit, time
deposits and bankers' acceptances) of banks subject to regulation by the U.S.
Government and having total assets of $1 billion or more, and instruments
secured by such obligations, not including obligations of foreign branches of
domestic banks except to the extent below;
 
    EURODOLLAR CERTIFICATES OF DEPOSIT.  Eurodollar certificates of deposit
issued by foreign branches of domestic banks having total assets of $1 billion
or more;
 
    OBLIGATIONS OF SAVINGS INSTITUTIONS.  Certificates of deposit of savings
banks and savings and loan associations, having total assets of $1 billion or
more;
 
    FULLY INSURED CERTIFICATES OF DEPOSIT.  Certificates of deposit of banks and
savings institutions, having total assets of less than $1 billion, if the
principal amount of the obligation is federally insured by the Bank Insurance
Fund or the Savings Association Insurance Fund (each of which is administered by
the FDIC), limited to $100,000 principal amount per certificate and to 10% or
less of the Fund's total assets in all such obligations and in all illiquid
assets, in the aggregate; and
 
    COMMERCIAL PAPER.  Commercial paper rated within the two highest grades by
Standard & Poor's Corporation ("S&P") or the two highest grades by Moody's
Investors Service, Inc. ("Moody's") or, if not rated, issued by a company having
an outstanding debt issue rated at least AA by S&P or Aa by Moody's.
 
    REPURCHASE AGREEMENTS.  The Fund may invest in repurchase agreements. When
cash may be available for only a few days, it may be invested by the Fund in
repurchase agreements until such time as it may otherwise be invested or used
for payments of obligations of the Fund. These agreements, which may be viewed
as a type of secured lending by the Fund, typically involve the acquisition by
the Fund of debt securities from a selling financial institution such as a bank,
savings and loan association or broker-
 
                                       10
<PAGE>
dealer. The agreement provides that the Fund will sell back to the institution,
and that the institution will repurchase, the underlying security serving as
collateral at a specified price and at a fixed time in the future, usually not
more than seven days from the date of purchase. The collateral will be
marked-to-market daily to determine that the value of the collateral, as
specified in the agreement, does not decrease below the purchase price plus
accrued interest. If such decrease occurs, additional collateral will be
requested and, when received, added to the account to maintain full
collateralization. The Fund will accrue interest from the institution until the
time when the repurchase is to occur. Although this date is deemed by the Fund
to be the maturity date of a repurchase agreement, the maturities of securities
subject to repurchase agreements are not subject to any limits.
 
    While repurchase agreements involve certain risks not associated with direct
investments in debt securities, the Fund follows procedures designed to minimize
such risks. These procedures include effecting repurchase transactions only with
large, well-capitalized and well-established financial institutions whose
financial condition will be continually monitored by the Investment Manager
subject to procedures established by the Trustees. In addition, as described
above, the value of the collateral underlying the repurchase agreement will be
at least equal to the repurchase price, including any accrued interest earned on
the repurchase agreement. In the event of a default or bankruptcy by a selling
financial institution, the Fund will seek to liquidate such collateral. However,
the exercising of the Fund's right to liquidate such collateral could involve
certain costs or delays and, to the extent that proceeds from any sale upon a
default of the obligation to repurchase were less than the repurchase price, the
Fund could suffer a loss.
 
    LENDING PORTFOLIO SECURITIES.  The Fund may lend its portfolio securities in
an amount not to exceed 25% of the value of its total assets. The Fund may lend
its portfolio securities to brokers, dealers and other financial institutions,
provided that the loans are callable at any time by the Fund, and are at all
times secured by cash or cash equivalents, which are maintained in a segregated
account pursuant to applicable regulations and that are equal to at least 100%
of the market value, determined daily, of the loaned securities. The advantage
of these loans is that the Fund continues to receive the income on the loaned
securities while at the same time earning interest on the cash amounts deposited
as collateral, which will be invested in short-term obligations.
 
    As with any extensions of credit, there are risks of delay in recovery and,
in some cases, even loss of rights in the collateral should the borrower of the
securities fail financially. However, these loans of portfolio securities will
only be made to firms deemed by the Fund's management to be creditworthy and
when the income which can be earned from such loans justifies the attendant
risks. Upon termination of the loan, the borrower is required to return the
securities to the Fund. Any gain or loss in the market price during the loan
period would inure to the Fund.
 
    When voting or consent rights which accompany loaned securities pass to the
borrower, the Fund will follow the policy of calling the loaned securities, to
be delivered within one day after notice, to permit the exercise of the rights
if the matters involved would have a material effect on the Fund's investment in
the loaned securities. The Fund will pay reasonable finder's, administrative and
custodial fees in connection with a loan of its securities.
 
    WHEN-ISSUED AND DELAYED DELIVERY SECURITIES AND FORWARD COMMITMENTS.  From
time to time the Fund may purchase securities on a when-issued or delayed
delivery basis or may purchase or sell securities on a forward commitment basis.
When these transactions are negotiated, the price is fixed at the time of the
commitment, but delivery and payment can take place a month or more after the
date of commitment. While the Fund will only purchase securities on a
when-issued, delayed delivery or forward commitment basis with the intention of
acquiring the securities, the Fund may sell the securities before the settlement
date, if it is deemed advisable. The securities so purchased or sold are subject
to market fluctuation and no interest or dividends accrue to the purchaser prior
to the settlement date.
 
                                       11
<PAGE>
    At the time the Fund makes the commitment to purchase or sell securities on
a when-issued, delayed delivery or forward commitment basis, it will record the
transaction and thereafter reflect the value, each day, of such security
purchased, or if a sale, the proceeds to be received, in determining its net
asset value. At the time of delivery of the securities, their value may be more
or less than the purchase or sale price. An increase in the percentage of the
Fund's assets committed to the purchase of securities on a when-issued, delayed
delivery or forward commitment basis may increase the volatility of its net
asset value. The Fund will also establish a segregated account on the Fund's
books in which it will continually maintain cash or cash equivalents or other
liquid portfolio securities equal in value to commitments to purchase securities
on a when-issued, delayed delivery or forward commitment basis.
 
    WHEN, AS AND IF ISSUED SECURITIES.  The Fund may purchase securities on a
"when, as and if issued" basis under which the issuance of the security depends
upon the occurrence of a subsequent event, such as approval of a merger,
corporate reorganization or debt restructuring. The commitment for the purchase
of any such security will not be recognized in the portfolio of the Fund until
the Investment Manager determines that issuance of the security is probable. At
that time, the Fund will record the transaction and, in determining its net
asset value, will reflect the value of the security daily. At that time, the
Fund will also establish a segregated account on the Fund's books in which it
will maintain cash or cash equivalents or other liquid portfolio securities
equal in value to recognized commitments for such securities.
 
    The value of the Fund's commitments to purchase the securities of any one
issuer, together with the value of all securities of such issuer owned by the
Fund, may not exceed 5% of the value of the Fund's total assets at the time the
initial commitment to purchase such securities is made. An increase in the
percentage of the Fund's assets committed to the purchase of securities on a
"when, as and if issued" basis may increase the volatility of its net asset
value. The Fund may also sell securities on a "when, as and if issued" basis
provided that the issuance of the security will result automatically from the
exchange or conversion of a security owned by the Fund at the time of sale.
 
    PRIVATE PLACEMENTS.  The Fund may invest up to 10% of its total assets in
securities which are subject to restrictions on resale because they have not
been registered under the Securities Act of 1933 (the "Securities Act"), or
which are otherwise not readily marketable. (Securities eligible for resale
pursuant to Rule 144A under the Securities Act, and determined to be liquid
pursuant to the procedures discussed in the following paragraph, are not subject
to the foregoing restriction.) These securities are generally referred to as
private placements or restricted securities. Limitations on the resale of these
securities may have an adverse effect on their marketability, and may prevent
the Fund from disposing of them promptly at reasonable prices. The Fund may have
to bear the expense of registering the securities for resale and the risk of
substantial delays in effecting the registration.
 
    Rule 144A permits the Fund to sell restricted securities to qualified
institutional buyers without limitation. The Investment Manager, pursuant to
procedures adopted by the Trustees, will make a determination as to the
liquidity of each restricted security purchased by the Fund. If a restricted
security is determined to be "liquid," the security will not be included within
the category "illiquid securities," which under current policy may not exceed
10% of the Fund's total assets. However, investing in Rule 144A securities could
have the effect of increasing the level of Fund illiquidity to the extent the
Fund, at a particular point in time, may be unable to find qualified
institutional buyers interested in purchasing such securities.
 
    WARRANTS AND SUBSCRIPTION RIGHTS.  The Fund may acquire warrants and
subscription rights attached to other securities. A warrant is, in effect, an
option to purchase equity securities at a specific price, generally valid for a
specific period of time, and has no voting rights, pays no dividends and has no
rights with respect to the corporation issuing it.
 
    A subscription right is a privilege granted to existing shareholders of a
corporation to subscribe to shares of a new issue of common stock before it is
offered to the public. A subscription right normally has a life of two to four
weeks and a subscription price lower than the current market value of the common
stock. A subscription right is freely transferable.
 
    YEAR 2000.  The investment management services provided to the Fund by the
Investment Manager and the services provided to shareholders by the Distributor
and the Transfer Agent depend on the
 
                                       12
<PAGE>
smooth functioning of their computer systems. Many computer software systems in
use today cannot recognize the year 2000, but revert to 1900 or some other date,
due to the manner in which dates were encoded and calculated. That failure could
have a negative impact on the handling of securities trades, pricing and account
services. The Investment Manager, the Distributor and the Transfer Agent have
been actively working on necessary changes to their own computer systems to
prepare for the year 2000 and expect that their systems will be adapted before
that date, but there can be no assurance that they will be successful, or that
interaction with other non-complying computer systems will not impair their
services at that time.
 
    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. In
addition, 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 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.
 
C. FUND POLICIES/INVESTMENT RESTRICTIONS
 
    The investment objective, policies and restrictions listed below have been
adopted by the Fund as fundamental policies. Under the Investment Company Act of
1940 (the "Investment Company Act"), a fundamental policy may not be changed
without the vote of a majority of the outstanding voting securities of the Fund.
The Investment Company Act defines a majority as the lesser of (a) 67% or more
of the shares present at a meeting of shareholders, if the holders of 50% of the
outstanding shares of the Fund are present or represented by proxy; or (b) more
than 50% of the outstanding shares of the Fund. For purposes of the following
restrictions: (i) all percentage limitations apply immediately after a purchase
or initial investment; and (ii) any subsequent change in any applicable
percentage resulting from market fluctuations or other changes in total or net
assets does not require elimination of any security from the portfolio.
 
    The Fund will:
 
         1.  Seek long-term capital appreciation.
 
    The Fund may not:
 
         1.  With respect to 75% of its total assets, invest more than 5% of the
    value of its total assets in the securities of any one issuer (other than
    obligations issued, or guaranteed by, the United States Government, its
    agencies or instrumentalities).
 
         2.  Purchase more than 10% of all outstanding voting securities or any
    class of securities of any one issuer.
 
         3.  Invest in warrants (other than warrants acquired by the Fund as
    part of a unit or attached to securities at the time of purchase) if, as a
    result, the investments would exceed 5% of the value of the Fund's total
    assets of which not more than 2% of the Fund's total assets may be invested
    in warrants not listed on the New York or American Stock Exchange or a
    recognized foreign stock exchange.
 
         4.  Invest in securities of any issuer if, to the knowledge of the
    Fund, any officer or trustee of the Fund or of the Investment Manager owns
    more than 1/2 of 1% of the outstanding securities of the issuer, and the
    officers and trustees who own more than 1/2 of 1% own in the aggregate more
    than 5% of the outstanding securities of the issuer.
 
         5.  Purchase or sell real estate or interests therein, although the
    Fund may purchase securities of issuers which engage in real estate
    operations and securities secured by real estate or interests therein.
 
         6.  Purchase or sell commodities (other than precious metals or
    minerals commodities or contracts), except the Fund may purchase or sell
    (write) futures and related options thereon.
 
                                       13
<PAGE>
         7.  Borrow money, except that the Fund may borrow from a bank for
    temporary or emergency purposes in amounts not exceeding 5% of its total
    assets (not including the amount borrowed).
 
         8.  Pledge its assets or assign or otherwise encumber them, except to
    secure permitted borrowings. For the purpose of this restriction, collateral
    arrangements with respect to the writing of options and collateral
    arrangements with respect to initial or variation margin for futures are not
    deemed to be pledges of assets.
 
         9.  Issue senior securities as defined in the Investment Company Act,
    except insofar as the Fund may be deemed to have issued a senior security by
    reason of (a) entering into any repurchase agreement; (b) purchasing any
    securities on a when-issued or delayed delivery basis; (c) purchasing or
    selling futures contracts, forward foreign exchange contracts or options;
    (d) borrowing money; or (e) lending portfolio securities.
 
        10.  Make loans of money or securities, except: (a) by the purchase of
    publicly distributed debt obligations; (b) by investment in repurchase
    agreements; or (c) by lending its portfolio securities.
 
        11.  Make short sales of securities.
 
        12.  Purchase securities on margin, except for the short-term loans as
    are necessary for the clearance of portfolio securities. The deposit or
    payment by the Fund of initial or variation margin in connection with
    futures contracts or related options thereon is not considered the purchase
    of a security on margin.
 
        13.  Engage in the underwriting of securities, except insofar as the
    Fund may be deemed an underwriter under the Securities Act in disposing of a
    portfolio security.
 
        14.  Invest for the purpose of exercising control or management of any
    other issuer.
 
        15.  Invest more than 10% of its total assets in "illiquid securities"
    (securities for which market quotations are not readily available) and
    repurchase agreements which have a maturity of longer than seven days.
 
        16.  Invest more than 5% of the value of its total assets in securities
    of issuers having a record, together with predecessors, of less than 3 years
    of continuous operation. This restriction shall not apply to any obligation
    of the United States Government, its agencies or instrumentalities.
 
        17.  Purchase securities of other investment companies, except in
    connection with a merger, consolidation, reorganization or acquisition of
    assets or, by purchase in the open market of securities of closed-end
    investment companies where no underwriter's or dealer's commission or
    profit, other than customary broker's commissions, is involved and only if
    immediately thereafter not more than 10% of the Fund's total assets would be
    invested in such securities.
 
    If a percentage restriction is adhered to at the time of investment, a later
increase or decrease in percentage resulting from a change in values of
portfolio securities or amount of total or net assets will not be considered a
violation of any of the foregoing restrictions.
 
    Notwithstanding any other investment policy or restriction, the Fund may
seek to achieve its investment objective by investing all or substantially all
of its assets in another investment company having substantially the same
investment objective and policies as the Fund.
 
III. MANAGEMENT OF THE FUND
- --------------------------------------------------------------------------------
 
A. BOARD OF TRUSTEES
 
    The Board of Trustees of the Fund oversees the management of the Fund but
does not itself manage the Fund. The Trustees review various services provided
by or under the direction of the Investment Manager to ensure that the Fund's
general investment policies and programs are properly carried out. The Trustees
also conduct their review to ensure that administrative services are provided to
the Fund in a satisfactory manner.
 
                                       14
<PAGE>
    Under state law, the duties of the Trustees are generally characterized as a
duty of loyalty and a duty of care. The duty of loyalty requires a Trustee to
exercise his or her powers in the interest of the Fund and not the Trustee's own
interest or the interest of another person or organization. A Trustee satisfies
his or her duty of care by acting in good faith with the care of an ordinarily
prudent person and in a manner the Trustee reasonably believes to be in the best
interest of the Fund and its shareholders.
 
B. MANAGEMENT INFORMATION
 
    TRUSTEES AND OFFICERS.  The Board of the Fund consists of nine (9) Trustees.
These same individuals also serve as directors or trustees for all of the Morgan
Stanley Dean Witter Funds. Seven Trustees (77% of the total number) have no
affiliation or business connection with the Investment Manager or any of its
affiliated persons and do not own any stock or other securities issued by the
Investment Manager's parent company, MSDW. These are the "non-interested" or
"independent" Trustees. The other two Trustees (the "management Trustees") are
affiliated with the Investment Manager. All of the Independent Trustees also
serve as Independent Trustees of "Discover Brokerage Index Series," a mutual
fund for which the Investment Manager is the investment advisor. Four of the
seven Independent Trustees are also Independent Trustees of certain other mutual
funds, referred to as the "TCW/DW Funds," for which MSDW Services Company is the
manager and TCW Funds Management, Inc. is the investment advisor.
 
    The Trustees and executive officers of the Fund, their principal business
occupations during the last five years and their affiliations, if any, with the
Investment Manager, and with the 84 Morgan Stanley Dean Witter Funds, the 11
TCW/DW Funds and Discover Brokerage Index Series, are shown below.
 
<TABLE>
<CAPTION>
      NAME, AGE, POSITION WITH FUND AND ADDRESS                PRINCIPAL OCCUPATIONS DURING LAST FIVE YEARS
- ------------------------------------------------------  ----------------------------------------------------------
<S>                                                     <C>
Michael Bozic (58) ...................................  Vice Chairman of Kmart Corporation (since December, 1998);
Trustee                                                 Director or Trustee of the Morgan Stanley Dean Witter
c/o Kmart Corporation                                   Funds; Trustee of Discover Brokerage Index Series;
3100 West Big Beaver Road                               formerly Chairman and Chief Executive Officer of Levitz
Troy, Michigan                                          Furniture Corporation (November, 1995-November, 1998) and
                                                        President and Chief Executive Officer of Hills Department
                                                        Stores (May, 1991-July, 1995); formerly variously
                                                        Chairman, Chief Executive Officer, President and Chief
                                                        Operating Officer (1987-1991) of the Sears Merchandise
                                                        Group of Sears, Roebuck and Co.; Director of Eaglemark
                                                        Financial Services, Inc. and Weirton Steel Corporation.
 
Charles A. Fiumefreddo* (65) .........................  Chairman, Director or Trustee, President and Chief
Chairman of the Board, President,                       Executive Officer of the Morgan Stanley Dean Witter Funds;
Chief Executive Officer and Trustee                     Chairman, Chief Executive Officer and Trustee of the
Two World Trade Center                                  TCW/DW Funds; Trustee of Discover Brokerage Index Series;
New York, New York                                      formerly Chairman, Chief Executive Officer and Director of
                                                        the Investment Manager, the Distributor and MSDW Services
                                                        Company; Executive Vice President and Director of Dean
                                                        Witter Reynolds; Chairman and Director of the Transfer
                                                        Agent; formerly Director and/or officer of various MSDW
                                                        subsidiaries (until June 1998).
</TABLE>
 
                                       15
<PAGE>
<TABLE>
<CAPTION>
      NAME, AGE, POSITION WITH FUND AND ADDRESS                PRINCIPAL OCCUPATIONS DURING LAST FIVE YEARS
- ------------------------------------------------------  ----------------------------------------------------------
<S>                                                     <C>
Edwin J. Garn (66) ...................................  Director or Trustee of the Morgan Stanley Dean Witter
Trustee                                                 Funds; Trustee of Discover Brokerage Index Series;
c/o Huntsman Corporation                                formerly United States Senator (R- Utah)(1974-1992) and
500 Huntsman Way                                        Chairman, Senate Banking Committee (1980-1986); formerly
Salt Lake City, Utah                                    Mayor of Salt Lake City, Utah (1971-1974); formerly
                                                        Astronaut, Space Shuttle Discovery (April 12-19, 1985);
                                                        Vice Chairman, Huntsman Corporation; Director of Franklin
                                                        Covey (time management systems), John Alden Financial
                                                        Corp. (health insurance), United Space Alliance (joint
                                                        venture between Lockheed Martin and the Boeing Company)
                                                        and Nuskin Asia Pacific (multilevel marketing); member of
                                                        the board of various civic and charitable organizations.
 
John R. Haire (74) ...................................  Chairman of the Audit Committee and Director or Trustee of
Trustee                                                 the Morgan Stanley Dean Witter Funds; Chairman of the
Two World Trade Center                                  Audit Committee and Trustee of the TCW/DW Funds; Chairman
New York, New York                                      of the Audit Committee and Trustee of Discover Brokerage
                                                        Index Series; formerly Chairman of the Independent
                                                        Directors or Trustees of the Morgan Stanley Dean Witter
                                                        Funds and the TCW/DW Funds (until June, 1998); formerly
                                                        President, Council for Aid to Education (1978-1989) and
                                                        Chairman and Chief Executive Officer of Anchor
                                                        Corporation, an investment advisor (1964-1978).
 
Wayne E. Hedien (65) .................................  Retired; Director or Trustee of the Morgan Stanley Dean
Trustee                                                 Witter Funds; Trustee of Discover Brokerage Index Series;
c/o Gordon Altman Butowsky                              Director of The PMI Group, Inc. (private mortgage
Weitzen Shalov & Wein                                   insurance); Trustee and Vice Chairman of The Field Museum
Counsel to the Independent Trustees                     of Natural History; formerly associated with the Allstate
114 West 47th Street                                    Companies (1966-1994), most recently as Chairman of The
New York, New York                                      Allstate Corporation (March, 1993-December, 1994) and
                                                        Chairman and Chief Executive Officer of its wholly-owned
                                                        subsidiary, Allstate Insurance Company (July,
                                                        1989-December, 1994); director of various other business
                                                        and charitable organizations.
 
Dr. Manuel H. Johnson (50) ...........................  Senior Partner, Johnson Smick International, Inc., a
Trustee                                                 consulting firm; Co-Chairman and a founder of the Group of
c/o Johnson Smick International, Inc.                   Seven Council (G7C), an international economic commission;
1133 Connecticut Avenue, N.W.                           Director or Trustee of the Morgan Stanley Dean Witter
Washington, D.C.                                        Funds; Trustee of the TCW/ DW Funds; Trustee of Discover
                                                        Brokerage Index Series; Director of NASDAQ (since June,
                                                        1995); Director of Greenwich Capital Markets, Inc.
                                                        (broker-dealer) and NVR, Inc. (home construction); Chair-
                                                        man and Trustee of the Financial Accounting Foundation
                                                        (oversight organization of the Financial Accounting
                                                        Standards Board); formerly Vice Chairman of the Board of
                                                        Governors of the Federal Reserve System (1986-1990) and
                                                        Assistant Secretary of the U.S. Treasury.
</TABLE>
 
                                       16
<PAGE>
<TABLE>
<CAPTION>
      NAME, AGE, POSITION WITH FUND AND ADDRESS                PRINCIPAL OCCUPATIONS DURING LAST FIVE YEARS
- ------------------------------------------------------  ----------------------------------------------------------
<S>                                                     <C>
Michael E. Nugent (62) ...............................  General Partner, Triumph Capital, L.P., a private
Trustee                                                 investment partnership; Director or Trustee of the Morgan
c/o Triumph Capital, L.P.                               Stanley Dean Witter Funds; Trustee of the TCW/DW Funds;
237 Park Avenue                                         Trustee of Discover Brokerage Index Series; formerly Vice
New York, New York                                      President, Bankers Trust Company and BT Capital
                                                        Corporation (1984-1988); director of various business
                                                        organizations.
 
Philip J. Purcell* (55) ..............................  Chairman of the Board of Directors and Chief Executive
Trustee                                                 Officer of MSDW, Dean Witter Reynolds and Novus Credit
1585 Broadway                                           Services Inc.; Director of the Distributor; Director or
New York, New York                                      Trustee of the Morgan Stanley Dean Witter Funds; Trustee
                                                        of Discover Brokerage Index Series; Director and/or
                                                        officer of various MSDW subsidiaries.
 
John L. Schroeder (68) ...............................  Retired; Director or Trustee of the Morgan Stanley Dean
Trustee                                                 Witter Funds; Trustee of the TCW/DW Funds; Trustee of
c/o Gordon Altman Butowsky                              Discover Brokerage Index Series; Director of Citizens
Weitzen Shalov & Wein                                   Utilities Company; formerly Executive Vice President and
Counsel to the Independent Trustees                     Chief Investment Officer of the Home Insurance Company
114 West 47th Street                                    (August, 1991-September, 1995).
New York, New York
 
Barry Fink (44) ......................................  Senior Vice President (since March, 1997) and Secretary
Vice President,                                         and General Counsel (since February, 1997) and Director
Secretary and General Counsel                           (since July, 1998) of the Investment Manager and MSDW
Two World Trade Center                                  Services Company; Senior Vice President (since March,
New York, New York                                      1997) and Assistant Secretary and Assistant General
                                                        Counsel (since February, 1997) of the Distributor;
                                                        Assistant Secretary of Dean Witter Reynolds (since August,
                                                        1996); Vice President, Secretary and General Counsel of
                                                        the Morgan Stanley Dean Witter Funds and the TCW/DW Funds
                                                        (since February, 1997); Vice President, Secretary and
                                                        General Counsel of Discover Brokerage Index Series;
                                                        previously First Vice President (June, 1993-February,
                                                        1997), Vice President and Assistant Secretary and
                                                        Assistant General Counsel of the Investment Manager and
                                                        MSDW Services Company and Assistant Secretary of the Mor-
                                                        gan Stanley Dean Witter Funds and the TCW/DW Funds.
 
Robert Rossetti (51) .................................  Vice President of the Investment Manager (since May,
Vice President                                          1995); formerly Vice President at Merrill Lynch & Co. Inc.
Two World Trade Center                                  (November, 1994-April, 1995) and prior thereto Vice
New York, New York                                      President at Prudential Securities for six years.
</TABLE>
 
                                       17
<PAGE>
<TABLE>
<CAPTION>
      NAME, AGE, POSITION WITH FUND AND ADDRESS                PRINCIPAL OCCUPATIONS DURING LAST FIVE YEARS
- ------------------------------------------------------  ----------------------------------------------------------
<S>                                                     <C>
Thomas F. Caloia (52) ................................  First Vice President and Assistant Treasurer of the
Treasurer                                               Investment Manager and MSDW Services Company; Treasurer of
Two World Trade Center                                  the Morgan Stanley Dean Witter Funds, the TCW/DW Funds and
New York, New York                                      Discover Brokerage Index Series.
</TABLE>
 
- ------------------------
*Denotes Trustees who are "interested persons" of the Fund as defined by the
Investment Company Act.
 
    In addition, MITCHELL M. MERIN, President, and Chief Operating Officer of
Asset Management of MSDW, President, Chief Executive Officer and Director of the
Investment Manager and MSDW Services Company, Chairman and Director of the
Distributor and the Transfer Agent, Executive Vice President and Director of
DWR, and Director of various MSDW subsidiaries, RONALD E. ROBISON, Executive
Vice President, Chief Administrative Officer and Director of the Investment
Manager and MSDW Services Company, ROBERT S. GIAMBRONE, Senior Vice President of
the Investment Manager, MSDW Services Company, the Distributor and the Transfer
Agent and Director of the Transfer Agent, and JOSEPH J. MCALINDEN, Executive
Vice President and Chief Investment Officer of the Investment Manager and
Director of the Transfer Agent, and MARK BAVOSO, IRA N. ROSS and PAUL D. VANCE,
Senior Vice Presidents of the Investment Manager are Vice Presidents of the
Fund.
 
    In addition, FRANK BRUTTOMESSO, MARILYN K. CRANNEY, LOU ANNE D. MCINNIS,
CARSTEN OTTO and RUTH ROSSI, First Vice Presidents and Assistant General
Counsels of the Investment Manager and MSDW Services Company, and TODD LEBO,
Vice President and Assistant General Counsel of the Investment Manager and MSDW
Services Company, are Assistant Secretaries of the Fund.
 
    INDEPENDENT TRUSTEES AND THE COMMITTEES.  Law and regulation establish both
general guidelines and specific duties for the Independent Trustees. The Morgan
Stanley Dean Witter Funds seek as Independent Trustees individuals of
distinction and experience in business and finance, government service or
academia; these are people whose advice and counsel are in demand by others and
for whom there is often competition. To accept a position on the Funds' Boards,
such individuals may reject other attractive assignments because the Funds make
substantial demands on their time. Indeed, by serving on the Funds' Boards,
certain Trustees who would otherwise be qualified and in demand to serve on bank
boards would be prohibited by law from doing so. All of the Independent Trustees
serve as members of the Audit Committee. Three of them also serve as members of
the Derivatives Committee. In addition, three of the Trustees, including two
Independent Trustees, serve as members of the Insurance Committee.
 
    The Independent Trustees are charged with recommending to the full Board
approval of management, advisory and administration contracts, Rule 12b-1 plans
and distribution and underwriting agreements; continually reviewing Fund
performance; checking on the pricing of portfolio securities, brokerage
commissions, transfer agent costs and performance, and trading among Funds in
the same complex; and approving fidelity bond and related insurance coverage and
allocations, as well as other matters that arise from time to time. The
Independent Trustees are required to select and nominate individuals to fill any
Independent Trustee vacancy on the Board of any Fund that has a Rule 12b-1 plan
of distribution. Most of the Morgan Stanley Dean Witter Funds have a Rule 12b-1
plan.
 
    The Audit Committee is charged with recommending to the full Board the
engagement or discharge of the Fund's independent accountants; directing
investigations into matters within the scope of the independent accountants'
duties, including the power to retain outside specialists; reviewing with the
independent accountants the audit plan and results of the auditing engagement;
approving professional services provided by the independent accountants and
other accounting firms prior to the performance of the services; reviewing the
independence of the independent accountants; considering the range of audit and
non-audit fees; reviewing the adequacy of the Fund's system of internal
controls; and preparing and submitting Committee meeting minutes to the full
Board.
 
                                       18
<PAGE>
    The Board of each Fund has a Derivatives Committee to approve parameters for
and monitor the activities of the Fund with respect to derivative investments,
if any, made by the Fund.
 
    Finally, the Board of each Fund has formed an Insurance Committee to review
and monitor the insurance coverage maintained by the Fund.
 
    ADVANTAGES OF HAVING SAME INDIVIDUALS AS INDEPENDENT TRUSTEES FOR ALL MORGAN
STANLEY DEAN WITTER FUNDS.  The Independent Trustees and the Funds' management
believe that having the same Independent Trustees for each of the Morgan Stanley
Dean Witter Funds avoids the duplication of effort that would arise from having
different groups of individuals serving as Independent Trustees for each of the
Funds or even of sub-groups of Funds. They believe that having the same
individuals serve as Independent Trustees of all the Funds tends to increase
their knowledge and expertise regarding matters which affect the Fund complex
generally and enhances their ability to negotiate on behalf of each Fund with
the Fund's service providers. This arrangement also precludes the possibility of
separate groups of Independent Trustees arriving at conflicting decisions
regarding operations and management of the Funds and avoids the cost and
confusion that would likely ensue. Finally, having the same Independent Trustees
serve on all Fund Boards enhances the ability of each Fund to obtain, at modest
cost to each separate Fund, the services of Independent Trustees, of the
caliber, experience and business acumen of the individuals who serve as
Independent Trustees of the Morgan Stanley Dean Witter Funds.
 
    TRUSTEE AND OFFICER INDEMNIFICATION.  The Fund's Declaration of Trust
provides that no Trustee, officer, employee or agent of the Fund is liable to
the Fund or to a shareholder, nor is any Trustee, officer, employee or agent
liable to any third persons in connection with the affairs of the Fund, except
as such liability may arise from his/her or its own bad faith, willful
misfeasance, gross negligence or reckless disregard of his/her or its duties. It
also provides that all third persons shall look solely to the Fund property for
satisfaction of claims arising in connection with the affairs of the Fund. With
the exceptions stated, the Declaration of Trust provides that a Trustee,
officer, employee or agent is entitled to be indemnified against all liability
in connection with the affairs of the Fund.
 
C. COMPENSATION
 
    The Fund pays each Independent Trustee an annual fee of $800 plus a per
meeting fee of $50 for meetings of the Board of Trustees, the Independent
Trustees or Committees of the Board of Trustees attended by the Trustee (the
Fund pays the Chairman of the Audit Committee an additional annual fee of $750).
If a Board meeting and a meeting of the Independent Trustees or a Committee
meeting, or a meeting of the Independent Trustees and/or more than one Committee
meeting, take place on a single day, the Trustees are paid a single meeting fee
by the Fund. The Fund also reimburses such Trustees for travel and other
out-of-pocket expenses incurred by them in connection with attending such
meetings. Trustees and officers of the Fund who are or have been employed by the
Investment Manager or an affiliated company receive no compensation or expenses
reimbursed from the Fund for their services as Trustee. Mr. Haire currently
serves as Chairman of the Audit Committee. Prior to June 1, 1998, Mr. Haire also
served as Chairman of the Independent Trustees for which services the Fund paid
him an additional annual fee of $1,200.
 
    The following table illustrates the compensation that the Fund paid to its
Independent Trustees for the fiscal year ended October 31, 1998.
 
                               FUND COMPENSATION
 
<TABLE>
<CAPTION>
                                                                   AGGREGATE
                                                                 COMPENSATION
NAME OF INDEPENDENT TRUSTEE                                      FROM THE FUND
- --------------------------------------------------------------  ---------------
<S>                                                             <C>
Michael Bozic.................................................      $1,450
Edwin J. Garn.................................................       1,600
John R. Haire.................................................       2,850
Wayne E. Hedien...............................................       1,550
Dr. Manuel H. Johnson.........................................       1,550
Michael E. Nugent.............................................       1,600
John L. Schroeder.............................................       1,600
</TABLE>
 
                                       19
<PAGE>
    The following table illustrates the compensation paid to the Fund's
Independent Trustees for the calendar year ended December 31, 1998 for services
to the 85 Morgan Stanley Dean Witter Funds and, in the case of Messrs. Haire,
Johnson, Nugent and Schroeder, the 11 TCW/DW Funds that were in operation at
December 31, 1998. Mr. Haire serves as Chairman of the Audit Committee of each
Morgan Stanley Dean Witter Fund and each TCW/DW Fund and, prior to June 1, 1998,
also served as Chairman of the Independent Directors or Trustees of those Funds.
With respect to Messrs. Haire, Johnson, Nugent and Schroeder, the TCW/DW Funds
are included solely because of a limited exchange privilege between those Funds
and five Morgan Stanley Dean Witter Money Market Funds. No compensation was paid
to the Fund's Independent Trustees by Discover Brokerage Index Series for the
calendar year ended December 31, 1998.
 
    CASH COMPENSATION FROM MORGAN STANLEY DEAN WITTER FUNDS AND TCW/DW FUNDS
 
<TABLE>
<CAPTION>
                                                                   FOR SERVICE AS
                                                                    CHAIRMAN OF                      TOTAL CASH
                                                                    INDEPENDENT      FOR SERVICE    COMPENSATION
                               FOR SERVICE                           DIRECTORS/          AS         FOR SERVICES
                              AS DIRECTOR OR                        TRUSTEES AND     CHAIRMAN OF         TO
                               TRUSTEE AND                             AUDIT         INDEPENDENT      85 MORGAN
                             COMMITTEE MEMBER    FOR SERVICE AS    COMMITTEES OF    TRUSTEES AND       STANLEY
                               OF 85 MORGAN       TRUSTEE AND        85 MORGAN          AUDIT        DEAN WITTER
                                 STANLEY        COMMITTEE MEMBER      STANLEY       COMMITTEES OF     FUNDS AND
NAME OF                        DEAN WITTER        OF 11 TCW/DW      DEAN WITTER       11 TCW/DW       11 TCW/DW
INDEPENDENT TRUSTEE               FUNDS              FUNDS             FUNDS            FUNDS           FUNDS
- ---------------------------  ----------------   ----------------   --------------   -------------   -------------
<S>                          <C>                <C>                <C>              <C>             <C>
Michael Bozic..............      $120,150           --                 --               --            $$120,150
Edwin J. Garn..............       132,450           --                 --               --             132,450
John R. Haire..............       136,450           $66,931           $161,338        $ 14,725         319,444
Wayne E. Hedien............       132,350           --                 --               --             132,350
Dr. Manuel H. Johnson......       128,400            62,331            --               --             190,731
Michael E. Nugent..........       132,450            62,131            --               --             194,581
John L. Schroeder..........       132,450            64,731            --               --             197,181
</TABLE>
 
    As of the date of this STATEMENT OF ADDITIONAL INFORMATION, 55 of the Morgan
Stanley Dean Witter Funds, not including the Fund, have adopted a retirement
program under which an Independent Trustee who retires after serving for at
least five years (or such lesser period as may be determined by the Board) as an
Independent Director or Trustee of any Morgan Stanley Dean Witter Fund that has
adopted the retirement program (each such Fund referred to as an "Adopting Fund"
and each such Trustee referred to as an "Eligible Trustee") is entitled to
retirement payments upon reaching the eligible retirement age (normally, after
attaining age 72). Annual payments are based upon length of service.
 
    Currently, upon retirement, each Eligible Trustee is entitled to receive
from the Adopting Fund, commencing as of his or her retirement date and
continuing for the remainder of his or her life, an annual retirement benefit
(the "Regular Benefit") equal to 30.22% of his or her Eligible Compensation plus
0.5036667% of such Eligible Compensation for each full month of service as an
Independent Director or Trustee of any Adopting Fund in excess of five years up
to a maximum of 60.44% after ten years of service. The foregoing percentages may
be changed by the Board.(1) "Eligible Compensation" is one-fifth of the total
compensation earned by such Eligible Trustee for service to the Adopting Fund in
the five year period prior to the date of the Eligible Trustee's retirement.
Benefits under the retirement program are not secured or funded by the Adopting
Funds.
 
- ------------------------
1    An Eligible Trustee may elect alternative payments of his or her retirement
     benefits based upon the combined life expectancy of the Eligible Trustee
     and his or her spouse on the date of such Eligible Trustee's retirement. In
     addition, the Eligible Trustee may elect that the surviving spouse's
     periodic payment of benefits will be equal to a lower percentage of the
     periodic amount when both spouses were alive. The amount estimated to be
     payable under this method, through the remainder of the later of the lives
     of the Eligible Trustee and spouse, will be the actuarial equivalent of the
     Regular Benefit.
 
                                       20
<PAGE>
    The following table illustrates the retirement benefits accrued to the
Fund's Independent Trustees by the 55 Morgan Stanley Dean Witter Funds (not
including the Fund) for the fiscal year ended December 31, 1998, and the
estimated retirement benefits for the Independent Trustees, to commence upon
their retirement, from the 55 Morgan Stanley Dean Witter Funds as of December
31, 1998.
 
         RETIREMENT BENEFITS FROM THE MORGAN STANLEY DEAN WITTER FUNDS
 
   
<TABLE>
<CAPTION>
                                                                                                           ESTIMATED
                                                             FOR ALL ADOPTING FUNDS          RETIREMENT     ANNUAL
                                                        ---------------------------------     BENEFITS     BENEFITS
                                                           ESTIMATED                         ACCRUED AS      UPON
                                                        CREDITED YEARS       ESTIMATED        EXPENSES     RETIREMENT
                                                         OF SERVICE AT     PERCENTAGE OF       BY ALL      FROM ALL
                                                          RETIREMENT         ELIGIBLE         ADOPTING     ADOPTING
NAME OF INDEPENDENT TRUSTEE                              (MAXIMUM 10)      COMPENSATION        FUNDS       FUNDS(2)
- ------------------------------------------------------  ---------------   ---------------   ------------   --------
<S>                                                     <C>               <C>               <C>            <C>
Michael Bozic.........................................          10             60.44%       $ 22,377       $52,250
Edwin J. Garn.........................................          10             60.44          35,225        52,250
John R. Haire.........................................          10             60.44         (12,211)(3)   134,705
Wayne E. Hedien.......................................           9             51.37          41,979        44,413
Dr. Manuel H. Johnson.................................          10             60.44          14,047        52,250
Michael E. Nugent.....................................          10             60.44          25,336        52,250
John L. Schroeder.....................................           8             50.37          45,117        44,343
</TABLE>
    
 
- ------------------------
2    Based on current levels of compensation. Amount of annual benefits also
     varies depending on the Trustee's elections described in Footnote (1)
     above.
 
3    This number reflects the effect of the extension of Mr. Haire's term as
     Director or Trustee until May 1, 1999.
 
IV. CONTROL PERSONS AND PRINCIPAL HOLDERS OF SECURITIES
- --------------------------------------------------------------------------------
 
   
    The following owned 5% or more of the outstanding shares of Class A on
February 9, 1999: Peter Manhard and Lynn Manhard JTWROS, 634 Williams Way,
Vernon Hills, IL 60061-3252--10.22%; Dean Witter Reynolds, custodian for William
D. Hill, FBO Pooled account, VIP Plus profit sharing DTD 1/1/96, 232 Forest
Road, Hurricane, WV 25526-9341--53.1. The following owned 5% or more of the
outstanding shares of Class C on February 9, 1999: Alan J. Stransky and Colleen
R. Stransky JTWROS, 11679 Valleybrook Place, Carmel, IN 46033-3374--14.96%; Dean
Witter Reynolds, custodian for Griffith L. Thomas, FBO Griffith L. Thomas, money
purchase plan DTD 6/26/85, PO Box 642, Tillamook, OR 97141-0642--8.91%;
Elizabeth F. Sheppard, 311 Park Avenue S, Winter Park FL 32789-4317--7.41%. The
following owned 5% or more of the outstanding shares of Class D on February 9,
1999: Morgan Stanley Dean Witter Advisors Inc., Attn: Maurice Bendrihem, 2 World
Trade Center 73rd Fl., New York, NY 10048-0203; Hare & Co., c/o The Bank of New
York, PO Box 11203, New York, NY 10286-1203--37.05%; Yolanda R. Bertoli TTEE,
Yolanda R. Bertoli Revocable Living Trust dated 6/9/94, 1025 Wilder Ave #5-B,
Honolulu, HI 96822-2629--57.48.
    
 
    As of the date of this STATEMENT OF ADDITIONAL INFORMATION, the aggregate
number of shares of beneficial interest of the Fund owned by the Fund's officers
and Trustees as a group was less than 1% of the Fund's shares of beneficial
interest outstanding.
 
V. INVESTMENT MANAGEMENT AND OTHER SERVICES
- --------------------------------------------------------------------------------
 
A. INVESTMENT MANAGER
 
    The Investment Manager to the Fund is Morgan Stanley Dean Witter Advisors
Inc., a Delaware corporation, whose address is Two World Trade Center, New York,
New York 10048. The Investment Manager is a wholly-owned subsidiary of MSDW, a
Delaware corporation. MSDW is a preeminent global financial services firm that
maintains leading market positions in each of its three primary businesses:
securities, asset management and credit services.
 
                                       21
<PAGE>
    Pursuant to an Investment Management Agreement (the "Management Agreement")
with the Investment Manager, the Fund has retained the Investment Manager to
provide administrative services and manage the investment of the Fund's assets,
including the placing of orders for the purchase and sale of portfolio
securities. The Fund pays the Investment Manager monthly compensation calculated
daily at the annual rate of 0.80% of the daily net assets of the Fund. The
management fee is allocated among the Classes pro rata based on the net assets
of the Fund attributable to each Class. For the fiscal years ended October 31,
1996, 1997 and 1998, the Investment Manager accrued total compensation under the
Management Agreement in the amounts of $523,635, $408,911 and $256,380,
respectively.
 
    The Investment Manager has retained its wholly-owned subsidiary, MSDW
Services Company, to perform administrative services for the Fund.
 
B. PRINCIPAL UNDERWRITER
 
    The Fund's principal underwriter is the Distributor (which has the same
address as the Investment Manager). In this capacity, the Fund's shares are
distributed by the Distributor. The Distributor has entered into a selected
dealer agreement with Dean Witter Reynolds, which through its own sales
organization sells shares of the Fund. In addition, the Distributor may enter
into similar agreements with other selected broker-dealers. The Distributor, a
Delaware corporation, is a wholly-owned subsidiary of MSDW.
 
    The Distributor bears all expenses it may incur in providing services under
the Distribution Agreement. These expenses include the payment of commissions
for sales of the Fund's shares and incentive compensation to Financial Advisors.
The Distributor also pays certain expenses in connection with the distribution
of the Fund's shares, including the costs of preparing, printing and
distributing advertising or promotional materials, and the costs of printing and
distributing prospectuses and supplements thereto used in connection with the
offering and sale of the Fund's shares. The Fund bears the costs of initial
typesetting, printing and distribution of prospectuses and supplements thereto
to shareholders. The Fund also bears the costs of registering the Fund and its
shares under federal and state securities laws and pays filing fees in
accordance with state securities laws.
 
    The Fund and the Distributor have agreed to indemnify each other against
certain liabilities, including liabilities under the Securities Act. Under the
Distribution Agreement, the Distributor uses its best efforts in rendering
services to the Fund, but in the absence of willful misfeasance, bad faith,
gross negligence or reckless disregard of its obligations, the Distributor is
not liable to the Fund or any of its shareholders for any error of judgment or
mistake of law or for any act or omission or for any losses sustained by the
Fund or its shareholders.
 
C. SERVICES PROVIDED BY THE INVESTMENT MANAGER AND FUND EXPENSES PAID BY THIRD
PARTIES
 
    The Investment Manager manages the investment of the Fund's assets,
including the placing of orders for the purchase and sale of portfolio
securities. The Investment Manager obtains and evaluates the information and
advice relating to the economy, securities markets, and specific securities as
it considers necessary or useful to continuously manage the assets of the Fund
in a manner consistent with its investment objective.
 
    Under the terms of the Management Agreement, in addition to managing the
Fund's investments, the Investment Manager maintains certain of the Fund's books
and records and furnishes, at its own expense, the office space, facilities,
equipment, clerical help, bookkeeping and certain legal services as the Fund may
reasonably require in the conduct of its business, including the preparation of
prospectuses, proxy statements and reports required to be filed with federal and
state securities commissions (except insofar as the participation or assistance
of independent accountants and attorneys is, in the opinion of the Investment
Manager, necessary or desirable). In addition, the Investment Manager pays the
salaries of all personnel, including officers of the Fund, who are employees of
the Investment Manager. The Investment Manager also bears the cost of telephone
service, heat, light, power and other utilities provided to the Fund.
 
                                       22
<PAGE>
    Expenses not expressly assumed by the Investment Manager under the
Management Agreement or by the Distributor, will be paid by the Fund. These
expenses will be allocated among the four Classes of shares pro rata based on
the net assets of the Fund attributable to each Class, except as described
below. Such expenses include, but are not limited to: expenses of the Plan of
Distribution pursuant to Rule 12b-1; charges and expenses of any registrar,
custodian, stock transfer and dividend disbursing agent; brokerage commissions;
taxes; engraving and printing share certificates; registration costs of the Fund
and its shares under federal and state securities laws; the cost and expense of
printing, including typesetting, and distributing prospectuses of the Fund and
supplements thereto to the Fund's shareholders; all expenses of shareholders'
and Trustees' meetings and of preparing, printing and mailing of proxy
statements and reports to shareholders; fees and travel expenses of Trustees or
members of any advisory board or committee who are not employees of the
Investment Manager or any corporate affiliate of the Investment Manager; all
expenses incident to any dividend, withdrawal or redemption options; charges and
expenses of any outside service used for pricing of the Fund's shares; fees and
expenses of legal counsel, including counsel to the Trustees who are not
interested persons of the Fund or of the Investment Manager (not including
compensation or expenses of attorneys who are employees of the Investment
Manager); fees and expenses of the Fund's independent accountants; membership
dues of industry associations; interest on Fund borrowings; postage; insurance
premiums on property or personnel (including officers and Trustees) of the Fund
which inure to its benefit; extraordinary expenses (including, but not limited
to, legal claims and liabilities and litigation costs and any indemnification
relating thereto); and all other costs of the Fund's operation. The 12b-1 fees
relating to a particular Class will be allocated directly to that Class. In
addition, other expenses associated with a particular Class (except advisory or
custodial fees) may be allocated directly to that Class, provided that such
expenses are reasonably identified as specifically attributable to that Class
and the direct allocation to that Class is approved by the Trustees.
 
    The Management Agreement provides that in the absence of willful
misfeasance, bad faith, gross negligence or reckless disregard of its
obligations thereunder, the Investment Manager is not liable to the Fund or any
of its investors for any act or omission by the Investment Manager or for any
losses sustained by the Fund or its investors.
 
    The Management Agreement remain in effect from year to year, provided
continuance of the Management Agreement is approved at least annually by the
vote of the holders of a majority, as defined in the Investment Company Act, of
the outstanding shares of the Fund, or by the Trustees; provided that in either
event such continuance is approved annually by the vote of a majority of the
Trustees.
 
D. DEALER REALLOWANCES
 
    Upon notice to selected broker-dealers, the Distributor may reallow up to
the full applicable front-end sales charge during periods specified in such
notice. During periods when 90% or more of the sales charge is reallowed, such
selected broker-dealers may be deemed to be underwriters as that term is defined
in the Securities Act.
 
E. RULE 12b-1 PLAN
 
    The Fund has adopted a Plan of Distribution pursuant to Rule 12b-1 under the
Investment Company Act (the "Plan") pursuant to which each Class, other than
Class D, pays the Distributor compensation accrued daily and payable monthly at
the following annual rates: 0.25% and 1.0% of the average daily net assets of
Class A and Class C, respectively, and, with respect to Class B, 1.0% of the
lesser of: (a) the average daily aggregate gross sales of the Fund's Class B
shares since the inception of the Fund (not including reinvestment of dividends
or capital gains distributions), less the average daily aggregate net asset
value of the Fund's Class B shares redeemed since the Fund's inception upon
which a contingent deferred sales charge has been imposed or upon which such
charge has been waived, or (b) the average daily net assets of Class B.
 
    The Distributor also receives the proceeds of front-end sales charges
("FSCs") and of contingent deferred sales charges ("CDSCs") imposed on certain
redemptions of shares, which are separate and apart from payments made pursuant
to the Plan. The Distributor has informed the Fund that it and/or
 
                                       23
<PAGE>
Dean Witter Reynolds received the proceeds of CDSCs and FSCs, for the last three
fiscal years ended October 31, in approximate amounts as provided in the table
below (the Distributor did not retain any of these amounts).
 
<TABLE>
<CAPTION>
                                                1998                   1997                     1996
                                         -------------------  -----------------------  -----------------------
<S>                                      <C>       <C>        <C>         <C>          <C>         <C>
Class A................................  FSCs:(4)  $   4,714  FSCs:       $         0  FSCS:               N/A
                                         CDSCs:    $       0  CDSCs:      $         0  CDSC:               N/A
Class B................................  CDSCs:    $  81,003  CDSCs:      $   168,786  CDSCs:      $   163,116
Class C................................  CDSCs:    $   1,677  CDSCs:      $       270  CDSC:               N/A
</TABLE>
 
- ------------------------
(4)  FSCs apply to Class A only. This Class commenced operations on July 28,
     1997.
 
    The Distributor has informed the Fund that the entire fee payable by Class A
and a portion of the fees payable by each of Class B and Class C each year
pursuant to the Plan equal to 0.25% of such Class' average daily net assets are
currently each characterized as a "service fee" under the Rules of the National
Association of Securities Dealers, Inc. (of which the Distributor is a member).
The "service fee" is a payment made for personal service and/or the maintenance
of shareholder accounts. The remaining portion of the Plan fees payable by a
Class, if any, is characterized as an "asset-based sales charge" as such is
defined by the Rules of the Association.
 
    Under the Plan and as required by Rule 12b-1, the Trustees receive and
review promptly after the end of each calendar quarter a written report provided
by the Distributor of the amounts expended under the Plan and the purpose for
which such expenditures were made. Class B shares of the Fund accrued amounts
payable to the Distributor under the Plan, during the fiscal year ended October
31, 1998, of $306,235. This amount is equal to 1.0% of the average daily net
assets of Class B for the fiscal year and was calculated pursuant to clause (b)
of the compensation formula under the Plan. For the fiscal year ended October
31, 1998, Class A and Class C shares of the Fund accrued payments under the Plan
amounting to $147 and $9,392, respectively, which amounts are equal to 0.23% and
1.00% of the average daily net assets of Class A and Class C, respectively, for
the fiscal year.
 
    The Plan was adopted in order to permit the implementation of the Fund's
method of distribution. Under this distribution method the Fund offers four
Classes, each with a different distribution arrangement.
 
    With respect to Class A shares, Dean Witter Reynolds compensates its
Financial Advisors by paying them, from proceeds of the FSC, commissions for the
sale of Class A shares, currently a gross sales credit of up to 5.0% of the
amount sold (except as provided in the following sentence) and an annual
residual commission, currently a residual of up to 0.25% of the current value of
the respective accounts for which they are the Financial Advisors or dealers of
record in all cases. On orders of $1 million or more (for which no sales charge
was paid) or net asset value purchases by employer-sponsored employee benefit
plans, whether or not qualified under the Internal Revenue Code, for which the
Transfer Agent serves as Trustee or Dean Witter Reynolds Retirement Plan
Services serves as recordkeeper pursuant to a written Recordkeeping Services
Agreement ("MSDW Eligible Plans"), the Investment Manager compensates Financial
Advisors by paying them, from its own funds, a gross sales credit of 1.0% of the
amount sold.
 
    With respect to Class B shares, Dean Witter Reynolds compensates its
Financial Advisors by paying them, from its own funds, commissions for the sale
of Class B shares, currently a gross sales credit of up to 5.0% of the amount
sold (except as provided in the following sentence) and an annual residual
commission, currently a residual of up to 0.25% of the current value (not
including reinvested dividends or distributions) of the amount sold in all
cases. In the case of Class B shares purchased by MSDW Eligible Plans, Dean
Witter Reynolds compensates its Financial Advisors by paying them, from its own
funds, a gross sales credit of 3.0% of the amount sold.
 
                                       24
<PAGE>
    With respect to Class C shares, Dean Witter Reynolds compensates its
Financial Advisors by paying them, from its own funds, commissions for the sale
of Class C shares, currently a gross sales credit of up to 1.0% of the amount
sold and an annual residual commission, currently up to 1.0% of the current
value of the respective accounts for which they are the Financial Advisors of
record.
 
    With respect to Class D shares other than shares held by participants in the
Investment Manager's mutual fund asset allocation program, the Investment
Manager compensates Dean Witter Reynolds's Financial Advisors by paying them,
from its own funds, commissions for the sale of Class D shares, currently a
gross sales credit of up to 1.0% of the amount sold. There is a chargeback of
100% of the amount paid if the Class D shares are redeemed in the first year and
a chargeback of 50% of the amount paid if the Class D shares are redeemed in the
second year after purchase. The Investment Manager also compensates Dean Witter
Reynolds's Financial Advisors by paying them, from its own funds, an annual
residual commission, currently up to 0.10% of the current value of the
respective accounts for which they are the Financial Advisors of record (not
including accounts of participants in the Investment Manager's mutual fund asset
allocation program).
 
    The gross sales credit is a charge which reflects commissions paid by Dean
Witter Reynolds to its Financial Advisors and Dean Witter Reynolds's
Fund-associated distribution-related expenses, including sales compensation, and
overhead and other branch office distribution-related expenses including (a) the
expenses of operating Dean Witter Reynolds's branch offices in connection with
the sale of Fund shares, including lease costs, the salaries and employee
benefits of operations and sales support personnel, utility costs,
communications costs and the costs of stationery and supplies, (b) the costs of
client sales seminars, (c) travel expenses of mutual fund sales coordinators to
promote the sale of Fund shares and (d) other expenses relating to branch
promotion of Fund sales.
 
    The distribution fee that the Distributor receives from the Fund under the
Plan, in effect, offsets distribution expenses incurred under the Plan on behalf
of the Fund and, in the case of Class B shares, opportunity costs, such as the
gross sales credit and an assumed interest charge thereon ("carrying charge").
In the Distributor's reporting of the distribution expenses to the Fund, in the
case of Class B shares, such assumed interest (computed at the "broker's call
rate") has been calculated on the gross credit as it is reduced by amounts
received by the Distributor under the Plan and any contingent deferred sales
charges received by the Distributor upon redemption of shares of the Fund. No
other interest charge is included as a distribution expense in the Distributor's
calculation of its distribution costs for this purpose. The broker's call rate
is the interest rate charged to securities brokers on loans secured by
exchange-listed securities.
 
    The Fund is authorized to reimburse expenses incurred or to be incurred in
promoting the distribution of the Fund's Class A and Class C shares and in
servicing shareholder accounts. Reimbursement will be made through payments at
the end of each month. The amount of each monthly payment may in no event exceed
an amount equal to a payment at the annual rate of 0.25%, in the case of Class
A, and 1.0%, in the case of Class C, of the average net assets of the respective
Class during the month. No interest or other financing charges, if any, incurred
on any distribution expenses on behalf of Class A and Class C will be
reimbursable under the Plan. With respect to Class A, in the case of all
expenses other than expenses representing the service fee, and, with respect to
Class C, in the case of all expenses other than expenses representing a gross
sales credit or a residual to Financial Advisors and other authorized financial
representatives, such amounts shall be determined at the beginning of each
calendar quarter by the Trustees, including, a majority of the Independent
Trustees. Expenses representing the service fee (for Class A) or a gross sales
credit or a residual to Financial Advisors and other authorized financial
representatives (for Class C) may be reimbursed without prior determination. In
the event that the Distributor proposes that monies shall be reimbursed for
other than such expenses, then in making quarterly determinations of the amounts
that may be reimbursed by the Fund, the Distributor will provide and the
Trustees will review a quarterly budget of projected distribution expenses to be
incurred on behalf of the Fund, together with a report explaining the purposes
and anticipated benefits of incurring such expenses. The Trustees will determine
which particular expenses, and the portions thereof, that may be borne by the
Fund, and in making such a determination shall consider the scope of the
Distributor's commitment to promoting the distribution of the Fund's Class A and
Class C shares.
 
                                       25
<PAGE>
    Each Class paid 100% of the amounts accrued under the Plan with respect to
that Class for the fiscal year ended October 31, 1998 to the Distributor. The
Distributor and Dean Witter Reynolds estimate that they have spent, pursuant to
the Plan, $8,157,643 on behalf of Class B since the inception of the Plan. It is
estimated that this amount was spent in approximately the following ways: (i)
25.96% ($2,117,665)-- advertising and promotional expenses; (ii) 1.85%
($150,962)--printing of prospectuses for distribution to other than current
shareholders; and (iii) 72.19% ($5,889,016)--other expenses, including the gross
sales credit and the carrying charge, of which 7.81% ($460,185) represents
carrying charges, 37.70% ($2,220,392) represents commission credits to Dean
Witter Reynolds branch offices and other selected broker-dealers for payments of
commissions to Financial Advisors and other authorized financial
representatives, and 54.49% ($3,208,439) represents overhead and other branch
office distribution-related expenses. The amounts accrued by Class A and Class C
for distribution during the fiscal year ended October 31, 1998 were for expenses
which relate to compensation of sales personnel and associated overhead
expenses.
 
    In the case of Class B shares, at any given time, the expenses of
distributing shares of the Fund may be more or less than the total of (i) the
payments made by the Fund pursuant to the Plan; and (ii) the proceeds of CDSCs
paid by investors upon redemption of shares. For example, if $1 million in
expenses in distributing Class B shares of the Fund had been incurred and
$750,000 had been received as described in (i) and (ii) above, the excess
expense would amount to $250,000. The Distributor has advised the Fund that in
the case of Class B shares the excess distribution expenses, including the
carrying charge designed to approximate the opportunity costs incurred by Dean
Witter Reynolds which arise from it having advanced monies without having
received the amount of any sales charges imposed at the time of sale of the
Fund's Class B shares, totaled $3,830,463 as of October 31, 1998 (the end of the
Fund's fiscal year), which was equal to 12.77% of the net assets of Class B on
such date. Because there is no requirement under the Plan that the Distributor
be reimbursed for all distribution expenses with respect to Class B shares or
any requirement that the Plan be continued from year to year, this excess amount
does not constitute a liability of the Fund. Although there is no legal
obligation for the Fund to pay expenses incurred in excess of payments made to
the Distributor under the Plan and the proceeds of CDSCs paid by investors upon
redemption of shares, if for any reason the Plan is terminated, the Trustees
will consider at that time the manner in which to treat such expenses. Any
cumulative expenses incurred, but not yet recovered through distribution fees or
CDSCs, may or may not be recovered through future distribution fees or CDSCs.
 
    In the case of Class A and Class C shares, expenses incurred pursuant to the
Plan in any calendar year in excess of 0.25% or 1.0% of the average daily net
assets of Class A or Class C, respectively, will not be reimbursed by the Fund
through payments in any subsequent year, except that expenses representing a
gross sales commission credited to Morgan Stanley Dean Witter Financial Advisors
and other authorized financial representatives at the time of sale may be
reimbursed in the subsequent calendar year. The Distributor has advised the Fund
that there were no unreimbursed expenses representing a gross sales commission
credited to Morgan Stanley Dean Witter Financial Advisors and other authorized
financial representatives at the time of sale in the case of Class C at December
31, 1998 (the end of the calendar year), and that there were no such expenses
that may be reimbursed in the subsequent year in the case of Class A on such
date. No interest or other financing charges will be incurred on any Class A or
Class C distribution expenses incurred by the Distributor under the Plan or on
any unreimbursed expenses due to the Distributor pursuant to the Plan.
 
    No interested person of the Fund nor any Independent Trustee has any direct
financial interest in the operation of the Plan except to the extent that the
Distributor, the Investment Manager, Dean Witter Reynolds, MSDW Services Company
or certain of their employees may be deemed to have such an interest as a result
of benefits derived from the successful operation of the Plan or as a result of
receiving a portion of the amounts expended thereunder by the Fund.
 
    On an annual basis the Trustees, including a majority of the Independent
Trustees, consider whether the Plan should be continued. Prior to approving the
last continuation of the Plan, the Trustees requested and received from the
Distributor and reviewed all the information which they deemed necessary to
arrive at an informed determination. In making their determination to continue
the Plan, the Trustees considered: (1) the Fund's experience under the Plan and
whether such experience indicates
 
                                       26
<PAGE>
that the Plan is operating as anticipated; (2) the benefits the Fund had
obtained, was obtaining and would be likely to obtain under the Plan, including
that: (a) the Plan is essential in order to give Fund investors a choice of
alternatives for payment of distribution and service charges and to enable the
Fund to continue to grow and avoid a pattern of net redemptions which, in turn,
are essential for effective investment management; and (b) without the
compensation to individual brokers and the reimbursement of distribution and
account maintenance expenses of Dean Witter Reynolds's branch offices made
possible by the 12b-1 fees, Dean Witter Reynolds could not establish and
maintain an effective system for distribution, servicing of Fund shareholders
and maintenance of shareholder accounts; and (3) what services had been provided
and were continuing to be provided under the Plan to the Fund and its
shareholders. Based upon their review, the Trustees, including each of the
Independent Trustees, determined that continuation of the Plan would be in the
best interest of the Fund and would have a reasonable likelihood of continuing
to benefit the Fund and its shareholders. In the Trustees' quarterly review of
the Plan, they will consider its continued appropriateness and the level of
compensation provided therein.
 
    The Plan may not be amended to increase materially the amount to be spent
for the services described therein without approval by the shareholders of the
affected Class or Classes of the Fund, and all material amendments to the Plan
must also be approved by the Trustees in the manner described above. The Plan
may be terminated at any time, without payment of any penalty, by vote of a
majority of the Independent Trustees or by a vote of a majority of the
outstanding voting securities of the Fund (as defined in the Investment Company
Act) on not more than thirty days' written notice to any other party to the
Plan. So long as the Plan is in effect, the election and nomination of
Independent Trustees shall be committed to the discretion of the Independent
Trustees.
 
F. OTHER SERVICE PROVIDERS
 
(1) TRANSFER AGENT/DIVIDEND-PAYING AGENT
 
    Morgan Stanley Dean Witter Trust FSB is the Transfer Agent for the Fund's
shares and the Dividend Disbursing Agent for payment of dividends and
distributions on Fund shares and Agent for shareholders under various investment
plans. The principal business address of the Transfer Agent is Harborside
Financial Center, Plaza Two, Jersey City, New Jersey 07311.
 
(2) CUSTODIAN AND INDEPENDENT ACCOUNTANTS
 
    The Bank of New York, 90 Washington Street, New York, New York 10286 is the
Custodian of the Fund's assets. Any of the Fund's cash balances with the
Custodian in excess of $100,000 are unprotected by federal deposit insurance.
These balances may, at times, be substantial.
 
    Wilmington Trust Company, Rodney Square North, Wilmington, Delaware 19890
acts as Sub-Custodian for the storing, transferring and delivering of the
precious metals owned by the Fund.
 
   
    PricewaterhouseCoopers LLP, 1177 Avenue of the Americas, New York, New York
10036 serves as the independent accountants of the Fund. The independent
accountants are responsible for auditing the annual financial statements of the
Fund.
    
 
(3) AFFILIATED PERSONS
 
    The Transfer Agent is an affiliate of the Investment Manager, and of the
Distributor. As Transfer Agent and Dividend Disbursing Agent, the Transfer
Agent's responsibilities include maintaining shareholder accounts, disbursing
cash dividends and reinvesting dividends, processing account registration
changes, handling purchase and redemption transactions, mailing prospectuses and
reports, mailing and tabulating proxies, processing share certificate
transactions, and maintaining shareholder records and lists. For these services,
the Transfer Agent receives a per shareholder account fee from the Fund.
 
VI. BROKERAGE ALLOCATION AND OTHER PRACTICES
- --------------------------------------------------------------------------------
 
A. BROKERAGE TRANSACTIONS
 
    Subject to the general supervision of the Trustees, the Investment Manager
is responsible for decisions to buy and sell securities for the Fund, the
selection of brokers and dealers to effect the
 
                                       27
<PAGE>
transactions, and the negotiation of brokerage commissions, if any. Purchases
and sales of securities on a stock exchange are effected through brokers who
charge a commission for their services. In the over-the-counter market,
securities are generally traded on a "net" basis with dealers acting as
principal for their own accounts without a stated commission, although the price
of the security usually includes a profit to the dealer. The Fund also expects
that securities will be purchased at times in underwritten offerings where the
price includes a fixed amount of compensation, generally referred to as the
underwriter's concession or discount. Options and futures transactions will
usually be effected through a broker and a commission will be charged. On
occasion, the Fund may also purchase certain money market instruments directly
from an issuer, in which case no commissions or discounts are paid.
 
    For the fiscal years ended October 31, 1996, 1997 and 1998, the Fund paid a
total of $227,064, $282,087 and $214,766, respectively, in brokerage
commissions.
 
B. COMMISSIONS
 
    Pursuant to an order of the SEC, the Fund may effect principal transactions
in certain money market instruments with Dean Witter Reynolds. The Fund will
limit its transactions with Dean Witter Reynolds to U.S. Government and
government agency securities, bank money instruments (i.e., certificates of
deposit and bankers' acceptances) and commercial paper. The transactions will be
effected with Dean Witter Reynolds only when the price available from Dean
Witter Reynolds is better than that available from other dealers.
 
    During the fiscal years ended October 31, 1996, 1997 and 1998, the Fund did
not effect any principal transactions with Dean Witter Reynolds.
 
    Consistent with the policy described above, brokerage transactions in
securities listed on exchanges or admitted to unlisted trading privileges may be
effected through Dean Witter Reynolds, Morgan Stanley & Co. and other affiliated
brokers and dealers. In order for an affiliated broker or dealer to effect any
portfolio transactions on an exchange for the Fund, the commissions, fees or
other remuneration received by the affiliated broker or dealer must be
reasonable and fair compared to the commissions, fees or other remuneration paid
to other brokers in connection with comparable transactions involving similar
securities being purchased or sold on an exchange during a comparable period of
time. This standard would allow the affiliated broker or dealer to receive no
more than the remuneration which would be expected to be received by an
unaffiliated broker in a commensurate arm's-length transaction. Furthermore, the
Trustees, including the Independent Trustees, have adopted procedures which are
reasonably designed to provide that any commissions, fees or other remuneration
paid to an affiliated broker or dealer are consistent with the foregoing
standard. The Fund does not reduce the management fee it pays to the Investment
Manager by any amount of the brokerage commissions it may pay to an affiliated
broker or dealer.
 
    During the fiscal years ended October 31, 1996, 1997 and 1998, the Fund paid
a total of $30,640, $750 and $13,415, respectively, in brokerage commissions to
Dean Witter Reynolds. During the fiscal year ended October 31, 1998, the
brokerage commissions paid to Dean Witter Reynolds represented approximately
6.25% of the total brokerage commissions paid by the Fund during the year and
were paid on account of transactions having an aggregate dollar value equal to
approximately 4.16% of the aggregate dollar value of all portfolio transactions
of the Fund during the year for which commissions were paid.
 
    During the period June 1 through October 31, 1997 and during the fiscal year
ended October 31, 1998, the Fund paid a total of $0 and $2,500, respectively, in
brokerage commissions to Morgan Stanley & Co., which broker-dealer became an
affiliate of the Investment Manager on May 31, 1997 upon consummation of the
merger of Dean Witter, Discover & Co. with Morgan Stanley Group Inc. During the
fiscal year ended October 31, 1998, the brokerage commissions paid to Morgan
Stanley & Co. represented approximately 1.16% of the total brokerage commissions
paid by the Fund for this period and were paid on account of transactions having
an aggregate dollar value equal to approximately 1.02% of the aggregate dollar
value of all portfolio transactions of the Fund during the year for which
commissions were paid.
 
                                       28
<PAGE>
C. BROKERAGE SELECTION
 
    The policy of the Fund regarding purchases and sales of securities for its
portfolio is that primary consideration will be given to obtaining the most
favorable prices and efficient executions of transactions. Consistent with this
policy, when securities transactions are effected on a stock exchange, the
Fund's policy is to pay commissions which are considered fair and reasonable
without necessarily determining that the lowest possible commissions are paid in
all circumstances. The Fund believes that a requirement always to seek the
lowest possible commission cost could impede effective portfolio management and
preclude the Fund and the Investment Manager from obtaining a high quality of
brokerage and research services. In seeking to determine the reasonableness of
brokerage commissions paid in any transaction, the Investment Manager relies
upon its experience and knowledge regarding commissions generally charged by
various brokers and on its judgment in evaluating the brokerage and research
services received from the broker effecting the transaction. These
determinations are necessarily subjective and imprecise, as in most cases an
exact dollar value for those services is not ascertainable.
 
    The Fund anticipates that certain of its transactions involving foreign
securities will be effected on securities exchanges. Fixed commissions on such
transactions are generally higher than negotiated commissions on domestic
transactions. There is also generally less government supervision and regulation
of foreign securities exchanges and brokers than in the United States.
 
    In seeking to implement the Fund's policies, the Investment Manager effects
transactions with those brokers and dealers who the Investment Manager believes
provide the most favorable prices and are capable of providing efficient
executions. If the Investment Manager believes the prices and executions are
obtainable from more than one broker or dealer, it may give consideration to
placing portfolio transactions with those brokers and dealers who also furnish
research and other services to the Fund or the Investment Manager. The services
may include, but are not limited to, any one or more of the following:
information as to the availability of securities for purchase or sale;
statistical or factual information or opinions pertaining to investment; wire
services; and appraisals or evaluations of portfolio securities. The information
and services received by the Investment Manager from brokers and dealers may be
of benefit to the Investment Manager in the management of accounts of some of
its other clients and may not in all cases benefit the Fund directly.
 
    The Investment Manager currently serves as investment manager to a number of
clients, including other investment companies, and may in the future act as
investment manager or advisor to others. It is the practice of the Investment
Manager to cause purchase and sale transactions to be allocated among the Fund
and others whose assets it manages in such manner as it deems equitable. In
making such allocations among the Fund and other client accounts, various
factors may be considered, including the respective investment objectives, the
relative size of portfolio holdings of the same or comparable securities, the
availability of cash for investment, the size of investment commitments
generally held and the opinions of the persons responsible for managing the
portfolios of the Fund and other client accounts. In the case of certain initial
and secondary public offerings, the Investment Manager utilizes a pro rata
allocation process based on the size of the Morgan Stanley Dean Witter Funds
involved and the number of shares available from the public offering.
 
D. DIRECTED BROKERAGE
 
    During the fiscal year ended October 31, 1998, the Fund paid $198,217 in
brokerage commissions in connection with transactions in the aggregate amount of
$24,082,466 to brokers because of research services provided.
 
E. REGULAR BROKER-DEALERS
 
    During the fiscal year ended October 31, 1998, the Fund did not purchase
securities issued by brokers or dealers that were among the ten brokers or the
ten dealers that executed transactions for or with the Fund in the largest
dollar amounts during the year. As of October 31, 1998, the Fund did not own any
securities issued by any of these issuers.
 
                                       29
<PAGE>
VII. CAPITAL STOCK AND OTHER SECURITIES
- --------------------------------------------------------------------------------
 
    The shareholders of the Fund are entitled to a full vote for each full share
of beneficial interest held. The Fund is authorized to issue an unlimited number
of shares of beneficial interest. All shares of beneficial interest of the Fund
are of $0.01 par value and are equal as to earnings, assets and voting
privileges except that each Class will have exclusive voting privileges with
respect to matters relating to distribution expenses borne solely by such Class
or any other matter in which the interests of one Class differ from the
interests of any other Class. In addition, Class B shareholders will have the
right to vote on any proposed material increase in Class A's expenses, if such
proposal is submitted separately to Class A shareholders. Also, Class A, Class B
and Class C bear expenses related to the distribution of their respective
shares.
 
    The Fund's Declaration of Trust permits the Trustees to authorize the
creation of additional series of shares (the proceeds of which would be invested
in separate, independently managed portfolios) and additional Classes of shares
within any series. The Trustees have not presently authorized any such
additional series or Classes of shares other than as set forth in the
PROSPECTUS.
 
    The Fund's Declaration of Trust permits the Trustees to authorize the
creation of additional series of shares (the proceeds of which would be invested
in separate, independently managed portfolios) and additional Classes of shares
within any series. The Trustees have not presently authorized any such
additional series or Classes of shares other than as set forth in the
PROSPECTUS.
 
    The Fund is not required to hold annual meetings of shareholders and in
ordinary circumstances the Fund does not intend to hold such meetings. The
Trustees may call special meetings of shareholders for action by shareholder
vote as may be required by the Investment Company Act or the Declaration of
Trust. Under certain circumstances, the Trustees may be removed by action of the
Trustees or by the shareholders.
 
    Under Massachusetts law, shareholders of a business trust may, under certain
limited circumstances, be held personally liable as partners for the obligations
of the Fund. However, the Declaration of Trust contains an express disclaimer of
shareholder liability for acts or obligations of the Fund, requires that notice
of such Fund obligations include such disclaimer, and provides for
indemnification out of the Fund's property for any shareholder held personally
liable for the obligations of the Fund. Thus, the risk of a shareholder
incurring financial loss on account of shareholder liability is limited to
circumstances in which the Fund itself would be unable to meet its obligations.
Given the above limitations on shareholder personal liability, and the nature of
the Fund's assets and operations, the possibility of the Fund being unable to
meet its obligations is remote and thus, in the opinion of Massachusetts counsel
to the Fund, the risk to Fund shareholders of personal liability is remote.
 
    All of the Trustees have been elected by the shareholders of the Fund, most
recently at a Special Meeting of Shareholders held on May 21, 1997. The Trustees
themselves have the power to alter the number and the terms of office of the
Trustees (as provided for in the Declaration of Trust), and they may at any time
lengthen or shorten their own terms or make their terms of unlimited duration
and appoint their own successors, provided that always at least a majority of
the Trustees has been elected by the shareholders of the Fund.
 
VIII. PURCHASE, REDEMPTION AND PRICING OF SHARES
- --------------------------------------------------------------------------------
 
A. PURCHASE/REDEMPTION OF SHARES
 
    Information concerning how Fund shares are offered to the public (and how
they are redeemed and exchanged) is provided in the Fund's PROSPECTUS.
 
    TRANSFER AGENT AS AGENT.  With respect to the redemption or repurchase of
Fund shares, the application of proceeds to the purchase of new shares in the
Fund or any other Morgan Stanley Dean Witter Funds and the general
administration of the exchange privilege, the Transfer Agent acts as agent for
the Distributor and for the shareholder's authorized broker-dealer, if any, in
the performance of such functions. With respect to exchanges, redemptions or
repurchases, the Transfer Agent shall be liable for
 
                                       30
<PAGE>
its own negligence and not for the default or negligence of its correspondents
or for losses in transit. The Fund shall not be liable for any default or
negligence of the Transfer Agent, the Distributor or any authorized
broker-dealer.
 
    The Distributor and any authorized broker-dealer have appointed the Transfer
Agent to act as their agent in connection with the application of proceeds of
any redemption of Fund shares to the purchase of shares of any other Morgan
Stanley Dean Witter Fund and the general administration of the exchange
privilege. No commission or discounts will be paid to the Distributor or any
authorized broker-dealer for any transaction pursuant to the exchange privilege.
 
    TRANSFERS OF SHARES.  In the event a shareholder requests a transfer of Fund
shares to a new registration, the shares will be transferred without sales
charge at the time of transfer. With regard to the status of shares which are
either subject to the CDSC or free of such charge (and with regard to the length
of time shares subject to the charge have been held), any transfer involving
less than all of the shares in an account will be made on a pro rata basis (that
is, by transferring shares in the same proportion that the transferred shares
bear to the total shares in the account immediately prior to the transfer). The
transferred shares will continue to be subject to any applicable CDSC as if they
had not been so transferred.
 
B. OFFERING PRICE
 
    The Fund's Class B, Class C and Class D shares are offered at net asset
value per share and the Class A shares are offered at net asset value per share
plus any applicable FSC which is distributed among the Fund's Distributor, Dean
Witter Reynolds and other authorized dealers as described in the section "V.
Investment Management and Other Services -- E. Rule 12b-1 Plan."
 
    The price of Fund shares, called "net asset value," is based on the value of
the Fund's portfolio securities. Net asset value per share of each Class is
calculated by dividing the value of the portion of the Fund's securities and
other assets attributable to that Class, less the liabilities attributable to
that Class, by the number of shares of that Class outstanding. The assets of
each Class of shares are invested in a single portfolio. The net asset value of
each Class, however, will differ because the Classes have different ongoing
fees.
 
    In the calculation of the Fund's net asset value: (1) an equity portfolio
security listed or traded on the New York or American Stock Exchange or other
stock exchange is valued at its latest sale price on that exchange, prior to the
time when assets are valued; if there were no sales that day, the security is
valued at the latest bid price (in cases where a security is traded on more than
one exchange, the security is valued on the exchange designated as the primary
market pursuant to procedures adopted by the Trustees); and (2) all other
portfolio securities for which over-the-counter market quotations are readily
available are valued at the latest bid price. When market quotations are not
readily available, including circumstances under which it is determined by the
Investment Manager that sale or bid prices are not reflective of a security's
market value, portfolio securities are valued at their fair value as determined
in good faith under procedures established by and under the general supervision
of the Fund's Trustees. For valuation purposes, quotations of foreign portfolio
securities, other assets and liabilities and forward contracts stated in foreign
currency are translated into U.S. dollar equivalents at the prevailing market
rates prior to the close of the New York Stock Exchange.
 
    Gold and silver bullion will be valued at the last spot settlement price on
the Commodity Exchange, Inc. and other precious metals (such as platinum and
palladium) and minerals will be valued at the last spot settlement price or, if
not available, the settlement price of the nearest contract month on the New
York Mercantile Exchange. If prices are not available on any of these exchanges
on any given day, the relevant precious metal or mineral will be valued at
prices in the bullion markets or other markets approved by the Trustees for that
purpose; if there is no readily available market quotation, then bullion will be
valued in a manner, at fair value, as determined in good faith by the Trustees.
 
    Short-term debt securities with remaining maturities of sixty days or less
at the time of purchase are valued at amortized cost, unless the Trustees
determine such does not reflect the securities' market value, in which case
these securities will be valued at their fair value as determined by the
Trustees.
 
                                       31
<PAGE>
    Certain of the Fund's portfolio securities may be valued by an outside
pricing service approved by the Fund's Trustees. The pricing service may utilize
a matrix system incorporating security quality, maturity and coupon as the
evaluation model parameters, and/or research evaluations by its staff, including
review of broker-dealer market price quotations in determining what it believes
is the fair valuation of the portfolio securities valued by such pricing
service.
 
    Listed options on debt securities are valued at the latest sale price on the
exchange on which they are listed unless no sales of such options have taken
place that day, in which case they will be valued at the mean between their
latest bid and asked prices. Unlisted options on debt securities and all options
on equity securities are valued at the mean between their latest bid and asked
prices. Futures are valued at the latest sale price on the commodities exchange
on which they trade unless the Trustees determine such price does not reflect
their market value, in which case they will be valued at their fair value as
determined in good faith under procedures established by and under the
supervision of the Trustees.
 
    Generally, trading in foreign securities, as well as corporate bonds, U.S.
Government securities and money market instruments, is substantially completed
each day at various times prior to the close of the New York Stock Exchange. The
values of such securities used in computing the net asset value of the Fund's
shares are determined as of such times. Foreign currency exchange rates are also
generally determined prior to the close of the New York Stock Exchange.
Occasionally, events which may affect the values of such securities and such
exchange rates may occur between the times at which they are determined and the
close of the New York Stock Exchange and will therefore not be reflected in the
computation of the Fund's net asset value. If events that may affect the value
of such securities occur during such period, then these securities may be valued
at their fair value as determined in good faith under procedures established by
and under the supervision of the Trustees.
 
IX. TAXATION OF THE FUND AND SHAREHOLDERS
- --------------------------------------------------------------------------------
 
    The Fund generally will make two basic types of distributions: ordinary
dividends and long-term capital gain distributions. These two types of
distributions are reported differently on a shareholder's income tax return and
they are also subject to different rates of tax. The tax treatment of the
investment activities of the Fund will affect the amount and timing and
character of the distributions made by the Fund. Tax issues relating to the Fund
are not generally a consideration for shareholders such as tax exempt entities
and tax-advantaged retirement vehicles such as an IRA or 401(k) plan.
Shareholders are urged to consult their own tax professionals regarding specific
questions as to federal, state or local taxes.
 
    INVESTMENT COMPANY TAXATION.  The Fund intends to remain qualified as a
regulated investment company under Subchapter M of the Internal Revenue Code of
1986. As such, the Fund will not be subject to federal income tax on its net
investment income and capital gains, if any, to the extent that it distributes
such income and capital gains to its shareholders.
 
    The Fund generally intends to distribute sufficient income and gains so that
the Fund will not pay corporate income tax on its earnings. The Fund also
generally intends to distribute to its shareholders in each calendar year a
sufficient amount of ordinary income and capital gains to avoid the imposition
of a 4% excise tax. However, the Fund may instead determine to retain all or
part of any net long-term capital gains in any year for reinvestment. In such
event, the Fund will pay federal income tax (and possibly excise tax) on such
retained gains.
 
    Gains or losses on sales of securities by the Fund will be long-term capital
gains or losses if the securities have a tax holding period of more than one
year. Gains or losses on the sale of securities with a tax holding period of one
year or less will be short-term gains or losses.
 
    Gains or losses on the Fund's transactions in listed non-equity options,
futures and options on futures generally are treated as 60% long-term and 40%
short-term. When the Fund engages in options and futures transactions, various
tax rules may accelerate or defer recognition of certain gains and losses,
change the character of certain gains or losses, or alter the holding period of
other investments
 
                                       32
<PAGE>
held by the Fund. The application of these rules would therefore also affect the
amount, timing and character of distributions made by the Fund. Under certain
tax rules, the Fund may be required to accrue a portion of any discount at which
certain securities are purchased as income each year even though the Fund
receives no payments in cash on the security during the year. To the extent that
the Fund invests in such securities, it would be required to pay out such
accrued discount as an income distribution in each year in order to avoid
taxation at the Fund level. Such distributions will be made from the available
cash of the Fund or by liquidation of portfolio securities if necessary. If a
distribution of cash necessitates the liquidation of portfolio securities, the
Investment Manager will select which securities to sell. The Fund may realize a
gain or loss from such sales. In the event the Fund realizes net capital gains
from such transactions, its shareholders may receive a larger capital gain
distribution, if any, than they would in the absence of such transactions.
 
    TAXATION OF DIVIDENDS AND DISTRIBUTIONS.  Shareholders normally will have to
pay federal income taxes, and any state and/or local income taxes, on the
dividends and other distributions they receive from the Fund. Such dividends and
distributions, to the extent that they are derived from net investment income or
short-term capital gains, are taxable to the shareholder as ordinary income
regardless of whether the shareholder receives such payments in additional
shares or in cash.
 
    Distributions of net long-term capital gains, if any, are taxable to
shareholders as long-term capital gains regardless of how long a shareholder has
held the Fund's shares and regardless of whether the distribution is received in
additional shares or in cash. The Taxpayer Relief Act of 1997 reduced the
maximum tax on long-term capital gains applicable to individuals from 28% to
20%.
 
    Shareholders are generally taxed on any ordinary dividend or capital gain
distributions from the Fund in the year they are actually distributed. However,
if any such dividends or distributions are declared in October, November or
December and paid in January then such amounts will be treated for tax purposes
as received by the shareholders on December 31, to shareholders of record of
such month.
 
    Shareholders who are not citizens or residents of the United States and
certain foreign entities may be subject to withholding of United States tax on
distributions made by the Fund of investment income and short term capital
gains.
 
    Subject to certain exceptions, a corporate shareholder may be eligible for a
70% dividends received deduction to the extent that the Fund earns and
distributes qualifying dividends from its investments in United States
corporations. Distributions of net capital gains by the Fund will not be
eligible for the dividends received deduction.
 
   
    After the end of each calendar year, shareholders will be sent full
information on their dividends and capital gain distributions for tax purposes,
including the portion taxable as ordinary income, the portion taxable as
long-term capital gains.
    
 
    PURCHASES AND REDEMPTIONS AND EXCHANGES OF FUND SHARES.  Any dividend or
capital gains distribution received by a shareholder from any investment company
will have the effect of reducing the net asset value of the shareholder's stock
in that company by the exact amount of the dividend or capital gains
distribution. Furthermore, such dividends and capital gains distributions are
subject to federal income taxes. If the net asset value of the shares should be
reduced below a shareholder's cost as a result of the payment of dividends or
the distribution of realized long-term capital gains, such payment or
distribution would be in part a return of the shareholder's investment but
nonetheless would be taxable to the shareholder. Therefore, an investor should
consider the tax implications of purchasing Fund shares immediately prior to a
distribution record date.
 
    In general, a sale of shares results in capital gain or loss, and for
individual shareholders, is taxable at a federal rate dependent upon the length
of time the shares were held. A redemption of a shareholder's Fund shares is
normally treated as a sale for tax purposes. Fund shares held for a period of
one year or less will, for tax purposes, generally result in short-term gains or
losses and those held for more than one year generally result in long-term gain
or loss. Any loss realized by shareholders upon a
 
                                       33
<PAGE>
redemption of shares within six months of the date of their purchase will be
treated as a long-term capital loss to the extent of any distributions of net
long-term capital gains with respect to such shares during the six-month period.
 
    Gain or loss on the sale or redemption of shares in the Fund is measured by
the difference between the amount received and the tax basis of the shares.
Shareholders should keep records of investments made (including shares acquired
through reinvestment of dividends and distributions) so they can compute the tax
basis of their shares. Under certain circumstances a shareholder may compute and
use an average cost basis in determining the gain or loss on the sale or
redemption of shares.
 
    Exchanges of Fund shares for shares of another fund, including shares of
other Morgan Stanley Dean Witter Funds, are also subject to similar tax
treatment. Such an exchange is treated for tax purposes as a sale of the
original shares in the first fund, followed by the purchase of shares in the
second fund.
 
    If a shareholder realizes a loss on the redemption or exchange of a fund's
shares and reinvests in that fund's shares within 30 days before or after the
redemption or exchange, the transactions may be subject to the "wash sale"
rules, resulting in a postponement of the recognition of such loss for tax
purposes.
 
X. UNDERWRITERS
- --------------------------------------------------------------------------------
 
    The Fund's shares are offered to the public on a continuous basis. The
Distributor, as the principal underwriter of the shares, has certain obligations
under the Distribution Agreement concerning the distribution of the shares.
These obligations and the compensation the Distributor receives are described
above in the sections titled "Principal Underwriter" and "Rule 12b-1 Plans."
 
XI. CALCULATION OF PERFORMANCE DATA
- --------------------------------------------------------------------------------
 
    From time to time, the Fund may quote its "total return" in advertisements
and sales literature. These figures are computed separately for Class A, Class
B, Class C and Class D shares. The Fund's "average annual total return"
represents an annualization of the Fund's total return over a particular period
and is computed by finding the annual percentage rate which will result in the
ending redeemable value of a hypothetical $1,000 investment made at the
beginning of a one, five or ten year period, or for the period from the date of
commencement of operations, if shorter than any of the foregoing. The ending
redeemable value is reduced by any contingent deferred sales charge ("CDSC") at
the end of the one, five, ten year or other period. For the purpose of this
calculation, it is assumed that all dividends and distributions are reinvested.
The formula for computing the average annual total return involves a percentage
obtained by dividing the ending redeemable value by the amount of the initial
investment (which in the case of Class A shares is reduced by the Class A
initial sales charge), taking a root of the quotient (where the root is
equivalent to the number of years in the period) and subtracting 1 from the
result. The average annual total returns for Class B for the one year, five year
and the life of the Fund periods ended October 31, 1998 were -30.52%, -12.44%
and -6.52%, respectively. The average annual total returns of Class A for the
fiscal year ended October 31, 1998 and for the period July 28, 1997 (inception
of the Class) through October 31, 1998 were -30.25% and -33.18%, respectively.
The average annual total returns of Class C for the fiscal year ended October
31, 1998 and for the period July 28, 1997 (inception of the Class) through
October 31, 1998 were -27.49% and -30.69%, respectively. The average annual
total returns of Class D for the fiscal year ended October 31, 1998 and for the
period July 28, 1997 (inception of the Class) through October 31, 1998 were
- -26.68% and -30.47%, respectively.
 
    In addition, the Fund may advertise its total return for each Class over
different periods of time by means of aggregate, average, year-by-year or other
types of total return figures. These calculations may or may not reflect the
imposition of the maximum front-end sales charge for Class A or the deduction of
the CDSC for each of Class B and Class C which, if reflected, would reduce the
performance quoted. For
 
                                       34
<PAGE>
example, the average annual total return of the Fund may be calculated in the
manner described above, but without deduction for any applicable sales charge.
Based on this calculation, the average annual total returns of Class B for the
one year, five year and the life of the Fund periods ended October 31, 1998,
were -26.86%, -12.13% and -6.52%, respectively. Based on this calculation, the
average annual total returns of Class A for the fiscal year ended October 31,
1998 and for the period July 28, 1997 through October 31, 1998 were -26.38% and
- -30.25%, respectively, the average annual total returns of Class C for the
fiscal year ended October 31, 1998 and for the period July 28, 1997 through
October 31, 1998 were -26.75% and -30.69%, respectively, and the average annual
total returns of Class D for the fiscal year ended October 31, 1998 and for the
period July 28, 1997 through October 31, 1998 were -26.68% and -30.47%,
respectively.
 
    In addition, the Fund may compute its aggregate total return for each Class
for specified periods by determining the aggregate percentage rate which will
result in the ending value of a hypothetical $1,000 investment made at the
beginning of the period. For the purpose of this calculation, it is assumed that
all dividends and distributions are reinvested. The formula for computing
aggregate total return involves a percentage obtained by dividing the ending
value (without reduction for any sales charge) by the initial $1,000 investment
and subtracting 1 from the result. Based on the foregoing calculation, the total
returns for Class B for the one year, five year and the life of the Fund periods
ended October 31, 1998, were -26.86%, -47.61% and -42.60%, respectively. Based
on the foregoing calculation, the total returns of Class A for the fiscal year
ended October 31, 1998 and for the period July 28, 1997 through October 31, 1998
were -26.38% and -36.48%, respectively, the total returns of Class C for the
fiscal year ended October 31, 1998 and for the period July 28, 1997 through
October 31, 1998 were -26.75% and -36.98%, respectively, and the total returns
of Class D for the fiscal year ended October 31, 1998 and for the period July
28, 1997 through October 31, 1998 were -26.68% and -36.73%, respectively.
 
    The Fund may also advertise the growth of hypothetical investments of
$10,000, $50,000 and $100,000 in each Class of shares of the Fund by adding 1 to
the Fund's aggregate total return to date (expressed as a decimal and without
taking into account the effect of any applicable CDSC) and multiplying by
$9,475, $48,000 and $97,000 in the case of Class A (investments of $10,000,
$50,000 and $100,000 adjusted for the initial sales charge) or by $10,000,
$50,000 and $100,000 in the case of each of Class B, Class C and Class D, as the
case may be. Investments of $10,000, $50,000 and $100,000 in each Class at
inception of the Class would have grown (declined) to the following amounts at
October 31, 1998:
 
<TABLE>
<CAPTION>
                                                                                   INVESTMENT AT INCEPTION OF:
                                                                     INCEPTION   -------------------------------
CLASS                                                                  DATE:      $10,000    $50,000   $100,000
- -------------------------------------------------------------------  ----------  ---------  ---------  ---------
<S>                                                                  <C>         <C>        <C>        <C>
Class A............................................................    07/28/97  $   6,019  $  30,490  $  61,614
Class B............................................................    08/06/90      5,740     28,700     57,400
Class C............................................................    07/28/97      6,302     31,510     63,020
Class D............................................................    07/28/97      6,327     31,635     63,270
</TABLE>
 
    The Fund from time to time may also advertise its performance relative to
certain performance rankings and indexes compiled by independent organizations.
 
XII. FINANCIAL STATEMENTS
- --------------------------------------------------------------------------------
 
   
    EXPERTS.  The financial statements of the Fund for the fiscal year ended
October 31, 1998 included in this STATEMENT OF ADDITIONAL INFORMATION and
incorporated by reference in the PROSPECTUS have been so included and
incorporated in reliance on the report of PricewaterhouseCoopers LLP,
independent accountants, given on the authority of said firm as experts in
auditing and accounting.
    
 
                                     *****
 
    This STATEMENT OF ADDITIONAL INFORMATION and the PROSPECTUS do not contain
all of the information set forth in the REGISTRATION STATEMENT the Fund has
filed with the SEC. The complete REGISTRATION STATEMENT may be obtained from the
SEC.
 
                                       35
<PAGE>
MORGAN STANLEY DEAN WITTER PRECIOUS METALS AND MINERALS TRUST
PORTFOLIO OF INVESTMENTS OCTOBER 31, 1998
<TABLE>
<CAPTION>
NUMBER OF
  SHARES                                                                                                VALUE
- ----------------------------------------------------------------------------------------------------------------
<C>         <S>                                                                                      <C>
            COMMON STOCKS (99.1%)
            AUSTRALIA (18.0%)
            GOLD MINING
   600,000  Delta Gold NL..........................................................................  $   980,928
   500,000  Resolute Ltd...........................................................................      430,560
 1,250,000  Ross Mining NL.........................................................................      811,200
                                                                                                     -----------
                                                                                                       2,222,688
                                                                                                     -----------
            PRECIOUS METALS
   700,000  Acacia Resources Ltd...................................................................    1,113,840
   300,000  Lihir Gold Ltd.*.......................................................................      415,584
    25,000  Lihir Gold Ltd. (ADR)*.................................................................      662,500
   800,000  Normandy Mining Ltd....................................................................      713,856
   200,000  Ranger Minerals NL*....................................................................      549,120
                                                                                                     -----------
                                                                                                       3,454,900
                                                                                                     -----------
 
            TOTAL AUSTRALIA........................................................................    5,677,588
                                                                                                     -----------
 
            CANADA (45.9%)
            GOLD MINING
    50,000  IAMGOLD, International African Mining Gold Corp.*......................................      141,005
    50,000  IAMGOLD, International African Mining Gold Corp. - 144A*...............................      141,005
   100,000  Sutton Resources Ltd.*.................................................................      385,738
   200,000  Yamana Resources, Inc.*................................................................      154,295
                                                                                                     -----------
                                                                                                         822,043
                                                                                                     -----------
            PRECIOUS METALS
    90,000  Aber Resources Ltd.*...................................................................      504,700
   200,000  Agnico-Eagle Mines Ltd.................................................................      998,379
    85,000  Barrick Gold Corp......................................................................    1,816,875
   200,000  Cambior Inc. (ADR).....................................................................    1,000,000
   135,000  Euro-Nevada Mining Corp................................................................    2,109,238
    75,000  Franco Nevada Mining Corp. Ltd.........................................................    1,446,515
   350,000  Geomaque Explorations Ltd.*............................................................      349,433
   200,000  Greenstone Resources Ltd.*.............................................................      286,548
   300,000  Meridian Gold Inc.*....................................................................    1,556,250
   125,000  Placer Dome, Inc. (ADR)................................................................    1,968,750
   100,000  Prime Resources Group, Inc. (ADR)......................................................      849,271
   125,000  Repadre Capital Corp.*.................................................................      202,593
   650,000  Vengold Inc.*..........................................................................      526,742
                                                                                                     -----------
                                                                                                      13,615,294
                                                                                                     -----------
            TOTAL CANADA...........................................................................   14,437,337
                                                                                                     -----------
 
            UNITED KINGDOM (3.1%)
            OTHER METALS/MINERALS
    20,000  Rio Tinto PLC (ADR)....................................................................      990,000
                                                                                                     -----------
 
            UNITED STATES (32.0%)
            CONSUMER SPECIALTIES
    50,000  Lazare Kaplan International, Inc.*.....................................................      387,500
                                                                                                     -----------
 
<CAPTION>
NUMBER OF
  SHARES                                                                                                VALUE
- ----------------------------------------------------------------------------------------------------------------
<C>         <S>                                                                                      <C>
            OTHER METALS/MINERALS
    75,000  Freeport-McMoran Copper & Gold, Inc. (Class A).........................................  $   895,313
    20,000  Freeport-McMoran Copper & Gold, Inc. (Class B).........................................      246,250
                                                                                                     -----------
                                                                                                       1,141,563
                                                                                                     -----------
            PRECIOUS METALS
   300,000  Battle Mountain Gold Co................................................................    1,631,250
   125,000  Crown Resources Corp.*.................................................................      312,500
    85,000  Getchell Gold Corp.*...................................................................    1,487,500
   100,000  Homestake Mining Co....................................................................    1,187,500
    70,375  Newmont Mining Corp....................................................................    1,495,469
    75,000  Stillwater Mining Co.*.................................................................    2,428,125
                                                                                                     -----------
                                                                                                       8,542,344
                                                                                                     -----------
 
            TOTAL UNITED STATES....................................................................   10,071,407
                                                                                                     -----------
 
            ZIMBABWE (0.1%)
            OTHER METALS/MINERALS
   120,000  Zimbabwe Platinum Mines Ltd.*..........................................................       29,203
                                                                                                     -----------
 
            TOTAL COMMON STOCKS
            (IDENTIFIED COST $39,486,619)..........................................................   31,205,535
                                                                                                     -----------
</TABLE>
 
<TABLE>
<CAPTION>
PRINCIPAL
AMOUNT IN
THOUSANDS
- ----------
<C>         <S>                                                                                      <C>
            SHORT-TERM INVESTMENT (2.2%)
            REPURCHASE AGREEMENT
$      684  The Bank of New York 5.125% due 11/02/98 (dated 10/30/98; proceeds $683,945)
              (IDENTIFIED COST $683,653) (a).......................................................      683,653
                                                                                                     -----------
</TABLE>
 
<TABLE>
<S>                                                                                          <C>     <C>
TOTAL INVESTMENTS
(IDENTIFIED COST $40,170,272) (b)..........................................................  101.3 %   31,889,188
 
LIABILITIES IN EXCESS OF OTHER ASSETS......................................................   (1.3)      (420,898)
                                                                                             ------  ------------
 
NET ASSETS.................................................................................  100.0 % $ 31,468,290
                                                                                             ------  ------------
                                                                                             ------  ------------
</TABLE>
 
- ---------------------
 
ADR  American Depository Receipt.
 *   Non-income producing security.
(a)  Collateralized by $697,301 Student Loan Marketing Association 5.077% due
     11/19/98 valued at $697,326.
(b)  The aggregate cost for federal income tax purposes approximates identified
     cost. The aggregate gross unrealized appreciation is $2,346,405 and the
     aggregate gross unrealized depreciation is $10,627,489, resulting in net
     unrealized depreciation of $8,281,084.
 
                       SEE NOTES TO FINANCIAL STATEMENTS
                                       36
<PAGE>
MORGAN STANLEY DEAN WITTER PRECIOUS METALS AND MINERALS TRUST
FINANCIAL STATEMENTS
 
STATEMENT OF ASSETS AND LIABILITIES
OCTOBER 31, 1998
 
<TABLE>
<S>                                                                                             <C>
ASSETS:
Investments in securities, at value
  (identified cost $40,170,272)...............................................................  $ 31,889,188
Receivable for:
    Shares of beneficial interest sold........................................................       149,650
    Dividends.................................................................................        30,654
Prepaid expenses and other assets.............................................................        39,781
                                                                                                ------------
     TOTAL ASSETS.............................................................................    32,109,273
                                                                                                ------------
LIABILITIES:
Payable for:
    Shares of beneficial interest repurchased.................................................       283,981
    Investments purchased.....................................................................       254,856
    Plan of distribution fee..................................................................        27,378
    Investment management fee.................................................................        22,099
Accrued expenses and other payables...........................................................        52,669
                                                                                                ------------
     TOTAL LIABILITIES........................................................................       640,983
                                                                                                ------------
     NET ASSETS...............................................................................  $ 31,468,290
                                                                                                ------------
                                                                                                ------------
COMPOSITION OF NET ASSETS:
Paid-in-capital...............................................................................  $ 60,013,917
Net unrealized depreciation...................................................................    (8,281,197)
Accumulated net investment loss...............................................................      (127,339)
Accumulated net realized loss.................................................................   (20,137,091)
                                                                                                ------------
     NET ASSETS...............................................................................  $ 31,468,290
                                                                                                ------------
                                                                                                ------------
CLASS A SHARES:
Net Assets....................................................................................       $91,152
Shares Outstanding (UNLIMITED AUTHORIZED, $.01 PAR VALUE).....................................        18,054
     NET ASSET VALUE PER SHARE................................................................         $5.05
                                                                                                ------------
                                                                                                ------------
 
     MAXIMUM OFFERING PRICE PER SHARE,
       (NET ASSET VALUE PLUS 5.54% OF NET ASSET VALUE)........................................         $5.33
                                                                                                ------------
                                                                                                ------------
CLASS B SHARES:
Net Assets....................................................................................   $30,005,023
Shares Outstanding (UNLIMITED AUTHORIZED, $.01 PAR VALUE).....................................     5,990,376
     NET ASSET VALUE PER SHARE................................................................         $5.01
                                                                                                ------------
                                                                                                ------------
CLASS C SHARES:
Net Assets....................................................................................    $1,045,540
Shares Outstanding (UNLIMITED AUTHORIZED, $.01 PAR VALUE).....................................       208,707
     NET ASSET VALUE PER SHARE................................................................         $5.01
                                                                                                ------------
                                                                                                ------------
CLASS D SHARES:
Net Assets....................................................................................      $326,575
Shares Outstanding (UNLIMITED AUTHORIZED, $.01 PAR VALUE).....................................        64,942
     NET ASSET VALUE PER SHARE................................................................         $5.03
                                                                                                ------------
                                                                                                ------------
</TABLE>
 
                       SEE NOTES TO FINANCIAL STATEMENTS
                                       37
<PAGE>
MORGAN STANLEY DEAN WITTER PRECIOUS METALS AND MINERALS TRUST
FINANCIAL STATEMENTS, CONTINUED
 
STATEMENT OF OPERATIONS
FOR THE YEAR ENDED OCTOBER 31, 1998
 
<TABLE>
<S>                                                                                             <C>
NET INVESTMENT LOSS:
 
INCOME
Dividends (net of $14,613 foreign withholding tax)............................................  $    247,239
Interest......................................................................................       145,797
                                                                                                ------------
 
     TOTAL INCOME.............................................................................       393,036
                                                                                                ------------
 
EXPENSES
Plan of distribution fee (Class A shares).....................................................           147
Plan of distribution fee (Class B shares).....................................................       306,235
Plan of distribution fee (Class C shares).....................................................         9,392
Investment management fee.....................................................................       256,380
Registration fees.............................................................................        88,745
Transfer agent fees and expenses..............................................................        86,657
Professional fees.............................................................................        53,618
Shareholder reports and notices...............................................................        49,175
Custodian fees................................................................................        16,621
Trustees' fees and expenses...................................................................        10,804
Other.........................................................................................         7,989
                                                                                                ------------
 
     TOTAL EXPENSES...........................................................................       885,763
                                                                                                ------------
 
     NET INVESTMENT LOSS......................................................................      (492,727)
                                                                                                ------------
 
NET REALIZED AND UNREALIZED LOSS:
Net realized loss on:
    Investments...............................................................................    (9,648,954)
    Foreign exchange transactions.............................................................          (629)
                                                                                                ------------
 
     NET LOSS.................................................................................    (9,649,583)
                                                                                                ------------
Net change in unrealized appreciation/depreciation on:
    Investments...............................................................................      (420,844)
    Translation of other assets and liabilities denominated in foreign currencies.............            22
                                                                                                ------------
 
     NET DEPRECIATION.........................................................................      (420,822)
                                                                                                ------------
 
     NET LOSS.................................................................................   (10,070,405)
                                                                                                ------------
 
NET DECREASE..................................................................................  $(10,563,132)
                                                                                                ------------
                                                                                                ------------
</TABLE>
 
                       SEE NOTES TO FINANCIAL STATEMENTS
                                       38
<PAGE>
MORGAN STANLEY DEAN WITTER PRECIOUS METALS AND MINERALS TRUST
FINANCIAL STATEMENTS, CONTINUED
 
STATEMENT OF CHANGES IN NET ASSETS
 
<TABLE>
<CAPTION>
                                                                        FOR THE YEAR    FOR THE YEAR
                                                                            ENDED           ENDED
                                                                         OCTOBER 31,     OCTOBER 31,
                                                                            1998            1997*
- -----------------------------------------------------------------------------------------------------
<S>                                                                     <C>             <C>
 
INCREASE (DECREASE) IN NET ASSETS:
 
OPERATIONS:
Net investment loss...................................................  $   (492,727)   $   (575,376)
Net realized loss.....................................................    (9,649,583)     (9,101,223)
Net change in unrealized depreciation.................................      (420,822)     (9,193,959)
                                                                        -------------   -------------
 
     NET DECREASE.....................................................   (10,563,132)    (18,870,558)
                                                                        -------------   -------------
 
DIVIDENDS AND DISTRIBUTIONS TO SHAREHOLDERS FROM:
Net investment income
    Class B shares....................................................       --             (656,572)
Net realized gain
    Class B shares....................................................       --           (3,712,483)
                                                                        -------------   -------------
 
     TOTAL DIVIDENDS AND DISTRIBUTIONS................................       --           (4,369,055)
                                                                        -------------   -------------
Net increase from transactions in shares of beneficial interest.......     3,551,128         878,665
                                                                        -------------   -------------
 
     NET DECREASE.....................................................    (7,012,004)    (22,360,948)
 
NET ASSETS:
Beginning of period...................................................    38,480,294      60,841,242
                                                                        -------------   -------------
 
     END OF PERIOD
    (INCLUDING NET INVESTMENT LOSSES OF $127,339 AND $191,129,
    RESPECTIVELY).....................................................  $ 31,468,290    $ 38,480,294
                                                                        -------------   -------------
                                                                        -------------   -------------
</TABLE>
 
- ---------------------
 
 *   Class A, Class C and Class D shares were issued July 28, 1997.
 
                       SEE NOTES TO FINANCIAL STATEMENTS
                                       39
<PAGE>
MORGAN STANLEY DEAN WITTER PRECIOUS METALS AND MINERALS TRUST
NOTES TO FINANCIAL STATEMENTS OCTOBER 31, 1998
 
1. ORGANIZATION AND ACCOUNTING POLICIES
 
Morgan Stanley Dean Witter Precious Metals and Minerals Trust (the "Fund"),
formerly Dean Witter Precious Metals and Minerals Trust, is registered under the
Investment Company Act of 1940, as amended (the "Act"), as a diversified,
open-end management investment company. The Fund's investment objective is
long-term capital appreciation. The Fund will attempt to achieve its investment
objective by investing principally in the securities of foreign and domestic
companies engaged in the exploration, mining, fabrication, processing,
distribution or trading of precious metals and minerals or in companies engaged
in financing, managing, controlling or operating companies engaged in these
activities and also by investing a portion of its assets in gold, silver,
platinum and palladium bullion and coins. The Fund was organized as a
Massachusetts business trust on December 28, 1989 and commenced operations on
August 6, 1990. On July 28, 1997, the Fund commenced offering three additional
classes of shares, with the then current shares designated as Class B shares.
 
The Fund offers Class A shares, Class B shares, Class C shares and Class D
shares. The four classes are substantially the same except that most Class A
shares are subject to a sales charge imposed at the time of purchase and some
Class A shares, and most Class B shares and Class C shares are subject to a
contingent deferred sales charge imposed on shares redeemed within one year, six
years and one year, respectively. Class D shares are not subject to a sales
charge. Additionally, Class A shares, Class B shares and Class C shares incur
distribution expenses.
 
The preparation of financial statements in accordance with generally accepted
accounting principles requires management to make estimates and assumptions that
affect reported amounts and disclosures. Actual results could differ from those
estimates.
 
The following is a summary of significant accounting policies:
 
A. VALUATION OF INVESTMENTS --  (1) an equity security listed or traded on the
New York, American or other domestic or foreign stock exchange is valued at its
latest sale price on that exchange prior to the time when assets are valued; if
there were no sales that day, the security is valued at the latest bid price (in
cases where securities are traded on more than one exchange, the securities are
valued on the exchange designated as the primary market pursuant to procedures
adopted by the Trustees); (2) all other portfolio securities for which
over-the-counter market quotations are readily available are valued at the
latest available bid price prior to the time of valuation; (3) when market
quotations are not readily available, including circumstances under which it is
determined by Morgan Stanley Dean
 
                                       40
<PAGE>
MORGAN STANLEY DEAN WITTER PRECIOUS METALS AND MINERALS TRUST
NOTES TO FINANCIAL STATEMENTS OCTOBER 31, 1998, CONTINUED
 
Witter Advisors Inc. (the "Investment Manager"), formerly Dean Witter
InterCapital Inc., that sale and bid prices are not reflective of a security's
market value, portfolio securities are valued at their fair value as determined
in good faith under procedures established by and under the general supervision
of the Trustees (valuation of debt securities for which market quotations are
not readily available may be based upon current market prices of securities
which are comparable in coupon, rating and maturity or an appropriate matrix
utilizing similar factors); and (4) short-term debt securities having a maturity
date of more than sixty days at time of purchase are valued on a mark-to-market
basis until sixty days prior to maturity and thereafter at amortized cost based
on their value on the 61st day. Short-term debt securities having a maturity
date of sixty days or less at the time of purchase are valued at amortized cost.
 
B. ACCOUNTING FOR INVESTMENTS --  Security transactions are accounted for on the
trade date (date the order to buy or sell is executed). Realized gains and
losses on security transactions are determined by the identified cost method.
Dividend income and other distributions are recorded on the ex-dividend date
except for certain dividends from foreign securities which are recorded as soon
as the Fund is informed after the ex-dividend date. Discounts are accreted over
the life of the respective securities. Interest income is accrued daily.
 
C. MULTIPLE CLASS ALLOCATIONS --  Investment income, expenses (other than
distribution fees), and realized and unrealized gains and losses are allocated
to each class of shares based upon the relative net asset value on the date such
items are recognized. Distribution fees are charged directly to the respective
class.
 
D. FOREIGN CURRENCY TRANSLATION --  The books and records of the Fund are
maintained in U.S. dollars as follows: (1) the foreign currency market value of
investment securities, other assets and liabilities and forward foreign currency
contracts are translated at the exchange rates prevailing at the end of the
period; and (2) purchases, sales, income and expenses are translated at the
exchange rates prevailing on the respective dates of such transactions. The
resultant exchange gains and losses are included in the Statement of Operations
as realized and unrealized gain/loss on foreign exchange transactions. Pursuant
to U.S. Federal income tax regulations, certain foreign exchange gains/losses
included in realized and unrealized gain/loss are included in or are a reduction
of ordinary income for federal income tax purposes. The Fund does not isolate
that portion of the results of operations arising as a result of changes in the
foreign exchange rates from the changes in the market prices of the securities.
 
                                       41
<PAGE>
MORGAN STANLEY DEAN WITTER PRECIOUS METALS AND MINERALS TRUST
NOTES TO FINANCIAL STATEMENTS OCTOBER 31, 1998, CONTINUED
 
E. FORWARD FOREIGN CURRENCY CONTRACTS --  The Fund may enter into forward
foreign currency contracts which are valued daily at the appropriate exchange
rates. The resultant unrealized exchange gains and losses are included in the
Statement of Operations as unrealized foreign currency gain or loss and in the
Statement of Assets and Liabilities as part of the related foreign currency
denominated asset or liability. The Fund records realized gains or losses on
delivery of the currency or at the time the forward contract is extinguished
(compensated) by entering into a closing transaction prior to delivery.
 
F. FEDERAL INCOME TAX STATUS --  It is the Fund's policy to comply with the
requirements of the Internal Revenue Code applicable to regulated investment
companies and to distribute all of its taxable income to its shareholders.
Accordingly, no federal income tax provision is required.
 
G. DIVIDENDS AND DISTRIBUTIONS TO SHAREHOLDERS --  The Fund records dividends
and distributions to its shareholders on the record date. The amount of
dividends and distributions from net investment income and net realized capital
gains are determined in accordance with federal income tax regulations which may
differ from generally accepted accounting principles. These "book/tax"
differences are either considered temporary or permanent in nature. To the
extent that these differences are permanent in nature, such amounts are
reclassified within the capital accounts based on their federal tax-basis
treatment; temporary differences do not require reclassification. Dividends and
distributions which exceed net investment income and net realized capital gains
for financial reporting purposes but not for tax purposes are reported as
dividends in excess of net investment income or distributions in excess of net
realized capital gains. To the extent they exceed net investment income and net
realized capital gains for tax purposes, they are reported as distributions of
paid-in-capital.
 
2. INVESTMENT MANAGEMENT AGREEMENT
 
Pursuant to an Investment Management Agreement, the Fund pays the Investment
Manager a management fee, accrued daily and payable monthly, by applying the
annual rate of 0.80% to the net assets of the Fund determined as of the close of
each business day.
 
Under the terms of the Agreement, in addition to managing the Fund's
investments, the Investment Manager maintains certain of the Fund's books and
records and furnishes, at its own expense, office space, facilities, equipment,
clerical, bookkeeping and certain legal services and pays the salaries of
 
                                       42
<PAGE>
MORGAN STANLEY DEAN WITTER PRECIOUS METALS AND MINERALS TRUST
NOTES TO FINANCIAL STATEMENTS OCTOBER 31, 1998, CONTINUED
 
all personnel, including officers of the Fund who are employees of the
Investment Manager. The Investment Manager also bears the cost of telephone
services, heat, light, power and other utilities provided to the Fund.
 
3. PLAN OF DISTRIBUTION
 
Shares of the Fund are distributed by Morgan Stanley Dean Witter Distributors
Inc. (the "Distributor"), an affiliate of the Investment Manager. The Fund has
adopted a Plan of Distribution (the "Plan") pursuant to Rule 12b-1 under the
Act. The Plan provides that the Fund will pay the Distributor a fee which is
accrued daily and paid monthly at the following annual rates: (i) Class A -- up
to 0.25% of the average daily net assets of Class A; (ii) Class B -- 1.0% of the
lesser of: (a) the average daily aggregate gross sales of the Class B shares
since the inception of the Fund (not including reinvestment of dividend or
capital gain distributions) less the average daily aggregate net asset value of
the Class B shares redeemed since the Fund's inception upon which a contingent
deferred sales charge has been imposed or waived; or (b) the average daily net
assets of Class B; and (iii) Class C -- up to 1.0% of the average daily net
assets of Class C. In the case of Class A shares, amounts paid under the Plan
are paid to the Distributor for services provided. In the case of Class B and
Class C shares, amounts paid under the Plan are paid to the Distributor for (1)
services provided and the expenses borne by it and others in the distribution of
the shares of these Classes, including the payment of commissions for sales of
these Classes and incentive compensation to, and expenses of, Morgan Stanley
Dean Witter Financial Advisors and others who engage in or support distribution
of the shares or who service shareholder accounts, including overhead and
telephone expenses; (2) printing and distribution of prospectuses and reports
used in connection with the offering of these shares to other than current
shareholders; and (3) preparation, printing and distribution of sales literature
and advertising materials. In addition, the Distributor may utilize fees paid
pursuant to the Plan, in the case of Class B shares, to compensate Dean Witter
Reynolds Inc. ("DWR"), an affiliate of the Investment Manager and Distributor,
and other selected broker-dealers for their opportunity costs in advancing such
amounts, which compensation would be in the form of a carrying charge on any
unreimbursed expenses.
 
In the case of Class B shares, provided that the Plan continues in effect, any
cumulative expenses incurred by the Distributor but not yet recovered may be
recovered through the payment of future distribution fees from the Fund pursuant
to the Plan and contingent deferred sales charges paid by investors upon
redemption of Class B shares. Although there is no legal obligation for the Fund
to pay expenses incurred in excess of payments made to the Distributor under the
Plan and the
 
                                       43
<PAGE>
MORGAN STANLEY DEAN WITTER PRECIOUS METALS AND MINERALS TRUST
NOTES TO FINANCIAL STATEMENTS OCTOBER 31, 1998, CONTINUED
 
proceeds of contingent deferred sales charges paid by investors upon redemption
of shares, if for any reason the Plan is terminated, the Trustees will consider
at that time the manner in which to treat such expenses. The Distributor has
advised the Fund that such excess amounts, including carrying charges, totaled
$3,830,463 at October 31, 1998.
 
In the case of Class A shares and Class C shares, expenses incurred pursuant to
the Plan in any calendar year in excess of 0.25% or 1.0% of the average daily
net assets of Class A or Class C, respectively, will not be reimbursed by the
Fund through payments in any subsequent year, except that expenses representing
a gross sales credit to Morgan Stanley Dean Witter Financial Advisors or other
selected broker-dealer representatives may be reimbursed in the subsequent
calendar year. For the year ended October 31, 1998, the distribution fee was
accrued for Class A shares and Class C shares at the annual rate of 0.23% and
1.0%, respectively.
 
The Distributor has informed the Fund that for the year ended October 31, 1998,
it received contingent deferred sales charges from certain redemptions of the
Fund's Class B shares and Class C shares of $81,003 and $1,677, respectively and
received approximately $4,714 in front-end sales charges from sales of the
Fund's Class A shares. The respective shareholders pay such charges which are
not an expense of the Fund.
 
4. SECURITY TRANSACTIONS AND TRANSACTIONS WITH AFFILIATES
 
The cost of purchases and proceeds from sales of portfolio securities, excluding
short-term investments, for the year ended October 31, 1998 aggregated
$15,521,451 and $10,677,356, respectively.
 
For the year ended October 31, 1998, the Fund incurred $13,415 in brokerage
commissions with DWR for portfolio transactions executed on behalf of the Fund.
 
For the year ended October 31, 1998, the Fund incurred $2,500 in brokerage
commissions with Morgan Stanley & Co., Inc., an affiliate of the Investment
Manager and Distributor, for portfolio transactions executed on behalf of the
Fund.
 
Morgan Stanley Dean Witter Trust FSB, an affiliate of the Investment Manager and
Distributor, is the Fund's transfer agent. At October 31, 1998, the Fund had
transfer agent fees and expenses payable of approximately $500.
 
                                       44
<PAGE>
MORGAN STANLEY DEAN WITTER PRECIOUS METALS AND MINERALS TRUST
NOTES TO FINANCIAL STATEMENTS OCTOBER 31, 1998, CONTINUED
 
5. SHARES OF BENEFICIAL INTEREST
 
Transaction in shares of beneficial interest were as follows:
 
<TABLE>
<CAPTION>
                                                                           FOR THE YEAR                  FOR THE YEAR
                                                                              ENDED                         ENDED
                                                                         OCTOBER 31, 1998             OCTOBER 31, 1997*
                                                                   ----------------------------   --------------------------
                                                                     SHARES          AMOUNT         SHARES         AMOUNT
                                                                   -----------   --------------   -----------   ------------
<S>                                                                <C>           <C>              <C>           <C>
CLASS A SHARES
Sold.............................................................      163,290   $      830,904         4,703   $     37,724
Redeemed.........................................................     (149,939)        (771,988)      --             --
                                                                   -----------   --------------   -----------   ------------
Net increase -- Class A..........................................       13,351           58,916         4,703         37,724
                                                                   -----------   --------------   -----------   ------------
CLASS B SHARES
Sold.............................................................   10,593,880       59,088,953    12,331,939    111,539,261
Reinvestment of dividends and distributions......................      --              --             402,436      4,004,238
Redeemed.........................................................  (10,149,788)     (56,742,708)  (12,648,999)  (115,262,441)
                                                                   -----------   --------------   -----------   ------------
Net increase -- Class B..........................................      444,092        2,346,245        85,376        281,058
                                                                   -----------   --------------   -----------   ------------
CLASS C SHARES
Sold.............................................................      604,559        3,428,478        95,151        732,145
Redeemed.........................................................     (465,261)      (2,500,980)      (25,742)      (182,272)
                                                                   -----------   --------------   -----------   ------------
Net increase -- Class C..........................................      139,298          927,498        69,409        549,873
                                                                   -----------   --------------   -----------   ------------
CLASS D SHARES
Sold.............................................................      362,666        2,036,922         1,259         10,010
Redeemed.........................................................     (298,983)      (1,818,453)      --             --
                                                                   -----------   --------------   -----------   ------------
Net increase -- Class D..........................................       63,683          218,469         1,259         10,010
                                                                   -----------   --------------   -----------   ------------
Net increase in Fund.............................................      660,424   $    3,551,128       160,747   $    878,665
                                                                   -----------   --------------   -----------   ------------
                                                                   -----------   --------------   -----------   ------------
</TABLE>
 
- ---------------------
 
 *   For Class A, C and D, for the period July 28, 1997 (issue date) through
     October 31, 1997.
 
6. FEDERAL INCOME TAX STATUS
 
At October 31, 1998, the Fund had a net capital loss carryover of approximately
$20,110,000 of which $10,239,000 will be available through October 31, 2005 and
$9,871,000 will be available through October 31, 2006 to offset future capital
gains to the extent provided by regulations.
 
As of October 31, 1998, the Fund had temporary book/tax differences attributable
to capital loss deferrals on wash sales and income from the mark-to-market of
passive foreign investment companies ("PFICs") and permanent book/tax
differences primarily attributable to a net operating loss and tax adjustments
on PFICs sold by the Fund. To reflect reclassifications arising from the
permanent differences, paid-in-capital was charged $404,421, accumulated net
realized loss was charged $152,096 and net investment loss was credited
$556,517.
 
                                       45
<PAGE>
MORGAN STANLEY DEAN WITTER PRECIOUS METALS AND MINERALS TRUST
NOTES TO FINANCIAL STATEMENTS OCTOBER 31, 1998, CONTINUED
 
7. PURPOSES OF AND RISKS RELATING TO CERTAIN FINANCIAL INSTRUMENTS
 
The Fund may enter into forward foreign currency contracts ("forward contracts")
to facilitate settlement of foreign currency denominated portfolio transactions
or to manage foreign currency exposure associated with foreign currency
denominated securities.
 
Forward contracts involve elements of market risk in excess of the amounts
reflected in the Statement of Assets and Liabilities. The Fund bears the risk of
an unfavorable change in the foreign exchange rates underlying the forward
contracts. Risks may also arise upon entering into these contracts from the
potential inability of the counterparties to meet the terms of their contracts.
 
At October 31, 1998, there were no outstanding forward contracts.
 
                                       46
<PAGE>
MORGAN STANLEY DEAN WITTER PRECIOUS METALS AND MINERALS TRUST
FINANCIAL HIGHLIGHTS
 
Selected ratios and per share data for a share of beneficial interest
outstanding throughout each period:
 
<TABLE>
<CAPTION>
                                                           FOR THE YEAR ENDED OCTOBER 31
                                          ----------------------------------------------------------------
                                           1998++       1997*++         1996          1995          1994
- ----------------------------------------------------------------------------------------------------------
 
<S>                                       <C>           <C>           <C>           <C>           <C>
CLASS B SHARES
 
SELECTED PER SHARE DATA:
 
Net asset value, beginning of period....  $   6.85      $  11.14      $   9.77      $  11.45      $  10.80
                                          --------      --------      --------      --------      --------
 
Income (loss) from investment
 operations:
   Net investment loss..................     (0.09)        (0.10)        (0.10)        (0.08)        (0.06)
   Net realized and unrealized gain
   (loss)...............................     (1.75)        (3.35)         1.66         (1.38)         0.73
                                          --------      --------      --------      --------      --------
 
Total income (loss) from investment
 operations.............................     (1.84)        (3.45)         1.56         (1.46)         0.67
                                          --------      --------      --------      --------      --------
 
Less dividends and distributions from:
   Net investment income................     --            (0.13)        --            --            --
   Net realized gain....................     --            (0.71)        (0.19)        (0.22)        (0.02)
                                          --------      --------      --------      --------      --------
 
Total dividends and distributions.......     --            (0.84)        (0.19)        (0.22)        (0.02)
                                          --------      --------      --------      --------      --------
 
Net asset value, end of period..........  $   5.01      $   6.85      $  11.14      $   9.77      $  11.45
                                          --------      --------      --------      --------      --------
                                          --------      --------      --------      --------      --------
 
TOTAL RETURN+...........................    (26.86)%      (33.29)%       15.93%       (12.78)%        6.18%
 
RATIOS TO AVERAGE NET ASSETS:
Expenses................................      2.78%(1)      2.36%         2.27%         2.29%         2.28%
 
Net investment loss.....................     (1.55)%(1)    (1.13)%       (0.84)%       (0.70)%       (0.87)%
 
SUPPLEMENTAL DATA:
Net assets, end of period, in
 thousands..............................   $30,005       $37,964       $60,841       $55,448       $73,444
 
Portfolio turnover rate.................        36%           53%           46%           23%           46%
</TABLE>
 
- ---------------------
 
 *   Prior to July 28, 1997, the Fund issued one class of shares. All shares of
     the Fund held prior to that date have been designated Class B shares.
++   The per share amounts were computed using an average number of shares
     outstanding during the period.
 +   Does not reflect the deduction of sales charges. Calculated based on the
     net asset value as of the last business day of the period.
(1)  Reflects overall Fund ratios for investment income and non-class specific
     expenses.
 
                       SEE NOTES TO FINANCIAL STATEMENTS
                                       47
<PAGE>
MORGAN STANLEY DEAN WITTER PRECIOUS METALS AND MINERALS TRUST
FINANCIAL HIGHLIGHTS, CONTINUED
 
<TABLE>
<CAPTION>
                                                                                  FOR THE PERIOD
                                                                FOR THE YEAR      JULY 28, 1997*
                                                                   ENDED         THROUGH OCTOBER
                                                              OCTOBER 31, 1998       31, 1997
- -------------------------------------------------------------------------------------------------
<S>                                                           <C>                <C>
CLASS A SHARES++
SELECTED PER SHARE DATA:
Net asset value, beginning of period........................      $  6.86            $  7.95
                                                                   ------             ------
Loss from investment operations:
   Net investment loss......................................        (0.05)           --
   Net realized and unrealized loss.........................        (1.76)             (1.09)
                                                                   ------             ------
Total loss from investment operations.......................        (1.81)             (1.09)
                                                                   ------             ------
Net asset value, end of period..............................      $  5.05            $  6.86
                                                                   ------             ------
                                                                   ------             ------
TOTAL RETURN+...............................................       (26.38)%           (13.71)%(1)
RATIOS TO AVERAGE NET ASSETS:
Expenses....................................................         2.01%(3)           1.61%(2)
Net investment loss.........................................        (0.78)%(3)         (0.08)%(2)
SUPPLEMENTAL DATA:
Net assets, end of period, in thousands.....................          $91                $32
Portfolio turnover rate.....................................           36%                53%
</TABLE>
 
<TABLE>
<S>                                                           <C>                <C>
CLASS C SHARES++
SELECTED PER SHARE DATA:
Net asset value, beginning of period........................        $6.84              $7.95
                                                                   ------             ------
Loss from investment operations:
   Net investment loss......................................        (0.09)             (0.02)
   Net realized and unrealized loss.........................        (1.74)             (1.09)
                                                                   ------             ------
Total loss from investment operations.......................        (1.83)             (1.11)
                                                                   ------             ------
Net asset value, end of period..............................        $5.01              $6.84
                                                                   ------             ------
                                                                   ------             ------
TOTAL RETURN+...............................................       (26.75)%           (13.96)%(1)
RATIOS TO AVERAGE NET ASSETS:
Expenses....................................................         2.78%(3)           2.37%(2)
Net investment loss.........................................        (1.55)%(3)         (0.79)%(2)
SUPPLEMENTAL DATA:
Net assets, end of period, in thousands.....................       $1,046               $475
Portfolio turnover rate.....................................           36%                53%
</TABLE>
 
- ---------------------
 
 *   The date shares were first issued.
++   The per share amounts were computed using an average number of shares
     outstanding during the period.
 +   Does not reflect the deduction of sales charges. Calculated based on the
     net asset value as of the last business day of the period.
(1)  Not annualized.
(2)  Annualized.
(3)  Reflects overall Fund ratios for investment income and non-class specific
     expenses.
 
                       SEE NOTES TO FINANCIAL STATEMENTS
                                       48
<PAGE>
MORGAN STANLEY DEAN WITTER PRECIOUS METALS AND MINERALS TRUST
FINANCIAL HIGHLIGHTS, CONTINUED
 
<TABLE>
<CAPTION>
                                                                                  FOR THE PERIOD
                                                                FOR THE YEAR      JULY 28, 1997*
                                                                   ENDED             THROUGH
                                                              OCTOBER 31, 1998   OCTOBER 31, 1997
- -------------------------------------------------------------------------------------------------
 
<S>                                                           <C>                <C>
CLASS D SHARES++
 
SELECTED PER SHARE DATA:
 
Net asset value, beginning of period........................      $  6.86            $  7.95
                                                                   ------             ------
 
Income (loss) from investment operations:
   Net investment income....................................         0.02            --
   Net realized and unrealized loss.........................        (1.85)             (1.09)
                                                                   ------             ------
 
Total loss from investment operations.......................        (1.83)             (1.09)
                                                                   ------             ------
 
Net asset value, end of period..............................      $  5.03            $  6.86
                                                                   ------             ------
                                                                   ------             ------
 
TOTAL RETURN+...............................................       (26.68)%           (13.71)%(1)
 
RATIOS TO AVERAGE NET ASSETS:
 
Expenses....................................................         1.78%(3)           1.35%(2)
 
Net investment income (loss)................................        (0.55)%(3)          0.22%(2)
 
SUPPLEMENTAL DATA:
 
Net assets, end of period, in thousands.....................         $327                 $9
 
Portfolio turnover rate.....................................           36%                53%
</TABLE>
 
- ---------------------
 
 *   The date shares were first issued.
++   The per share amounts were computed using an average number of shares
     outstanding during the period.
 +   Calculated based on the net asset value as of the last business day of the
     period.
(1)  Not annualized.
(2)  Annualized.
(3)  Reflects overall Fund ratios for investment income and non-class specific
     expenses.
 
                       SEE NOTES TO FINANCIAL STATEMENTS
                                       49
<PAGE>
 
MORGAN STANLEY DEAN WITTER PRECIOUS METALS AND
MINERALS TRUST
REPORT OF INDEPENDENT ACCOUNTANTS
 
TO THE SHAREHOLDERS AND TRUSTEES
OF MORGAN STANLEY DEAN WITTER PRECIOUS METALS AND MINERALS TRUST
 
In our opinion, the accompanying statement of assets and liabilities, including
the portfolio of investments, and the related statements of operations and of
changes in net assets and the financial highlights present fairly, in all
material respects, the financial position of Morgan Stanley Dean Witter Precious
Metals and Minerals Trust (the "Fund"), formerly Dean Witter Precious Metals and
Minerals Trust at October 31, 1998, the results of its operations for the year
then ended, the changes in its net assets for each of the two years in the
period then ended and the financial highlights for each of the periods
presented, in conformity with generally accepted accounting principles. These
financial statements and financial highlights (hereafter referred to as
"financial statements") are the responsibility of the Fund's management; our
responsibility is to express an opinion on these financial statements based on
our audits. We conducted our audits of these financial statements in accordance
with generally accepted auditing standards which require that we plan and
perform the audit to obtain reasonable assurance about whether the financial
statements are free of material misstatement. An audit includes examining, on a
test basis, evidence supporting the amounts and disclosures in the financial
statements, assessing the accounting principles used and significant estimates
made by management, and evaluating the overall financial statement presentation.
We believe that our audits, which included confirmation of securities at October
31, 1998 by correspondence with the custodian and brokers, provide a reasonable
basis for the opinion expressed above.
 
PricewaterhouseCoopers LLP
1177 AVENUE OF THE AMERICAS
NEW YORK, NEW YORK 10036
DECEMBER 7, 1998
 
                                       50


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