MORGAN STANLEY DEAN WITTER INTERMEDIATE INCOME SECURITIES
497, 1998-11-05
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<PAGE>
              PROSPECTUS
              OCTOBER 30, 1998
 
              Morgan Stanley Dean Witter Intermediate Income Securities (the
"Fund") is an open-end, diversified management investment company, whose
investment objective is high current income consistent with safety of principal.
The Fund seeks to achieve its investment objective by investing primarily in
intermediate term, investment grade fixed-income securities. See "Investment
Objective and Policies."
 
               The Fund offers four classes of shares (each, a "Class"), each
with a different combination of sales charges, ongoing fees and other features.
The different distribution arrangements permit an investor to choose the method
of purchasing shares that the investor believes is most beneficial given the
amount of the purchase, the length of time the investor expects to hold the
shares and other relevant circumstances. See "Purchase of Fund
Shares--Alternative Purchase Arrangements."
 
               This Prospectus sets forth concisely the information you should
know before investing in the Fund. It should be read and retained for future
reference. Additional information about the Fund is contained in the Statement
of Additional Information, dated October 30, 1998, which has been filed with the
Securities and Exchange Commission, and which is available at no charge upon
request of the Fund at the address or telephone numbers listed on this page. The
Statement of Additional Information is incorporated herein by reference.
 
     MORGAN STANLEY DEAN WITTER
     DISTRIBUTORS INC.
      DISTRIBUTOR
 
      TABLE OF CONTENTS
 
Prospectus Summary/2
Summary of Fund Expenses/4
Financial Highlights/6
The Fund and its Management/9
Investment Objective and Policies/9
  Risk Considerations/13
Investment Restrictions/14
Purchase of Fund Shares/14
Shareholder Services/26
Redemptions and Repurchases/29
Dividends, Distributions and Taxes/30
Performance Information/31
Additional Information/32
 
SHARES OF THE FUND ARE NOT DEPOSITS OR OBLIGATIONS OF, OR GUARANTEED OR ENDORSED
BY, ANY BANK, AND THE SHARES ARE NOT FEDERALLY INSURED BY THE FEDERAL DEPOSIT
INSURANCE CORPORATION, THE FEDERAL RESERVE BOARD, OR ANY OTHER AGENCY.
 
THESE SECURITIES HAVE NOT BEEN APPROVED OR DISAPPROVED BY THE SECURITIES AND
EXCHANGE COMMISSION OR ANY STATE SECURITIES COMMISSION NOR HAS THE SECURITIES
AND EXCHANGE COMMISSION OR ANY STATE SECURITIES COMMISSION PASSED UPON THE
ACCURACY OR ADEQUACY OF THIS PROSPECTUS. ANY REPRESENTATION TO THE CONTRARY IS A
CRIMINAL OFFENSE.
 
    Morgan Stanley Dean Witter
    Intermediate Income Securities
    Two World Trade Center
    New York, New York 10048
    (212) 392-2550 or
    (800) 869-NEWS (toll-free)
<PAGE>
PROSPECTUS SUMMARY
- --------------------------------------------------------------------------------
 
   
<TABLE>
<S>                 <C>
The                 The Fund is organized as a Trust, commonly known as a Massachusetts business trust, and is an open- end,
Fund                diversified management investment company. The Fund invests primarily in intermediate term, investment grade
                    fixed-income securities.
- ------------------------------------------------------------------------------------------------------------------------------------
Shares              Shares of beneficial interest with $0.01 par value (see page 32). The Fund offers four Classes of shares, each
Offered             with a different combination of sales charges, ongoing fees and other features (see pages 14).
- ------------------------------------------------------------------------------------------------------------------------------------
Minimum             The minimum initial investment for each Class is $1,000 ($100 if the account is opened through EasyInvest-SM-).
Purchase            Class D shares are only available to persons investing $5 million ($25 million for certain qualified plans) or
                    more and to certain other limited categories of investors. For the purpose of meeting the minimum $5 million (or
                    $25 million) investment for Class D shares, and subject to the $1,000 minimum initial investment for each Class
                    of the Fund, an investor's existing holdings of Class A shares and shares of funds for which Morgan Stanley Dean
                    Witter Advisors Inc. serves as investment manager ("Morgan Stanley Dean Witter Funds") that are sold with a
                    front-end sales charge, and concurrent investments in Class D shares of the Fund and other Morgan Stanley Dean
                    Witter Funds that are multiple class funds, will be aggregated. The minimum subsequent investment is $100 (see
                    page 14).
- ------------------------------------------------------------------------------------------------------------------------------------
Investment          The investment objective of the Fund is high current income consistent with safety of principal (see page 9).
Objective
- ------------------------------------------------------------------------------------------------------------------------------------
Investment          Morgan Stanley Dean Witter Advisors Inc., the Investment Manager of the Fund, and its wholly-owned subsidiary,
Manager             Morgan Stanley Dean Witter Services Company Inc., serve in various investment management, advisory, management
                    and administrative capacities to 100 investment companies and other portfolios with assets of approximately
                    $113.7 billion at September 30, 1998 (see page 9).
- ------------------------------------------------------------------------------------------------------------------------------------
Management          The Investment Manager receives a monthly fee at the annual rate of 0.60% of daily net assets, scaled down on
Fee                 assets over $500 million (see page 9).
- ------------------------------------------------------------------------------------------------------------------------------------
Distributor         Morgan Stanley Dean Witter Distributors Inc. is the Distributor of the Fund's shares. The Fund has adopted a
and                 distribution plan pursuant to Rule 12b-1 under the Investment Company Act (the "12b-1 Plan") with respect to the
Distribution        distribution fees paid by the Class A, Class B and Class C shares of the Fund to the Distributor. The entire
Fee                 12b-1 fee payable by Class A and a portion of the 12b-1 fee payable by each of Class B and Class C equal to
                    0.20% of the average daily net assets of Class B and 0.25% of the average daily net assets of Class C are
                    currently each characterized as a service fee within the meaning of the National Association of Securities
                    Dealers, Inc. guidelines. The remaining portion of the 12b-1 fee, if any, is characterized as an asset-based
                    sales charge (see pages 14 and 24).
- ------------------------------------------------------------------------------------------------------------------------------------
Alternative         Four classes of shares are offered:
Purchase
Arrangements        - Class A shares are offered with a front-end sales charge, starting at 4.25% and reduced for larger purchases.
                    Investments of $1 million or more (and investments by certain other limited categories of investors) are not
                    subject to any sales charge at the time of purchase but a contingent deferred sales charge ("CDSC") of 1.0% may
                    be imposed on redemptions within one year of purchase. The Fund is authorized to reimburse the Distributor for
                    specific expenses incurred in promoting the distribution of the Fund's Class A shares and servicing shareholder
                    accounts pursuant to the Fund's 12b-1 Plan. Reimbursement may in no event exceed an amount equal to payments at
                    an annual rate of 0.25% of average daily net assets of the Class (see pages 14, 18 and 24).
</TABLE>
    
 
- --------------------------------------------------------------------------------
 
                                       2
<PAGE>
- --------------------------------------------------------------------------------
   
<TABLE>
<S>                 <C>
                    - Class B shares are offered without a front-end sales charge, but will in most cases be subject to a CDSC
                    (scaled down from 5.0% to 1.0%) if redeemed within six years after purchase. The CDSC will be imposed on any
                    redemption of shares if after such redemption the aggregate current value of a Class B account with the Fund
                    falls below the aggregate amount of the investor's purchase payments made during the six years preceding the
                    redemption. A different CDSC schedule applies to investments by certain qualified plans. Class B shares are also
                    subject to a 12b-1 fee assessed at the annual rate of 0.85% of the lesser of: (a) the average daily net sales of
                    the Fund's Class B shares or (b) the average daily net assets of Class B. All shares of the Fund held prior to
                    July 28, 1997 (other than the shares held by certain employee benefit plans established by certain subsidiaries
                    of Morgan Stanley Dean Witter & Co.) have been designated Class B shares. Shares held by those employee benefit
                    plans prior to July 28, 1997 have been designated Class D shares. Shares held before May 1, 1997 that have been
                    designated Class B shares will convert to Class A shares in May 2007. In all other instances, Class B shares
                    convert to Class A shares approximately ten years after the date of the original purchase (see pages 14, 20 and
                    24).
                    - Class C shares are offered without a front-end sales charge, but will in most cases be subject to a CDSC of
                    1.0% if redeemed within one year after purchase. The Fund is authorized to reimburse the Distributor for
                    specific expenses incurred in promoting the distribution of the Fund's Class C shares and servicing shareholder
                    accounts pursuant to the Fund's 12b-1 Plan. Reimbursement may in no event exceed an amount equal to payments at
                    an annual rate of 0.85% of average daily net assets of the Class (see pages 14, 23 and 24).
                    - Class D shares are offered only to investors meeting an initial investment minimum of $5 million ($25 million
                    for certain qualified plans) and to certain other limited categories of investors. Class D shares are offered
                    without a front-end sales charge or CDSC and are not subject to any 12b-1 fee (see pages 14, 23 and 24).
- ------------------------------------------------------------------------------------------------------------------------------------
Dividends           Dividends are declared daily, and either paid monthly in additional shares of the Fund or, at the shareholder's
and                 option, paid monthly in cash. Dividends from net short-term, mid-term and long-term capital gains, if any, are
Capital Gains       distributed at least once each year. The Fund may, however, determine to retain all or part of any net long-term
Distributions       and net mid-term capital gains in any year for reinvestment. Dividends and capital gains distributions paid on
                    shares of a Class are automatically reinvested in additional shares of the same Class at net asset value unless
                    the shareholder elects to receive cash. Shares acquired by dividend and distribution reinvestment will not be
                    subject to any sales charge or CDSC (see pages 26 and 30).
- ------------------------------------------------------------------------------------------------------------------------------------
Redemption          Shares are redeemable by the shareholder at net asset value less any applicable CDSC on Class A, Class B or
                    Class C shares. An account may be involuntarily redeemed if the total value of the account is less than $100 or,
                    if the account was opened through EasyInvest-SM-, if after twelve months the shareholder has invested less than
                    $1,000 in the account (see page 29).
- ------------------------------------------------------------------------------------------------------------------------------------
Risk                The net asset value of the Fund's shares will fluctuate with changes in the market value of its portfolio
Considerations      securities. Interest rate fluctuations will affect the Fund's net asset value but not the income received by the
                    Fund from its portfolio securities. The Fund may engage in various investment strategies including reverse
                    repurchase agreements, when-issued and delayed delivery securities and forward commitments and when, as and if
                    issued securities. The risks associated with these investments are included in their description (pages 9-12)
                    and in the "Risk Considerations" section (page 13).
</TABLE>
    
 
- --------------------------------------------------------------------------------
 
  THE ABOVE IS QUALIFIED IN ITS ENTIRETY BY THE DETAILED INFORMATION APPEARING
                ELSEWHERE IN THE PROSPECTUS AND IN THE STATEMENT
                           OF ADDITIONAL INFORMATION.
 
                                       3
<PAGE>
SUMMARY OF FUND EXPENSES
- --------------------------------------------------------------------------------
 
    The following table illustrates all expenses and fees that a shareholder of
the Fund will incur. The expenses and fees set forth in the table are based on
the expenses and fees for the fiscal year ended August 31, 1998.
 
   
<TABLE>
<CAPTION>
                                                                                   CLASS A    CLASS B    CLASS C    CLASS D
                                                                                  ---------   -------   ---------   -------
<S>                                                                               <C>         <C>       <C>         <C>
SHAREHOLDER TRANSACTION EXPENSES
- --------------------------------------------------------------------------------
Maximum Sales Charge Imposed on Purchases (as a percentage of offering price)...   4.25%(1)    None      None        None
Sales Charge Imposed on Dividend Reinvestments..................................   None        None      None        None
Maximum Contingent Deferred Sales Charge (as a percentage of original purchase
  price or redemption proceeds).................................................   None(2)     5.00%(3)  1.00%(4)    None
Redemption Fees.................................................................   None        None      None        None
Exchange Fee....................................................................   None        None      None        None
ANNUAL FUND OPERATING EXPENSES (AS A PERCENTAGE OF AVERAGE NET ASSETS)
- --------------------------------------------------------------------------------
Management Fees.................................................................   0.60%       0.60%     0.60%       0.60%
12b-1 Fees (5) (6)..............................................................   0.24%       0.85%     0.85%       None
Other Expenses..................................................................   0.26%       0.26%     0.26%       0.26%
Total Fund Operating Expenses...................................................   1.10%       1.71%     1.71%       0.86%
</TABLE>
    
 
- ------------
(1) REDUCED FOR PURCHASES OF $25,000 AND OVER (SEE "PURCHASE OF FUND
    SHARES--INITIAL SALES CHARGE ALTERNATIVE--CLASS A SHARES").
 
(2) INVESTMENTS THAT ARE NOT SUBJECT TO ANY SALES CHARGE AT THE TIME OF PURCHASE
    ARE SUBJECT TO A CDSC OF 1.00% THAT WILL BE IMPOSED ON REDEMPTIONS MADE
    WITHIN ONE YEAR AFTER PURCHASE, EXCEPT FOR CERTAIN SPECIFIC CIRCUMSTANCES
    (SEE "PURCHASE OF FUND SHARES--INITIAL SALES CHARGE ALTERNATIVE--CLASS A
    SHARES").
 
(3) THE CDSC IS SCALED DOWN TO 1.00% DURING THE SIXTH YEAR, REACHING ZERO
    THEREAFTER.
 
   
(4) ONLY APPLICABLE TO REDEMPTIONS MADE WITHIN ONE YEAR AFTER PURCHASE (SEE
    "PURCHASE OF FUND SHARES-- LEVEL LOAD ALTERNATIVE--CLASS C SHARES").
    
 
   
(5) THE 12B-1 FEE IS ACCRUED DAILY AND PAYABLE MONTHLY. THE ENTIRE 12B-1 FEE
    PAYABLE BY CLASS A AND A PORTION OF THE 12B-1 FEE PAYABLE BY EACH OF CLASS B
    AND CLASS C EQUAL TO 0.20% OF THE AVERAGE DAILY NET ASSETS OF CLASS B AND
    0.25% OF THE AVERAGE DAILY NET ASSETS OF CLASS C ARE CURRENTLY EACH
    CHARACTERIZED AS A SERVICE FEE WITHIN THE MEANING OF NATIONAL ASSOCIATION OF
    SECURITIES DEALERS, INC. ("NASD") GUIDELINES AND ARE PAYMENTS MADE FOR
    PERSONAL SERVICE AND/OR MAINTENANCE OF SHAREHOLDER ACCOUNTS. THE REMAINDER
    OF THE 12B-1 FEE, IF ANY, IS AN ASSET-BASED SALES CHARGE, AND IS A
    DISTRIBUTION FEE PAID TO THE DISTRIBUTOR TO COMPENSATE IT FOR THE SERVICES
    PROVIDED AND THE EXPENSES BORNE BY THE DISTRIBUTOR AND OTHERS IN THE
    DISTRIBUTION OF THE FUND'S SHARES (SEE "PURCHASE OF FUND SHARES--PLAN OF
    DISTRIBUTION").
    
 
   
(6) UPON CONVERSION OF CLASS B SHARES TO CLASS A SHARES, SUCH SHARES WILL BE
    SUBJECT TO THE LOWER 12B-1 FEE APPLICABLE TO CLASS A SHARES. NO SALES CHARGE
    IS IMPOSED AT THE TIME OF CONVERSION OF CLASS B SHARES TO CLASS A SHARES.
    CLASS C SHARES DO NOT HAVE A CONVERSION FEATURE AND, THEREFORE, ARE SUBJECT
    TO AN ONGOING 0.85% DISTRIBUTION FEE (SEE "PURCHASE OF FUND
    SHARES--ALTERNATIVE PURCHASE ARRANGEMENTS").
    
 
                                       4
<PAGE>
- --------------------------------------------------------------------------------
 
<TABLE>
<CAPTION>
EXAMPLES                                            1 Year   3 Years   5 Years   10 Years
- --------------------------------------------------  ------   -------   -------   --------
<S>                                                 <C>      <C>       <C>       <C>
You would pay the following expenses on a $1,000
 investment assuming (1) a 5% annual return and
 (2) redemption at the end of each time period:
    Class A.......................................   $53       $76       $100      $171
    Class B.......................................   $67       $84       $113      $202
    Class C.......................................   $27       $54       $93       $202
    Class D.......................................   $ 9       $27       $48       $106
 
You would pay the following expenses on the same
 $1,000 investment assuming no redemption at the
 end of the period:
    Class A.......................................   $53       $76       $100      $171
    Class B.......................................   $17       $54       $93       $202
    Class C.......................................   $17       $54       $93       $202
    Class D.......................................   $ 9       $27       $48       $106
</TABLE>
 
    THE ABOVE EXAMPLES SHOULD NOT BE CONSIDERED A REPRESENTATION OF PAST OR
FUTURE EXPENSES OR PERFORMANCE. ACTUAL EXPENSES OF EACH CLASS MAY BE GREATER OR
LESS THAN THOSE SHOWN.
 
    The purpose of this table is to assist the investor in understanding the
various costs and expenses that an investor in the Fund will bear directly or
indirectly. For a more complete description of these costs and expenses, see
"The Fund and Its Management," "Purchase of Fund Shares--Plan of Distribution"
and "Redemptions and Repurchases."
 
    Long-term shareholders of Class B and Class C may pay more in sales charges,
including distribution fees, than the economic equivalent of the maximum
front-end sales charges permitted by the NASD.
 
                                       5
<PAGE>
FINANCIAL HIGHLIGHTS
- --------------------------------------------------------------------------------
 
    The following ratios and per share data for a share of beneficial interest
outstanding throughout each period have been audited by PricewaterhouseCoopers
LLP, independent accountants. The financial highlights should be read in
conjunction with the financial statements, notes thereto, and the unqualified
report of independent accountants, which are contained in the Statement of
Additional Information. Further information about the performance of the Fund is
contained in the Fund's Annual Report to Shareholders, which may be obtained
without charge upon request to the Fund.
   
<TABLE>
<CAPTION>
                                        FOR THE YEAR ENDED AUGUST 31
                             ---------------------------------------------------
CLASS B SHARES               1998++     1997**++    1996       1995       1994
                             -------    -------    -------    -------    -------
<S>                          <C>        <C>        <C>        <C>        <C>
PER SHARE OPERATING
 PERFORMANCE:
Net asset value, beginning
 of period................   $  9.59    $  9.39    $  9.69    $  9.51    $ 10.26
                             -------    -------    -------    -------    -------
Net investment income.....      0.51       0.53       0.55       0.59       0.58
Net realized and
 unrealized gain (loss)...      0.11       0.20      (0.30)      0.19      (0.73)
                             -------    -------    -------    -------    -------
Total from investment
 operations...............      0.62       0.73       0.25       0.78      (0.15)
                             -------    -------    -------    -------    -------
Less dividends and
 distributions from:
   Net investment
    income................     (0.51)     (0.53)     (0.55)     (0.59)     (0.56)
   Net realized gain......        --         --         --      (0.01)     (0.04)
                             -------    -------    -------    -------    -------
Total dividends and
 distributions............     (0.51)     (0.53)     (0.55)     (0.60)     (0.60)
                             -------    -------    -------    -------    -------
Net asset value, end of
 period...................   $  9.70    $  9.59    $  9.39    $  9.69    $  9.51
                             -------    -------    -------    -------    -------
                             -------    -------    -------    -------    -------
TOTAL INVESTMENT
 RETURN+..................     6.53%      7.93%      2.58%      8.56%    (1.50)%
RATIOS TO AVERAGE NET
 ASSETS:
Expenses..................     1.71%(4)   1.65%      1.62%      1.63%      1.63%
Net investment income.....     5.19%(4)   5.52%      5.69%      6.23%      5.80%
SUPPLEMENTAL DATA:
Net assets, end of period,
 in thousands.............   $151,515   $162,959   $208,911   $232,752   $245,750
Portfolio turnover rate...       98%        98%       115%       114%       122%
 
<CAPTION>
                                                                         FOR THE PERIOD
                                                                          MAY 3, 1989*
                                                                             THROUGH
CLASS B SHARES                1993       1992       1991       1990      AUGUST 31, 1989
                             -------    -------    -------    -------    ---------------
<S>                          <C>        <C>        <C>        <C>        <C>
PER SHARE OPERATING
 PERFORMANCE:
Net asset value, beginning
 of period................   $ 10.05    $  9.59    $  9.42    $  9.98    $   10.00
                             -------    -------    -------    -------      -------
Net investment income.....      0.62       0.70       0.79       0.86         0.28
Net realized and
 unrealized gain (loss)...      0.20       0.46       0.17      (0.55)       (0.02)
                             -------    -------    -------    -------      -------
Total from investment
 operations...............      0.82       1.16       0.96       0.31         0.26
                             -------    -------    -------    -------      -------
Less dividends and
 distributions from:
   Net investment
    income................     (0.61)     (0.70)     (0.79)     (0.86)       (0.28)
   Net realized gain......        --         --         --      (0.01)          --
                             -------    -------    -------    -------      -------
Total dividends and
 distributions............     (0.61)     (0.70)     (0.79)     (0.87)       (0.28)
                             -------    -------    -------    -------      -------
Net asset value, end of
 period...................   $ 10.26    $ 10.05    $  9.59    $  9.42    $    9.98
                             -------    -------    -------    -------      -------
                             -------    -------    -------    -------      -------
TOTAL INVESTMENT
 RETURN+..................     8.43%     12.58%     10.78%      3.22%        2.57%(1)
RATIOS TO AVERAGE NET
 ASSETS:
Expenses..................     1.62%      1.69%      1.69%      1.75%        1.42%(2)(3)
Net investment income.....     6.12%      7.11%      8.49%      8.78%        8.18%(2)(3)
SUPPLEMENTAL DATA:
Net assets, end of period,
 in thousands.............   $254,431   $187,285   $115,204   $114,086     $69,946
Portfolio turnover rate...      132%        93%       150%       135%          30%(1)
</TABLE>
    
 
- ---------------
 * COMMENCEMENT OF OPERATIONS.
 ** PRIOR TO JULY 28, 1997, THE FUND ISSUED ONE CLASS OF SHARES. ALL SHARES OF
    THE FUND HELD PRIOR TO THAT DATE, OTHER THAN SHARES HELD BY CERTAIN EMPLOYEE
    BENEFIT PLANS ESTABLISHED BY DEAN WITTER REYNOLDS INC. AND ITS AFFILIATE,
    SPS TRANSACTION SERVICES, INC., HAVE BEEN DESIGNATED AS CLASS B SHARES.
    SHARES HELD BY THOSE EMPLOYEE BENEFIT PLANS PRIOR TO JULY 28, 1997 HAVE BEEN
    DESIGNATED CLASS D SHARES.
 ++ THE PER SHARE AMOUNTS WERE COMPUTED USING AN AVERAGE NUMBER OF SHARES
    OUTSTANDING DURING THE PERIOD.
 + DOES NOT REFLECT THE DEDUCTION OF SALES CHARGE. CALCULATED BASED ON THE NET
   ASSET VALUE AS OF THE LAST BUSINESS DAY OF THE PERIOD.
(1) NOT ANNUALIZED.
(2) ANNUALIZED.
(3) IF THE FUND HAD BORNE ALL THE EXPENSES THAT WERE ASSUMED OR WAIVED BY THE
    INVESTMENT MANAGER, THE ABOVE EXPENSE AND NET INVESTMENT INCOME RATIOS WOULD
    HAVE BEEN 2.15% AND 7.44%, RESPECTIVELY.
(4) REFLECTS OVERALL FUND RATIOS FOR INVESTMENT INCOME AND NON-CLASS SPECIFIC
EXPENSES.
 
                                       6
<PAGE>
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<TABLE>
<CAPTION>
                                                                                            FOR THE PERIOD
                                                                          FOR THE YEAR      JULY 28, 1997*
                                                                             ENDED             THROUGH
                                                                           AUGUST 31,         AUGUST 31,
CLASS A SHARES                                                               1998++             1997++
                                                                        ----------------   ----------------
<S>                                                                     <C>                <C>
PER SHARE OPERATING PERFORMANCE:
Net asset value, beginning of period..................................      $  9.59            $  9.68
                                                                            -------            -------
Net investment income.................................................         0.56               0.06
Net realized and unrealized gain (loss)...............................         0.13              (0.10)
                                                                            -------            -------
Total from investment operations......................................         0.69              (0.04)
                                                                            -------            -------
Less dividends from net investment income.............................        (0.57)             (0.05)
                                                                            -------            -------
Net asset value, end of period........................................      $  9.71            $  9.59
                                                                            -------            -------
                                                                            -------            -------
TOTAL INVESTMENT RETURN+..............................................         7.30%             (0.46)%(1)
RATIOS TO AVERAGE NET ASSETS:
Expenses..............................................................         1.10%(3)           2.18%(2)
Net investment income.................................................         5.80%(3)           6.10%(2)
SUPPLEMENTAL DATA:
Net assets, end of period, in thousands...............................       $3,457             $1,855
Portfolio turnover rate...............................................           98%                98%
 
<CAPTION>
 
CLASS C SHARES
<S>                                                                     <C>                <C>
PER SHARE OPERATING PERFORMANCE:
Net asset value, beginning of period..................................      $  9.61            $  9.68
                                                                            -------            -------
Net investment income.................................................         0.49               0.04
Net realized and unrealized gain (loss)...............................         0.11              (0.07)
                                                                            -------            -------
Total from investment operations......................................         0.60              (0.03)
                                                                            -------            -------
Less dividends from net investment income.............................        (0.50)             (0.04)
                                                                            -------            -------
Net asset value, end of period........................................      $  9.71            $  9.61
                                                                            -------            -------
                                                                            -------            -------
TOTAL INVESTMENT RETURN+..............................................         6.39%             (0.31)%(1)
RATIOS TO AVERAGE NET ASSETS:
Expenses..............................................................         1.71%(3)           2.02%(2)
Net investment income.................................................         5.19%(3)           4.22%(2)
SUPPLEMENTAL DATA:
Net assets, end of period, in thousands...............................         $457                $38
Portfolio turnover rate...............................................           98%                98%
</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 CHARGE. 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.
 
                                       7
<PAGE>
- --------------------------------------------------------------------------------
 
<TABLE>
<CAPTION>
                                                                                            FOR THE PERIOD
                                                                                            JULY 28, 1997*
                                                                          FOR THE YEAR         THROUGH
                                                                              ENDED           AUGUST 31,
CLASS D SHARES                                                          AUGUST 31, 1998++       1997++
                                                                        -----------------   --------------
<S>                                                                     <C>                 <C>
PER SHARE OPERATING PERFORMANCE:
Net asset value, beginning of period..................................       $ 9.59             $ 9.68
                                                                            -------            -------
Net investment income.................................................         0.59               0.05
Net realized and unrealized gain (loss)...............................         0.11              (0.09)
                                                                            -------            -------
Total from investment operations......................................         0.70              (0.04)
                                                                            -------            -------
Less dividends from net investment income.............................        (0.59)             (0.05)
                                                                            -------            -------
Net asset value, end of period........................................       $ 9.70             $ 9.59
                                                                            -------            -------
                                                                            -------            -------
 
TOTAL INVESTMENT RETURN+..............................................         7.43%             (0.44)%(1)
 
RATIOS TO AVERAGE NET ASSETS:
Expenses..............................................................         0.86%(3)           1.11%(2)
Net investment income.................................................         6.04%(3)           5.91%(2)
 
SUPPLEMENTAL DATA:
Net assets, end of period, in thousands...............................       $5,726             $4,880
Portfolio turnover rate...............................................           98%                98%
</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.
 
                                       8
<PAGE>
THE FUND AND ITS MANAGEMENT
- --------------------------------------------------------------------------------
 
    Morgan Stanley Dean Witter Intermediate Income Securities (formerly named
Dean Witter Intermediate Income Securities) (the "Fund") is an open-end,
diversified management investment company. The Fund is a trust of the type
commonly known as a "Massachusetts business trust" and was organized under the
laws of the Commonwealth of Massachusetts on September 1, 1988.
 
   
    Morgan Stanley Dean Witter Advisors Inc. ("MSDW Advisors" or the "Investment
Manager"), whose address is Two World Trade Center, New York, New York 10048, is
the Fund's Investment Manager. 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. The
Investment Manager, which was incorporated in July, 1992 under the name Dean
Witter InterCapital Inc., changed its name to Morgan Stanley Dean Witter
Advisors Inc. on June 22, 1998.
    
 
    MSDW Advisors and its wholly-owned subsidiary, Morgan Stanley Dean Witter
Services Company Inc. ("MSDW Services"), serve in various investment management,
advisory, management and administrative capacities to 100 investment companies,
28 of which are listed on the New York Stock Exchange, with combined assets of
approximately $109.6 billion at September 30, 1998. The Investment Manager also
manages portfolios of pension plans, other institutions and individuals which
aggregated approximately $4.1 billion at such date.
 
    The Fund has retained the Investment Manager to provide administrative
services, manage its business affairs and manage the investment of the Fund's
assets, including the placing of orders for the purchase and sale of portfolio
securities. MSDW Advisors has retained MSDW Services to provide the
aforementioned administrative services to the Fund. The Fund's Trustees review
the various services provided by or under the direction of the Investment
Manager to ensure that the Fund's general investment policies and programs are
being properly carried out and that administrative services are being provided
to the Fund in a satisfactory manner.
 
    As full compensation for the services and facilities furnished to the Fund
and for expenses of the Fund assumed by the Investment Manager, the Fund pays
the Investment Manager monthly compensation calculated daily by applying the
annual rate of 0.60% to the Fund's daily net assets up to $500 million, scaled
down at various levels to 0.30% on assets over $1 billion. For the fiscal year
ended August 31, 1998, the Fund accrued total compensation to the Investment
Manager amounting to 0.60% of the Fund's average daily net assets and the total
expenses of each Class amounted to 1.10%, 1.71%, 1.71% and 0.86% of the average
daily net assets of Class A, Class B, Class C and Class D, respectively.
 
INVESTMENT OBJECTIVE AND POLICIES
- --------------------------------------------------------------------------------
 
    The investment objective of the Fund is high current income consistent with
safety of principal. There is no assurance that the objective will be achieved.
This investment objective is a fundamental policy and may not be changed without
approval of the Fund's shareholders. The Fund seeks to achieve its objective by
investing at least 65% of its total assets in intermediate term, investment
grade fixed-income securities. The Fund will maintain an average weighted
maturity of approximately seven years or less and may not invest in securities
with remaining maturities greater than twelve years. Under normal conditions,
the Fund's average weighted maturity will not be less than three years. (Under
the current interpretation by the staff of the Securities and Exchange
Commission, an intermediate bond fund must have an average weighted maturity
between three and ten years.)
 
                                       9
<PAGE>
    Under normal circumstances, the Fund will invest primarily in corporate debt
securities and preferred stock of investment grade, which consists of securities
which are rated at the time of purchase Baa or better by Moody's Investors
Service, Inc. ("Moody's") or BBB or better by Standard & Poor's Corporation
("Standard & Poor's"), or which, if unrated, are deemed to be of comparable
quality by the Fund's Trustees. Fixed-income securities rated Baa by Moody's
have speculative characteristics. (A more detailed description of bond ratings
is contained in the Appendix to the Statement of Additional Information.) The
Fund may also purchase U.S. Government securities (securities guaranteed as to
principal and interest by the United States or its agencies or
instrumentalities) and investment grade securities, denominated in U.S. Dollars,
issued by foreign governments or issuers. U.S. Government securities in which
the Fund may invest include zero coupon securities and mortgage-backed
securities, such as securities issued by the Government National Mortgage
Association, the Federal National Mortgage Association and the Federal Home Loan
Mortgage Corporation. There can be no assurance that the investment objective of
the Fund will be achieved.
 
    The Investment Manager believes that the Fund's policies of purchasing
intermediate term securities will reduce the volatility of the Fund's net asset
value over the long term. Although the values of fixed-income securities
generally increase during periods of declining interest rates and decrease
during periods of increasing interest rates, the extent of these fluctuations
has historically generally been smaller for intermediate term securities than
for securities with longer maturities. Conversely, the yield available on
intermediate term securities has also historically been lower than those
available from long term securities.
 
    Investment by the Fund in U.S. Dollar denominated fixed-income securities
issued by foreign governments and other foreign issuers may involve certain
risks not associated with U.S. issued securities. Those risks include the
political or economic instability of the issuer or of the country of issue, the
difficulty of predicting international trade patterns and the possibility of
imposition of exchange controls. In addition, there may be less publicly
available information about a foreign company than about a domestic company. A
more detailed description of the general risks of foreign issuers is contained
in the Statement of Additional Information. The Fund believes that those risks
are substantially lessened because the foreign securities in which the Fund may
invest are investment grade.
 
    While the Fund will invest primarily in investment grade fixed-income
securities, under ordinary circumstances it also may invest up to 35% of its
total assets in money market instruments, repurchase agreements, as discussed
below, and up to 5% of the Fund's net assets may be invested in lower rated
fixed-income securities.
 
    Lower rated fixed-income securities, which are those rated from Ba to C or
BB to C by Moody's or Standard & Poor's, respectively, are considered to be
speculative investments. Such lower rated securities, while producing higher
yield than investment grade securities, are subject to credit risk to a greater
extent than investment grade securities. The Fund does not have any minimum
quality rating standard with respect to the portion (up to 5%) of its net assets
which may be invested in lower rated securities. See the Statement of Additional
Information for a description of the special risks and characteristics of lower
rated fixed-income securities.
 
    There may be periods during which, in the opinion of the Investment Manager,
market conditions warrant reduction of some or all of the Fund's securities
holdings. During such periods, the Fund may adopt a temporary "defensive"
posture in which greater than 35% of its total assets are invested in cash or
money market instruments. Money market instruments in which the Fund may invest
are securities issued or guaranteed by the U.S. Government (Treasury bills,
notes and bonds, including zero coupon securities); bank obligations; Eurodollar
certificates of deposit; obligations of savings institutions; fully insured
certificates of deposit; and commercial paper rated within the two highest
 
                                       10
<PAGE>
grades by Moody's or Standard & Poor's or, if not rated, are issued by a company
having an outstanding debt issue rated at least AA by Standard & Poor's or Aa by
Moody's.
 
    ZERO COUPON SECURITIES.  A portion of the fixed-income securities purchased
by the Fund may be zero coupon securities. Such securities are purchased at a
discount from their face amount, giving the purchaser the right to receive their
full value at maturity. The interest earned on such securities is, implicitly,
automatically compounded and paid out at maturity. While such compounding at a
constant rate eliminates the risk of receiving lower yields upon reinvestment of
interest if prevailing interest rates decline, the owner of a zero coupon
security will be unable to participate in higher yields upon reinvestment of
interest received on interest-paying securities if prevailing interest rates
rise.
 
    A zero coupon security pays no interest to its holder during its life.
Therefore, to the extent the Fund invests in zero coupon securities, it will not
receive current cash available for distribution to shareholders. In addition,
zero coupon securities are subject to substantially greater price fluctuations
during periods of changing prevailing interest rates than are comparable
securities which pay interest on a current basis. Current federal tax law
requires that a holder (such as the Fund) of a zero coupon security accrue a
portion of the discount at which the security was purchased as income each year
even though the Fund receives no interest payments in cash on the security
during the year.
 
    REPURCHASE AGREEMENTS.  The Fund may enter into repurchase agreements, which
may be viewed as a type of secured lending by the Fund, and which 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-dealer. The
agreement provides that the Fund will sell back to the institution, and that the
institution will repurchase, the underlying security at a specified price and at
a fixed time in the future, usually not more than seven days from the date of
purchase. While repurchase agreements involve certain risks not associated with
direct investments in debt securities, including the risks of default or
bankruptcy of the selling financial institution, the Fund follows procedures
designed to minimize those risks. These procedures include effecting repurchase
transactions only with large, well-capitalized and well established financial
institutions and maintaining adequate collateralization.
 
    REVERSE REPURCHASE AGREEMENTS.  The Fund may also use reverse repurchase
agreements for purposes of meeting redemptions or as part of its investment
strategy. Reverse repurchase agreements involve sales by the Fund of portfolio
assets concurrently with an agreement by the Fund to repurchase the same assets
at a later date at a fixed price. Generally, the effect of such a transaction is
that the Fund can recover all or most of the cash invested in the portfolio
securities involved during the term of the reverse repurchase agreement, while
it will be able to keep the interest income associated with those portfolio
securities. Such transactions are only advantageous if the interest cost to the
Fund of the reverse repurchase transaction is less than the cost of obtaining
the cash otherwise. Opportunities to achieve this advantage may not always be
available, and the Fund intends to use the reverse repurchase technique only
when it will be to its advantage to do so. The Fund will establish a segregated
account with its custodian bank in which it will maintain cash, U.S. Government
securities or other liquid portfolio securities equal in value to its
obligations in respect of reverse repurchase agreements. Reverse repurchase
agreements are considered borrowings by the Fund. The use of borrowed funds for
other than emergency purposes constitutes leveraging, which is a speculative
technique. Reverse repurchase agreements may not exceed 10% of the Fund's total
assets.
 
    WHEN-ISSUED AND DELAYED DELIVERY SECURITIES AND FORWARD COMMITMENTS.  From
time to time, in the ordinary course of business, the Fund may purchase
securities on a when-issued or delayed delivery basis or may purchase or sell
securities on
 
                                       11
<PAGE>
a forward commitment basis. When such 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 the commitment. There is no overall limit on the
percentage of the Fund's assets which may be committed to the purchase of
securities on a when-issued, delayed delivery or forward commitment basis. 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 the Fund's net asset value.
 
    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, leveraged buyout or debt restructuring. If the
anticipated event does not occur and the securities are not issued, the Fund
will have lost an investment opportunity. There is no overall limit on the
percentage of the Fund's assets which may be committed to the purchase of
securities on a "when, as and if issued" basis. 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.
 
    PRIVATE PLACEMENTS.  The Fund may invest up to 5% 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, as amended (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
such 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 such securities for resale and the
risk of substantial delays in effecting such registration.
 
    The Securities and Exchange Commission has adopted Rule 144A under the
Securities Act, which permits the Fund to sell restricted securities to
qualified institutional buyers without limitation. The Investment Manager,
pursuant to procedures adopted by the Trustees of the Fund, 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," such security will
not be included within the category "illiquid securities," which is limited by
the Fund's investment restrictions to 10% of the Fund's total assets. 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.
 
    LENDING OF PORTFOLIO SECURITIES.  Consistent with applicable regulatory
requirements, the Fund may lend its portfolio securities to brokers, dealers and
other financial institutions, provided that such loans are callable at any time
by the Fund (subject to certain notice provisions described in the Statement of
Additional Information), 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 at least equal to the market value, determined daily,
of the loaned securities.
 
PORTFOLIO MANAGEMENT
 
    The Fund's portfolio is actively managed by its Investment Manager with a
view to achieving the Fund's investment objective. In determining which
securities to purchase for the Fund or hold in the Fund's portfolio, the
Investment Manager will rely on information from various sources, including
research, analysis and appraisals of brokers and dealers; the views of Trustees
of the Fund and others regarding economic developments and interest rate trends;
and the Investment Manager's own analysis of factors it deems relevant. The
Fund's portfolio is managed within MSDW Advisors'
 
                                       12
<PAGE>
Taxable Income Group, which manages twenty-one funds and fund portfolios, with
approximately $14.1 billion in assets as of September 30, 1998. Rochelle G.
Siegel, Senior Vice President of MSDW Advisors and a member of MSDW Advisors'
Taxable Group, has been the primary portfolio manager since the Fund's inception
and has been a portfolio manager at MSDW Advisors since July, 1985.
 
    Pursuant to an order of the Securities and Exchange Commission, the Fund may
effect principal transactions in certain money market instruments with Dean
Witter Reynolds Inc. In addition, the Fund may incur brokerage commissions on
transactions conducted through Dean Witter Reynolds Inc., Morgan Stanley and Co.
Incorporated and other brokers and dealers that are affiliates of MSDW Advisors.
It is not anticipated that the portfolio trading will result in the Fund's
portfolio turnover rate exceeding 200%. A high portfolio turnover rate may
increase the Fund's capital gains, which are passed along to Fund shareholders
as distributions. This, in turn, may increase your tax liability as a Fund
shareholder. A more extensive discussion of the Fund's portfolio brokerage
policies is set forth in the Statement of Additional Information. Except as
specifically noted, all investment objectives, policies and practices discussed
above are not fundamental policies of the Fund and, as such, may be changed
without shareholder approval.
 
RISK CONSIDERATIONS
 
    An increase in prevailing levels of interest rates will generally reduce the
value of securities in the Fund's portfolio, while a decline in rates will
generally increase the value of these securities. As a result, the fluctuations
or changes in interest rates will cause the Fund's net asset value to rise and
fall, in an inverse relationship; however, the income received by the Fund from
its portfolio securities will not be affected. Because yields on debt securities
available for purchase by a Fund vary over time, no specific yield on shares of
the Fund can be assured. In addition, if the bonds in the Fund's portfolio
contain call, prepayment or redemption provisions, during a period of declining
interest rates, these securities are likely to be redeemed, and the Fund will
probably be unable to replace them with securities having an equal yield.
 
    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 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.
 
    For additional risk disclosure, please refer to the "Investment Objective
and Policies" section of the Prospectus and to the "Investment Practices and
Policies" section in the Statement of Additional Information.
 
                                       13
<PAGE>
INVESTMENT RESTRICTIONS
- --------------------------------------------------------------------------------
 
    The investment restrictions listed below are among the restrictions which
have been adopted by the Fund as fundamental policies. Under the Investment
Company Act of 1940, as amended (the "Act"), a fundamental policy may not be
changed without the vote of a majority of the outstanding voting securities of
the Fund, as defined in the Act. For purposes of the following limitations: (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 may not:
 
   1. 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 25% or more of the value of its total assets in securities of
issuers in any one industry. This restriction does not apply to obligations
issued or guaranteed by the United States Government or its agencies or
instrumentalities.
 
   4. 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.
 
   5. Invest more than 5% of the value of its total assets in securities of
issuers having a record, together with predecessors, of less than three years of
continuous operation. This restriction shall not apply to any obligation issued
or guaranteed by the United States Government, its agencies or
instrumentalities.
 
   6. Borrow money, except that the Fund may borrow from banks for temporary or
emergency purposes in an amount up to 5% (taken at the lower of cost or current
value) of its total assets (not including the amount borrowed), and may enter
into reverse repurchase agreements in an amount not exceeding 10% of the Fund's
total assets.
 
    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.
 
PURCHASE OF FUND SHARES
- --------------------------------------------------------------------------------
 
GENERAL
 
    The Fund offers each class of its shares for sale to the public on a
continuous basis. Pursuant to a Distribution Agreement between the Fund and
Morgan Stanley Dean Witter Distributors Inc. ("MSDW Distributors" or the
"Distributor"), an affiliate of the Investment Manager, shares of the Fund are
distributed by the Distributor and offered by Dean Witter Reynolds Inc. ("DWR"),
a selected dealer and a subsidiary of Morgan Stanley Dean Witter & Co., and
other dealers who have entered into selected dealer agreements with the
Distributor ("Selected Broker-Dealers"). It is anticipated that DWR will undergo
a change of corporate name which is expected to incorporate the brand name of
"Morgan Stanley Dean Witter," pending approval of various regulatory
authorities. The principal executive office of the Distributor is located at Two
World Trade Center, New York, New York 10048.
 
    The Fund offers four classes of shares (each, a "Class"). Class A shares are
sold to investors with an initial sales charge that declines to zero for larger
 
                                       14
<PAGE>
purchases; however, Class A shares sold without an initial sales charge are
subject to a contingent deferred sales charge ("CDSC") of 1.0% if redeemed
within one year of purchase, except for certain specific circumstances. Class B
shares are sold without an initial sales charge but are subject to a CDSC
(scaled down from 5.0% to 1.0%) payable upon most redemptions within six years
after purchase. (Class B shares purchased by certain qualified plans are subject
to a CDSC scaled down from 2.0% to 1.0% if redeemed within three years after
purchase.) Class C shares are sold without an initial sales charge but are
subject to a CDSC of 1.0% on most redemptions made within one year after
purchase. Class D shares are sold without an initial sales charge or CDSC and
are available only to investors meeting an initial investment minimum of $5
million ($25 million for certain qualified plans), and to certain other limited
categories of investors. At the discretion of the Board of Trustees of the Fund,
Class A shares may be sold to categories of investors in addition to those set
forth in this prospectus at net asset value without a front-end sales charge,
and Class D shares may be sold to certain other categories of investors, in each
case as may be described in the then current prospectus of the Fund. See
"Alternative Purchase Arrangements--Selecting a Particular Class" for a
discussion of factors to consider in selecting which Class of shares to
purchase.
 
    The minimum initial purchase is $1,000 for each Class of shares, although
Class D shares are only available to persons investing $5 million ($25 million
for certain qualified plans), or more and to certain other limited categories of
investors. For the purpose of meeting the minimum $5 million (or $25 million)
initial investment for Class D shares, and subject to the $1,000 minimum initial
investment for each Class of the Fund, an investor's existing holdings of Class
A shares of the Fund and other Morgan Stanley Dean Witter Funds that are
multiple class funds ("Morgan Stanley Dean Witter Multi-Class Funds") and shares
of Morgan Stanley Dean Witter Funds sold with a front-end sales charge ("FSC
Funds") and concurrent investments in Class D shares of the Fund and other
Morgan Stanley Dean Witter Multi-Class Funds will be aggregated. Subsequent
purchases of $100 or more may be made by sending a check, payable to Morgan
Stanley Dean Witter Intermediate Income Securities, directly to Morgan Stanley
Dean Witter Trust FSB (the "Transfer Agent" or "MSDW Trust") at P.O. Box 1040,
Jersey City, NJ 07303 or by contacting a Morgan Stanley Dean Witter Financial
Advisor or other Selected Broker-Dealer representative. When purchasing shares
of the Fund, investors must specify whether the purchase is for Class A, Class
B, Class C or Class D shares. If no Class is specified, the Transfer Agent will
not process the transaction until the proper Class is identified. The minimum
initial purchase in the case of investments through EasyInvest-SM-, an automatic
purchase plan (see "Shareholder Services"), is $100, provided that the schedule
of automatic investments will result in investments totalling at least $1,000
within the first twelve months. The minimum initial purchase in the case of an
"Education IRA" is $500, if the Distributor has reason to believe that
additional investments will increase the investment in the account to $1,000
within three years. In the case of investments pursuant to (i) Systematic
Payroll Deduction Plans (including Individual Retirement Plans), (ii) the MSDW
Advisors mutual fund asset allocation program and (iii) fee-based programs
approved by the Distributor, pursuant to which participants pay an asset based
fee for services in the nature of investment advisory, administrative and/or
brokerage services, the Fund, in its discretion, may accept investments without
regard to any minimum amounts which would otherwise be required, provided, in
the case of Systematic Payroll Deduction Plans, that the Distributor has reason
to believe that additional investments will increase the investment in all
accounts under such Plans to at least $1,000. Certificates for shares purchased
will not be issued unless a request is made by the shareholder in writing to the
Transfer Agent.
 
    Shares of the Fund are sold through the Distributor on a normal three
business day settlement basis; that is, payment is due on the third business day
(settlement date) after the order is placed with
 
                                       15
<PAGE>
the Distributor. Shares of the Fund purchased through the Distributor are
entitled to dividends beginning on the next business day following settlement
date. Since DWR and other Selected Broker-Dealers forward investors' funds on
settlement date, they will benefit from the temporary use of the funds where
payment is made prior thereto. Shares purchased through the Transfer Agent are
entitled to dividends beginning on the next business day following receipt of an
order. As noted above, orders placed directly with the Transfer Agent must be
accompanied by payment. Investors will be entitled to receive capital gains
distributions if their order is received by the close of business on the day
prior to the record date for such distributions. Sales personnel of a Selected
Broker-Dealer are compensated for selling shares of the Fund at the time of
their sale by the Distributor or any of its affiliates and/or the Selected
Broker-Dealer. In addition, some sales personnel of the Selected Broker-Dealer
will receive various types of non-cash compensation as special sales incentives,
including trips, educational and/or business seminars and merchandise. The Fund
and the Distributor reserve the right to reject any purchase orders.
 
ALTERNATIVE PURCHASE ARRANGEMENTS
 
    The Fund offers several Classes of shares to investors designed to provide
them with the flexibility of selecting an investment best suited to their needs.
The general public is offered three Classes of shares: Class A shares, Class B
shares and Class C shares, which differ principally in terms of sales charges
and rate of expenses to which they are subject. A fourth Class of shares, Class
D shares, is offered only to limited categories of investors (see "No Load
Alternative--Class D Shares" below).
 
    Each Class A, Class B, Class C or Class D share of the Fund represents an
identical interest in the investment portfolio of the Fund except that Class A,
Class B and Class C shares bear the expenses of the ongoing shareholder service
fees, Class B and Class C shares bear the expenses of the ongoing distribution
fees and Class A, Class B and Class C shares which are redeemed subject to a
CDSC bear the expense of the additional incremental distribution costs resulting
from the CDSC applicable to shares of those Classes. The ongoing distribution
fees that are imposed on Class A, Class B and Class C shares will be imposed
directly against those Classes and not against all assets of the Fund and,
accordingly, such charges against one Class will not affect the net asset value
of any other Class or have any impact on investors choosing another sales charge
option. See "Plan of Distribution" and "Redemptions and Repurchases."
 
    Set forth below is a summary of the differences between the Classes and the
factors an investor should consider when selecting a particular Class. This
summary is qualified in its entirety by detailed discussion of each Class that
follows this summary.
 
    CLASS A SHARES.  Class A shares are sold at net asset value plus an initial
sales charge of up to 4.25%. The initial sales charge is reduced for certain
purchases. Investments of $1 million or more (and investments by certain other
limited categories of investors) are not subject to any sales charges at the
time of purchase but are subject to a CDSC of 1.0% on redemptions made within
one year after purchase, except for certain specific circumstances. Class A
shares are also subject to a 12b-1 fee of up to 0.25% of the average daily net
assets of the Class. See "Initial Sales Charge Alternative--Class A Shares."
 
    CLASS B SHARES.  Class B shares are offered at net asset value with no
initial sales charge but are subject to a CDSC (scaled down from 5.0% to 1.0%)
if redeemed within six years of purchase. (Class B shares purchased by certain
qualified plans are subject to a CDSC scaled down from 2.0% to 1.0% if redeemed
within three years after purchase.) This CDSC may be waived for certain
redemptions. Class B shares are also subject to an annual 12b-1 fee of 0.85% of
the lesser of: (a) the average daily aggregate gross sales of the Fund's Class B
shares
 
                                       16
<PAGE>
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 redeemed since the Fund's inception upon which a
CDSC has been imposed or waived, or (b) the average daily net assets of Class B.
The Class B shares' distribution fee will cause that Class to have higher
expenses and pay lower dividends than Class A or Class D shares.
 
    After approximately ten (10) years, Class B shares will convert
automatically to Class A shares of the Fund, based on the relative net asset
values of the shares of the two Classes on the conversion date. In addition, a
certain portion of Class B shares that have been acquired through the
reinvestment of dividends and distributions will be converted at that time. See
"Contingent Deferred Sales Charge Alternative--Class B Shares."
 
    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 redemptions made within one
year after purchase. This CDSC may be waived for certain redemptions. They are
subject to an annual 12b-1 fee of up to 0.85% of the average daily net assets of
the Class C shares. 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. See
"Level Load Alternative--Class C Shares."
 
    CLASS D SHARES.  Class D shares are available only to limited categories of
investors (see "No Load Alternative--Class D Shares" below). Class D shares are
sold at net asset value with no initial sales charge or CDSC. They are not
subject to any 12b-1 fees. See "No Load Alternative--Class D Shares."
 
    SELECTING A PARTICULAR CLASS.  In deciding which Class of Fund shares to
purchase, investors should consider the following factors, as well as any other
relevant facts and circumstances:
 
    The decision as to which Class of shares is more beneficial to an investor
depends on the amount and intended length of his or her investment. Investors
who prefer an initial sales charge alternative may elect to purchase Class A
shares. Investors qualifying for significantly reduced or, in the case of
purchases of $1 million or more, no initial sales charges may find Class A
shares particularly attractive because similar sales charge reductions are not
available with respect to Class B or Class C shares. Moreover, Class A shares
are subject to lower ongoing expenses than are Class B or Class C shares over
the term of the investment. As an alternative, Class B and Class C shares are
sold without any initial sales charge so the entire purchase price is
immediately invested in the Fund. Any investment return on these additional
investment amounts may partially or wholly offset the higher annual expenses of
these Classes. Because the Fund's future return cannot be predicted, however,
there can be no assurance that this would be the case.
 
    Finally, investors should consider the effect of the CDSC period and any
conversion rights of the Classes in the context of their own investment time
frame. For example, although Class C shares are subject to a significantly lower
CDSC upon redemptions, they do not, unlike Class B shares, convert into Class A
shares after approximately ten years, and, therefore, are subject to an ongoing
12b-1 fee of 0.85% (rather than the 0.25% fee applicable to Class A shares) for
an indefinite period of time. Thus, Class B shares may be more attractive than
Class C shares to investors with longer term investment outlooks. Other
investors, however, may elect to purchase Class C shares if, for example, they
determine that they do not wish to be subject to a front-end sales charge and
they are uncertain as to the length of time they intend to hold their shares.
 
    For the purpose of meeting the $5 million (or $25 million) minimum
investment amount for Class D shares, holdings of Class A shares in all Morgan
Stanley Dean Witter Multi-Class Funds, shares of FSC Funds and shares of Morgan
Stanley Dean Witter Funds for which such shares have been
 
                                       17
<PAGE>
exchanged will be included together with the current investment amount.
 
    Sales personnel may receive different compensation for selling each Class of
shares. Investors should understand that the purpose of a CDSC is the same as
that of the initial sales charge in that the sales charges applicable to each
Class provide for the financing of the distribution of shares of that Class.
 
    Set forth below is a chart comparing the sales charge, 12b-1 fees and
conversion options applicable to each Class of shares:
 
<TABLE>
<CAPTION>
- -----------------------------------------------------------
                                              CONVERSION
  CLASS       SALES CHARGE     12b-1 FEE       FEATURE
<C>        <S>                 <C>         <C>
- -----------------------------------------------------------
    A      Maximum 4.25%         0.25%            No
           initial sales
           charge reduced for
           purchases of
           $25,000 and over;
           shares sold
           without an initial
           sales charge
           generally subject
           to a 1.0% CDSC
           during first year.
- -----------------------------------------------------------
    B      Maximum 5.0% CDSC     0.85%     B shares convert
           during the first                to A shares
           year decreasing to              automatically
           0 after six years               after
                                           approximately
                                           ten years
- -----------------------------------------------------------
    C      1.0% CDSC during      0.85%            No
           first year
- -----------------------------------------------------------
    D             None            None            No
</TABLE>
 
    See "Purchase of Fund Shares" and "The Fund and its Management" for a
complete description of the sales charges and service and distribution fees for
each Class of shares and "Determination of Net Asset Value," "Dividends,
Distributions and Taxes" and "Shareholder Services--Exchange Privilege" for
other differences between the Classes of shares.
 
INITIAL SALES CHARGE ALTERNATIVE--
CLASS A SHARES
 
    Class A shares are sold at net asset value plus an initial sales charge. In
some cases, reduced sales charges may be available, as described below.
Investments of $1 million or more (and investments by certain other limited
categories of investors) are not subject to any sales charges at the time of
purchase but are subject to a CDSC of 1.0% on redemptions made within one year
after purchase (calculated from the last day of the month in which the shares
were purchased), except for certain specific circumstances. The CDSC will be
assessed on an amount equal to the lesser of the current market value or the
cost of the shares being redeemed. The CDSC will not be imposed (i) in the
circumstances set forth below in the section "Contingent Deferred Sales Charge
Alternative--Class B Shares--CDSC Waivers," except that the references to six
years in the first paragraph of that section shall mean one year in the case of
Class A shares, and (ii) in the circumstances identified in the section
"Additional Net Asset Value Purchase Options" below. Class A shares are also
subject to an annual 12b-1 fee of up to 0.25% of the average daily net assets of
the Class.
 
    The offering price of Class A shares will be the net asset value per share
next determined following receipt of an order (see "Determination of Net Asset
Value" below), plus a sales charge (expressed as a percentage of the offering
price) on a single transaction as shown in the following table:
 
<TABLE>
<CAPTION>
                                          SALES CHARGE
                           ------------------------------------------
                              PERCENTAGE OF          APPROXIMATE
        AMOUNT OF            PUBLIC OFFERING    PERCENTAGE OF AMOUNT
   SINGLE TRANSACTION             PRICE               INVESTED
- -------------------------  -------------------  ---------------------
<S>                        <C>                  <C>
Less than $25,000........           4.25%                 4.44%
$25,000 but less
     than $50,000........           4.00%                 4.17%
$50,000 but less
     than $100,000.......           3.50%                 3.63%
$100,000 but less
     than $250,000.......           2.75%                 2.83%
$250,000 but less
     than $1 million.....           1.75%                 1.78%
$1 million and over......              0                     0
</TABLE>
 
                                       18
<PAGE>
    Upon notice to all Selected Broker-Dealers, the Distributor may reallow up
to the full applicable sales charge as shown in the above schedule 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 of 1933.
 
    The above schedule of sales charges is applicable to purchases in a single
transaction by, among others: (a) an individual; (b) an individual, his or her
spouse and their children under the age of 21 purchasing shares for his, her or
their own accounts; (c) a trustee or other fiduciary purchasing shares for a
single trust estate or a single fiduciary account; (d) a pension, profit-sharing
or other employee benefit plan qualified or non-qualified under Section 401 of
the Internal Revenue Code; (e) tax-exempt organizations enumerated in Section
501(c)(3) or (13) of the Internal Revenue Code; (f) employee benefit plans
qualified under Section 401 of the Internal Revenue Code of a single employer or
of employers who are "affiliated persons" of each other within the meaning of
Section 2(a)(3)(c) of the Act; and for investments in Individual Retirement
Accounts of employees of a single employer through Systematic Payroll Deduction
plans; or (g) any other organized group of persons, whether incorporated or not,
provided the organization has been in existence for at least six months and has
some purpose other than the purchase of redeemable securities of a registered
investment company at a discount.
 
    COMBINED PURCHASE PRIVILEGE.  Investors may have the benefit of reduced
sales charges in accordance with the above schedule by combining purchases of
Class A shares of the Fund in single transactions with the purchase of Class A
shares of other Morgan Stanley Dean Witter Multi-Class Funds and shares of FSC
Funds. The sales charge payable on the purchase of the Class A shares of the
Fund, the Class A shares of the other Morgan Stanley Dean Witter Multi-Class
Funds and the shares of the FSC Funds will be at their respective rates
applicable to the total amount of the combined concurrent purchases of such
shares.
 
    RIGHT OF ACCUMULATION.  The above persons and entities may benefit from a
reduction of the sales charges in accordance with the above schedule if the
cumulative net asset value of Class A shares purchased in a single transaction,
together with shares of the Fund and other Morgan Stanley Dean Witter Funds
previously purchased at a price including a front-end sales charge (including
shares of the Fund and other Morgan Stanley Dean Witter Funds acquired in
exchange for those shares, and including in each case shares acquired through
reinvestment of dividends and distributions), which are held at the time of such
transaction, amounts to $25,000 or more. If such investor has a cumulative net
asset value of shares of FSC Funds and Class A and Class D shares that, together
with the current investment amount, is equal to at least $5 million ($25 million
for certain qualified plans), such investor is eligible to purchase Class D
shares subject to the $1,000 minimum initial investment requirement of that
Class of the Fund. See "No Load Alternative--Class D Shares" below.
 
    The Distributor must be notified by DWR or a Selected Broker-Dealer or the
shareholder 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 by the dealer or shareholder when such an order is
placed by mail. The reduced sales charge will not be granted if: (a) such
notification is not furnished at the time of the order; or (b) a review of the
records of the Selected Broker-Dealer or the Transfer Agent fails to confirm the
investor's represented holdings.
 
    LETTER OF INTENT.  The foregoing schedule of reduced sales charges will also
be available to investors who enter into a written Letter of Intent providing
for the purchase, within a thirteen-month period, of Class A shares of the Fund
from DWR or other Selected Broker-Dealers. The cost of Class A shares of the
Fund or shares of other Morgan
 
                                       19
<PAGE>
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 date of receipt by
the Distributor of the Letter of Intent, or of Class A shares of the Fund or
shares of other Morgan Stanley Dean Witter Funds acquired in exchange for shares
of such funds purchased during such period at a price including a front-end
sales charge, which are still owned by the shareholder, may also be included in
determining the applicable reduction.
 
    ADDITIONAL NET ASSET VALUE PURCHASE OPTIONS. In addition to investments of
$1 million or more, Class A shares also may be purchased at net asset value by
the following:
 
    (1) trusts for which MSDW Trust (which is an affiliate of the Investment
Manager) provides discretionary trustee services;
 
    (2) persons participating in a fee-based program approved by the
Distributor, pursuant to which such persons pay an asset based fee for services
in the nature of investment advisory, administrative and/or brokerage services
(such investments are subject to all of the terms and conditions of such
programs, which may include termination fees, mandatory redemption upon
termination and such other circumstances as specified in the programs'
agreements, and restrictions on transferability of Fund shares);
 
    (3) employer-sponsored 401(k) and other plans qualified under Section 401(a)
of the Internal Revenue Code ("Qualified Retirement Plans") with at least 200
eligible employees and for which MSDW Trust serves as Trustee or DWR's
Retirement Plan Services serves as recordkeeper pursuant to a written
Recordkeeping Services Agreement;
 
    (4) Qualified Retirement Plans for which MSDW Trust serves as Trustee or
DWR's Retirement Plan Services serves as recordkeeper pursuant to a written
Recordkeeping Services Agreement whose Class B shares have converted to Class A
shares, regardless of the plan's asset size or number of eligible employees;
 
    (5) investors who are clients of a Morgan Stanley Dean Witter Financial
Advisor who joined Morgan Stanley Dean Witter from another investment firm
within six months prior to the date of purchase of Fund shares by such
investors, if the shares are being purchased with the proceeds from a redemption
of shares of an open-end proprietary mutual fund of the Financial Advisor's
previous firm which imposed either a front-end or deferred sales charge,
provided such purchase was made within sixty days after the redemption and the
proceeds of the redemption had been maintained in the interim in cash or a money
market fund; and
 
    (6) other categories of investors, at the discretion of the Board, as
disclosed in the then current prospectus of the Fund.
 
    No CDSC will be imposed on redemptions of shares purchased pursuant to
paragraphs (1), (2) or (5), above.
 
    For further information concerning purchases of the Fund's shares, contact
DWR or another Selected Broker-Dealer or consult the Statement of Additional
Information.
 
CONTINGENT DEFERRED SALES CHARGE
ALTERNATIVE--CLASS B SHARES
 
    Class B shares are sold at net asset value next determined without an
initial sales charge so that the full amount of an investor's purchase payment
may be immediately invested in the Fund. A CDSC, however, will be imposed on
most Class B shares redeemed within six years after purchase. The CDSC will be
imposed on any redemption of shares if after such redemption the aggregate
current value of a Class B account with the Fund falls below the aggregate
amount of the investor's purchase payments for Class B shares made during the
six years (or, in the case of shares held by certain Qualified Retirement Plans,
three years) preceding the redemption. In addition, Class B shares are subject
to an annual 12b-1 fee of 0.85% of the lesser
 
                                       20
<PAGE>
of: (a) the average daily aggregate gross sales 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 redeemed since the Fund's inception upon which a
CDSC has been imposed or waived, or (b) the average daily net assets of Class B.
 
    Except as noted below, Class B shares of the Fund which are held for six
years or more after purchase (calculated from the last day of the month in which
the shares were purchased) will not be subject to any CDSC upon redemption.
Shares redeemed earlier than six years after purchase may, however, be subject
to a CDSC which will be a percentage of the dollar amount of shares redeemed and
will be assessed on an amount equal to the lesser of the current market value or
the cost of the shares being redeemed. The size of this percentage will depend
upon how long the shares have been held, as set forth in the following table:
 
<TABLE>
<CAPTION>
         YEAR SINCE PURCHASE            CDSC AS A PERCENTAGE
             PAYMENT MADE                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>
 
    In the case of Class B shares of the Fund purchased on or after July 28,
1997 by Qualified Retirement Plans for which MSDW Trust serves as Trustee or
DWR's Retirement Plan Services serves as recordkeeper pursuant to a written
Recordkeeping Services Agreement, shares held for three years or more after
purchase (calculated as described in the paragraph above) will not be subject to
any CDSC upon redemption. However, shares redeemed earlier than three years
after purchase may be subject to a CDSC (calculated as described in the
paragraph above), the percentage of which will depend on how long the shares
have been held, as set forth in the following table:
 
<TABLE>
<CAPTION>
         YEAR SINCE PURCHASE            CDSC AS A PERCENTAGE
             PAYMENT MADE                OF AMOUNT REDEEMED
- --------------------------------------  ---------------------
<S>                                     <C>
First.................................          2.0%
Second................................          2.0%
Third.................................          1.0%
Fourth and thereafter.................          None
</TABLE>
 
    CDSC WAIVERS.  A CDSC will not be imposed on: (i) any amount which
represents an increase in value of shares purchased within the six years (or, in
the case of shares held by certain Qualified Retirement Plans, three years)
preceding the redemption; (ii) the current net asset value of shares purchased
more than six years (or, in the case of shares held by certain Qualified
Retirement Plans, three years) prior to the redemption; and (iii) the current
net asset value of shares purchased through reinvestment of dividends or
distributions and/or shares acquired in exchange for shares of FSC Funds or of
other Morgan Stanley Dean Witter Funds acquired in exchange for such shares.
Moreover, in determining whether a CDSC is applicable it will be assumed that
amounts described in (i), (ii) and (iii) above (in that order) are redeemed
first.
 
    In addition, the CDSC, if otherwise applicable, will be waived in the case
of:
 
    (1) redemptions of shares held at the time a shareholder dies or becomes
disabled, only if the shares are:  (a) registered either in the name of an
individual shareholder (not a trust), or in the names of such shareholder and
his or her spouse as joint tenants with right of survivorship; or  (b) held in a
qualified corporate or self-employed retirement plan, Individual Retirement
Account ("IRA") or Custodial Account under Section 403(b)(7) of the Internal
Revenue Code ("403(b) Custodial Account"), provided in either case that the
redemption is requested within one year of the death or initial determination of
disability;
 
    (2) redemptions in connection with the following retirement plan
distributions:  (a) lump-sum or
 
                                       21
<PAGE>
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); (b) distributions from an IRA or 403(b)
Custodial Account following attainment of age 59 1/2; or  (c) a tax-free return
of an excess contribution to an IRA;
 
    (3) all redemptions of shares held for the benefit of a participant in a
Qualified Retirement Plan which offers investment companies managed by the
Investment Manager or its subsidiary, MSDW Services, as self-directed investment
alternatives and for which MSDW Trust serves as Trustee or DWR's Retirement Plan
Services serves as recordkeeper pursuant to a written Recordkeeping Services
Agreement ("Eligible Plan"), provided that either:  (a) the plan continues to be
an Eligible Plan after the redemption; or  (b) the redemption is in connection
with the complete termination of the plan involving the distribution of all plan
assets to participants; and
 
    (4) certain redemptions pursuant to the Fund's Systematic Withdrawal Plan
(see "Shareholder Services--Systematic Withdrawal Plan").
 
    With reference to (1) above, for the purpose of determining disability, the
Distributor utilizes the definition of disability contained in Section 72(m)(7)
of the Internal Revenue Code, which relates to the inability to engage in
gainful employment. With reference to (2) above, the term "distribution" does
not encompass a direct transfer of IRA, 403(b) Custodial Account or retirement
plan assets to a successor custodian or trustee. All waivers will be granted
only following receipt by the Distributor of confirmation of the shareholder's
entitlement.
 
    CONVERSION TO CLASS A SHARES.  All shares of the Fund held prior to July 28,
1997 (other than shares held by certain employee benefit plans established by
DWR and its affiliate, SPS Transaction Services, Inc.) have been designated
Class B shares. Shares held before May 1, 1997 that have been designated Class B
shares will convert to Class A shares in May, 2007. In all other instances Class
B shares will convert automatically to Class A shares, based on the relative net
asset values of the shares of the two Classes on the conversion date, which will
be approximately ten (10) years after the date of the original purchase. The ten
year period is calculated 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 or
a series of exchanges, from the last day of the month in which the original
Class B shares were purchased, provided that shares originally purchased before
May 1, 1997 will convert to Class A shares in May, 2007. The conversion of
shares purchased on or after May 1, 1997 will take place in the month following
the tenth anniversary of the purchase. There will also be converted at that time
such proportion of Class B shares acquired through automatic reinvestment of
dividends and distributions owned by the shareholder as the total number of his
or her Class B shares converting at the time bears to the total number of
outstanding Class B shares purchased and owned by the shareholder. In the case
of Class B shares held by a Qualified Retirement Plan for which MSDW Trust
serves as Trustee or DWR's Retirement Plan Services serves as recordkeeper
pursuant to a written Recordkeeping Services Agreement, 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 first shares of a Morgan Stanley Dean Witter Multi-Class
Fund purchased by that plan. In the case of Class B shares previously exchanged
for shares of an "Exchange Fund" (see "Shareholder Services-- Exchange
Privilege"), the period of time the shares were held in the Exchange Fund
(calculated from the last day of the month in which the Exchange Fund shares
were acquired) is excluded from the holding period for conversion. If those
shares are subsequently re-exchanged for Class B shares of a Morgan Stanley Dean
Witter Multi-Class Fund, the holding period resumes on the last day of the month
in which Class B shares are reacquired.
 
    If a shareholder has received share certificates for Class B shares, such
certificates must be delivered to the Transfer Agent at least one week prior to
the date for conversion. Class B shares evidenced by
 
                                       22
<PAGE>
share certificates that are not received by the Transfer Agent at least one week
prior to any conversion date will be converted into Class A shares on the next
scheduled conversion date after such certificates are received.
 
    Effectiveness of the conversion feature is subject to the continuing
availability of a ruling of the Internal Revenue Service or an opinion of
counsel that (i) the conversion of shares does not constitute a taxable event
under the Internal Revenue Code, (ii) Class A shares received on conversion will
have a basis equal to the shareholder's basis in the converted Class B shares
immediately prior to the conversion, and (iii) Class A shares received on
conversion will have a holding period that includes the holding period of the
converted Class B shares. The conversion feature may be suspended if the ruling
or opinion is no longer available. In such event, Class B shares would continue
to be subject to Class B 12b-1 fees.
 
LEVEL LOAD ALTERNATIVE--CLASS C SHARES
 
    Class C shares are sold at net asset value next determined without an
initial sales charge but are subject to a CDSC of 1.0% on most redemptions made
within one year after purchase (calculated from the last day of the month in
which the shares were purchased). The CDSC will be assessed on an amount equal
to the lesser of the current market value or the cost of the shares being
redeemed. The CDSC will not be imposed in the circumstances set forth above in
the section "Contingent Deferred Sales Charge Alternative--Class B Shares--CDSC
Waivers," except that the references to six years in the first paragraph of that
section shall mean one year in the case of Class C shares. Class C shares are
subject to an annual 12b-1 fee of up to 0.85% of the average daily net assets of
the Class. Unlike Class B shares, Class C shares have no conversion feature and,
accordingly, an investor that purchases Class C shares will be subject to 12b-1
fees applicable to Class C shares for an indefinite period subject to annual
approval by the Fund's Board of Trustees and regulatory limitations.
 
NO LOAD ALTERNATIVE--CLASS D SHARES
 
    Class D shares are offered without any sales charge on purchase or
redemption and without any 12b-1 fee. Class D shares are offered only to
investors meeting an initial investment minimum of $5 million ($25 million for
Qualified Retirement Plans for which MSDW Trust serves as Trustee or DWR's
Retirement Plan Services serves as recordkeeper pursuant to a written
Recordkeeping Services Agreement) and the following categories of investors: (i)
investors participating in the MSDW Advisors mutual fund asset allocation
program pursuant to which such persons pay an asset based fee; (ii) persons
participating in a fee-based program approved by the Distributor, pursuant to
which such persons pay an asset based fee for services in the nature of
investment advisory, administrative and/or brokerage services (subject to all of
the terms and conditions of such programs, referred to in (i) and (ii) above,
which may include termination fees, mandatory redemption upon termination and
such other circumstances as specified in the programs agreements, and
restrictions on transferability of Fund shares); (iii) 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; (iv) certain Unit Investment Trusts sponsored by DWR; (v) certain
other open-end investment companies whose shares are distributed by the
Distributor; (vi) investors who were shareholders of Dean Witter Retirement
Series on September 11, 1998 (with respect to additional purchases for their
former Dean Witter Retirement Series accounts); and (vii) other categories of
investors, at the discretion of the Board, as disclosed in the then current
prospectus of the Fund. Investors who require a $5 million (or $25 million)
minimum initial investment to qualify to purchase Class D shares may satisfy
that requirement by investing that amount in a single transaction in Class D
shares of the Fund and other Morgan Stanley Dean Witter Multi-Class Funds,
subject to the $1,000 minimum initial investment required for that Class of the
Fund. In addition, for the purpose of meeting the $5 million (or $25 million)
minimum
 
                                       23
<PAGE>
investment amount, holdings of Class A shares in all Morgan Stanley Dean Witter
Multi-Class Funds, shares of FSC Funds and shares of Morgan Stanley Dean Witter
Funds for which such shares have been exchanged will be included together with
the current investment amount. If a shareholder redeems Class A shares and
purchases Class D shares, such redemption may be a taxable event.
 
PLAN OF DISTRIBUTION
 
    The Fund has adopted a Plan of Distribution pursuant to Rule 12b-1 under the
Act with respect to the distribution of Class A, Class B and Class C shares of
the Fund. In the case of Class A and Class C shares, the Plan provides that the
Fund will reimburse the Distributor and others for the expenses of certain
activities and services incurred by them specifically on behalf of those shares.
Reimbursements for these expenses will be made in monthly payments by the Fund
to the Distributor, which will in no event exceed amounts equal to payments at
the annual rates of 0.25% and 0.85% of the average daily net assets of Class A
and Class C, respectively. In the case of Class B shares, the Plan provides that
the Fund will pay the Distributor a fee, which is accrued daily and paid
monthly, at the annual rate of 0.85% 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 reinvestments 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 CDSC has been imposed or
waived, or (b) the average daily net assets of Class B. The fee is treated by
the Fund as an expense in the year it is accrued. In the case of Class A shares,
the entire amount of the fee currently represents a service fee within the
meaning of the NASD guidelines. In the case of Class B and Class C shares, a
portion of the fee payable pursuant to the Plan, equal to 0.20% and 0.25% of the
average daily net assets of each of these Classes, respectively, is currently
characterized as a service fee. A service fee is a payment made for personal
service and/or the maintenance of shareholder accounts.
 
    Additional amounts paid under the Plan in the case of Class B and Class C
shares are paid to the Distributor for services provided and the expenses borne
by the Distributor and others in the distribution of the shares of those
Classes, including the payment of commissions for sales of the shares of those
Classes and incentive compensation to and expenses of Morgan Stanley Dean Witter
Financial Advisors and others who engage in or support distribution of shares or
who service shareholder accounts, including overhead and telephone expenses;
printing and distribution of prospectuses and reports used in connection with
the offering of the Fund's shares to other than current shareholders; and
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 DWR 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.
 
    For the fiscal year ended August 31, 1998, Class B shares of the Fund
accrued payments under the Plan amounting to $1,300,714, which amount is equal
to 0.85% of the average daily net assets of Class B for the fiscal year. These
payments were calculated pursuant to clause (b) of the compensation formula
under the Plan. For the fiscal year ended August 31, 1998, Class A and Class C
shares of the Fund accrued payments under the Plan amounting to $4,202 and
$1,925, respectively, which amounts are equal to 0.24% and 0.85% of the average
daily net assets of Class A and Class C, respectively, for the fiscal year.
 
    In the case of Class B shares, at any given time, the expenses in
distributing Class B shares of the Fund may be in excess of the total of (i) the
payments made by the Fund pursuant to the Plan, and (ii) the proceeds of CDSCs
paid by investors upon the redemption of Class B 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
 
                                       24
<PAGE>
expense would amount to $250,000. The Distributor has advised the Fund that such
excess amounts, including the carrying charge described above, totalled
$5,232,570 at August 31, 1998, which was equal to 3.45% 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 or any requirement that
the Plan be continued from year to year, such 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 0.85% 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 Selected Broker-Dealer representatives at the time of sale may be
reimbursed in the subsequent calendar year. The Distributor has advised the Fund
that unreimbursed expenses representing a gross sales commission credited to
Morgan Stanley Dean Witter Financial Advisors and other Selected Broker-Dealer
representatives at the time of sale totalled $2,528 in the case of Class C at
December 31, 1997, which was equal to 1.05% of the net assets of Class C on such
date, and that there were no such expenses which 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.
 
DETERMINATION OF NET ASSET VALUE
 
    The net asset value per share is determined once daily at 4:00 p.m., New
York time (or, on days when the New York Stock Exchange closes prior to 4:00
p.m., at such earlier time), on each day that the New York Stock Exchange is
open by taking the net assets of the Fund, dividing by the number of shares
outstanding and adjusting to the nearest cent. The assets belonging to the Class
A, Class B, Class C and Class D shares will be invested together in a single
portfolio. The net asset value of each Class, however, will be determined
separately by subtracting each Class's accrued expenses and liabilities. The net
asset value per share will not be determined on Good Friday and on such other
federal and non-federal holidays as are observed by the New York Stock Exchange.
 
    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
domestic or foreign exchange is valued at its latest sale price on that exchange
prior to the time 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
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 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 Board of Trustees.
 
    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
 
                                       25
<PAGE>
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. (See "Determination of Net Asset Value" in the Statement of Additional
Information.)
 
SHAREHOLDER SERVICES
- --------------------------------------------------------------------------------
 
    AUTOMATIC INVESTMENT OF DIVIDENDS AND DISTRIBUTIONS.  All income dividends
and capital gains distributions are automatically paid in full and fractional
shares of the applicable Class of the Fund (or, if specified by the shareholder,
in shares of any other open-end Morgan Stanley Dean Witter Fund), unless the
shareholder requests that they be paid in cash. Shares so acquired are acquired
at net asset value and are not subject to the imposition of a front-end sales
charge or a CDSC (see "Redemptions and Repurchases"). Such dividends and
distributions will be paid, at the net asset value per share (without sales
charge), in shares of the applicable Class of the Fund (or in cash if the
shareholder so requests) on the monthly payment date, which will be no later
than the last business day of the month for which the dividend or distribution
is payable. Processing of dividend checks begins immediately following the
monthly payment date. Shareholders who have requested to receive dividends in
cash will normally receive their monthly dividend check during the first ten
days of the following month.
 
    EASYINVEST-SM-.  Shareholders may subscribe to EasyInvest, an automatic
purchase plan which provides for any amount from $100 to $5,000 to be
transferred automatically from a checking or savings account, or following
redemption of shares of a Morgan Stanley Dean Witter money market fund, on a
semi-monthly, monthly or quarterly basis, to the Fund's Transfer Agent for
investment in shares of the Fund (see "Purchases of Fund Shares" and
"Redemptions and Repurchases--Involuntary Redemption").
 
    INVESTMENT OF DIVIDENDS OR DISTRIBUTIONS RECEIVED IN CASH.  Any shareholder
who receives a cash payment representing a dividend or capital gains
distribution may invest such dividend or distribution in shares of the
applicable Class at the net asset value per share next determined after receipt
by the Transfer Agent, by returning the check or the proceeds to the Transfer
Agent within thirty days after the payment date. Shares so acquired are acquired
at net asset value and are not subject to the imposition of a front-end sales
charge or a CDSC (see "Redemptions and Repurchases").
 
    SYSTEMATIC WITHDRAWAL PLAN.  A systematic withdrawal plan (the "Withdrawal
Plan") is available for shareholders whose shares of Morgan Stanley Dean Witter
Funds have an aggregate value of $10,000 or more. Shares of any Fund from which
redemptions will be made pursuant to the Plan must have a value of $1,000 or
more (referred to as a "SWP Fund"). The required share values are determined on
the date the shareholder establishes the Withdrawal Plan. The Withdrawal Plan
provides for monthly, quarterly, semi-annual or annual payments in any amount
not less than $25, or in any whole percentage of the value of the SWP Funds'
shares, on an annualized basis. Any applicable CDSC will be imposed on shares
redeemed under the Withdrawal Plan (see "Purchase of Fund Shares"), except that
the CDSC, if any, will be waived on redemptions under the Withdrawal Plan of up
to 12% annually of the value of each SWP Fund account, based on the share values
next determined after the shareholder establishes the Withdrawal Plan.
Redemptions for which this CDSC waiver policy applies may be in amounts up to 1%
per month, 3% per quarter, 6% semi-annually or 12% annually. Under this CDSC
waiver policy, amounts withdrawn each period will be paid by first redeeming
shares not subject to a CDSC because the shares were purchased by the
reinvestment of dividends or capital gains distributions, the CDSC period has
elapsed or some other waiver of the CDSC applies. If shares subject to a CDSC
must be redeemed, shares held for the longest period of time will be redeemed
first and continuing with shares
 
                                       26
<PAGE>
held the next longest period of time until shares held the shortest period of
time are redeemed. Any shareholder participating in the Withdrawal Plan will
have sufficient shares redeemed from his or her account so that the proceeds
(net of any applicable CDSC) to the shareholder will be the designated monthly,
quarterly, semi-annual or annual amount.
 
    A shareholder may suspend or terminate participation in the Withdrawal Plan
at any time. A shareholder who has suspended participation may resume payments
under the Withdrawal Plan, without requiring a new determination of the account
value for the 12% CDSC waiver. The Withdrawal Plan may be terminated or revised
at any time by the Fund.
 
    Prior to adding an additional SWP Fund to an existing Withdrawal Plan, the
required $10,000/$1,000 share values must be met, to be calculated on the date
the shareholder adds the additional SWP Fund. However, the addition of a new SWP
Fund will not change the account value for the 12% CDSC waiver for the SWP Funds
already participating in the Withdrawal Plan.
 
    Withdrawal Plan payments should not be considered dividends, yields or
income. If periodic Withdrawal Plan payments continuously exceed net investment
income and net capital gains, the shareholder's original investment will be
correspondingly reduced and ultimately exhausted. Each withdrawal constitutes a
redemption of shares and any gain or loss realized must be recognized for
federal income tax purposes.
 
    Shareholders should contact their Morgan Stanley Dean Witter Financial
Advisor or other Selected Broker-Dealer representative or the Transfer Agent for
further information about any of the above services.
 
    TAX-SHELTERED RETIREMENT PLANS.  Retirement plans are available for use by
corporations, the self-employed, eligible Individual Retirement Accounts and
Custodial Accounts under Section 403(b)(7) of the Internal Revenue Code.
Adoption of such plans should be on advice of legal counsel or tax advisor.
 
    For further information regarding plan administration, custodial fees and
other details, investors should contact their Morgan Stanley Dean Witter
Financial Advisor or other Selected Broker-Dealer representative or the Transfer
Agent.
 
EXCHANGE PRIVILEGE
 
    Shares of each Class may be exchanged for shares of the same Class of any
other Morgan Stanley Dean Witter Multi-Class Fund without the imposition of any
exchange fee. Shares may also be exchanged for shares of the following funds:
Morgan Stanley Dean Witter Short-Term U.S. Treasury Trust, Morgan Stanley Dean
Witter Limited Term Municipal Trust, Morgan Stanley Dean Witter Short-Term Bond
Fund and five Morgan Stanley Dean Witter Funds which are money market funds (the
"Exchange Funds"). Class A shares may also be exchanged for shares of Morgan
Stanley Dean Witter Multi-State Municipal Series Trust and Morgan Stanley Dean
Witter Hawaii Municipal Trust, which are Morgan Stanley Dean Witter Funds sold
with a front-end sales charge ("FSC Funds"). Exchanges may be made after the
shares of the Fund acquired by purchase (not by exchange or dividend
reinvestment) have been held for thirty days. There is no waiting period for
exchanges of shares acquired by exchange or dividend reinvestment.
 
    An exchange to another Morgan Stanley Dean Witter Multi-Class Fund, any FSC
Fund or any Exchange Fund that is not a money market fund is on the basis of the
next calculated net asset value per share of each fund after the exchange order
is received. When exchanging into a money market fund from the Fund, shares of
the Fund are redeemed out of the Fund at their next calculated net asset value
and the proceeds of the redemption are used to purchase shares of the money
market fund at their net asset value determined the following business day.
Subsequent exchanges between any of the Morgan Stanley Dean Witter Multi-Class
Funds, FSC Funds or any Exchange Fund that is not a
 
                                       27
<PAGE>
money market fund can be effected on the same basis.
 
    No CDSC is imposed at the time of any exchange of shares, although any
applicable CDSC will be imposed upon ultimate redemption. During the period of
time the shareholder remains in an Exchange Fund (calculated from the last day
of the month in which the Exchange Fund shares were acquired), the holding
period (for the purpose of determining the rate of the CDSC) is frozen. If those
shares are subsequently re-exchanged for shares of a Morgan Stanley Dean Witter
Multi-Class Fund, the holding period previously frozen when the first exchange
was made resumes on the last day of the month in which shares of a Morgan
Stanley Dean Witter Multi-Class Fund are reacquired. Thus, the CDSC is based
upon the time (calculated as described above) the shareholder was invested in
shares of a Morgan Stanley Dean Witter Multi-Class Fund (see "Purchase of Fund
Shares"). In the case of exchanges of Class A shares which are subject to a
CDSC, the holding period also includes the time (calculated as described above)
the shareholder was invested in shares of a FSC Fund. In the case of shares
exchanged into an Exchange Fund on or after April 23, 1990, upon a redemption of
shares which results in a CDSC being imposed, a credit (not to exceed the amount
of the CDSC) will be given in an amount equal to the Exchange Fund 12b-1
distribution fees incurred on or after that date which are attributable to those
shares. (Exchange Fund 12b-1 distribution fees are described in the prospectuses
for those funds.) Class B shares of the Fund acquired in exchange for Class B
shares of another Morgan Stanley Dean Witter Multi-Class Fund having a different
CDSC schedule than that of this Fund will be subject to the higher CDSC
schedule, even if such shares are subsequently re-exchanged for shares of the
fund with the lower CDSC schedule.
 
    ADDITIONAL INFORMATION REGARDING EXCHANGES. Purchases and exchanges should
be made for investment purposes only. A pattern of frequent exchanges may be
deemed by the Investment Manager to be abusive and contrary to the best
interests of the Fund's other shareholders and, at the Investment Manager's
discretion, may be limited by the Fund's refusal to accept additional purchases
and/or exchanges from the investor. Although the Fund does not have any specific
definition of what constitutes a pattern of frequent exchanges, and will
consider all relevant factors in determining whether a particular situation is
abusive and contrary to the best interests of the Fund and its other
shareholders, investors should be aware that the Fund and each of the other
Morgan Stanley Dean Witter Funds may in their discretion limit or otherwise
restrict the number of times this Exchange Privilege may be exercised by any
investor. Any such restriction will be made by the Fund on a prospective basis
only, upon notice of the shareholder not later than ten days following such
shareholder's most recent exchange. Also, the Exchange Privilege may be
terminated or revised at any time by the Fund and/or any of such Morgan Stanley
Dean Witter Funds for which shares of the Fund have been exchanged, upon such
notice as may be required by applicable regulatory agencies. Shareholders
maintaining margin accounts with DWR or another Selected Broker-Dealer are
referred to their Morgan Stanley Dean Witter Financial Advisor or other Selected
Broker-Dealer representative regarding restrictions on exchange of shares of the
Fund pledged in the margin account.
 
    The current prospectus for each fund describes its investment objective and
policies, and shareholders should obtain a copy and examine it carefully before
investing. Exchanges are subject to the minimum investment requirement of each
Class of shares and any other conditions imposed by each fund. In the case of a
shareholder holding a share certificate or certificates, no exchanges may be
made until all applicable share certificates have been received by the Transfer
Agent and deposited in the shareholder's account. An exchange will be treated
for federal income tax purposes the same as a repurchase or redemption of
shares, on which the shareholder may realize a capital gain or loss. However,
the ability to deduct capital losses on an exchange may be limited in situations
where there is an exchange of shares within ninety days after the
 
                                       28
<PAGE>
shares are purchased. The Exchange Privilege is only available in states where
an exchange may legally be made.
 
    If DWR or another Selected Broker-Dealer is the current dealer of record and
its account numbers are part of the account information, shareholders may
initiate an exchange of shares of the Fund for shares of any of the Morgan
Stanley Dean Witter Funds (for which the Exchange Privilege is available)
pursuant to this Exchange Privilege by contacting their Morgan Stanley Dean
Witter Financial Advisor or other Selected Broker-Dealer representative (no
Exchange Privilege Authorization Form is required). Other shareholders (and
those shareholders who are clients of DWR or other Selected Broker-Dealers but
who wish to make exchanges directly by writing or telephoning the Transfer
Agent) must complete and forward to the Transfer Agent an Exchange Privilege
Authorization Form, copies of which may be obtained from the Transfer Agent, to
initiate an exchange. If the Authorization Form is used, exchanges may be made
in writing or by contacting the Transfer Agent at (800) 869-NEWS (toll-free).
 
    The Fund will employ reasonable procedures to confirm that exchange
instructions communicated over the telephone are genuine. Such procedures may
include requiring various forms of personal identification such as name, mailing
address, social security or other tax identification number and DWR or other
Selected Broker-Dealer account number (if any). Telephone instructions may also
be recorded. If such procedures are not employed, the Fund may be liable for any
losses due to unauthorized or fraudulent instructions.
 
    Telephone exchange instructions will be accepted if received by the Transfer
Agent between 9:00 a.m. and 4:00 p.m., New York time, on any day the New York
Stock Exchange is open. Any shareholder wishing to make an exchange who has
previously filed an Exchange Privilege Authorization Form and who is unable to
reach the Fund by telephone should contact his or her Morgan Stanley Dean Witter
Financial Advisor or other Selected Broker-Dealer representative, if
appropriate, or make a written exchange request. Shareholders are advised that
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 experience with the Morgan Stanley Dean Witter Funds in the past.
 
    For further information regarding the Exchange Privilege, shareholders
should contact their Morgan Stanley Dean Witter Financial Advisor or other
Selected Broker-Dealer representative or the Transfer Agent.
 
REDEMPTIONS AND REPURCHASES
- --------------------------------------------------------------------------------
 
    REDEMPTION.  Shares of each Class of the Fund can be redeemed for cash at
any time at the net asset value per share next determined less the amount of any
applicable CDSC in the case of Class A, Class B or Class C shares (see "Purchase
of Fund Shares"). If shares are held in a shareholder's account without a share
certificate, a written request for redemption to the Fund's Transfer Agent at
P.O. Box 983, Jersey City, NJ 07303 is required. If certificates are held by the
shareholder, the shares may be redeemed by surrendering the certificates with a
written request for redemption along with any additional documentation required
by the Transfer Agent.
    REPURCHASE.  DWR and other Selected Broker-Dealers are authorized to
repurchase shares represented by a share certificate which is delivered to any
of their offices. Shares held in a shareholder's account without a share
certificate may also be repurchased by DWR and other Selected Broker-Dealers
upon the telephonic or telegraphic request of the shareholder. The repurchase
price is the net asset value next computed (see "Purchase of Fund Shares") after
such repurchase order is received by DWR and other Selected Broker-Dealers,
reduced by any applicable CDSC.
 
    The CDSC, if any, will be the only fee imposed by the Fund or the
Distributor. The offer by DWR and
 
                                       29
<PAGE>
other Selected Broker-Dealers to repurchase shares may be suspended without
notice by them at any time. In that event, shareholders may redeem their shares
through the Fund's Transfer Agent as set forth above under "Redemption."
 
    PAYMENT FOR SHARES REDEEMED OR REPURCHASED. Payment for shares presented for
repurchase or redemption will be made by check within seven days after receipt
by the Transfer Agent of the certificate and/or written request in good order.
Such payment may be postponed or the right of redemption suspended under unusual
circumstances, e.g., when normal trading is not taking place on the New York
Stock Exchange. If the shares to be redeemed have recently been purchased by
check, payment of the redemption proceeds may be delayed for the minimum time
needed to verify that the check used for investment has been honored (not more
than fifteen days from the time of receipt of the check by the Transfer Agent).
Shareholders maintaining margin accounts with DWR or another Selected Broker-
Dealer are referred to their Morgan Stanley Dean Witter Financial Advisor or
other Selected Broker-Dealer representative regarding restrictions on redemption
of shares of the Fund pledged in the margin account.
 
    REINSTATEMENT PRIVILEGE.  A shareholder who has had his or her shares
redeemed or repurchased and has not previously exercised this reinstatement
privilege may, within 35 days after the date of the redemption or repurchase,
reinstate any portion or all of the proceeds of such redemption or repurchase in
shares of the Fund in the same Class from which such shares were redeemed or
repurchased, at their net asset value next determined after a reinstatement
request, together with the proceeds, is received by the Transfer Agent and
receive a pro rata credit for any CDSC paid in connection with such redemption
or repurchase.
 
    INVOLUNTARY REDEMPTION.  The Fund reserves the right to redeem, on sixty
days' notice and at net asset value, the shares (other than shares held in an
Individual Retirement Account or Custodial Account under Section 403(b)(7) of
the Internal Revenue Code) of any shareholder whose shares, due to redemptions
by the shareholder, have a value of less than $100 or such lesser amount as may
be fixed by the Trustees or, in the case of an account opened through
EasyInvest-SM-, if after twelve months the shareholder has invested less than
$1,000 in the account. However, before the Fund redeems such shares and sends
the proceeds to the shareholder it will notify the shareholder that the value of
the shares is less than the applicable amount and allow the shareholder sixty
days to make an additional investment in an amount which will increase the value
of the account to at least the applicable amount before the redemption is
processed. No CDSC will be imposed on any involuntary redemption.
 
DIVIDENDS, DISTRIBUTIONS AND TAXES
- --------------------------------------------------------------------------------
 
    DIVIDENDS AND DISTRIBUTIONS.  The Fund declares dividends separately for
each Class of shares and intends to declare dividends from net investment income
on each day the New York Stock Exchange is open for business (see "Purchase of
Fund Shares"). The amount of the dividend declared may fluctuate from day to
day. Dividends are declared daily and paid monthly in additional shares of the
Fund. The Fund intends to distribute dividends from net short-term and long-term
capital gains, if any, at least once each year. The Fund may, however, elect to
retain all or a portion of any net long-term capital gains in any year.
    All dividends and any capital gains distributions will be paid in additional
shares of the same Class and automatically credited to the shareholder's account
without issuance of a share certificate unless the shareholder requests in
writing that all dividends or all dividends and distributions be paid in cash.
Shares acquired by dividend and distribution reinvestments will not be subject
to any front-end sales charge or CDSC. Class B shares acquired through
 
                                       30
<PAGE>
dividend and distribution reinvestments will become eligible for conversion to
Class A shares on a pro rata basis. Distributions paid on Class A and Class D
shares will be higher than for Class B and Class C shares because distribution
fees paid by Class B and Class C shares are higher. (See "Shareholder
Services--Automatic Investment of Dividends and Distributions".)
 
    TAXES.  Because the Fund intends to distribute all of its net investment
income and capital gains to shareholders and otherwise continue to qualify as a
regulated investment company under Subchapter M of the Internal Revenue Code, it
is not expected that the Fund will be required to pay any federal income tax.
Shareholders who are required to pay taxes on their income will normally have to
pay federal income taxes, and any state and local income taxes, on the dividends
and distributions they receive from the Fund. Such dividends and distributions,
to the extent that they are derived from net investment income or net short-term
capital gains, are taxable to the shareholder as ordinary dividend income
regardless of whether the shareholder receives such payments in additional
shares or in cash. Any dividends declared in the last quarter of any calendar
year which are paid to shareholders of record in such period in the following
year prior to February 1 will be deemed, for tax purposes, to have been received
by the shareholder in the prior year.
 
    Long-term and short-term capital gains may be generated by the sale of
portfolio securities by the Fund. 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. After the end of the
calendar year, shareholders will receive full information on their dividends and
capital gains distributions for tax purposes, including information as to the
portion taxable as ordinary income and the portion taxable as mid-term and
long-term capital gains. Shareholders will also be notified if their
proportionate share of long-term capital gains distributions that are eligible
for a reduced rate of tax under the Taxpayer Relief Act of 1997.
 
    The Fund may at times make payments from sources other than income or net
capital gains. Payments from such sources would, in effect, represent a return
of a portion of each shareholder's investment. All, or a portion, of such
payments would not be taxable to shareholders.
 
    To avoid being subject to a 31% federal backup withholding tax on taxable
dividends, capital gains distributions and the proceeds of redemptions and
repurchases, shareholders' taxpayer identification numbers must be furnished and
certified as to accuracy. The foregoing discussion relates solely to the federal
income tax consequences of an investment in the Fund. Distributions may also be
subject to state and local taxes; therefore, each shareholder is advised to
consult his or her own tax advisor.
 
PERFORMANCE INFORMATION
- --------------------------------------------------------------------------------
 
    From time to time the Fund may quote its "yield" and/or its "total return"
in advertisements and sales literature. These figures are computed separately
for Class A, Class B, Class C and Class D shares. Both the yield and the total
return of the Fund are based on historical earnings and are not intended to
indicate future performance. The yield of each Class of the Fund is computed by
dividing the Class's net investment income over a 30-day period by an average
value (using the average number of shares entitled to receive dividends and the
maximum offering price per share at the end of the period), all in accordance
with applicable regulatory requirements. Such amount is compounded for six
months and then annualized for a twelve-month period to derive the Fund's yield
for each Class.
 
    The "average annual total return" of the Fund refers to a figure reflecting
the average annualized
 
                                       31
<PAGE>
percentage increase (or decrease) in the value of an initial investment in a
Class of the Fund of $1,000 over periods of one, five and ten years, or over the
life of the Fund, if less than any of the foregoing. Average annual total return
reflects all income earned by the Fund, any appreciation or depreciation of the
Fund's assets, all expenses incurred by the applicable Class and all sales
charges incurred by shareholders, for the stated periods. It also assumes
reinvestment of all dividends and distributions paid by the Fund.
 
    In addition to the foregoing, 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. 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. Such calculations may or may not reflect the
deduction of any sales charge which, if reflected, would reduce the performance
quoted. The Fund from time to time may also advertise its performance relative
to certain performance rankings and indexes compiled by independent
organizations, such as mutual fund performance rankings of Lipper Analytical
Services, Inc.
 
ADDITIONAL INFORMATION
- --------------------------------------------------------------------------------
 
    VOTING RIGHTS.  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, as discussed herein, Class A, Class B
and Class C bear the expenses related to the distribution of their respective
shares.
 
    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 Act or the Declaration of Trust.
 
    Under Massachusetts law, shareholders of a business trust may, under certain
circumstances, be held personally liable as partners for 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 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, in the opinion of Massachusetts counsel to the Fund, the risk to
Fund shareholders of personal liability is remote.
 
    CODE OF ETHICS.  Directors, officers and employees of MSDW Advisors, MSDW
Services and MSDW Distributors are subject to a strict Code of Ethics adopted by
those companies. The Code of Ethics is intended to ensure that the interests of
shareholders and other clients are placed ahead of any personal interest, that
no undue personal benefit is obtained from a person's employment activities and
that actual and potential conflicts of interest are avoided. To achieve these
goals and comply with regulatory requirements, the Code of Ethics requires,
among other things, that personal securities transactions by employees of the
companies be subject to an advance clearance process to monitor that no Morgan
Stanley Dean Witter Fund is engaged at the same time in a purchase or sale of
 
                                       32
<PAGE>
the same security. The Code of Ethics bans the purchase of securities in an
initial public offering, and also prohibits engaging in futures and options
transactions and profiting on short-term trading (that is, a purchase within
sixty days of a sale or a sale within sixty days of a purchase) of a security.
In addition, investment personnel may not purchase or sell a security for their
personal account within thirty days before or after any transaction in any
Morgan Stanley Dean Witter Fund managed by them. Any violations of the Code of
Ethics are subject to sanctions, including reprimand, demotion or suspension or
termination of employment. The Code of Ethics comports with regulatory
requirements and the recommendations in the 1994 report by the Investment
Company Institute Advisory Group on Personal Investing.
 
    MASTER/FEEDER CONVERSION.  The Fund reserves the right to seek to achieve
its investment objective by investing all of its investable assets in a
diversified, open-end management investment company having the same investment
objective and policies and substantially the same investment restrictions as
those applicable to the Fund.
 
    SHAREHOLDER INQUIRIES.  All inquiries regarding the Fund should be directed
to the Fund at the telephone numbers or address set forth on the front cover of
this Prospectus.
 
                                       33
<PAGE>
Morgan Stanley Dean Witter
Intermediate
Income Securities
Two World Trade Center
New York, New York 10048
 
TRUSTEES
 
Michael Bozic
Charles A. Fiumefreddo
Edwin J. Garn
John R. Haire
Wayne E. Hedien
Dr. Manuel H. Johnson
Michael E. Nugent
Philip J. Purcell
John L. Schroeder
 
OFFICERS
 
Charles A. Fiumefreddo
Chairman and Chief Executive Officer
Barry Fink
Vice President, Secretary and General Counsel
Rochelle G. Siegel
Vice President
Thomas F. Caloia
Treasurer
 
CUSTODIAN
 
The Bank of New York
90 Washington Street
New York, New York 10286
 
TRANSFER AGENT AND
DIVIDEND DISBURSING AGENT
 
Morgan Stanley Dean Witter Trust FSB
Harborside Financial Center
Plaza Two
Jersey City, New Jersey 07311
 
INDEPENDENT ACCOUNTANTS
 
PricewaterhouseCoopers LLP
1177 Avenue of the Americas
New York, New York 10036
 
INVESTMENT MANAGER
 
Morgan Stanley Dean Witter Advisors Inc.
 
MORGAN STANLEY
DEAN WITTER
INTERMEDIATE
INCOME SECURITIES
 
                              [GRAPHIC]
                                                  PROSPECTUS -- OCTOBER 30, 1998
<PAGE>
   
STATEMENT OF ADDITIONAL INFORMATION
DEAN WITTER
INTERMEDIATE INCOME
SECURITIES
OCTOBER 30, 1997
    
 
- --------------------------------------------------------------------------------
 
   
    Morgan Stanley Dean Witter Intermediate Income Securities (the "Fund") is an
open-end, diversified management investment company whose investment objective
is high current income consistent with the safety of principal. The Fund seeks
to achieve its investment objective by investing primarily in intermediate term,
investment grade fixed-income securities. See "Investment Objective and
Policies."
    
 
   
    A Prospectus for the Fund dated October 30, 1998, which provides the basic
information you should know before investing in the Fund, may be obtained
without charge from the Fund at the address or telephone numbers listed below,
from the Fund's Distributor, Morgan Stanley Dean Witter Distributors Inc., or
from Dean Witter Reynolds Inc. at any of its branch offices. This Statement of
Additional Information is not a Prospectus. It contains information in addition
to and more detailed than that set forth in the Prospectus. It is intended to
provide additional information regarding the activities and operations of the
Fund, and should be read in conjunction with the Prospectus.
    
 
   
Morgan Stanley Dean Witter
Intermediate Income Securities
Two World Trade Center
New York, New York 10048
(212) 392-2550 or
(800) 869-NEWS (Toll-Free)
    
<PAGE>
TABLE OF CONTENTS
- --------------------------------------------------------------------------------
 
   
<TABLE>
  <S>                                       <C>
  The Fund and its Management.............     3
 
  Trustees and Officers...................     7
 
  Investment Practices and Policies.......    13
 
  Investment Restrictions.................    17
 
  Portfolio Transactions and Brokerage....    18
 
  The Distributor.........................    20
 
  Determination of Net Asset Value........    24
 
  Purchase of Fund Shares.................    25
 
  Shareholder Services....................    27
 
  Redemptions and Repurchases.............    32
 
  Dividends, Distributions and Taxes......    34
 
  Performance Information.................    35
 
  Description of Shares...................    37
 
  Custodian and Transfer Agent............    37
 
  Independent Accountants.................    38
 
  Reports to Shareholders.................    38
 
  Legal Counsel...........................    38
 
  Experts.................................    38
 
  Registration Statement..................    38
 
  Financial Statements--August 31, 1998...    39
 
  Report of Independent Accountants.......    53
 
  Appendix................................    54
</TABLE>
    
 
                                       2
<PAGE>
THE FUND AND ITS MANAGEMENT
- --------------------------------------------------------------------------------
 
THE FUND
 
   
    The Fund is a trust of the type commonly known as a "Massachusetts business
trust" and was organized under the laws of the Commonwealth of Massachusetts on
September 1, 1988 under the name Dean Witter Intermediate Income Securities. On
June 22, 1998, the Fund adopted an Amendment to the Declaration of Trust of the
Fund changing the name of the Fund to Morgan Stanley Dean Witter Intermediate
Income Securities.
    
 
THE INVESTMENT MANAGER
 
   
    Morgan Stanley Dean Witter Advisors Inc. (the "Investment Manager" or "MSDW
Advisors"), a Delaware Corporation, whose address is Two World Trade Center, New
York, New York 10048, is the Fund's Investment Manager. MSDW Advisors is a
wholly-owned subsidiary of Morgan Stanley Dean Witter & Co. ("MSDW"), a Delaware
corporation. The daily management of the Fund and research relating to the
Fund's portfolio are conducted by or under the direction of officers of the Fund
and of the Investment Manager, subject to review by the Fund's Board of
Trustees. Information as to these Trustees and Officers is contained under the
caption "Trustees and Officers."
    
 
   
    MSDW Advisors is the investment manager or investment advisor of the
following investment companies, which are collectively referred to as the
"Morgan Stanley Dean Witter Funds":
    
 
   
<TABLE>
<CAPTION>
OPEN-END FUNDS
 
<C>        <S>
        1  Active Assets California Tax-Free Trust
        2  Active Assets Government Securities Trust
        3  Active Assets Money Trust
        4  Active Assets Tax-Free Trust
        5  Morgan Stanley Dean Witter American Value Fund
        6  Morgan Stanley Dean Witter Balanced Growth Fund
        7  Morgan Stanley Dean Witter Balanced Income Fund
        8  Morgan Stanley Dean Witter California Tax-Free Daily Income Trust
        9  Morgan Stanley Dean Witter California Tax-Free Income Fund
       10  Morgan Stanley Dean Witter Capital Appreciation Fund
       11  Morgan Stanley Dean Witter Capital Growth Securities
       12  Morgan Stanley Dean Witter Competitive Edge Fund, "BEST IDEAS" Portfolio
       13  Morgan Stanley Dean Witter Convertible Securities Trust
       14  Morgan Stanley Dean Witter Developing Growth Securities Trust
       15  Morgan Stanley Dean Witter Diversified Income Trust
       16  Morgan Stanley Dean Witter Dividend Growth Securities Inc.
       17  Morgan Stanley Dean Witter Equity Fund
       18  Morgan Stanley Dean Witter European Growth Fund Inc.
       19  Morgan Stanley Dean Witter Federal Securities Trust
       20  Morgan Stanley Dean Witter Financial Services Trust
       21  Morgan Stanley Dean Witter Fund of Funds
       22  Morgan Stanley Dean Witter Global Dividend Growth Securities
       23  Morgan Stanley Dean Witter Global Short-Term Income Fund Inc.
       24  Morgan Stanley Dean Witter Global Utilities Fund
       25  Morgan Stanley Dean Witter Growth Fund
       26  Morgan Stanley Dean Witter Hawaii Municipal Trust
       27  Morgan Stanley Dean Witter Health Sciences Trust
       28  Morgan Stanley Dean Witter High Yield Securities Inc.
       29  Morgan Stanley Dean Witter Income Builder Fund
       30  Morgan Stanley Dean Witter Information Fund
       31  Morgan Stanley Dean Witter Intermediate Income Securities
</TABLE>
    
 
                                       3
<PAGE>
   
<TABLE>
<C>        <S>
       32  Morgan Stanley Dean Witter International SmallCap Fund
       33  Morgan Stanley Dean Witter Japan Fund
       34  Morgan Stanley Dean Witter Limited Term Municipal Trust
       35  Morgan Stanley Dean Witter Liquid Asset Fund Inc.
       36  Morgan Stanley Dean Witter Market Leader Trust
       37  Morgan Stanley Dean Witter Mid-Cap Dividend Growth Securities
       38  Morgan Stanley Dean Witter Mid-Cap Growth Fund
       39  Morgan Stanley Dean Witter Multi-State Municipal Series Trust
       40  Morgan Stanley Dean Witter Natural Resource Development Securities Inc.
       41  Morgan Stanley Dean Witter New York Municipal Money Market Trust
       42  Morgan Stanley Dean Witter New York Tax-Free Income Fund
       43  Morgan Stanley Dean Witter Pacific Growth Fund Inc.
       44  Morgan Stanley Dean Witter Precious Metals and Minerals Trust
       45  Morgan Stanley Dean Witter Select Dimensions Investment Series
       46  Morgan Stanley Dean Witter Select Municipal Reinvestment Fund
       47  Morgan Stanley Dean Witter Short-Term Bond Fund
       48  Morgan Stanley Dean Witter Short-Term U.S. Treasury Trust
       49  Morgan Stanley Dean Witter Special Value Fund
       50  Morgan Stanley Dean Witter S&P 500 Index Fund
       51  Morgan Stanley Dean Witter S&P 500 Select Fund
       52  Morgan Stanley Dean Witter Strategist Fund
       53  Morgan Stanley Dean Witter Tax-Exempt Securities Trust
       54  Morgan Stanley Dean Witter Tax-Free Daily Income Trust
       55  Morgan Stanley Dean Witter U.S. Government Money Market Trust
       56  Morgan Stanley Dean Witter U.S. Government Securities Trust
       57  Morgan Stanley Dean Witter Utilities Fund
       58  Morgan Stanley Dean Witter Value-Added Market Series
       59  Morgan Stanley Dean Witter Value Fund
       60  Morgan Stanley Dean Witter Variable Investment Series
       61  Morgan Stanley Dean Witter World Wide Income Trust
<CAPTION>
 
CLOSED-END FUNDS
<C>        <S>
 
        1  InterCapital California Insured Municipal Income Trust
        2  InterCapital California Quality Municipal Securities
        3  Dean Witter Government Income Trust
        4  High Income Advantage Trust
        5  High Income Advantage Trust II
        6  High Income Advantage Trust III
        7  InterCapital Income Securities Inc.
        8  InterCapital Insured California Municipal Securities
        9  InterCapital Insured Municipal Bond Trust
       10  InterCapital Insured Municipal Income Trust
       11  InterCapital Insured Municipal Securities
       12  InterCapital Insured Municipal Trust
       13  Municipal Income Opportunities Trust
       14  Municipal Income Opportunities Trust II
       15  Municipal Income Opportunities Trust III
       16  Municipal Income Trust
       17  Municipal Income Trust II
       18  Municipal Income Trust III
       19  Municipal Premium Income Trust
       20  InterCapital New York Quality Municipal Securities
</TABLE>
    
 
                                       4
<PAGE>
   
<TABLE>
<C>        <S>
       21  Morgan Stanley Dean Witter Prime Income Trust
       22  InterCapital Quality Municipal Income Trust
       23  InterCapital Quality Municipal Investment Trust
       24  InterCapital Quality Municipal Securities
</TABLE>
    
 
   
    In addition, Morgan Stanley Dean Witter Services Company Inc. ("MSDW
Services"), a wholly-owned subsidiary of MSDW Advisors, serves as manager for
the following investment companies for which TCW Funds Management, Inc. is the
investment advisor (the "TCW/DW Funds"):
    
   
<TABLE>
<CAPTION>
OPEN-END FUNDS
 
<C>        <S>
        1  TCW/DW Emerging Markets Opportunities Trust
        2  TCW/DW Global Telecom Trust
        3  TCW/DW Income and Growth Fund
        4  TCW/DW Latin American Growth Fund
        5  TCW/DW Mid-Cap Equity Trust
        6  TCW/DW North American Government Income Trust
        7  TCW/DW Small Cap Growth Fund
        8  TCW/DW Total Return Trust
 
<CAPTION>
 
CLOSED-END FUNDS
<C>        <S>
 
        1  TCW/DW Term Trust 2000
        2  TCW/DW Term Trust 2002
        3  TCW/DW Term Trust 2003
</TABLE>
    
 
   
    MSDW Advisors also serves as: (i) administrator of The BlackRock Strategic
Term Trust Inc., a closed-end investment company; (ii) sub-administrator of
Templeton Global Governments Income Trust, a closed-end investment company; and
(iii) investment advisor of Offshore Dividend Growth Fund and Offshore Money
Market Fund, mutual funds established under the laws of the Cayman Islands and
available only to investors who are participants in the International Active
Assets Account program and are neither citizens nor residents of the United
States.
    
 
   
    Pursuant to an Investment Management Agreement (the "Agreement") with the
Investment Manager, the Fund has retained the Investment Manager to manage 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 such 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 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, such office space,
facilities, equipment, clerical help and bookkeeping and legal services as the
Fund may reasonably require in the conduct of its business, including the
preparation of prospectuses, statements of additional information, 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. The
Investment Manager has retained MSDW Services to provide its administrative
services under the Agreement.
    
 
   
    Expenses not expressly assumed by the Investment Manager under the Agreement
or by the Distributor of the Fund's shares, Morgan Stanley Dean Witter
Distributors Inc. ("MSDW Distributors" or "The Distributor") will be paid by the
Fund. These expenses will be allocated among the four classes of shares of the
Fund (each, a "Class") 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
    
 
                                       5
<PAGE>
Distribution pursuant to Rule 12b-1 (the "12b-1 fee") (see "The Distributor"),
charges and expenses of any registrar, custodian, stock transfer and dividend
disbursing agent; brokerage commissions; taxes; engraving and printing of 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 and Statements of Additional Information 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) and 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.
 
   
    As full compensation for the services and facilities furnished to the Fund
and expenses of the Fund assumed by the Investment Manager, the Fund pays the
Investment Manager monthly compensation calculated daily by applying the
following annual rates to the net assets of the Fund, determined as of the close
of business on every business day: 0.60% of the portion of the daily net assets
not exceeding $500 million; 0.50% of the portion of daily net assets exceeding
$500 million but not exceeding $750 million; 0.40% of the portion of the daily
net assets exceeding $750 million but not exceeding $1 billion; and 0.30% of the
portion of the daily net assets exceeding $1 billion. The management fee is
allocated among the Classes pro rata based on the net assets of the Fund
attributable to each Class. Total compensation accrued to the Investment Manager
under the Agreement for the fiscal years ended August 31, 1996, 1997 and 1998
was $1,337,360, $1,116,809, and $964,411, respectively.
    
 
    The 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 Agreement in no way restricts the Investment Manager from
acting as investment manager or adviser to others.
 
    The Agreement was initially approved by the Trustees on February 21, 1997
and by the shareholders of the Fund at a Special Meeting of Shareholders held on
May 21, 1997. The Agreement is substantially identical to a prior investment
management agreement which was initially approved by the Board of Trustees on
October 30, 1992 and by the shareholders of the Fund at a Special Meeting of
Shareholders held on January 12, 1993. The Agreement took effect on May 31, 1997
upon the consummation of the merger of Dean Witter, Discover & Co. with Morgan
Stanley Group Inc. The Agreement may be terminated at any time, without penalty,
on thirty days' notice by the Board of Trustees of the Fund, by the holders of a
majority, as defined in the Investment Company Act of 1940 (the "Act"), of the
outstanding shares of the Fund, or by the Investment Manager. The Agreement will
automatically terminate in the event of its assignment (as defined in the Act).
 
    Under its terms, the Agreement has an initial term ending April 30, 1999,
and provides that it will continue in effect from year to year thereafter,
provided continuance of the Agreement is approved at least annually by the vote
of the holders of a majority, as defined in the Act, of the outstanding shares
of the Fund, or by the Trustees of the Fund; provided that in either event such
continuance is approved annually by the vote of a majority of the Trustees of
the Fund who are not parties to the Agreement or
 
                                       6
<PAGE>
"interested persons" (as defined in the Act) of any such party (the "Independent
Trustees"), which vote must be cast in person at a meeting called for the
purpose of voting on such approval.
 
   
    The following owned more than 5% of the outstanding shares of Class A of the
Fund on October 12, 1998: MSDWT FSB Trustee, West Coast Beauty Supply Co,
Retirement Savings Plan, P.O. Box 957, Jersey City, NJ 07303-0957--33.5%; Elaine
Marie Moscone REV TR AGRMNT, DTD 3/29/90, Elaine Marie Moscone TT, 382 Cranbrook
Ct., Bloomfield Hills, MI 48304-3525--21.3%; The David Arno Hughey Revocable TR,
DTD 11/25/96, David Arno Hughey and Susan E. Hughey TTEES, P.O. Box 501,
Merideth NH 03253-0501--6.7%; MSDW Trust Trustee, Morristown Hamblen 401k Plan,
P.O. Box 957, Jersey City, NJ 07303-0957--6.6%; Rita J. Kennedy, 840 Fenimore
Rd, Larchmont, NY 10538-1115-- 6.5%; MSDW Trust as Trustee, VVP America Salary
Deferral Plan, P.O. Box 957, Jersey City, NJ 07303-0957--6.4%. The following
owned more than 5% of the outstanding shares of Class C of the Fund on October
12, 1998: Barbara L. Strom, Gordon W. Strom & Kristine S. Erickson TTES of the
Barbara L. Strom REV TST DTD 11/04/96, 95 Woodland Circle, Edina, MN
55424-1454--39.9%; Robert E. Walker and Sarah M. Walker TEN/COM, 3713 NW
Ridgeway Circle, Bremerton, WA 98312-1711--13.7%; Dean Witter Reynolds CUST for
Thomas H. Carpenter, IRA Rollover Dated 09/16/97, 12 Sunset Drive, Fredonia, NY
14063-1629--6.5%. The following owned more than 5% of the outstanding shares of
Class D of the Fund on October 12, 1998: Melon Bank N.A., Mutual Funds
Operations, P.O. Box 3198, Pittsburgh, PA 15230-3198, as trustee of the Morgan
Stanley Dean Witter START Plan and the SPS Transaction Services, Inc. START
Plan, employee benefit plans established by certain subsidiaries of MSDW for
their employees as qualified under Sections 401(a) and 401(k) of the Internal
Revenue Code--64.9%; Morgan Stanley Dean Witter Trust Trustee Private Business
Profit Sharing Plan, P.O. Box 957, Jersey City, NJ 07303-0957--8.2%; IAM & AW
Local Lodge PM#2848, Multi-Emp Wage Reduc 401K PSP 03/06/86, TTEE J.
Winterhalter, P.O. Box 3039, Birmingham, MI 48012-3039--4.9%.
    
 
   
    The Fund has acknowledged that the name "Morgan Stanley Dean Witter" is a
property right of MSDW. The Fund has agreed that MSDW, or any corporate
affiliate of MSDW, may use, or at any time permit others to use, the name
"Morgan Stanley Dean Witter." The Fund has also agreed that in the event the
investment management contract between MSDW Advisors and the Fund is terminated,
or if the affiliation between the Investment Manager and its parent company is
terminated, the Fund will eliminate the name "Morgan Stanley Dean Witter" from
its name if MSDW shall so request.
    
 
TRUSTEES AND OFFICERS
- --------------------------------------------------------------------------------
 
   
    The Trustees and Executive Officers of the Fund, their principal business
occupations during the last five years and their affiliations, if any, with MSDW
Advisors and with the 85 Morgan Stanley Dean Witter Funds and the 11 TCW/DW
Funds are shown below.
    
 
   
<TABLE>
<CAPTION>
      NAME, AGE, POSITION WITH FUND AND ADDRESS                PRINCIPAL OCCUPATIONS DURING LAST FIVE YEARS
- ------------------------------------------------------  ----------------------------------------------------------
<S>                                                     <C>
Michael Bozic (57) ...................................  Chairman and Chief Executive Officer of Levitz Furniture
Trustee                                                 Corporation (since November, 1995); Director or Trustee of
c/o Levitz Furniture Corporation                        the Morgan Stanley Dean Witter Funds; formerly President
7887 N. Federal Highway                                 and Chief Executive Officer of Hills Department Stores
Boca Raton, Florida                                     (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.
</TABLE>
    
 
                                       7
<PAGE>
   
<TABLE>
<CAPTION>
      NAME, AGE, POSITION WITH FUND AND ADDRESS                PRINCIPAL OCCUPATIONS DURING LAST FIVE YEARS
- ------------------------------------------------------  ----------------------------------------------------------
<S>                                                     <C>
Charles A. Fiumefreddo* (65) .........................  Chairman, Director or Trustee, President and Chief
Chairman of the Board,                                  Executive Officer of the Morgan Stanley Dean Witter Funds;
 President and Chief Executive                          Chairman, Chief Executive Officer and Trustee of the
 Officer and Trustee                                    TCW/DW Funds; formerly Chairman, Chief Executive Officer
Two World Trade Center                                  and Director of MSDW Advisors, MSDW Distributors and MSDW
New York, New York                                      Services, Executive Vice President and Director of Dean
                                                        Witter Reynolds Inc. ("DWR"), Chairman and Director of
                                                        Morgan Stanley Dean Witter Trust FSB ("MSDW Trust"), and
                                                        Director and/or officer of various MSDW subsidiaries
                                                        (until June, 1998).
Edwin J. Garn (66) ...................................  Director or Trustee of the Morgan Stanley Dean Witter
Trustee                                                 Funds; formerly United States Senator (R-Utah) (1974-1992)
c/o Huntsman Corporation                                and Chairman, Senate Banking Committee (1980-1986);
500 Huntsman Way                                        formerly Mayor of Salt Lake City, Utah (1971-1974);
Salt Lake City, Utah                                    formerly Astronaut, Space Shuttle Discovery (April 12-19,
                                                        1985); Vice Chairman, Huntsman Corporation (since January,
                                                        1993); 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 (73) ...................................  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; formerly
New York, New York                                      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 Adviser
                                                        (1964-1978).
Wayne E. Hedien (64) .................................  Retired; Director or Trustee of the Morgan Stanley Dean
Trustee                                                 Witter Funds; Director of The PMI Group, Inc. (private
c/o Gordon Altman Butowsky                              mortgage insurance); Trustee and Vice Chairman of The
 Weitzen Shalov & Wein                                  Field Museum of Natural History; formerly associated with
Counsel to the Independent Trustees                     the Allstate Companies (1966-1994), most recently as
114 West 47th Street                                    Chairman of The Allstate Corporation (March,
New York, New York                                      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.
</TABLE>
    
 
                                       8
<PAGE>
   
<TABLE>
<CAPTION>
      NAME, AGE, POSITION WITH FUND AND ADDRESS                PRINCIPAL OCCUPATIONS DURING LAST FIVE YEARS
- ------------------------------------------------------  ----------------------------------------------------------
<S>                                                     <C>
Dr. Manuel H. Johnson (49) ...........................  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, DC                                          Funds; Trustee of the TCW/DW Funds; Director of NASDAQ
                                                        (since June, 1995); Director of Greenwich Capital Markets,
                                                        Inc. (broker-dealer) and NVR, Inc. (home construction);
                                                        Chairman and Trustee of the Financial Accounting
                                                        Foundation (oversight organization for 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.
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                                         formerly Vice President, Bankers Trust Company and BT
New York, New York                                      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, DWR and Novus Credit Services Inc.;
1585 Broadway                                           Director of MSDW Distributors; Director or Trustee of the
New York, New York                                      Morgan Stanley Dean Witter Funds; 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; Director of
c/o Gordon Altman Butowsky                              Citizens Utilities Company; formerly Executive Vice
  Weitzen Shalov & Wein                                 President and Chief Investment Officer of the Home
Counsel to the Independent Trustees                     Insurance Company (August, 1991-September, 1995).
114 West 47th Street
New York, New York
Barry Fink (43) ......................................  Senior Vice President (since March, 1997) and Secretary
Vice President, Secretary                               and General Counsel (since February, 1997) and Director
 and General Counsel                                    (since July, 1998) of MSDW Advisors and MSDW Services;
Two World Trade Center                                  Senior Vice President (since March, 1997) and Assistant
New York, New York                                      Secretary and Assistant General Counsel (since February,
                                                        1997) of MSDW Distributors; Assistant Secretary of DWR
                                                        (since August, 1996); Vice President, Secretary and
                                                        General Counsel of the Morgan Stanley Dean Witter Funds
                                                        and the TCW/DW Funds (since February, 1997); previously
                                                        First Vice President (June, 1993-February, 1997), Vice
                                                        President (until June, 1993) and Assistant Secretary and
                                                        Assistant General Counsel of MSDW Advisors and MSDW
                                                        Services and Assistant Secretary of the Morgan Stanley
                                                        Dean Witter Funds and the TCW/DW Funds.
</TABLE>
    
 
                                       9
<PAGE>
   
<TABLE>
<CAPTION>
      NAME, AGE, POSITION WITH FUND AND ADDRESS                PRINCIPAL OCCUPATIONS DURING LAST FIVE YEARS
- ------------------------------------------------------  ----------------------------------------------------------
<S>                                                     <C>
Rochelle G. Siegel (50) ..............................  Senior Vice President of MSDW Advisors; Vice President of
Vice President                                          various Morgan Stanley Dean Witter Funds.
Two World Trade Center
New York, New York
Thomas F. Caloia (52) ................................  First Vice President and Assistant Treasurer of MSDW
Treasurer                                               Advisors and MSDW Services; Treasurer of the Morgan
Two World Trade Center                                  Stanley Dean Witter Funds and the TCW/DW Funds.
New York, New York
</TABLE>
    
 
- ------------
 *  Denotes Trustees who are "interested persons" of the Fund, as defined in the
Act.
 
   
    In addition, Mitchell M. Merin, President, Chief Executive Officer and
Director of MSDW Advisors and MSDW Services, Chairman and Director of MSDW
Distributors and MSDW Trust, Executive Vice President and Director of DWR, and
Director of various MSDW subsidiaries, Robert M. Scanlan, President, Chief
Operating Officer and Director of MSDW Advisors and MSDW Services, Executive
Vice President of MSDW Distributors and MSDW Trust and Director of MSDW Trust,
Ronald E. Robison, Executive Vice President and Chief Administrative Officer of
MSDW Advisors of MSDW Services, Robert S. Giambrone, Senior Vice President of
MSDW Advisors, MSDW Services, MSDW Distributors and MSDW Trust and Director of
MSDW Trust, and Joseph McAlinden, Executive Vice President and Chief Investment
Officer of MSDW Advisors and Director of MSDW Trust and Kevin Hurley, James F.
Willison, Peter M. Avelar, and Jonathan R. Page, Senior Vice Presidents of MSDW
Advisors are Vice Presidents of the Fund. Marilyn K. Cranney and Carsten Otto,
First Vice Presidents and Assistant General Counsels of MSDW Advisors and MSDW
Services, Frank Bruttomesso, LouAnne D. McInnis and Ruth Rossi, Vice Presidents
and Assistant General Counsels of MSDW Advisors and MSDW Services, and Todd Lebo
a Staff Attorney with MSDW Advisors, are Assistant Secretaries of the Fund.
    
 
   
THE BOARD OF TRUSTEES, THE INDEPENDENT TRUSTEES, AND THE COMMITTEES
    
 
   
    The Board of Trustees consists of nine (9) trustees. These same individuals
also serve as directors or trustees for all of the Morgan Stanley Dean Witter
Funds, and are referred to in this section as Trustees. As of the date of this
Statement of Additional Information, there are a total of 85 Morgan Stanley Dean
Witter Funds, comprised of 121 portfolios. As of September 30, 1998, the Morgan
Stanley Dean Witter Funds had total net assets of approximately $105.3 billion
and more than six million shareholders.
    
 
   
    Seven Trustees (77% of the total number) have no affiliation or business
connection with MSDW Advisors or any of its affiliated persons and do not own
any stock or other securities issued by MSDW Advisors' parent company, MSDW.
These are the "disinterested" or "independent" Trustees. Four of the seven
independent Trustees are also Independent Trustees of the TCW/DW Funds.
    
 
   
    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. During the calendar year ended December 31, 1997, the
Audit Committee, the Derivatives Committee and the Independent Trustees held a
combined total of seventeen meetings.
    
 
                                       10
<PAGE>
   
    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 such a 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 such services; reviewing the
independence of the independent accountants; considering the range of audit and
non-audit fees; and reviewing the adequacy of the Fund's system of internal
controls.
    
 
   
    The Board of each Fund has formed 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.
    
 
   
COMPENSATION OF INDEPENDENT TRUSTEES
    
 
   
    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 expense
reimbursement 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.
    
 
                                       11
<PAGE>
   
    The following table illustrates the compensation paid to the Fund's
Independent Trustees by the Fund for the fiscal year ended August 31, 1998.
    
 
   
                               FUND COMPENSATION
    
 
   
<TABLE>
<CAPTION>
                                                                   AGGREGATE
                                                                 COMPENSATION
NAME OF INDEPENDENT TRUSTEE                                      FROM THE FUND
- --------------------------------------------------------------  ---------------
<S>                                                             <C>
Michael Bozic.................................................      $1,650
Edwin J. Garn.................................................       1,750
John R. Haire.................................................       3,250
Wayne E. Hedien...............................................       1,732
Dr. Manuel H. Johnson.........................................       1,650
Michael E. Nugent.............................................       1,700
John L. Schroeder.............................................       1,700
</TABLE>
    
 
   
    The following table illustrates the compensation paid to the Fund's
Independent Trustees for the calendar year ended December 31, 1997 for services
to the 84 Morgan Stanley Dean Witter Funds and, in the case of Messrs. Haire,
Johnson, Nugent and Schroeder, the 14 TCW/DW Funds that were in operation at
December 31, 1997. 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. Mr. Hedien's term as
Director or Trustee of each Morgan Stanley Dean Witter Fund commenced on
September 1, 1997.
    
 
   
    CASH COMPENSATION FROM MORGAN STANLEY DEAN WITTER FUNDS AND TCW/DW FUNDS
    
 
   
<TABLE>
<CAPTION>
                                                                   FOR SERVICE AS                    TOTAL CASH
                                                                    CHAIRMAN OF      FOR SERVICE    COMPENSATION
                               FOR SERVICE                          INDEPENDENT          AS              FOR
                              AS DIRECTOR OR                       DIRECTORS/TRUSTEES  CHAIRMAN OF   SERVICES TO
                               TRUSTEE AND                           AND AUDIT       INDEPENDENT         84
                                COMMITTEE        FOR SERVICE AS    COMMITTEES OF      TRUSTEES         MORGAN
                               MEMBER OF 84       TRUSTEE AND            84           AND AUDIT        STANLEY
                              MORGAN STANLEY       COMMITTEE       MORGAN STANLEY   COMMITTEES OF    DEAN WITTER
NAME OF                        DEAN WITTER        MEMBER OF 14      DEAN WITTER          14         FUNDS AND 14
INDEPENDENT TRUSTEE               FUNDS           TCW/DW FUNDS         FUNDS        TCW/DW FUNDS    TCW/DW FUNDS
- ---------------------------  ----------------   ----------------   --------------   -------------   -------------
<S>                          <C>                <C>                <C>              <C>             <C>
Michael Bozic..............      $133,602           --                 --               --            $133,602
Edwin J. Garn..............       149,702           --                 --               --             149,702
John R. Haire..............       149,702           $73,725           $157,463        $ 25,350         406,240
Wayne E. Hedien............        39,010           --                 --               --              39,010
Dr. Manuel H. Johnson......       145,702            71,125            --               --             216,827
Michael E. Nugent..........       149,702            73,725            --               --             223,427
John L. Schroeder..........       149,702            73,725            --               --             223,427
</TABLE>
    
 
   
    As of the date of this Statement of Additional Information, 57 of the Morgan
Stanley Dean Witter Funds, 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 29.41% of his or her Eligible Compensation plus 0.4901667% 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 58.82% after ten years of service. The foregoing
    
 
                                       12
<PAGE>
   
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.
    
 
   
    The following table illustrates the retirement benefits accrued to the
Fund's Independent Trustees by the Fund for the fiscal year ended August 31,
1998 and by the 57 Morgan Stanley Dean Witter Funds (including the Fund) for the
year ended December 31, 1997, and the estimated retirement benefits for the
Fund's Independent Trustees, to commence upon their retirement, from the Fund as
of August 31, 1998, and from the 57 Morgan Stanley Dean Witter Funds as of
December 31, 1997.
    
 
   
   RETIREMENT BENEFITS FROM THE FUND AND ALL MORGAN STANLEY DEAN WITTER FUNDS
    
 
   
<TABLE>
<CAPTION>
                                     FOR ALL ADOPTING FUNDS
                                   ---------------------------                            ESTIMATED ANNUAL
                                    ESTIMATED                     RETIREMENT BENEFITS         BENEFITS
                                     CREDITED                     ACCRUED AS EXPENSES           UPON
                                      YEARS        ESTIMATED                               RETIREMENT(2)
                                    OF SERVICE     PERCENTAGE     -------------------     ----------------
                                        AT             OF                     BY ALL       FROM   FROM ALL
                                    RETIREMENT      ELIGIBLE      BY THE     ADOPTING      THE    ADOPTING
NAME OF INDEPENDENT TRUSTEE        (MAXIMUM 10)   COMPENSATION     FUND       FUNDS        FUND    FUNDS
- ---------------------------------  ------------   ------------    ------     --------     ------  --------
<S>                                <C>            <C>             <C>        <C>          <C>     <C>
Michael Bozic....................       10           58.82%       $  403     $ 20,499     $1,029  $ 55,026
Edwin J. Garn....................       10           58.82           604       30,878      1,029    55,026
John R. Haire....................       10           58.82          (133)(3)  (19,823)(3)  2,418   132,002
Wayne E. Hedien..................        9           50.00           524            0        875    46,772
Dr. Manuel H. Johnson............       10           58.82           246       12,832      1,029    55,026
Michael E. Nugent................       10           58.82           429       22,546      1,029    55,026
John L. Schroeder................        8           49.02           804       39,350        861    46,123
</TABLE>
    
 
- ---------------
   
(1) An Eligible Trustee may elect alternate payments of his or her retirement
    benefits based upon the combined life expectancy of such Eligible Trustee
    and his or her spouse on the date of such Eligible Trustee's retirement. The
    amount estimated to be payable under this method, through the remainder of
    the later of the lives of such Eligible Trustee and spouse, will be the
    actuarial equivalent of the Regular Benefit. In addition, the Eligible
    Trustee may elect that the surviving spouse's periodic payment of benefits
    will be equal to either 50% or 100% of the previous periodic amount, an
    election that, respectively, increases or decreases the previous periodic
    amount so that the resulting payments will be the actuarial equivalent of
    the Regular Benefit.
    
 
   
(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.
    
 
   
    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 percent of the Fund's shares of
beneficial interest outstanding.
    
 
INVESTMENT PRACTICES AND POLICIES
- --------------------------------------------------------------------------------
 
SPECIAL INVESTMENT CONSIDERATIONS
 
    As stated in the Prospectus, the Fund may invest up to 5% of its net assets
in lower rated fixed-income securities, sometimes referred to as high yield
securities. Because of the special nature of high yield securities, the
Investment Manager must take account certain special considerations in assessing
the risks associated with such investments. Although the growth of the high
yield securities market in the 1980s had paralleled a long economic expansion,
recently many issuers have been affected by adverse economic and market
conditions. It should be recognized that an economic downturn or increase in
interest rates is likely to have a negative effect on the high yield bond market
and on the value of the high yield securities held by the Fund, as well as on
the ability of the securities' issuers to repay principal and interest on their
borrowings.
 
    The prices of high yield securities have been found to be less sensitive to
changes in prevailing interest rates than higher-rated investments, but are
likely to be more sensitive to adverse economic
 
                                       13
<PAGE>
changes or individual corporate developments. During an economic downturn or
substantial period of rising interest rates, highly leveraged issuers may
experience financial stress which would adversely affect their ability to
service their principal and interest payment obligations, to meet their
projected business goals or to obtain additional financing. If the issuer of a
fixed-income security owned by the Fund defaults, the Fund may incur additional
expenses to seek recovery. In addition, periods of economic uncertainty and
change can be expected to result in an increased volatility of market prices of
high yield securities and a concomitant volatility in the net asset value of a
share of the Fund. Moreover, the market prices of certain of the Fund's
portfolio securities which are structured as zero coupon and payment-in-kind
securities are affected to a greater extent by interest rate changes and thereby
tend to be more volatile than securities which pay interest periodically and in
cash (see "Dividends, Distributions and Taxes" for a discussion of the tax
ramifications of investments in such securities).
 
    The secondary market for high yield securities may be less liquid than the
markets for higher quality securities and, as such, may have an adverse effect
on the market prices of certain securities. The limited liquidity of the market
may also adversely affect the ability of the Fund's Trustees to arrive at a fair
value for certain high yield securities at certain times and could make it
difficult for the Fund to sell certain securities.
 
    Current laws and proposed new laws may have a potentially negative impact on
the market for high yield bonds. For example, legislation requires
federally-insured savings and loan associations to divest their investments in
high yield bonds. This legislation and other proposed legislation may have an
adverse effect upon the value of high yield securities and a concomitant
negative impact upon the net asset value of a share of the Fund.
 
    U.S. GOVERNMENT SECURITIES.  As stated in the Prospectus, while the Fund
under normal circumstances will invest primarily in corporate debt securities,
it may also invest in U.S. Government securities. Securities issued by the U.S.
Government, its agencies or instrumentalities in which the Fund may invest
include:
 
        (1) U.S. Treasury bills (maturities of one year or less), U.S. Treasury
    notes (maturities of one to ten years) and U.S. Treasury bonds (generally
    maturities of greater than ten years), all of which are direct obligations
    of the U.S. Government and, as such, are backed by the "full faith and
    credit" of the United States.
 
        (2) Securities issued by agencies and instrumentalities of the U.S.
    Government which are backed by the full faith and credit of the United
    States. Among the agencies and instrumentalities issuing such obligations
    are the Federal Housing Administration, the Government National Mortgage
    Association ("GNMA"), the Department of Housing and Urban Development, the
    Export-Import Bank, the Farmers Home Administration; the General Services
    Administration, the Maritime Administration and the Small Business
    Administration. The maturities of such obligations range from three months
    to thirty years although the Fund may not invest in securities with
    remaining maturities of more than twelve years.
 
        (3) Securities issued by agencies and instrumentalities which are not
    backed by the full faith and credit of the United States, but whose issuing
    agency or instrumentality has the right to borrow, to meet its obligations,
    from an existing line of credit with the U.S. Treasury. Among the agencies
    and instrumentalities issuing such obligations are the Tennessee Valley
    Authority, the Federal National Mortgage Association ("FNMA"), the Federal
    Home Loan Mortgage Corporation ("FHLMC") and the U.S. Postal Service.
 
        (4) Securities issued by agencies and instrumentalities which are not
    backed by the full faith and credit of the United States, but which are
    backed by the credit of the issuing agency or instrumentality. Among the
    agencies and instrumentalities issuing such obligations are the Federal Farm
    Credit System and the Federal Home Loan Banks.
 
    ZERO COUPON SECURITIES.  A portion of the U.S. Government securities
purchased by the Fund may be zero coupon securities. Such securities are
purchased at a discount from their face amount, giving
 
                                       14
<PAGE>
the purchaser the right to receive their full value at maturity. The interest
earned on such securities is, implicitly, automatically compounded and paid out
at maturity. While such compounding at a constant rate eliminates the risk of
receiving lower yields upon reinvestment of interest if prevailing interest
rates decline, the owner of a zero coupon security will be unable to participate
in higher yields upon reinvestment of interest received if prevailing interest
rates rise. For this reason, zero coupon securities are subject to substantially
greater price fluctuations during periods of changing prevailing interest rates
than are comparable securities which pay interest currently. Zero coupon
securities may not exceed 5% of the Fund's total assets.
 
    SECURITIES OF FOREIGN ISSUERS.  As stated in the Prospectus, the Fund may
invest in fixed-income securities issued by foreign governments and other
foreign issuers, provided such securities are denominated in U.S. Dollars. With
regard to foreign fixed-income securities, the Investment Manager believes that
in many instances such securities may provide higher yields than similar
securities of domestic issuers. With the expiration of the Interest Equalization
Tax in 1974, many of these investments currently enjoy increased liquidity,
although such securities are generally less liquid than the securities of United
States corporations, and are certainly less liquid than securities issued by the
United States Government or its agencies.
 
    Foreign investments involve certain risks, including the political or
economic instability of the issuer or of the country of issue, the difficulty of
predicting international trade patterns and the possibility of imposition of
exchange controls. Such securities may also be subject to greater fluctuations
in price than securities of United States corporations or of the United States
Government. In addition, there may be less publicly available information about
a foreign company than about a domestic company. Foreign companies generally are
not subject to uniform accounting, auditing and financial reporting standards
comparable to those applicable to domestic companies. There is generally less
government regulation of stock exchanges, brokers and listed companies abroad
than in the United States, and with respect to certain foreign countries, there
is a possibility of expropriation or confiscatory taxation, or diplomatic
developments which could affect investment in those countries. Finally, in the
event of a default of any such foreign debt obligations, it may be more
difficult for the Fund to obtain or to enforce a judgment against the issuers of
such securities.
 
LENDING OF PORTFOLIO SECURITIES
 
    As discussed in the Prospectus, consistent with applicable regulatory
requirements, the Fund may lend its portfolio securities to brokers, dealers and
other financial institutions, provided that such loans are callable at any time
by the Fund (subject to notice provisions described below), 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 the
market value, including accrued interest, determined daily, of the loaned
securities. The advantage of such 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. The Fund will not lend its portfolio securities if such loans are
not permitted by the laws or regulations of any state in which its shares are
qualified for sale and will not lend more than 25% of the value of its total
assets. A loan may be terminated by the borrower on one business day's notice,
or by the Fund on two business days' notice. If the borrower fails to deliver
the loaned securities within two days after receipt of notice, the Fund could
use the collateral to replace the securities while holding the borrower liable
for any excess of replacement cost over the value of the collateral. 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. The creditworthiness of firms to which the Fund lends its
portfolio securities will be monitored on an ongoing basis by the Investment
Manager pursuant to procedures adopted and reviewed, on an ongoing basis, by the
Board of Trustees of the Fund.
 
                                       15
<PAGE>
    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 such rights
if the matters involved would have a material effect on the Fund's investment in
such loaned securities. The Fund will pay reasonable finder's, administrative
and custodial fees in connection with a loan of its securities. However, the
Fund does not presently intend to lend any of its portfolio securities in the
foreseeable future.
 
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. A repurchase agreement may be
viewed as a type of secured lending by the Fund which typically involves the
acquisition by the Fund of government securities from a selling financial
institution such as a bank, savings and loan association or broker-dealer. The
agreement provides that the Fund will sell back to the institution, and that the
institution will repurchase, the underlying security ("collateral") at a
specified price and at a fixed time in the future, usually not more than seven
days from the date of purchase. In the event the original seller defaults on its
obligation to repurchase, as a result of its bankruptcy or otherwise, the Fund
will seek to sell the collateral, which action could involve costs or delays. In
such case, the Fund's ability to dispose of the collateral to recover its
investment may be restricted or delayed.
 
    The Fund will accrue interest from the institution until the time when the
repurchase is to occur. Although such 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 and may exceed one year.
 
    While repurchase agreements involve certain risks not associated with direct
investments in debt securities, the Fund follows procedures designed to minimize
such risks. Repurchase agreements will be transacted only with large,
well-capitalized and well-established financial institutions whose financial
condition will be continuously monitored by the Investment Manager subject to
procedures established by the Trustees. The procedures also require that the
collateral underlying the agreement be specified. The Fund does not presently
intend to enter into repurchase agreements so that more than 5% of the Fund's
net assets are subject to such agreements.
 
WHEN-ISSUED AND DELAYED DELIVERY SECURITIES
 
   
    As discussed in the Prospectus, from time to time, in the ordinary course of
business, the Fund may purchase securities on a when-issued or delayed delivery
basis--i.e., delivery and payment can take place a month or more after the date
of the transactions. The securities so purchased are subject to market
fluctuation and no interest accrues to the purchaser during this period. 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. At the time the Fund makes the commitment to purchase securities on a
when-issued or delayed delivery basis, the Fund will record the transaction and
thereafter reflect the value, each day, of such security in determining the net
asset value of the Fund. At the time of delivery of the securities, the value
may be more or less than the purchase price. The Fund will also establish a
segregated account with the Fund's custodian bank in which it will continuously
maintain cash or U.S. Government securities or other liquid portfolio securities
equal in value to commitments for such when-issued or delayed delivery
securities; subject to this requirement, the Fund may purchase securities on
such basis without limit. An increase in the percentage of the Fund's assets
committed to the purchase of securities on a when-issued or delayed delivery
basis may increase the volatility of the Fund's net asset value.
    
 
WHEN, AS AND IF ISSUED SECURITIES
 
    As discussed in the Prospectus, 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, leveraged buyout or debt restructuring. The commitment for the
purchase of any such security will not be recognized in the portfolio of the
Fund until
 
                                       16
<PAGE>
   
the Investment Manager determines that issuance of the security is probable. At
such time, the Fund will record the transaction and, in determining its net
asset value, will reflect the value of the security daily. At such time, the
Fund will also establish a segregated account with its custodian bank in which
it will continuously maintain cash or U.S. Government securities or other liquid
portfolio securities equal in value to recognized commitments for such
securities. Settlement of the trade will occur within five business days of the
occurrence of the subsequent event. 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 (see "Investment Restrictions"). Subject to the foregoing
restrictions, the Fund may purchase securities on such basis without limit. 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.
    
 
OPTIONS TRANSACTIONS
 
    The Fund has no current intention to engage in options transactions. In the
event the Fund wishes to engage in options transactions in the future, the
Fund's Prospectus and Statement of Additional Information will be amended and
sent to shareholders in advance of the change.
 
PORTFOLIO TURNOVER
 
   
    The Fund's portfolio turnover rate for the fiscal years ended August 31,
1997 and 1998 were approximately 98% and 98%, respectively. A 100% turnover rate
would occur, for example, if 100% of the securities held in the Fund's portfolio
(excluding all securities whose maturities at acquisition were one year or less)
were sold and replaced within one year.
    
 
INVESTMENT RESTRICTIONS
- --------------------------------------------------------------------------------
 
    In addition to the investment restrictions enumerated in the Prospectus, the
investment restrictions listed below have been adopted by the Fund as
fundamental policies, except as otherwise indicated. Under the Act, a
fundamental policy may not be changed without the vote of a majority of the
outstanding voting securities of the Fund, as defined in the Act. Such a
majority is defined 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.
 
    The Fund may not:
 
         1. Invest in securities of any issuer if, to the knowledge of the Fund,
    any officer or trustee/ director of the Fund or of the Investment Manager
    owns more than 1/2 of 1% of the outstanding securities of such issuer, and
    such officers and trustees/directors who own more than 1/2 of 1% own in the
    aggregate more than 5% of the outstanding securities of such issuers.
 
         2. 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.
 
         3. Purchase oil, gas or other mineral leases, rights or royalty
    contracts or exploration or development programs, except that the Fund may
    invest in the securities of companies which operate, invest in, or sponsor
    such programs.
 
         4. Purchase securities of other investment companies, except in
    connection with a merger, consolidation, reorganization or acquisition of
    assets.
 
                                       17
<PAGE>
         5. Pledge its assets or assign or otherwise encumber them except to
    secure borrowings effected within the limitations set forth in restriction
    (6) in the Prospectus.
 
         6. Issue senior securities as defined in the Act except insofar as the
    Fund may be deemed to have issued a senior security by reason of borrowing
    money in accordance with restriction (6) in the Prospectus.
 
         7. Make loans of money or securities, except: (a) by the purchase of
    publicly distributed debt obligations in which the Fund may invest
    consistent with its investment objective and policies; (b) by investment in
    repurchase agreements; or (c) by lending its portfolio securities.
 
         8. Make short sales of securities.
 
         9. Purchase or sell commodities or commodity futures contracts.
 
        10. Purchase securities on margin, except for such short-term loans as
    are necessary for the clearance of portfolio securities.
 
        11. Engage in the underwriting of securities, except insofar as the Fund
    may be deemed an underwriter under the Securities Act of 1933 in disposing
    of a portfolio security.
 
        12. Invest for the purpose of exercising control or management of any
    other issuer.
 
    In addition, the Fund, as a non-fundamental policy, will not invest in
warrants, although it may acquire warrants attached to other securities
purchased by the Fund.
 
    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.
 
PORTFOLIO TRANSACTIONS AND BROKERAGE
- --------------------------------------------------------------------------------
 
   
    Subject to the general supervision of the Board of Trustees of the Fund, the
Investment Manager is responsible for the investment decisions and the placing
of orders for portfolio transactions for the Fund. The Fund's portfolio
transactions will occur primarily with issuers, underwriters or major dealers in
fixed-income securities acting as principals. Such transactions are normally on
a net basis which do not involve payment of brokerage commissions. The cost of
securities purchased from an underwriter usually includes a commission paid by
the issuer to the underwriter; transactions with dealers normally reflect the
spread between bid and asked prices. During the fiscal years ended August 31,
1996, 1997 and 1998, the Fund did not pay any brokerage commissions.
    
 
   
    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 adviser 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.
    
 
    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
 
                                       18
<PAGE>
transactions. 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 such 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. Such 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. While the receipt of such information and services is useful in
varying degrees and would generally reduce the amount of research or services
otherwise performed by the Investment Manager and thereby reduce its expenses,
it is of indeterminable value and the management fee paid to the Investment
Manager is not reduced by any amount that may be attributable to the value of
such services.
 
   
    Pursuant to an order of the Securities and Exchange Commission, the Fund may
effect principal transactions in certain money market instruments with DWR. The
Fund will limit its transactions with DWR to U.S. Government and Government
Agency Securities, Bank Money Instruments (i.e., Certificates of Deposit and
Bankers' Acceptances) and Commercial Paper. Such transactions will be effected
with DWR only when the price available from DWR is better than that available
from other dealers. During the fiscal years ended August 31, 1996, 1997 and
1998, the Fund did not effect any principal transactions with DWR.
    
 
   
    Consistent with the policy described above, brokerage transactions in
securities listed on exchanges or admitted to unlisted trading privileges may be
effected through DWR, Morgan Stanley & Co. Incorporated ("MS&Co.") and other
affiliated brokers and dealers. In order for an affiliated broker or dealer to
effect any portfolio transactions 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 Board of Trustees of
the Fund, including a majority of the Trustees who are not "interested persons"
of the Fund, as defined in the Act, 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. For the
fiscal years ended August 31, 1996, 1997 and 1998, the Fund did not effect any
securities transactions with or through DWR. During the period June 1 through
August 31, 1997 and during the fiscal year ended August 31, 1998, the Fund did
not effect any securities transactions with or through MS&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. 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 year ended August 31, 1998 the Fund held
bonds of Salomon Brothers Inc., Merrill Lynch, Pierce, Fenner & Smith Inc. and
Donaldson, Lufkin & Jenrette, which issuers were among the ten brokers or the
ten dealers which executed transactions for or with the Fund in the largest
dollar amounts during the year. At August 31, 1998, the Fund held $3,238,272 of
Salomon Brothers Inc., 6.5% bonds maturing 03/01/2000, $1,509,480 Merrill Lynch,
Pierce Fenner & Smith Inc., 6.0% bonds maturing 01/15/2001 and $2,517,175 of
Donaldson, Lufkin & Jenrette, 6.11% bonds maturing 05/15/2001.
    
 
                                       19
<PAGE>
THE DISTRIBUTOR
- --------------------------------------------------------------------------------
 
   
    As discussed in the Prospectus, shares of the Fund are distributed by Morgan
Stanley Dean Witter Distributors Inc. (the "Distributor"). The Distributor has
entered into a selected dealer agreement with DWR, which through its own sales
organization sells shares of the Fund. In addition, the Distributor may enter
into selected dealer agreements with other selected broker-dealers. The
Distributor, a Delaware corporation, is a wholly-owned subsidiary of MSDW. The
Trustees of the Fund, including a majority of the Trustees who are not, and were
not at the time they voted, interested persons of the Fund, as defined in the
Act (the "Independent Trustees"), approved, at their meeting held on June 30,
1997, the current Distribution Agreement appointing the Distributor exclusive
distributor of the Fund's shares and providing for the Distributor to bear
distribution expenses not borne by the Fund. By its terms, the Distribution
Agreement had an initial term ending April 30, 1998 and will remain in effect
from year to year thereafter if approved by the Board. At their meeting held on
April 30, 1998, the Trustees of the Fund, including a majority of the
Independent Trustees, approved the continuation of the Distribution Agreement
until April 30, 1999.
    
 
   
    The Distributor bears all expenses it may incur in providing services under
the Distribution Agreement. Such expenses include the payment of commissions for
sales of the Fund's shares and incentive compensation to Morgan Stanley Dean
Witter Financial Advisors or other selected broker-dealer representatives. 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 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 of 1933, as amended. 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.
    
 
PLAN OF DISTRIBUTION.
 
   
    The Fund has adopted a Plan of Distribution pursuant to Rule 12b-1 under the
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 0.85% of the average daily net assets of Class A and
Class C, respectively, and, with respect to Class B, 0.85% 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 reinvestments 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 and of contingent deferred
sales charges imposed on certain redemptions of shares, which are separate and
apart from payments made pursuant to the Plan (see "Purchase of Fund Shares" in
the Prospectus). The Distributor has informed the Fund that it and/or DWR
received (a) approximately $364,492, $285,035 and $191,024 in contingent
deferred sales charges from Class B for the fiscal years ended August 31, 1996,
1997 and 1998, respectively, (b) approximately $722 in contingent deferred sales
charges from Class C for the fiscal year ended August 31, 1998, and (c)
approximately $12,907 in front-end sales charges from Class A for the fiscal
year ended August 31, 1998, none of which was retained by the Distributor. No
front-end sales charges were received from Class A during the fiscal year ended
August 31, 1997, no contingent deferred sales charges were received from Class A
during the fiscal years ended August 31, 1997 and 1998, and no contingent
deferred sales charges were received from Class C during the fiscal year ended
August 31, 1997.
    
 
                                       20
<PAGE>
    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 0.20% of the average daily net assets of Class B
and 0.25% of the average daily net assets of Class C are currently each
characterized as a "service fee" under the Rules of the Association 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 aforementioned Rules of the Association.
 
    The Plan was adopted by a vote of the Trustees of the Fund on April 27,
1989, at a Meeting of the Trustees called for the purpose of voting on such
Plan. The vote included the vote of a majority of the Trustees of the Fund who
are not "interested persons" of the Fund (as defined in the Act) and who have no
direct or indirect financial interest in the operation of the Plan (the
"Independent 12b-1 Trustees"). In making their decision to adopt the Plan, the
Trustees requested from DWR and received such information as they deemed
necessary to make an informed determination as to whether or not adoption of the
Plan was in the best interests of the shareholders of the Fund. After due
consideration of the information received, the Trustees, including the
Independent 12b-1 Trustees, determined that adoption of the Plan would benefit
the shareholders of the Fund. DWR, as then sole shareholder of the Fund,
approved the Plan on April 28, 1989, and the Plan was approved by shareholders
of the Fund at a Meeting of Shareholders on December 21, 1989.
 
    At their meeting held on October 30, 1992, the Trustees of the Fund,
including all of the Independent 12b-1 Trustees, approved certain amendments to
the Plan which took effect in January, 1993 and were designed to reflect the
fact that upon an internal reorganization the share distribution activities
theretofore performed for the Fund by DWR were assumed by the Distributor and
DWR's sales activities are now being performed pursuant to the terms of a
selected dealer agreement between the Distributor and DWR. The amendments
provide that payments under the Plan will be made to the Distributor rather than
to DWR as before the amendment, and that the Distributor in turn is authorized
to make payments to DWR, its affiliates or other selected broker-dealers (or
direct that the Fund pay such entities directly). The Distributor is also
authorized to retain part of such fee as compensation for its own
distribution-related expenses. At their meeting held on April 28, 1993, the
Trustees, including a majority of the Independent 12b-1 Trustees, also approved
certain technical amendments to the Plan in connection with amendments adopted
by the National Association of Securities Dealers, Inc. to its Rules of the
Association. At their meeting held on October 26, 1995, the Trustees of the
Fund, including all of the Independent 12b-1 Trustees, approved an amendment to
the Plan to permit payments to be made under the Plan with respect to certain
distribution expenses incurred in connection with the distribution of shares,
including personal services to shareholders with respect to holdings of such
shares, of an investment company whose assets are acquired by the Fund in a
tax-free reorganization. At their meeting held on June 30, 1997, the Trustees,
including a majority of the Independent 12b-1 Trustees, approved amendments to
the Plan to reflect the multiple-class structure for the Fund, which took effect
on July 28, 1997.
 
   
    Under the Plan and as required by Rule 12b-1, the Trustees will receive and
review promptly after the end of each fiscal quarter a written report provided
by the Distributor of the amounts expended by the Distributor under the Plan and
the purpose for which such expenditures were made. Class B shares of the Fund
accrued $1,300,714 payable to the Distributor, pursuant to the Plan, for the
fiscal year ended August 31, 1998. This is an accrual at an annual rate of 0.85%
of the average daily net assets of Class B and was calculated pursuant to clause
(b) of the compensation formula under the Plan. This amount is treated by the
Fund as an expense in the year it is accrued. For the fiscal year ended August
31, 1998, Class A and Class C shares of the Fund accrued payments under the Plan
amounting to $4,202 and $1,925, respectively, which amounts are equal to 0.24%
and 0.85% 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 of shares, each with a different distribution arrangement as set forth
in the Prospectus.
 
                                       21
<PAGE>
   
    With respect to Class A shares, DWR compensates its account executives by
paying them, from proceeds of the front-end sales charge, commissions for the
sale of Class A shares, currently a gross sales credit of up to 4.0% of the
amount sold (except as provided in the following sentence) and an annual
residual commission, currently a residual of up to 0.20% 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 employer sponsored 401(k) and other plans
qualified under Section 401(a) of the Internal Revenue Code ("Qualified
Retirement Plans") for which Morgan Stanley Dean Witter Trust FSB ("MSDW Trust")
serves as Trustee or DWR's Retirement Plan Services serves as recordkeeper
pursuant to a written Recordkeeping Services Agreement, the Investment Manager
compensates DWR's 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, DWR 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 4.0% of the amount sold (except as
provided in the following sentence) and an annual residual commission, currently
a residual of up to 0.20% 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 on or after July 28, 1997 by Qualified Retirement Plans
for which MSDW Trust serves as Trustee or DWR's Retirement Plan Services serves
as recordkeeper pursuant to a written Recordkeeping Services Agreement, DWR
compensates its Financial Advisors by paying them, from its own funds, a gross
sales credit of 3.0% of the amount sold.
    
 
   
    With respect to Class C shares, DWR 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 a residual of up to 0.85% 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
MSDW Advisors mutual fund asset allocation program, the Investment Manager
compensates DWR'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 DWR's Financial Advisors by
paying them, from its own funds, an annual residual commission, currently a
residual of 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 MSDW Advisors mutual fund asset allocation program).
    
 
   
    The gross sales credit is a charge which reflects commissions paid by DWR to
its Financial Advisors and DWR's Fund-associated distribution-related expenses,
including sales compensation, and overhead and other branch office
distribution-related expenses including (a) the expenses of operating DWR'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.
    
 
                                       22
<PAGE>
   
    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 0.85%, 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 Morgan Stanley Dean Witter Financial Advisors or
other selected broker-dealer representatives, such amounts shall be determined
at the beginning of each calendar quarter by the Trustees, including a majority
of the Independent 12b-1 Trustees. Expenses representing the service fee (for
Class A) or a gross sales credit or a residual to Morgan Stanley Dean Witter
Financial Advisors or other selected broker-dealer 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.
    
 
   
    Each Class paid 100% of the amounts accrued under the Plan with respect to
the Class for the fiscal year ended August 31, 1998, to the Distributor. The
Distributor and DWR estimate that they have spent, pursuant to the Plan,
$22,570,107 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)
11.98% ($2,703,259)--advertising and promotional expenses; (ii) 0.83%
($187,321)--printing of prospectuses for distribution to other than current
shareholders; and (iii) 87.19% ($19,679,527)--other expenses, including the
gross sales credit and the carrying charge, of which 9.95% ($1,957,424)
represents carrying charges, 36.83% ($7,248,340) represents commission credits
to DWR branch offices and other selected broker-dealers for payments of
commissions to Morgan Stanley Dean Witter Financial Advisors and other selected
broker-dealer representatives, and 53.22% ($10,473,763) 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 August 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 in
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
contingent deferred sales charges paid by investors upon redemption of shares.
The Distributor has advised the Fund that in the case of Class B shares such
excess amount, including the carrying charge designed to approximate the
opportunity costs incurred 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, totalled $5,232,570 as of August 31, 1998. Because
there is no requirement under the Plan that the Distributor be reimbursed for
all 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
distribution expenses in excess of payments made under the Plan and the 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. Any cumulative expenses
incurred, but not yet recovered through distribution fees or contingent deferred
sales charges, may or may not be recovered through future distribution fees or
contingent deferred sales charges.
    
 
    No interested person of the Fund, nor any Trustee of the Fund who is not an
interested person of the Fund, as defined in the Act, has any direct or indirect
financial interest in the operation of the Plan except
 
                                       23
<PAGE>
   
to the extent that the Distributor, MSDW Advisors, MSDW Services, DWR 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.
    
 
   
    Under its terms, the Plan continued until April 30, 1990 and will remain in
effect from year to year thereafter, provided such continuance is approved
annually by a vote of the Trustees in the manner described above. The most
recent continuance of the Plan for one year, until April 30, 1999, was approved
by the Board of Trustees of the Fund, including a majority of the Independent
12b-1 Trustees, at a Board meeting held on April 30, 1998. Prior to approving
the 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 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; and (3) what services had been provided and were continuing to
be provided under the Plan the Distributor to the Fund and its shareholders.
Based upon their review, the Trustees of the Fund, including each of the
Independent 12b-1 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 of the shareholders of the
affected Class or Classes of the Fund, and all material amendments of 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 12b-1 Trustees or by a vote of a majority of the
outstanding voting securities of the Fund (as defined in the 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 12b-1 Trustees
shall be committed to the discretion of the Independent 12b-1 Trustees.
 
DETERMINATION OF NET ASSET VALUE
- --------------------------------------------------------------------------------
 
    Short-term 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.
Other short-term debt securities will be valued on a mark-to-market basis until
such time as they reach a remaining maturity of sixty days, whereupon they will
be valued at amortized cost using their value on the 61st day 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. All other securities and other assets are valued at their fair value
as determined in good faith under procedures established by and under the
supervision of the Trustees.
 
    As discussed in the Prospectus, the net asset value per share for each Class
of shares of the Fund is determined once daily at 4:00 p.m., New York time (or,
on days when the New York Stock Exchange closes prior to 4:00 p.m., at such
earlier time), on each day that the New York Stock Exchange is open by taking
the value of all assets of the Fund, subtracting its liabilities, dividing by
the number of shares outstanding and adjusting to the nearest cent. The New York
Stock Exchange currently observes the following holidays: New Year's Day,
Reverend Dr. Martin Luther King, Jr. Day, Presidents' Day, Good Friday, Memorial
Day, Independence Day, Labor Day, Thanksgiving Day and Christmas Day.
 
                                       24
<PAGE>
PURCHASE OF FUND SHARES
- --------------------------------------------------------------------------------
 
    As discussed in the Prospectus, the Fund offers four Classes of shares as
follows:
 
INITIAL SALES CHARGE ALTERNATIVE--CLASS A SHARES
 
    Class A shares are sold to investors with an initial sales charge that
declines to zero for larger purchases; however, Class A shares sold without an
initial sales charge are subject to a contingent deferred sales charge ("CDSC")
of 1.0% if redeemed within one year of purchase, except in the circumstances
discussed in the Prospectus.
 
   
    RIGHT OF ACCUMULATION.  As discussed in the Prospectus, investors may
combine the current value of shares purchased in separate transactions for
purposes of benefitting from the reduced sales charges available for purchases
of shares of the Fund totalling at least $25,000 in net asset value. For
example, if any person or entity who qualifies for this privilege holds Class A
shares of the Fund and/or other Morgan Stanley Dean Witter Funds that are
multiple class funds ("Morgan Stanley Dean Witter Multi-Class Funds") or shares
of other Morgan Stanley Dean Witter Funds sold with a front-end sales charge
purchased at a price including a front-end sales charge having a current value
of $5,000, and purchases $20,000 of additional shares of the Fund, the sales
charge applicable to the $20,000 purchase would be 4.0% of the offering price.
    
 
   
    The Distributor must be notified by the selected broker-dealer or the
shareholder 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 by the selected broker-dealer or shareholder when such
an order is placed by mail. The reduced sales charge will not be granted if: (a)
such notification is not furnished at the time of the order; or (b) a review of
the records of the Distributor or Morgan Stanley Dean Witter Trust FSB (the
"Transfer Agent") fails to confirm the investor's represented holdings.
    
 
    LETTER OF INTENT.  As discussed in the Prospectus, reduced sales charges are
available to investors who enter into a written Letter of Intent providing for
the purchase, within a thirteen-month period, of Class A shares of the Fund from
the Distributor or from a single Selected Broker-Dealer.
 
    A Letter of Intent permits an investor to establish a total investment goal
to be achieved by any number of purchases over a thirteen-month period. Each
purchase of Class A shares made during the period will receive the reduced sales
commission applicable to the amount represented by the goal, as if it were a
single purchase. A number of shares equal in value to 5% of the dollar amount of
the Letter of Intent will be held in escrow by the Transfer Agent, in the name
of the shareholder. The initial purchase under a Letter of Intent must be equal
to at least 5% of the stated investment goal.
 
    The Letter of Intent does not obligate the investor to purchase, nor the
Fund to sell, the indicated amount. In the event the Letter of Intent goal is
not achieved within the thirteen-month period, the investor is required to pay
the difference between the sales charge otherwise applicable to the purchases
made during this period and sales charges actually paid. Such payment may be
made directly to the Distributor or, if not paid, the Distributor is authorized
by the shareholder to liquidate a sufficient number of his or her escrowed
shares to obtain such difference.
 
   
    If the goal is exceeded and purchases pass the next sales charge level, the
sales charge on the entire amount of the purchase that results in passing that
level and on subsequent purchases will be subject to further reduced sales
charges in the same manner as set forth above under "Right of Accumulation," but
there will be no retroactive reduction of sales charges on previous purchases.
For the purpose of determining whether the investor is entitled to a further
reduced sales charge applicable to purchases at or above a sales charge level
which exceeds the stated goal of a Letter of Intent, the cumulative current net
asset value of any shares owned by the investor in any other Morgan Stanley Dean
Witter Funds held by the shareholder which were previously purchased at a price
including a front-end sales charge (including shares of the Fund and other
Morgan Stanley Dean Witter Funds acquired in exchange for those shares, and
including in each case shares acquired through reinvestment of dividends and
distributions) will be added to the cost or net asset value of shares of the
Fund owned by
    
 
                                       25
<PAGE>
   
the investor. However, shares of "Exchange Funds" (see "Shareholder
Services--Exchange Privilege") and the purchase of shares of other Morgan
Stanley Dean Witter Funds will not be included in determining whether the stated
goal of a Letter of Intent has been reached.
    
 
    At any time while a Letter of Intent is in effect, a shareholder may, by
written notice to the Distributor, increase the amount of the stated goal. In
that event, only shares purchased during the previous 90-day period and still
owned by the shareholder will be included in the new sales charge reduction. The
5% escrow and minimum purchase requirements will be applicable to the new stated
goal. Investors electing to purchase shares of the Fund pursuant to a Letter of
Intent should carefully read such Letter of Intent.
 
CONTINGENT DEFERRED SALES CHARGE ALTERNATIVE--CLASS B SHARES
 
   
    Class B shares are sold without an initial sales charge but are subject to a
CDSC payable upon most redemptions within six years after purchase. As stated in
the Prospectus, a CDSC will be imposed on any redemption by an investor if after
such redemption the current value of the investor's Class B shares of the Fund
is less than the dollar amount of all payments by the shareholder for the
purchase of Class B shares during the preceding six years (or, in the case of
shares held by certain Qualified Retirement Plans, three years). However, no
CDSC will be imposed to the extent that the net asset value of the shares
redeemed does not exceed: (a) the current net asset value of shares purchased
more than six years (or, in the case of shares held by certain Qualified
Retirement Plans, three years) prior to the redemption, plus (b) the current net
asset value of shares purchased through reinvestment of dividends or
distributions of the Fund or another Morgan Stanley Dean Witter Fund (see
"Shareholder Services-- Targeted Dividends"), plus (c) the current net asset
value of shares acquired in exchange for (i) shares of Morgan Stanley Dean
Witter front-end sales charge funds, or (ii) shares of other Morgan Stanley Dean
Witter Funds for which shares of front-end sales charge funds have been
exchanged (see "Shareholder Services--Exchange Privilege"), plus (d) increases
in the net asset value of the investor's shares above the total amount of
payments for the purchase of Fund shares made during the preceding six (three)
years. The CDSC will be paid to the Distributor.
    
 
   
    In determining the applicability of the CDSC to each redemption, the amount
which represents an increase in the net asset value of the investor's shares
above the amount of the total payments for the purchase of shares within the
last six years (or, in the case of shares held by certain Qualified Retirement
Plans, three years) will be redeemed first. In the event the redemption amount
exceeds such increase in value, the next portion of the amount redeemed will be
the amount which represents the net asset value of the investor's shares
purchased more than six (three) years prior to the redemption and/or shares
purchased through reinvestment of dividends or distributions and/or shares
acquired in exchange for shares of Morgan Stanley Dean Witter front-end sales
charge funds, or for shares of other Morgan Stanley Dean Witter Funds for which
shares of front-end sales charge funds have been exchanged. A portion of the
amount redeemed which exceeds an amount which represents both such increase in
value and the value of shares purchased more than six years (or, in the case of
shares held by certain Qualified Retirement Plans, three years) prior to the
redemption and/or shares purchased through reinvestment of dividends or
distributions and/or shares acquired in the above-described exchanges will be
subject to a CDSC.
    
 
    The amount of the CDSC, if any, will vary depending on the number of years
from the time of payment for the purchase of Class B shares of the Fund until
the time of redemption of such shares. For purposes of determining the number of
years from the time of any payment for the purchase of shares, all payments made
during a month will be aggregated and deemed to have been made on the last day
of
 
                                       26
<PAGE>
the month. The following table sets forth the rates of the CDSC applicable to
most Class B shares of the Fund:
 
<TABLE>
<CAPTION>
                                       YEAR SINCE
                                        PURCHASE                                             CDSC AS A PERCENTAGE OF
                                      PAYMENT MADE                                               AMOUNT REDEEMED
- -----------------------------------------------------------------------------------------  ---------------------------
<S>                                                                                        <C>
First....................................................................................                5.0%
Second...................................................................................                4.0%
Third....................................................................................                3.0%
Fourth...................................................................................                2.0%
Fifth....................................................................................                2.0%
Sixth....................................................................................                1.0%
Seventh and thereafter...................................................................             None
</TABLE>
 
   
    The following table sets forth the rates of the CDSC applicable to Class B
shares of the Fund purchased on or after July 28, 1997 by Qualified Retirement
Plans for which MSDW Trust serves as Trustee or DWR's Retirement Plan Services
serves as a recordkeeper pursuant to a written Recordkeeping Services Agreement.
    
 
<TABLE>
<CAPTION>
                                       YEAR SINCE
                                        PURCHASE                                             CDSC AS A PERCENTAGE OF
                                      PAYMENT MADE                                               AMOUNT REDEEMED
- -----------------------------------------------------------------------------------------  ---------------------------
<S>                                                                                        <C>
First....................................................................................                2.0%
Second...................................................................................                2.0%
Third....................................................................................                1.0%
Fourth and thereafter....................................................................             None
</TABLE>
 
   
    In determining the rate of the CDSC, it will be assumed that a redemption is
made of shares held by the investor for the longest period of time within the
applicable six-year or three-year period. This will result in any such CDSC
being imposed at the lowest possible rate. The CDSC will be imposed, in
accordance with the table shown above, on any redemptions within six years (or,
in the case of shares held by certain Qualified Retirement Plans, three years)
of purchase which are in excess of these amounts and which redemptions do not
qualify for waiver of the CDSC, as described in the Prospectus.
    
 
LEVEL LOAD ALTERNATIVE--CLASS C SHARES
 
    Class C shares are sold without a sales charge but are subject to a CDSC of
1.0% on most redemptions made within one year after purchase, except in the
circumstances discussed in the Prospectus.
 
NO LOAD ALTERNATIVE--CLASS D SHARES
 
    Class D shares are offered without any sales charge on purchase or
redemption. Class D shares are offered only to those persons meeting the
qualifications set forth in the Prospectus.
 
SHAREHOLDER SERVICES
- --------------------------------------------------------------------------------
 
   
    Upon the purchase of shares of the Fund, a Shareholder Investment Account is
opened for the investor on the books of the Fund and maintained by Morgan
Stanley Dean Witter Trust FSB (the "Transfer Agent"). This is an open account in
which shares owned by the investor are credited by the Transfer Agent in lieu of
issuance of a share certificate. If a share certificate is desired, it must be
requested in writing for each transaction. Certificates are issued only for full
shares and may be redeposited in the account at any time. There is no charge to
the investor for issuance of a certificate. Whenever a shareholder-instituted
transaction takes place in the Shareholder Investment Account, the shareholder
will be mailed a confirmation of the transaction from the Fund or from DWR or
another selected broker-dealer.
    
 
    INVESTMENT OF DIVIDENDS OR DISTRIBUTIONS RECEIVED IN CASH.  As discussed in
the Prospectus, any shareholder who receives a cash payment representing a
dividend or distribution may invest such
 
                                       27
<PAGE>
dividend or distribution in shares of the applicable Class at net asset value,
without the imposition of a CDSC upon redemption, by returning the check or the
proceeds to the Transfer Agent within 30 days after the payment date. If the
shareholder returns the proceeds of a dividend or distribution, such funds must
be accompanied by a signed statement indicating that the proceeds constitute a
dividend or distribution to be invested. Such investment will be made at the net
asset value per share next determined after receipt of the check or proceeds by
the Transfer Agent.
 
    AUTOMATIC INVESTMENT OF DIVIDENDS AND DISTRIBUTIONS.  As stated in the
Prospectus, all income dividends and capital gains distributions are
automatically paid in full and fractional shares of the applicable Class of the
Fund, unless the shareholder requests that they be paid in cash. Each purchase
of shares of the Fund is made upon the condition that the Transfer Agent is
thereby automatically appointed as agent of the investor to receive all
dividends and capital gains distributions on shares owned by the investor. Such
dividends and distributions will be paid, at the net asset value per share, in
shares of the applicable Class of the Fund (or in cash if the shareholder so
requests) as of the close of business on the monthly payment date, as stated in
the Prospectus. At any time an investor may request the Transfer Agent, in
writing, to have subsequent dividends and/or capital gains distributions paid to
him or her in cash rather than shares. To assure sufficient time to process the
change, such request should be received by the Transfer Agent as least five
business days prior to the payment date of the dividend or distribution or the
record date of the distribution. In the case of recently purchased shares for
which registration instructions have not been received on the record date, cash
payments will be made to the Distributor, which will be forwarded to the
shareholder, upon the receipt of proper instructions. It has been and remains
the Fund's policy and practice that, if checks for dividends or distributions
paid in cash remain uncashed, no interest will accrue on amounts represented by
such uncashed checks.
 
   
    TARGETED DIVIDENDS-SM-.  In states where it is legally permissible,
shareholders may also have all income dividends and capital gains distributions
automatically invested in shares of any Class of a Morgan Stanley Dean Witter
Fund other than Morgan Stanley Dean Witter Intermediate Income Securities or in
another Class of Morgan Stanley Dean Witter Intermediate Income Securities. Such
investment will be made as described above for automatic investment in shares of
the applicable Class of the Fund, at the net asset value per share of the
selected Morgan Stanley Dean Witter Fund as of the close of business on the
payment date of the dividend or distribution and will begin to earn dividends,
if any, in the selected Morgan Stanley Dean Witter Fund the next business day.
To participate in the Targeted Dividends program, shareholders should contact
their Morgan Stanley Dean Witter Financial Advisor or other selected
broker-dealer representative or the Transfer Agent. Shareholders of the Fund
must be shareholders of the selected Class of the Morgan Stanley Dean Witter
Fund targeted to receive investments from dividends at the time they enter the
Targeted Dividends program. Investors should review the prospectus of the
targeted Morgan Stanley Dean Witter Fund before entering the program.
    
 
   
    EASYINVEST-SM-.  Shareholders may subscribe to EasyInvest, an automatic
purchase plan which provides for any amount from $100 to $5,000 to be
transferred automatically from a checking or savings account or following
redemption of shares of a Morgan Stanley Dean Witter money market fund, on a
semi-monthly, monthly or quarterly basis, to the Transfer Agent for investment
in shares of the Fund. Shares purchased through EasyInvest will be added to the
shareholder's existing account at the net asset value calculated the same
business day the transfer of funds is effected (subject to any applicable sales
charges). Shares of the Morgan Stanley Dean Witter money market funds redeemed
in connection with EasyInvest are redeemed on the business day preceding the
transfer of funds. For further information or to subscribe to EasyInvest,
shareholders should contact their Morgan Stanley Dean Witter Financial Advisor
or other selected broker-dealer representative or the Transfer Agent.
    
 
   
    SYSTEMATIC WITHDRAWAL PLAN.  As discussed in the Prospectus, a systematic
withdrawal plan (the "Withdrawal Plan") is available for shareholders whose
shares of Morgan Stanley Dean Witter Funds have an aggregate value of $10,000 or
more. Shares of any Fund from which redemptions will be made pursuant to the
Plan must have a value of $1,000 or more (referred to as a "SWP Fund"). The
required share values are determined on the date the shareholder establishes the
Withdrawal Plan. The Withdrawal Plan provides for monthly, quarterly,
semi-annual or annual payments in any amount not less
    
 
                                       28
<PAGE>
   
than $25, or in any whole percentage of the value of the SWP Funds' shares, on
an annualized basis. Any applicable Contingent Deferred Sales Charge ("CDSC")
will be imposed on shares redeemed under the Withdrawal Plan (see "Purchase of
Fund Shares"), except that the CDSC, if any, will be waived on redemptions under
the Withdrawal Plan of up to 12% annually of the value of each SWP Fund account,
based on the share values next determined after the shareholder establishes the
Withdrawal Plan. Redemptions for which this CDSC waiver policy applies may be in
amounts up to 1% per month, 3% per quarter, 6% semi-annually or 12% annually.
Under this CDSC waiver policy, amounts withdrawn each period will be paid by
first redeeming shares not subject to a CDSC because the shares were purchased
by the reinvestment of dividends or capital gains distributions, the CDSC period
has elapsed or some other waiver of the CDSC applies. If shares subject to a
CDSC must be redeemed, shares held for the longest period of time will be
redeemed first and continuing with shares held the next longest period of time
until shares held the shortest period of time are redeemed. Any shareholder
participating in the Withdrawal Plan will have sufficient shares redeemed from
his or her account so that the proceeds (net of any applicable CDSC) to the
shareholder will be the designated monthly, quarterly, semi-annual or annual
amount.
    
 
   
    A shareholder may suspend or terminate participation in the Withdrawal Plan
at any time. A shareholder who has suspended participation may resume payments
under the Withdrawal Plan, without requiring a new determination of the account
value for the 12% CDSC waiver. The Withdrawal Plan may be terminated or revised
at any time by the Fund.
    
 
   
    Prior to adding an additional SWP Fund to an existing Withdrawal Plan, the
required $10,000/$1,000 share values must be met, to be calculated on the date
the shareholder adds the additional SWP Fund. However, the addition of a new SWP
Fund will not change the account value for the 12% CDSC waiver for the SWP Funds
already participating in the Withdrawal Plan.
    
 
   
    The Transfer Agent acts as agent for the shareholder in tendering to the
Fund for redemption sufficient full and fractional shares to provide the amount
of the periodic withdrawal payment designated in the application. The shares
will be redeemed at their net asset value determined, at the shareholder's
option, on the tenth or twenty-fifth day (or next following business day) of the
relevant month, quarter, or semi-annual or annual period and normally a check
for the proceeds will be mailed by the Transfer Agent, or amounts credited to a
shareholder's Dean Witter Reynolds Inc. or other selected broker-dealer
brokerage account, or amounts deposited electronically into the shareholder's
bank account via the Automated Clearing House, within five business days after
the date of redemption.
    
 
   
    Withdrawal Plan payments should not be considered as dividends, yields or
income. If periodic withdrawal plan payments continuously exceed net investment
income and net capital gains, the shareholder's original investment will be
correspondingly reduced and ultimately exhausted. Each withdrawal constitutes a
redemption of shares and any gain or loss realized must be recognized for
federal income tax purposes. Although a shareholder may make additional
investments while participating in the Withdrawal Plan, withdrawals made
concurrently with purchases of additional shares are inadvisable because of
sales charges applicable to purchases or redemptions of shares (see "Purchase of
Fund Shares" in the Prospectus).
    
 
   
    Any shareholder who wishes to have payments under the Withdrawal Plan made
to a third party or sent to an address other than the one listed on the account
must send complete written instructions to the Transfer Agent to enroll in the
Withdrawal Plan. The shareholder's signature on such instructions must be
guaranteed by an eligible guarantor acceptable to the Transfer Agent
(shareholders should contact the Transfer Agent for a determination as to
whether a particular institution is such an eligible guarantor). A shareholder
may, at any time, change the amount and interval of withdrawal payments through
his or her Morgan Stanley Dean Witter Financial Advisor or other selected
broker-dealer representative or by written notification to the Transfer Agent.
In addition, the party and/or the address to which checks are mailed may be
changed by written notification to the Transfer Agent, with signature guarantees
required in the manner described above. The shareholder may also terminate the
Withdrawal Plan at any time by written notice to the Transfer Agent. In the
event of such termination, the
    
 
                                       29
<PAGE>
   
account will be continued as a regular Shareholder Investment Account. The
shareholder may also redeem all or part of the shares held in the Withdrawal
Plan account (see "Redemptions and Repurchases" in the Prospectus) at any time.
    
 
   
    DIRECT INVESTMENTS THROUGH TRANSFER AGENT.  As discussed in the Prospectus,
shareholders may make additional investments in any Class of shares of the Fund
for which they qualify at any time by sending a check in any amount, not less
than $100, payable to Morgan Stanley Dean Witter Intermediate Income Securities,
and indicating the selected Class, directly to the Fund's Transfer Agent. In the
case of Class A shares, after deduction of any applicable sales charge, the
balance will be applied to the purchase of Fund shares, and, in the case of
shares of the other Classes, the entire amount will be applied to the purchase
of Fund shares, at the net asset value per share next computed after receipt of
the check or purchase payment by the Transfer Agent. The shares so purchased
will be credited to the investor's account.
    
 
EXCHANGE PRIVILEGE
 
   
    As discussed in the Prospectus, the Fund makes available to its shareholders
an Exchange Privilege whereby shareholders of each Class of shares of the Fund
may exchange their shares for shares of the same Class of shares of any other
Morgan Stanley Dean Witter Multi-Class Fund without the imposition of any
exchange fee. Shares may also be exchanged for shares of any of the following
funds: Morgan Stanley Dean Witter Short-Term U.S. Treasury Trust, Morgan Stanley
Dean Witter Limited Term Municipal Trust, Morgan Stanley Dean Witter Short-Term
Bond Fund and five Morgan Stanley Dean Witter Funds which are money market funds
(the foregoing eight funds are hereinafter referred to as the "Exchange Funds").
Class A shares may also be exchanged for shares of Morgan Stanley Dean Witter
Multi-State Municipal Series Trust and Morgan Stanley Dean Witter Hawaii
Municipal Trust, which are Morgan Stanley Dean Witter Funds sold with a
front-end sales charge ("FSC Funds"). Exchanges may be made after the shares of
the Fund acquired by purchase (not by exchange or dividend reinvestment) have
been held for thirty days. There is no waiting period for exchanges of shares
acquired by exchange or dividend reinvestment. An exchange will be treated for
federal income tax purposes the same as a repurchase or redemption of shares, on
which the shareholder may realize a capital gain or loss.
    
 
    Any new account established through the Exchange Privilege will have the
same registration and cash dividend or dividend reinvestment plan as the present
account, unless the Transfer Agent receives written notification to the
contrary. For telephone exchanges, the exact registration of the existing
account and the account number must be provided.
 
    Any shares held in certificate form cannot be exchanged but must be
forwarded to the Transfer Agent and deposited into the shareholder's account
before being eligible for exchange. (Certificates mailed in for deposit should
not be endorsed.)
 
   
    As described below, and in the Prospectus under the caption "Purchase of
Fund Shares," a CDSC may be imposed upon a redemption, depending on a number of
factors, including the number of years from the time of purchase until the time
of redemption or exchange ("holding period"). When shares of a Morgan Stanley
Dean Witter Multi-Class Fund are exchanged for shares of an Exchange Fund, the
exchange is executed at no charge to the shareholder, without the imposition of
the CDSC at the time of the exchange. During the period of time the shareholder
remains in the Exchange Fund (calculated from the last day of the month in which
the Exchange Fund shares were acquired), the holding period or "year since
purchase payment made" is frozen. When shares are redeemed out of the Exchange
Fund, they will be subject to a CDSC which would be based upon the period of
time the shareholder held shares in a Morgan Stanley Dean Witter Multi-Class
Fund. However, in the case of shares exchanged into an Exchange Fund on or after
April 23, 1990, upon a redemption of shares which results in a CDSC being
imposed, a credit (not to exceed the amount of the CDSC) will be given in an
amount equal to the Exchange Fund 12b-1 distribution fees incurred on or after
that date which are attributable to those shares. Shareholders acquiring shares
of an Exchange Fund pursuant to this exchange privilege may exchange those
shares back into a Morgan Stanley Dean Witter Multi-Class Fund from the Exchange
Fund, with no CDSC being imposed on such exchange. The holding period previously
frozen when
    
 
                                       30
<PAGE>
   
shares were first exchanged for shares of the Exchange Fund resumes on the last
day of the month in which shares of a Morgan Stanley Dean Witter Multi-Class
Fund are reacquired. A CDSC is imposed only upon an ultimate redemption, based
upon the time (calculated as described above) the shareholder was invested in a
Morgan Stanley Dean Witter Multi-Class Fund. In the case of exchanges of Class A
shares which are subject to a CDSC, the holding period also includes the time
(calculated as described above) the shareholder was invested in a FSC Fund.
    
 
   
    When shares initially purchased in a Morgan Stanley Dean Witter Multi-Class
Fund are exchanged for shares of a Morgan Stanley Dean Witter Multi-Class Fund,
shares of a FSC Fund, or shares of an Exchange Fund, the date of purchase of the
shares of the fund exchanged into, for purposes of the CDSC upon redemption,
will be the last day of the month in which the shares being exchanged were
originally purchased. In allocating the purchase payments between funds for
purposes of the CDSC, the amount which represents the current net asset value of
shares at the time of the exchange which were (i) purchased more than one, three
or six years (depending on the CDSC schedule applicable to the shares) prior to
the exchange, (ii) originally acquired through reinvestment of dividends or
distributions and (iii) acquired in exchange for shares of FSC Funds, or for
shares of other Morgan Stanley Dean Witter Funds for which shares of FSC Funds
have been exchanged (all such shares called "Free Shares"), will be exchanged
first. After an exchange, all dividends earned on shares in an Exchange Fund
will be considered Free Shares. If the exchanged amount exceeds the value of
such Free Shares, an exchange is made, on a block-by-block basis, of non-Free
Shares held for the longest period of time (except that, with respect to Class B
shares, if shares held for identical periods of time but subject to different
CDSC schedules are held in the same Exchange Privilege account, the shares of
that block that are subject to a lower CDSC rate will be exchanged prior to the
shares of that block that are subject to a higher CDSC rate). Shares equal to
any appreciation in the value of non-Free Shares exchanged will be treated as
Free Shares, and the amount of the purchase payments for the non-Free Shares of
the fund exchanged into will be equal to the lesser of (a) the purchase payments
for, or (b) the current net asset value of, the exchanged non-Free Shares. If an
exchange between funds would result in exchange of only part of a particular
block of non-Free Shares, then shares equal to any appreciation in the value of
the block (up to the amount of the exchange) will be treated as Free Shares and
exchanged first, and the purchase payment for that block will be allocated on a
pro rata basis between the non-Free Shares of that block to be retained and the
non-Free Shares to be exchanged. The prorated amount of such purchase payment
attributable to the retained non-Free Shares will remain as the purchase payment
for such shares, and the amount of purchase payment for the exchanged non-Free
Shares will be equal to the lesser of (a) the prorated amount of the purchase
payment for, or (b) the current net asset value of, those exchanged non-Free
Shares. Based upon the procedures described in the Prospectus under the caption
"Purchase of Fund Shares," any applicable CDSC will be imposed upon the ultimate
redemption of shares of any fund, regardless of the number of exchanges since
those shares were originally purchased.
    
 
    With respect to the redemption or repurchase of shares of the Fund, the
application of proceeds to the purchase of new shares in the Fund or any other
of the funds and the general administration of the Exchange Privilege, the
Transfer Agent acts as agent for the Distributor and for the shareholder's
selected broker-dealer, if any, in the performance of such functions. With
respect to exchanges, redemptions or repurchases, the Transfer Agent shall be
liable for 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 selected
broker-dealer.
 
    The Distributor and any selected broker-dealer have authorized and 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
fund and the general administration of the Exchange Privilege. No commission or
discounts will be paid to the Distributor or any selected broker-dealer for any
transactions pursuant to this Exchange Privilege.
 
    Exchanges are subject to the minimum investment requirement and any other
conditions imposed by each fund. (The minimum initial investment for the
Exchange Privilege account of each Class is
 
                                       31
<PAGE>
   
$5,000 for Morgan Stanley Dean Witter Liquid Asset Fund Inc., Morgan Stanley
Dean Witter Tax-Free Daily Income Trust, Morgan Stanley Dean Witter California
Tax-Free Daily Income Trust and Morgan Stanley Dean Witter New York Municipal
Money Market Trust, although those funds may, at their discretion, accept
initial investments of as low as $1,000. The minimum initial investment for the
Exchange Privilege account of each Class is $10,000 for Morgan Stanley Dean
Witter Short-Term U.S. Treasury Trust, although that fund, in its discretion,
may accept initial purchases as low as $5,000. The minimum initial investment
for the Exchange Privilege account of each Class is $5,000 for Morgan Stanley
Dean Witter Special Value Fund. The minimum initial investment for the Exchange
Privilege account of each Class for all other Morgan Stanley Dean Witter Funds
for which the Exchange Privilege is available is $1,000.) Upon exchange into an
Exchange Fund, the shares of that fund will be held in a special Exchange
Privilege Account separately from accounts of those shareholders who have
acquired their shares directly from that fund. As a result, certain services
normally available to shareholders of those funds, including the check writing
feature, will not be available for funds held in that account.
    
 
   
    The Fund and each of the other Morgan Stanley Dean Witter Funds may limit
the number of times this Exchange Privilege may be exercised by any investor
within a specified period of time. Also, the Exchange Privilege may be
terminated or revised at any time by the Fund and/or any of the Morgan Stanley
Dean Witter Funds for which shares of the Fund have been exchanged, upon such
notice as may be required by applicable regulatory agencies (presently sixty
days' prior written notice for termination or material revision), provided that
six months' prior written notice of termination will be given to the
shareholders who hold shares of Exchange Funds, pursuant to the Exchange
Privilege, and provided further that the Exchange Privilege may be terminated or
materially revised without notice at times (a) when the New York Stock Exchange
is closed for other than customary weekends and holidays, (b) when trading on
that Exchange is restricted, (c) when an emergency exists as a result of which
disposal by the Fund of securities owned by it is not reasonably practicable or
it is not reasonably practicable for the Fund fairly to determine the value of
its net assets, (d) during any other period when the Securities and Exchange
Commission by order so permits (provided that applicable rules and regulations
of the Securities and Exchange Commission shall govern as to whether the
conditions prescribed in (b) or (c) exist) or (e) if the Fund would be unable to
invest amounts effectively in accordance with its investment objective, policies
and restrictions.
    
 
    The current prospectus for each fund describes its investment objectives and
policies, and shareholders should obtain a copy and examine it carefully before
investing. An exchange will be treated for federal income tax purposes the same
as a repurchase or redemption of shares, on which the shareholder may realize a
capital gain or loss. However, the ability to deduct capital losses on an
exchange may be limited in situations where there is an exchange of shares
within ninety days after the shares are purchased. The Exchange Privilege is
only available in states where an exchange may legally be made.
 
   
    For further information regarding the Exchange Privilege, shareholders
should contact their Morgan Stanley Dean Witter Financial Advisor or other
selected broker-dealer representative or the Transfer Agent.
    
 
REDEMPTIONS AND REPURCHASES
- --------------------------------------------------------------------------------
 
    REDEMPTION.  As stated in the Prospectus, shares of each Class of the Fund
can be redeemed for cash at any time at the net asset value per share next
determined; however, such redemption proceeds will be reduced by the amount of
any applicable CDSC. If shares are held in shareholder's account without a share
certificate, a written request for redemption to the Fund's Transfer Agent at
P.O. Box 983, Jersey City, NJ 07303 is required. If certificates are held by the
shareholder, the shares may be redeemed by surrendering the certificates with a
written request for redemption. The share certificate, or an accompanying stock
power, and the request for redemption, must be signed by the shareholder or
shareholders exactly as the shares are registered. Each request for redemption,
whether or not accompanied by a share certificate, must be sent to the Fund's
Transfer Agent, which will redeem the shares at their net asset value next
computed (see "Purchase of Fund Shares") after it receives the request, and
 
                                       32
<PAGE>
certificate, if any, in good order. Any redemption request received after such
computation will be redeemed at the next determined net asset value. The term
"good order" means that the share certificate, if any, and request for
redemption are properly signed, accompanied by any documentation required by the
Transfer Agent, and bear signature guarantees when required by the Fund or the
Transfer Agent. If redemption is requested by a corporation, partnership, trust
or fiduciary, the Transfer Agent may require that written evidence of authority
acceptable to the Transfer Agent be submitted before such request is accepted.
 
    Whether certificates are held by the shareholder or shares are held in a
shareholder's account, if the proceeds are to be paid to any person other than
the record owner, or if the proceeds are to be paid to a corporation (other than
the Distributor or a selected broker-dealer for the account of the shareholder),
partnership, trust or fiduciary, or sent to a shareholder at an address other
than the registered address, signatures must be guaranteed by an eligible
guarantor. A stock power may be obtained from any dealer or commercial bank. The
Fund may change the signature guarantee requirements from time to time upon
notice to shareholders, which may be by means of a supplement to the prospectus
or a new prospectus.
 
    REPURCHASE.  As stated in the Prospectus, DWR and other selected
broker-dealers are authorized to repurchase shares represented by a share
certificate which is delivered to any of their offices. Shares held in a
shareholder's account without a share certificate may also be repurchased by DWR
and other selected broker-dealers upon the telephonic request of the
shareholder. The repurchase price is the net asset value next computed after
such purchase order is received by DWR or other selected broker-dealer reduced
by any applicable CDSC.
 
   
    PAYMENT FOR SHARES REDEEMED OR REPURCHASED.  As discussed in the Prospectus,
payment for shares of any Class presented for repurchase or redemption will be
made by check within seven days after receipt by the Transfer Agent of the
certificate and/or written request in good order. Such payment may be postponed
or the right of redemption suspended at times (a) when the New York Stock
Exchange is closed for other than customary weekends and holidays, (b) when
trading on that Exchange is restricted, (c) when an emergency exists as a result
of which disposal by the Fund of securities owned by it is not reasonably
practicable or it is not reasonably practicable for the Fund fairly to determine
the value of its net assets, or (d) during any other period when the Securities
and Exchange Commission by order so permits; provided that applicable rules and
regulations of the Securities and Exchange Commission shall govern as to whether
the conditions prescribed in (b) or (c) exist. If the shares to be redeemed have
recently been purchased by check (including a certified check or bank cashier's
check), payment of the redemption proceeds may be delayed for the minimum time
needed to verify that the check used for investment has been honored (not more
than fifteen days from the time of receipt of the check by the Transfer Agent).
It has been and remains the Fund's policy and practice that, if checks for
redemption proceeds remain uncashed, no interest will accrue on amounts
represented by such uncashed checks. Shareholders maintaining accounts with DWR
or another selected broker-dealer are referred to their Morgan Stanley Dean
Witter Financial Advisor or other selected broker-dealer representative
regarding restrictions on redemption of shares of the Fund pledged in the margin
account.
    
 
    TRANSFERS OF SHARES.  In the event a shareholder requests a transfer of any
shares to a new registration, such 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.
 
    REINSTATEMENT PRIVILEGE.  As discussed in the Prospectus, a shareholder who
has had his or her shares redeemed or repurchased and has not previously
exercised this reinstatement privilege may
 
                                       33
<PAGE>
within 35 days after the date of redemption or repurchase reinstate any portion
or all of the proceeds of such redemption or repurchase in shares of the Fund in
the same Class at the net asset value next determined after a reinstatement
request, together with such proceeds, is received by the Transfer Agent.
 
    Exercise of the reinstatement privilege will not affect the federal income
tax treatment of any gain or loss realized upon the redemption or repurchase,
except that if the redemption or repurchase resulted in a loss and reinstatement
is made in shares of the Fund, some or all of the loss, depending on the amount
reinstated, will not be allowed as a deduction for federal income tax purposes,
but will be applied to adjust the cost basis of the shares acquired upon
reinstatement.
 
DIVIDENDS, DISTRIBUTIONS AND TAXES
- --------------------------------------------------------------------------------
 
   
    As discussed in the Prospectus, the Fund will determine either to distribute
or to retain all or part of any net long-term capital gains in any year for
reinvestment. If any such gains are retained, the Fund will pay federal income
tax thereon, and will notify shareholders that, following an election by the
Fund, the shareholders will be required to include such undistributed gains in
determining their taxable income and may claim their share of the tax paid by
the Fund as a credit against their individual federal income tax.
    
 
    In computing net investment income, the Fund will not amortize premiums or
accrue discounts on fixed-income securities in the portfolio, except those
original issue discounts for which amortization is required for federal income
tax purposes. Additionally, with respect to market discounts on bonds issued
after July 18, 1984, and all bonds purchased after April 30, 1993, a portion of
any capital gain realized upon disposition may be re-characterized as taxable
ordinary income in accordance with the provisions of the Internal Revenue Code.
Realized gains and losses on security transactions are determined on the
identified cost method.
 
   
    Gains or losses on sales of securities by the Fund will be long-term capital
gains or losses if the securities have been held by the Fund for more than
twelve months. Gains or losses on the sale of securities held for twelve months
or less will be short-term gains or losses.
    
 
    Because the Fund intends to distribute all of its net investment income and
capital gains to shareholders and otherwise continue to qualify as a regulated
investment company under Subchapter M of the Internal Revenue Code, it is not
expected that the Fund will be required to pay any federal income tax.
Shareholders will normally have to pay federal income taxes, and any state
income taxes, on the dividends and 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. Any dividends declared in the last quarter of any
year to shareholders of record of such period which are paid in the following
calendar year prior to February 1 will be deemed received by the shareholder in
the prior calendar year.
 
   
    Any dividend or capital gains distribution received by a shareholder from
any regulated 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, capital gains distributions
and dividends 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 realized net long-term capital gains, such payment would be in
part a return of the shareholder's investment to the extent of such reduction
below the shareholder's cost, but nonetheless would be fully taxable. Therefore,
an investor should consider the tax implications of purchasing Fund shares
immediately prior to a distribution record date.
    
 
   
    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 reduces the maximum tax
    
 
                                       34
<PAGE>
   
on long-term capital gains from 28% to 20%. The lower rates do not apply to
collectibles and certain other assets. Additionally, the maximum capital gain
rate for assets that are held more than 5 years and that are acquired after
December 31, 2000 is 18%.
    
 
    Dividend payments will be eligible for the federal dividends received
deduction available to the Fund's corporate shareholders only to the extent the
aggregate dividends received by the Fund would be eligible for the deduction if
the Fund were the shareholder claiming the dividends received deduction. The
amount of dividends paid by the Fund which may qualify for the dividends
received deduction is limited to the aggregate amount of qualifying dividends
which the Fund derives from its portfolio investments which the Fund has held
for a minimum period, usually 46 days within a 90 day period beginning 45 days
before the ex-dividend date of each qualifying dividend. Shareholders must meet
a similar holding period requirement with respect to their shares to claim the
dividends received deduction with respect to any distribution of qualifying
dividends. Any long-term and mid-term capital gain distributions will also not
be eligible for the dividends received deduction. The ability to take the
dividends received deduction will also be limited in the case of a Fund
shareholder which incurs or continues indebtedness which is directly
attributable to its investment in the Fund.
 
   
    After the end of the calendar year, shareholders will be sent full
information on their dividends and capital gains distributions for tax purposes,
including information as to the portion taxable as ordinary income, the portion
taxable as long-term capital gains and the portion eligible for the dividends
received deduction. To avoid being subject to a 31% federal backup withholding
tax on taxable dividends, capital gains distributions and the proceeds of
redemptions and repurchases, shareholders' taxpayer identification numbers must
be furnished and certified as to their accuracy.
    
 
   
    Shareholders are urged to consult their attorneys or tax advisors regarding
specific questions as to federal, state or local taxes.
    
 
PERFORMANCE INFORMATION
- --------------------------------------------------------------------------------
 
   
    As discussed in the Prospectus, from time to time the Fund may quote its
"yield" and/or its "total return" in advertisements and sales literature. These
figures are computed separately for Class A, Class B, Class C and Class D
shares. Yield is calculated for any 30-day period as follows: the amount of
interest income for each security in the Fund's portfolio is determined in
accordance with regulatory requirements; the total for the entire portfolio
constitutes the Fund's gross income for the period. Expenses accrued during the
period are subtracted to arrive at "net investment income" of each Class. The
resulting amount is divided by the product of the maximum offering price per
share on the last day of the period multiplied by the average number of shares
of the applicable Class outstanding during the period that were entitled to
dividends. This amount is added to 1 and raised to the sixth power. 1 is then
subtracted from the result and the difference is multiplied by 2 to arrive at
the annualized yield. The yields for the 30-day period ended August 31, 1998,
calculated pursuant to this formula, were 4.96% for Class A, 4.58% for Class B,
4.57% for Class C and 5.44% for Class D.
    
 
   
    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 the Fund's
operations, if shorter than any of the foregoing. The ending redeemable value is
reduced by any CDSC at the end of the one, five or 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, 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 of Class B for the fiscal year
ended August 31, 1998, the five year period ended August 31, 1998 and for the
period from May 3, 1989 (commencement of operations) through August 31, 1998
were 1.53%, 4.43% and 6.54%, respectively. The average annual total returns of
Class A for the fiscal year ended August 31, 1998 and for the period July 28,
1997 (inception of the
    
 
                                       35
<PAGE>
   
Class) through August 31, 1998 were 2.74% and 2.07%, respectively. The average
annual total returns of Class C for the fiscal year ended August 31, 1998 and
for the period July 28, 1997 (inception of the Class) through August 31, 1998
were 5.39% and 5.53%, respectively. The average annual total returns of Class D
for the fiscal year ended August 31, 1998 and for the period July 28, 1997
(inception of the Class) through August 31, 1998 were 7.43% and 6.35%,
respectively.
    
 
   
    In addition to the foregoing, 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. Such 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 example, the average annual
total returns 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 for Class B for the fiscal year ended August
31, 1998, the five year period ended August 31, 1998 and for the period from May
3, 1989 through August 31, 1998 were 6.53%, 4.75% and 6.54%, respectively. Based
on this calculation, the average annual total returns of Class A for the fiscal
year ended August 31, 1998 and for the period July 28, 1997 through August 31,
1998 were 7.30% and 6.21%, respectively, the average annual total returns of
Class C for the fiscal year ended August 31, 1998 and for the period July 28,
1997 through August 31, 1998 were 6.39% and 5.53%, respectively, and the average
annual total returns of Class D for the fiscal year ended August 31, 1998 and
for the period July 28, 1997 through August 31, 1998 were 7.43% and 6.35%,
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 fiscal year ended August 31, 1998 was 6.53% and the
total return for the five year period ended August 31, 1998 and for the period
from May 3, 1989 through August 31, 1998 were 26.11% and 80.56%, respectively.
Based on the foregoing calculations, the total returns for Class A for the
fiscal year ended August 31, 1998 and for the period July 28, 1997 through
August 31, 1998 were 7.30% and 6.80%, respectively, the total returns of Class C
for the fiscal year ended August 31, 1998 and for the period July 28, 1997
through August 31, 1998 were 6.39% and 6.05%, respectively, and the total
returns of Class D for the fiscal year ended August 31, 1998 and for the period
July 28, 1997 through August 31, 1998 were 7.43% and 6.95%, 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
$9,575, $48,250 and $97,250 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 to the following amounts at August 31,
1998:
    
 
   
<TABLE>
<CAPTION>
                           INVESTMENT AT INCEPTION OF:
            INCEPTION   ---------------------------------
  CLASS       DATE:      $10,000    $50,000    $100,000
- ---------  -----------  ---------  ---------  -----------
<S>        <C>          <C>        <C>        <C>
Class A       7/28/97   $  10,226  $  51,531  $   103,863
Class B        5/3/89      18,056     90,280      180,560
Class C       7/28/97      10,605     53,025      106,050
Class D       7/28/97      10,695     53,475      106,950
</TABLE>
    
 
    The Fund from time to time may also advertise its performance relative to
certain performance rankings and indices compiled by independent organizations.
 
                                       36
<PAGE>
DESCRIPTION OF SHARES
- --------------------------------------------------------------------------------
 
    As discussed in the Prospectus, the shareholders of the Fund are entitled to
a full vote for each full share held. All of the Trustees have been elected by
the shareholders of the Fund, most recently at a Special Meeting of Shareholders
on May 21, 1997. The Trustees themselves have the power to alter the number and
the terms of office of the Trustees, and they may at any time lengthen 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. Under certain circumstances the
Trustees may be removed by action of the Trustees. The shareholders also have
the right under certain circumstances to remove the Trustees. The voting rights
of shareholders are not cumulative, so that holders of more than 50 percent of
the shares voting can, if they choose, elect all Trustees being selected, while
the holders of the remaining shares would be unable to elect any Trustees.
 
    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 Act or the Declaration of Trust.
 
    The 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 authorized any such additional series
or classes of shares other than as set forth in the Prospectus.
 
    Under Massachusetts law, shareholders of a business trust may, under certain
limited circumstances, be held personally liable as partners for 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 Fund
obligations include such disclaimer, and provides for indemnification and
reimbursement of expenses 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, in the opinion of Massachusetts
counsel to the Fund, the risk to shareholders of personal liability is remote.
 
    The Declaration of Trust further 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's 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.
 
    The Fund is authorized to issue an unlimited number of shares of beneficial
interest. The Fund shall be of unlimited duration subject to the provisions in
the Declaration of Trust concerning termination by action of the shareholders.
 
CUSTODIAN AND TRANSFER AGENT
- --------------------------------------------------------------------------------
 
    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.
Such balances may, at times, be substantial.
 
   
    Morgan Stanley Dean Witter Trust FSB ("MSDW Trust"), Harborside Financial
Center, Plaza Two, Jersey City, New Jersey 07311 is the Transfer Agent of the
Fund's shares and Dividend Disbursing Agent for payment of dividends and
distributions on Fund shares and Agent for shareholders under various investment
plans described herein. MSDW Trust is an affiliate of Morgan Stanley Dean Witter
Advisors Inc., the Fund's Investment Manager, and of Morgan Stanley Dean Witter
Distributors Inc., the Fund's
    
 
                                       37
<PAGE>
   
Distributor. As Transfer Agent and Dividend Disbursing Agent, MSDW Trust'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 MSDW Trust
receives a per shareholder account fee from the Fund.
    
 
INDEPENDENT ACCOUNTANTS
- --------------------------------------------------------------------------------
 
   
    PricewaterhouseCoopers LLP serves as the independent accountants of the
Fund. The independent accountants are responsible for auditing the annual
financial statements of the Fund.
    
 
REPORTS TO SHAREHOLDERS
- --------------------------------------------------------------------------------
 
    The Fund will send to shareholders, at least semi-annually, reports showing
the Fund's portfolio and other information. An annual report containing
financial statements, together with a report of its independent accountants,
will be sent to shareholders each year.
 
    The Fund's fiscal year ends on August 31. The financial statements of the
Fund must be audited at least once a year by independent accountants whose
selection is made annually by the Fund's Board of Trustees.
 
LEGAL COUNSEL
- --------------------------------------------------------------------------------
 
    Barry Fink, Esq., who is an officer and the General Counsel of the
Investment Manager, is an officer and the General Counsel of the Fund.
 
EXPERTS
- --------------------------------------------------------------------------------
 
   
    The annual financial statements of the Fund for the fiscal year ended August
31, 1998, which are 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.
    
 
REGISTRATION STATEMENT
- --------------------------------------------------------------------------------
 
    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 Securities and Exchange Commission. The complete Registration
Statement may be obtained from the Securities and Exchange Commission upon
payment of the fee prescribed by the rules and regulations of the Commission.
 
                                       38
<PAGE>
MORGAN STANLEY DEAN WITTER INTERMEDIATE INCOME SECURITIES
PORTFOLIO OF INVESTMENTS AUGUST 31, 1998
 
<TABLE>
<CAPTION>
PRINCIPAL
AMOUNT IN                                                                                   COUPON   MATURITY
THOUSANDS                                                                                    RATE      DATE       VALUE
- ---------------------------------------------------------------------------------------------------------------------------
<C>        <S>                                                                              <C>      <C>       <C>
           CORPORATE BONDS (81.2%)
           AEROSPACE (1.8%)
$  2,850   Raytheon Co....................................................................   6.30%   08/15/00  $  2,877,104
                                                                                                               ------------
           AUTOMOBILE - RENTALS (2.0%)
   3,250   Hertz Corp. ...................................................................   6.00    01/15/03     3,264,885
                                                                                                               ------------
           AUTOMOTIVE - FINANCE (3.2%)
   4,975   General Motors Acceptance Corp. ...............................................   8.40    10/15/99     5,120,320
                                                                                                               ------------
           BANK HOLDING COMPANIES (3.2%)
   4,975   Star Bank N.A. ................................................................   6.375   03/01/04     5,077,037
                                                                                                               ------------
           CABLE & TELECOMMUNICATIONS (2.6%)
   4,000   Time Warner Entertainment......................................................   7.25    09/01/08     4,164,840
                                                                                                               ------------
           CASINO/GAMBLING (1.8%)
   2,900   Mirage Resorts, Inc............................................................   6.75    02/01/08     2,823,556
                                                                                                               ------------
           CELLULAR TELEPHONE (0.8%)
   1,260   AirTouch Communications, Inc. .................................................   7.125   07/15/01     1,312,366
                                                                                                               ------------
           COMPUTER SOFTWARE (1.2%)
   1,900   Oracle Corp. ..................................................................   6.91    02/15/07     1,963,346
                                                                                                               ------------
           DISCOUNT CHAINS (1.9%)
   3,000   TJX Companies, Inc.............................................................   6.625   06/15/00     3,011,550
                                                                                                               ------------
           FINANCE & BROKERAGE (6.3%)
   2,500   Donaldson Lufkin & Jenrette Inc................................................   6.11    05/15/01     2,517,175
   1,500   Merrill Lynch & Co., Inc. .....................................................   6.00    01/15/01     1,509,480
   3,200   Salomon, Inc...................................................................   6.50    03/01/00     3,238,272
   3,000   Salomon Smith Barney Holdings..................................................   6.25    06/15/05     3,024,840
                                                                                                               ------------
                                                                                                                 10,289,767
                                                                                                               ------------
           FINANCE COMPANIES (1.2%)
   2,000   Ikon Capital Inc. .............................................................   6.73    06/15/01     1,987,240
                                                                                                               ------------
           FOREIGN GOVERNMENT (1.6%)
   2,450   Israel (State of)..............................................................   6.375   12/15/05     2,519,360
                                                                                                               ------------
           FUNERAL SERVICES (1.9%)
   3,000   Stewart Enterprises, Inc.......................................................   6.70    12/01/03     3,044,550
                                                                                                               ------------
           INDUSTRIAL MACHINERY (2.0%)
   3,000   Atlas Copco (Sweden) - 144A*...................................................   6.50    04/01/08     3,143,940
                                                                                                               ------------
           MAJOR BANKS (12.8%)
   3,900   Bank One Texas N.A.............................................................   6.25    02/15/08     3,908,619
   2,500   Bankers Trust Corp.............................................................   6.70    10/01/07     2,535,725
   3,000   Banque Nationale De Paris (France).............................................   7.20    01/15/07     3,135,900
   5,045   Shawmut Bank Connecticut, N.A..................................................   8.625   02/15/05     5,777,130
   5,000   Societe Generale N.A. Inc. (France) ...........................................   7.40    06/01/06     5,273,400
                                                                                                               ------------
                                                                                                                 20,630,774
                                                                                                               ------------
</TABLE>
 
                       SEE NOTES TO FINANCIAL STATEMENTS
                                       39
<PAGE>
MORGAN STANLEY DEAN WITTER INTERMEDIATE INCOME SECURITIES
PORTFOLIO OF INVESTMENTS AUGUST 31, 1998, CONTINUED
 
<TABLE>
<CAPTION>
PRINCIPAL
AMOUNT IN                                                                                   COUPON   MATURITY
THOUSANDS                                                                                    RATE      DATE       VALUE
- ---------------------------------------------------------------------------------------------------------------------------
<C>        <S>                                                                              <C>      <C>       <C>
           MAJOR U.S. TELECOMMUNICATIONS (3.3%)
$  2,000   US West Capital Funding Inc. ..................................................   6.375%  07/15/08  $  2,005,020
   3,000   WorldCom, Inc. ................................................................   7.75    04/01/07     3,254,010
                                                                                                               ------------
                                                                                                                  5,259,030
                                                                                                               ------------
           MEDIA CONGLOMERATES (1.2%)
   2,000   News American Holdings, Inc. ..................................................   6.625   01/09/08     1,960,300
                                                                                                               ------------
           MID-SIZED BANK (1.9%)
   3,000   Capital One Bank...............................................................   6.375   02/15/03     3,057,510
                                                                                                               ------------
           NATURAL GAS - DISTRIBUTION (1.3%)
   2,000   Columbia Energy Group (Series A)...............................................   6.39    11/28/00     2,036,460
                                                                                                               ------------
           NON-U.S. UTILITIES (4.3%)
   2,000   Israel Electric Co., Ltd. - 144A*..............................................   7.125   07/15/05     2,012,780
   5,000   United Utilities Corp. (United Kingdom)........................................   6.45    04/01/08     4,923,300
                                                                                                               ------------
                                                                                                                  6,936,080
                                                                                                               ------------
           OIL INTEGRATED - INTERNATIONAL (3.1%)
   5,000   Societe Nationale Elf Aquitaine (France).......................................   7.75    05/01/99     5,067,200
                                                                                                               ------------
           OIL PRODUCTION - DOMESTIC (1.2%)
   2,000   Union Pacific Resource Group...................................................   6.50    05/15/05     1,930,200
                                                                                                               ------------
           PAPER & FOREST PRODUCTS (3.1%)
   4,949   Noranda Forest, Inc. (Canada)..................................................   6.875   11/15/05     4,917,029
                                                                                                               ------------
           PROPERTY/CASUALTY INSURANCE (3.2%)
   5,037   Nac Re Corp....................................................................   8.00    06/15/99     5,127,162
                                                                                                               ------------
           SEMICONDUCTOR EQUIPMENT (2.8%)
   4,500   Applied Materials, Inc.........................................................   6.75    10/15/07     4,564,260
                                                                                                               ------------
           SPECIALTY CHEMICALS (2.3%)
   2,000   Lyondell Petrochemical Co......................................................   6.50    02/15/06     1,840,420
   2,000   Millennium America, Inc........................................................   7.00    11/15/06     2,001,180
                                                                                                               ------------
                                                                                                                  3,841,600
                                                                                                               ------------
           STEEL (1.6%)
   4,000   Pohang Iron & Steel Co. (South Korea)..........................................   7.125   11/01/06     2,518,320
                                                                                                               ------------
           TEXTILES (1.9%)
   2,975   Burlington Industries, Inc.....................................................   7.25    09/15/05     3,105,781
                                                                                                               ------------
           UTILITIES - ELECTRIC (5.7%)
   2,000   Commonwealth Edison Co. .......................................................   7.50    01/01/01     2,015,320
   1,000   Niagara Mohawk Power Corp......................................................   7.25    10/01/02       998,480
   3,000   System Energy Resources, Inc. .................................................   7.71    08/01/01     3,139,410
   3,000   Western Resources, Inc. .......................................................   6.875   08/01/04     3,103,350
                                                                                                               ------------
                                                                                                                  9,256,560
                                                                                                               ------------
 
           TOTAL CORPORATE BONDS
           (IDENTIFIED COST $130,430,368)....................................................................   130,808,127
                                                                                                               ------------
</TABLE>
 
                       SEE NOTES TO FINANCIAL STATEMENTS
                                       40
<PAGE>
MORGAN STANLEY DEAN WITTER INTERMEDIATE INCOME SECURITIES
PORTFOLIO OF INVESTMENTS AUGUST 31, 1998, CONTINUED
 
<TABLE>
<CAPTION>
PRINCIPAL
AMOUNT IN                                                                                   COUPON   MATURITY
THOUSANDS                                                                                    RATE      DATE       VALUE
- ---------------------------------------------------------------------------------------------------------------------------
<C>        <S>                                                                              <C>      <C>       <C>
           U.S. GOVERNMENT & AGENCY OBLIGATIONS (12.1%)
$  2,000   Federal Home Loan Banks........................................................   5.80%   09/02/08  $  2,033,440
      85   Federal Home Loan Mortgage Corp. ..............................................   8.50    12/01/01        86,053
      60   Federal Home Loan Mortgage Corp. ..............................................   8.50    01/01/02        61,100
     193   Federal Home Loan Mortgage Corp. ..............................................   8.50    07/01/02       196,758
      99   Federal Home Loan Mortgage Corp. ..............................................   9.00    08/01/02       101,671
   1,000   Federal National Mortgage Assoc. ..............................................   6.00    12/15/00     1,000,750
   2,000   Federal National Mortgage Assoc. ..............................................   5.95    03/09/01     2,007,540
   1,450   Federal National Mortgage Assoc. ..............................................   5.90    06/18/01     1,480,856
      32   Federal National Mortgage Assoc. ..............................................   8.50    12/01/01        33,033
   2,000   Federal National Mortgage Assoc. ..............................................   7.55    06/10/04     2,031,700
   2,000   Federal National Mortgage Assoc. ..............................................   7.73    08/26/04     2,044,180
   2,160   Private Export Funding Corp....................................................   6.86    04/30/04     2,269,037
   2,000   U.S. Treasury Note.............................................................   6.25    03/31/99     2,013,080
   3,000   U.S. Treasury Note.............................................................   6.375   05/15/00     3,070,020
   1,000   U.S. Treasury Note.............................................................   6.875   05/15/06     1,112,520
                                                                                                               ------------
 
           TOTAL U.S. GOVERNMENT & AGENCY OBLIGATIONS
           (IDENTIFIED COST $19,014,420).....................................................................    19,541,738
                                                                                                               ------------
 
           SHORT-TERM INVESTMENT (a) (7.8%)
           U.S. GOVERNMENT AGENCY
  12,500   Federal Home Loan Mortgage Corp.
             (IDENTIFIED COST $12,500,000)................................................   5.70    09/01/98    12,500,000
                                                                                                               ------------
           TOTAL INVESTMENTS
           (IDENTIFIED COST $161,944,788) (B).....................................................   101.1%     162,849,865
 
           LIABILITIES IN EXCESS OF CASH AND OTHER ASSETS.........................................    (1.1)      (1,694,605)
                                                                                                    -------   -------------
 
           NET ASSETS.............................................................................   100.0%   $ 161,155,260
                                                                                                    -------   -------------
                                                                                                    -------   -------------
</TABLE>
 
- ---------------------
 
 *   Resale is restricted to qualified institutional investors.
(a)  Security was purchased on a discount basis. The interest rate shown has
     been adjusted to reflect a money market equivalent yield.
(b)  The aggregate cost for federal income tax purposes approximates identified
     cost. The aggregate gross unrealized appreciation is $3,256,500 and the
     aggregate gross unrealized depreciation is $2,351,423, resulting in net
     unrealized appreciation of $905,077.
 
                       SEE NOTES TO FINANCIAL STATEMENTS
                                       41
<PAGE>
   
MORGAN STANLEY DEAN WITTER INTERMEDIATE INCOME SECURITIES
    
   
FINANCIAL STATEMENTS
    
 
   
STATEMENT OF ASSETS AND LIABILITIES
    
   
AUGUST 31, 1998
    
 
   
<TABLE>
<S>                                                                                             <C>
ASSETS:
Investments in securities, at value (identified cost $161,944,788)............................  $162,849,865
Cash..........................................................................................        42,242
Receivable for:
    Interest..................................................................................     2,614,273
    Shares of beneficial interest sold........................................................       153,538
    Principal paydowns........................................................................        14,050
Prepaid expenses and other assets.............................................................        49,489
                                                                                                ------------
     TOTAL ASSETS.............................................................................   165,723,457
                                                                                                ------------
LIABILITIES:
Payable for:
    Investments purchased.....................................................................     3,515,090
    Shares of beneficial interest repurchased.................................................       679,398
    Plan of distribution fee..................................................................       107,419
    Dividends and distributions to shareholders...............................................        87,548
    Investment management fee.................................................................        80,172
Accrued expenses and other payables...........................................................        98,570
                                                                                                ------------
     TOTAL LIABILITIES........................................................................     4,568,197
                                                                                                ------------
     NET ASSETS...............................................................................  $161,155,260
                                                                                                ------------
                                                                                                ------------
COMPOSITION OF NET ASSETS:
Paid-in-capital...............................................................................  $169,681,311
Net unrealized appreciation...................................................................       905,077
Accumulated undistributed net investment income...............................................        15,315
Accumulated net realized loss.................................................................    (9,446,443)
                                                                                                ------------
     NET ASSETS...............................................................................  $161,155,260
                                                                                                ------------
                                                                                                ------------
CLASS A SHARES:
Net Assets....................................................................................    $3,456,826
Shares Outstanding (UNLIMITED AUTHORIZED, $.01 PAR VALUE).....................................       356,015
     NET ASSET VALUE PER SHARE................................................................         $9.71
                                                                                                ------------
                                                                                                ------------
     MAXIMUM OFFERING PRICE PER SHARE,
       (NET ASSET VALUE PLUS 4.44% OF NET
      ASSET VALUE)............................................................................        $10.14
                                                                                                ------------
                                                                                                ------------
CLASS B SHARES:
Net Assets....................................................................................  $151,515,225
Shares Outstanding (UNLIMITED AUTHORIZED, $.01 PAR VALUE).....................................    15,613,607
     NET ASSET VALUE PER SHARE................................................................         $9.70
                                                                                                ------------
                                                                                                ------------
CLASS C SHARES:
Net Assets....................................................................................      $457,016
Shares Outstanding (UNLIMITED AUTHORIZED, $.01 PAR VALUE).....................................        47,087
     NET ASSET VALUE PER SHARE................................................................         $9.71
                                                                                                ------------
                                                                                                ------------
CLASS D SHARES:
Net Assets....................................................................................    $5,726,193
Shares Outstanding (UNLIMITED AUTHORIZED, $.01 PAR VALUE).....................................       590,213
     NET ASSET VALUE PER SHARE................................................................         $9.70
                                                                                                ------------
                                                                                                ------------
</TABLE>
    
 
   
STATEMENT OF OPERATIONS
    
   
FOR THE YEAR ENDED AUGUST 31, 1998
    
 
   
<TABLE>
<S>                                                                                              <C>
NET INVESTMENT INCOME:
 
INTEREST INCOME................................................................................  $11,087,299
                                                                                                 -----------
 
EXPENSES
Plan of distribution fee (Class A shares)......................................................        4,202
Plan of distribution fee (Class B shares)......................................................    1,300,714
Plan of distribution fee (Class C shares)......................................................        1,925
Investment management fee......................................................................      964,411
Transfer agent fees and expenses...............................................................      166,274
Registration fees..............................................................................       96,385
Shareholder reports and notices................................................................       58,323
Professional fees..............................................................................       45,394
Trustees' fees and expenses....................................................................       21,090
Custodian fees.................................................................................       19,216
Other..........................................................................................        6,257
                                                                                                 -----------
 
     TOTAL EXPENSES............................................................................    2,684,191
                                                                                                 -----------
 
     NET INVESTMENT INCOME.....................................................................    8,403,108
                                                                                                 -----------
 
NET REALIZED AND UNREALIZED GAIN:
Net realized gain..............................................................................    1,768,354
Net change in unrealized appreciation..........................................................      134,510
                                                                                                 -----------
 
     NET GAIN..................................................................................    1,902,864
                                                                                                 -----------
 
NET INCREASE...................................................................................  $10,305,972
                                                                                                 -----------
                                                                                                 -----------
</TABLE>
    
 
                       SEE NOTES TO FINANCIAL STATEMENTS
                                       42
<PAGE>
   
MORGAN STANLEY DEAN WITTER INTERMEDIATE INCOME SECURITIES
    
   
FINANCIAL STATEMENTS, CONTINUED
    
 
   
STATEMENT OF CHANGES IN NET ASSETS
    
 
   
<TABLE>
<CAPTION>
                                                                            FOR THE YEAR      FOR THE YEAR
                                                                                ENDED            ENDED
                                                                           AUGUST 31, 1998  AUGUST 31, 1997*
- ------------------------------------------------------------------------------------------------------------
<S>                                                                        <C>              <C>
 
INCREASE (DECREASE) IN NET ASSETS:
 
OPERATIONS:
Net investment income....................................................  $     8,403,108  $     10,272,537
Net realized gain (loss).................................................        1,768,354        (2,567,762)
Net change in unrealized appreciation/depreciation.......................          134,510         6,828,218
                                                                           ---------------  ----------------
 
     NET INCREASE........................................................       10,305,972        14,532,993
                                                                           ---------------  ----------------
 
DIVIDENDS TO SHAREHOLDERS FROM NET INVESTMENT INCOME:
Class A shares...........................................................         (100,388)              (58)
Class B shares...........................................................       (7,980,246)      (10,229,881)
Class C shares...........................................................          (11,414)              (83)
Class D shares...........................................................         (348,107)          (25,048)
                                                                           ---------------  ----------------
 
     TOTAL DIVIDENDS.....................................................       (8,440,155)      (10,255,070)
                                                                           ---------------  ----------------
Net decrease from transactions in shares of beneficial interest..........      (10,443,102)      (43,456,259)
                                                                           ---------------  ----------------
 
     NET DECREASE........................................................       (8,577,285)      (39,178,336)
 
NET ASSETS:
Beginning of period......................................................      169,732,545       208,910,881
                                                                           ---------------  ----------------
 
     END OF PERIOD
    (INCLUDING UNDISTRIBUTED NET INVESTMENT INCOME OF $15,315 AND
    $52,362, RESPECTIVELY)...............................................  $   161,155,260  $    169,732,545
                                                                           ---------------  ----------------
                                                                           ---------------  ----------------
</TABLE>
    
 
- ---------------------
 
   
 *   Class A, Class C and Class D shares were issued July 28, 1997.
 
                       SEE NOTES TO FINANCIAL STATEMENTS
    
                                       43
<PAGE>
   
MORGAN STANLEY DEAN WITTER INTERMEDIATE INCOME SECURITIES
    
   
NOTES TO FINANCIAL STATEMENTS AUGUST 31, 1998
    
 
   
1. ORGANIZATION AND ACCOUNTING POLICIES
    
 
   
Morgan Stanley Dean Witter Intermediate Income Securities (the "Fund"), formerly
Dean Witter Intermediate Income Securities, 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 high current
income consistent with safety of principal. The Fund was organized as a
Massachusetts business trust on September 1, 1988 and commenced operations on
May 3, 1989. On July 28, 1997, the Fund commenced offering three additional
classes of shares, with the then current shares, other than shares held by
certain employee benefit plans established by Dean Witter Reynolds Inc. and its
affiliate, SPS Transaction Services, Inc., designated as Class B shares. Shares
held by those employee benefit plans prior to July 28, 1997 have been designated
Class D 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 the 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;
(2) all other portfolio securities for which over-the-counter market quotations
are readily available are valued at the latest available bid price; (3) when
market quotations are not readily available, including circumstances under which
it is determined by Morgan Stanley Dean 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
    
 
                                       44
<PAGE>
   
MORGAN STANLEY DEAN WITTER INTERMEDIATE INCOME SECURITIES
    
   
NOTES TO FINANCIAL STATEMENTS AUGUST 31, 1998, CONTINUED
    
 
   
be based upon current market prices of securities which are comparable in
coupon, rating and maturity or an appropriate matrix utilizing similar factors);
(4) certain portfolio securities may be valued by an outside pricing service
approved by the Trustees. The pricing service may utilize a matrix system
incorporating security quality, maturity and coupon as the evaluation model
parameters, and/or research and 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; and
(5) 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 on the identified cost method.
Dividend income and other distributions are recorded on 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. 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.
    
 
   
E. 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 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
    
 
                                       45
<PAGE>
   
MORGAN STANLEY DEAN WITTER INTERMEDIATE INCOME SECURITIES
    
   
NOTES TO FINANCIAL STATEMENTS AUGUST 31, 1998, CONTINUED
    
 
   
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, calculated daily and payable monthly, by applying the
following annual rates to the net assets of the Fund determined as of the close
of each business day: 0.60% of the portion of daily net assets not exceeding
$500 million; 0.50% of the portion of daily net assets exceeding $500 million
but not exceeding $750 million; 0.40% of the portion of the daily net assets
exceeding $750 million but not exceeding $1 billion; and 0.30% of the portion of
the daily net assets exceeding $1 billion.
    
 
   
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 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 -- 0.85% 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 had been imposed or waived; (b) the average daily net
assets of Class B; and (iii) Class C -- up to 0.85% 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
services provided and the expenses borne by it and others in the distribution of
the shares of these Classes, including
    
 
                                       46
<PAGE>
   
MORGAN STANLEY DEAN WITTER INTERMEDIATE INCOME SECURITIES
    
   
NOTES TO FINANCIAL STATEMENTS AUGUST 31, 1998, CONTINUED
    
 
   
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; printing and distribution
of prospectuses and reports used in connection with the offering of these shares
to other than current shareholders; and 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 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 $5,232,570 at August 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 0.85% 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 August 31, 1998, the distribution fee was
accrued for Class A shares and Class C shares at the annual rate of 0.24% and
0.85%, respectively.
    
 
   
The Distributor has informed the Fund that for the year ended August 31, 1998,
it received contingent deferred sales charges from certain redemptions of the
Fund's Class B shares and Class C shares of $191,024, and $722, respectively and
received $12,907, 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.
    
 
                                       47
<PAGE>
   
MORGAN STANLEY DEAN WITTER INTERMEDIATE INCOME SECURITIES
    
   
NOTES TO FINANCIAL STATEMENTS AUGUST 31, 1998, CONTINUED
    
 
   
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 August 31, 1998, aggregated
$151,333,080 and $167,039,940, respectively. Included in the aforementioned are
purchases and sales of U.S. Government securities of $50,005,085 and
$56,430,499, respectively.
    
 
   
Morgan Stanley Dean Witter Trust FSB, an affiliate of the Investment Manager and
Distributor, is the Fund's transfer agent. At August 31, 1998, the Fund had
transfer agent fees and expenses payable of approximately $880.
    
 
   
The Fund has an unfunded noncontributory defined benefit pension plan covering
all independent Trustees of the Fund who will have served as independent
Trustees for at least five years at the time of retirement. Benefits under this
plan are based on years of service and compensation during the last five years
of service. Aggregate pension costs for the year ended August 31, 1998 included
in Trustees' fees and expenses in the Statement of Operations amounted to
$5,177. At August 31, 1998, the Fund had an accrued pension liability of $50,913
which is included in accrued expenses in the Statement of Assets and
Liabilities.
    
 
   
5. FEDERAL INCOME TAX STATUS
    
 
   
At August 31, 1998, the Fund had a net capital loss carryover of approximately
$9,446,000, which may be used to offset future capital gains to the extent
provided by regulations, which is available through August 31 of the following
years:
    
 
   
<TABLE>
<CAPTION>
           AMOUNT IN THOUSANDS
- ------------------------------------------
  2003       2004       2005       2006
- ---------  ---------  ---------  ---------
<S>        <C>        <C>        <C>
$   6,656  $     313  $   2,351  $     126
- ---------  ---------  ---------  ---------
- ---------  ---------  ---------  ---------
</TABLE>
    
 
                                       48
<PAGE>
   
MORGAN STANLEY DEAN WITTER INTERMEDIATE INCOME SECURITIES
    
   
NOTES TO FINANCIAL STATEMENTS AUGUST 31, 1998, CONTINUED
    
 
   
6. SHARES OF BENEFICIAL INTEREST
    
 
   
Transactions in shares of beneficial interest were as follows:
    
 
   
<TABLE>
<CAPTION>
                                                                           FOR THE YEAR                  FOR THE YEAR
                                                                              ENDED                         ENDED
                                                                         AUGUST 31, 1998              AUGUST 31, 1997+*
                                                                   ----------------------------   --------------------------
                                                                     SHARES          AMOUNT         SHARES         AMOUNT
                                                                   -----------   --------------   -----------   ------------
<S>                                                                <C>           <C>              <C>           <C>
CLASS A SHARES
Sold.............................................................      432,771   $    4,200,291       193,347   $  1,854,318
Reinvestment of dividends........................................        6,280           60,968             5             54
Redeemed.........................................................     (276,388)      (2,677,083)      --             --
                                                                   -----------   --------------   -----------   ------------
Net increase - Class A...........................................      162,663        1,584,176       193,352      1,854,372
                                                                   -----------   --------------   -----------   ------------
 
CLASS B SHARES
Sold.............................................................   19,728,435      191,353,800     8,499,296     80,974,547
Reinvestment of dividends........................................      435,921        4,221,022       587,192      5,604,585
Redeemed.........................................................  (21,536,089)    (208,796,829)  (13,839,797)  (131,962,423)
                                                                   -----------   --------------   -----------   ------------
Net decrease - Class B...........................................   (1,371,733)     (13,222,007)   (4,753,309)   (45,383,291)
                                                                   -----------   --------------   -----------   ------------
 
CLASS C SHARES
Sold.............................................................       57,617          558,111         3,993         38,561
Reinvestment of dividends........................................          842            8,164             6             56
Redeemed.........................................................     ( 15,371)        (148,714)      --             --
                                                                   -----------   --------------   -----------   ------------
Net increase - Class C...........................................       43,088          417,561         3,999         38,617
                                                                   -----------   --------------   -----------   ------------
 
CLASS D SHARES
Sold.............................................................      339,652        3,280,027        10,611        102,479
Reinvestment of dividends........................................       34,184          331,043         2,476         23,704
Redeemed.........................................................     (292,464)      (2,833,902)       (9,547)       (92,140)
                                                                   -----------   --------------   -----------   ------------
Net increase - Class D...........................................       81,372          777,168         3,540         34,043
                                                                   -----------   --------------   -----------   ------------
Net decrease in Fund.............................................   (1,084,610)  $  (10,443,102)   (4,552,418)  $(43,456,259)
                                                                   -----------   --------------   -----------   ------------
                                                                   -----------   --------------   -----------   ------------
</TABLE>
    
 
- ---------------------
 
   
 +   On July 28, 1997, 505,301 shares representing $4,891,310 were transferred
     to Class D.
 *   For Class A, C and D shares, for the period July 28, 1997 (issue date)
     through August 31, 1997.
 
    
 
   
7. SUBSEQUENT EVENT
    
 
   
As of the close of business on September 11, 1998, the Fund acquired all the net
assets of Dean Witter Retirement Series -- Intermediate Income Securities Series
("Retirement Intermediate") pursuant to a plan of reorganization approved by the
shareholders of Retirement Intermediate on August 19, 1998. The acquisition was
accomplished by a tax-free exchange of 250,724 Class D shares of the Fund at a
net asset value of $9.74 per share for 247,422 shares of Retirement
Intermediate. The net assets of the Fund and Retirement Intermediate immediately
before the acquisition were $159,153,039, and $2,441,399, respectively,
including unrealized appreciation of $62,584 for Retirement Intermediate.
Immediately after the acquisition, the combined net assets of the Fund amounted
to $161,594,438.
    
 
                                       49
<PAGE>
   
MORGAN STANLEY DEAN WITTER INTERMEDIATE INCOME SECURITIES
    
   
FINANCIAL HIGHLIGHTS
    
 
   
Selected ratios and per share data for a share of beneficial interest
outstanding throughout each period:
    
   
<TABLE>
<CAPTION>
                                                       FOR THE YEAR ENDED AUGUST 31
                      -----------------------------------------------------------------------------------------------
                       1998++    1997**++     1996       1995      1994       1993       1992       1991       1990
- ---------------------------------------------------------------------------------------------------------------------
<S>                   <C>        <C>        <C>        <C>        <C>       <C>        <C>        <C>        <C>
CLASS B SHARES
PER SHARE OPERATING
PERFORMANCE:
Net asset value,
 beginning
 of period..........  $   9.59   $   9.39   $   9.69   $   9.51   $ 10.26   $  10.05   $   9.59   $   9.42   $   9.98
                      --------   --------   --------   --------   -------   --------   --------   --------   --------
Net investment
 income.............      0.51       0.53       0.55       0.59      0.58       0.62       0.70       0.79       0.86
Net realized and
 unrealized gain
 (loss).............      0.11       0.20      (0.30)      0.19     (0.73)      0.20       0.46       0.17      (0.55)
                      --------   --------   --------   --------   -------   --------   --------   --------   --------
Total from
 investment
 operations.........      0.62       0.73       0.25       0.78     (0.15)      0.82       1.16       0.96       0.31
                      --------   --------   --------   --------   -------   --------   --------   --------   --------
Less dividends and
 distributions from:
   Net investment
   income...........     (0.51)     (0.53)     (0.55)     (0.59)    (0.56)     (0.61)     (0.70)     (0.79)     (0.86)
   Net realized
   gain.............     --         --         --         (0.01)    (0.04)     --         --         --         (0.01)
                      --------   --------   --------   --------   -------   --------   --------   --------   --------
Total dividends and
 distributions......     (0.51)     (0.53)     (0.55)     (0.60)    (0.60)     (0.61)     (0.70)     (0.79)     (0.87)
                      --------   --------   --------   --------   -------   --------   --------   --------   --------
Net asset value, end
 of period..........  $   9.70   $   9.59   $   9.39   $   9.69   $  9.51   $  10.26   $  10.05   $   9.59   $   9.42
                      --------   --------   --------   --------   -------   --------   --------   --------   --------
                      --------   --------   --------   --------   -------   --------   --------   --------   --------
TOTAL INVESTMENT
RETURN+.............      6.53%      7.93%      2.58%      8.56%    (1.50)%     8.43%     12.58%     10.78%      3.22%
RATIOS TO AVERAGE
NET ASSETS:
Expenses............      1.71%(4)     1.65%     1.62%     1.63%     1.63%      1.62%      1.69%      1.69%      1.75%
Net investment
 income.............      5.19%(4)     5.52%     5.69%     6.23%     5.80%      6.12%      7.11%      8.49%      8.78%
SUPPLEMENTAL DATA:
Net assets, end of
 period, in
 thousands..........  $151,515   $162,959   $208,911   $232,752   $245,750  $254,431   $187,285   $115,204   $114,086
Portfolio turnover
 rate...............        98%        98%       115%       114%      122%       132%        93%       150%       135%
 
<CAPTION>
                      FOR THE PERIOD
                        AUGUST 31,
                           1989
- ---------------------------------------------------
<S>                   <C>
CLASS B SHARES
PER SHARE OPERATING
PERFORMANCE:
Net asset value,
 beginning
 of period..........  $ 10.00
                       ------
Net investment
 income.............     0.28
Net realized and
 unrealized gain
 (loss).............    (0.02)
                       ------
Total from
 investment
 operations.........     0.26
                       ------
Less dividends and
 distributions from:
   Net investment
   income...........    (0.28)
   Net realized
   gain.............    --
                       ------
Total dividends and
 distributions......    (0.28)
                       ------
Net asset value, end
 of period..........  $  9.98
                       ------
                       ------
TOTAL INVESTMENT
RETURN+.............     2.57%(1)
RATIOS TO AVERAGE
NET ASSETS:
Expenses............     1.42%(2)(3)
Net investment
 income.............     8.18%(2)(3)
SUPPLEMENTAL DATA:
Net assets, end of
 period, in
 thousands..........  $69,946
Portfolio turnover
 rate...............       30%(1)
</TABLE>
    
 
- ---------------------
 
   
 *   Commencement of operations.
**   Prior to July 28, 1997, the Fund issued one class of shares. All shares of
     the Fund held prior to that date, other than shares held by certain
     employee benefit plans established by Dean Witter Reynolds Inc. and its
     affiliate, SPS Transaction Services, Inc., have been designated as Class B
     shares. Shares held by those employee benefit plans prior to July 28, 1997
     have been designated Class D shares.
++   The per share amounts were computed using an average number of shares
     outstanding during the period.
 +   Does not reflect the deduction of sales charge. Calculated based on the net
     asset value as of the last business day of the period.
(1)  Not annualized.
(2)  Annualized.
(3)  If the Fund had borne all the expenses that were assumed or waived by the
     Investment Manager, the above expense and net investment income ratios
     would have been 2.15% and 7.44%, respectively.
(4)  Reflects overall Fund ratios for investment income and non-class specific
     expenses.
 
    
 
                       SEE NOTES TO FINANCIAL STATEMENTS
                                       50
<PAGE>
   
MORGAN STANLEY DEAN WITTER INTERMEDIATE INCOME SECURITIES
    
   
FINANCIAL HIGHLIGHTS, CONTINUED
    
 
   
<TABLE>
<CAPTION>
                                                                                            FOR THE PERIOD
                                                                                            JULY 28, 1997*
                                                                          FOR THE YEAR         THROUGH
                                                                              ENDED           AUGUST 31,
                                                                        AUGUST 31, 1998++       1997++
- ----------------------------------------------------------------------------------------------------------
<S>                                                                     <C>                 <C>
CLASS A SHARES
PER SHARE OPERATING PERFORMANCE:
Net asset value, beginning of period..................................       $ 9.59             $ 9.68
                                                                             ------             ------
Net investment income.................................................         0.56               0.06
Net realized and unrealized gain (loss)...............................         0.13              (0.10)
                                                                             ------             ------
Total from investment operations......................................         0.69              (0.04)
                                                                             ------             ------
Less dividends from net investment income.............................        (0.57)             (0.05)
                                                                             ------             ------
Net asset value, end of period........................................       $ 9.71             $ 9.59
                                                                             ------             ------
                                                                             ------             ------
TOTAL INVESTMENT RETURN+..............................................         7.30%             (0.46)%(1)
RATIOS TO AVERAGE NET ASSETS:
Expenses..............................................................         1.10%(3)           2.18%(2)
Net investment income.................................................         5.80%(3)           6.10%(2)
SUPPLEMENTAL DATA:
Net assets, end of period, in thousands...............................       $3,457             $1,855
Portfolio turnover rate...............................................           98%                98%
 
CLASS C SHARES
PER SHARE OPERATING PERFORMANCE:
Net asset value, beginning of period..................................       $ 9.61             $ 9.68
                                                                             ------             ------
Net investment income.................................................         0.49               0.04
Net realized and unrealized gain (loss)...............................         0.11              (0.07)
                                                                             ------             ------
Total from investment operations......................................         0.60              (0.03)
                                                                             ------             ------
Less dividends from net investment income.............................        (0.50)             (0.04)
                                                                             ------             ------
Net asset value, end of period........................................       $ 9.71             $ 9.61
                                                                             ------             ------
                                                                             ------             ------
TOTAL INVESTMENT RETURN+..............................................         6.39%             (0.31)%(1)
RATIOS TO AVERAGE NET ASSETS:
Expenses..............................................................         1.71%(3)           2.02%(2)
Net investment income.................................................         5.19%(3)           4.22%(2)
SUPPLEMENTAL DATA:
Net assets, end of period, in thousands...............................         $457                $38
Portfolio turnover rate...............................................           98%                98%
</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 charge. 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
                                       51
<PAGE>
   
MORGAN STANLEY DEAN WITTER INTERMEDIATE INCOME SECURITIES
    
   
FINANCIAL HIGHLIGHTS, CONTINUED
    
 
   
<TABLE>
<CAPTION>
                                                                                            FOR THE PERIOD
                                                                          FOR THE YEAR      JULY 28, 1997*
                                                                              ENDED         THROUGH AUGUST
                                                                        AUGUST 31, 1998++     31, 1997++
- ----------------------------------------------------------------------------------------------------------
 
<S>                                                                     <C>                 <C>
CLASS D SHARES
 
PER SHARE OPERATING PERFORMANCE:
 
Net asset value, beginning of period..................................       $ 9.59             $ 9.68
                                                                             ------             ------
 
Net investment income.................................................         0.59               0.05
 
Net realized and unrealized gain (loss)...............................         0.11              (0.09)
                                                                             ------             ------
 
Total from investment operations......................................         0.70              (0.04)
                                                                             ------             ------
 
Less dividends from net investment income.............................        (0.59)             (0.05)
                                                                             ------             ------
 
Net asset value, end of period........................................       $ 9.70             $ 9.59
                                                                             ------             ------
                                                                             ------             ------
 
TOTAL INVESTMENT RETURN+..............................................         7.43%             (0.44)%(1)
 
RATIOS TO AVERAGE NET ASSETS:
Expenses..............................................................         0.86%(3)           1.11%(2)
 
Net investment income.................................................         6.04%(3)           5.91%(2)
 
SUPPLEMENTAL DATA:
Net assets, end of period, in thousands...............................       $5,726             $4,880
 
Portfolio turnover rate...............................................           98%                98%
</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
                                       52
<PAGE>
   
MORGAN STANLEY DEAN WITTER INTERMEDIATE INCOME SECURITIES
    
   
REPORT OF INDEPENDENT ACCOUNTANTS
    
 
   
TO THE SHAREHOLDERS AND TRUSTEES
OF MORGAN STANLEY DEAN WITTER INTERMEDIATE INCOME SECURITIES
    
 
   
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
Intermediate Income Securities (the "Fund"), formerly Dean Witter Intermediate
Income Securities, at August 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 August
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
OCTOBER 9, 1998
    
 
                                       53
<PAGE>
APPENDIX
- --------------------------------------------------------------------------------
 
RATINGS OF INVESTMENTS
MOODY'S INVESTORS SERVICE INC. ("MOODY'S")
 
                                  BOND RATINGS
 
<TABLE>
<S>        <C>
Aaa        Bonds which are rated Aaa are judged to be of the best quality. They carry the
           smallest degree of investment risk and are generally referred to as "gilt edge."
           Interest payments are protected by a large or by an exceptionally stable margin and
           principal is secure. While the various protective elements are likely to change,
           such changes as can be visualized are
           most unlikely to impair the fundamentally strong position of such issues.
Aa         Bonds which are rated Aa are judged to be of high quality by all standards.
           Together with the Aaa group they comprise what are generally known as high grade
           bonds. They are rated lower than the best bonds because margins of protection may
           not be as large as in Aaa securities or fluctuation of protective elements may be
           of greater amplitude or there may be other elements present which make the
           long-term risks appear somewhat larger than in Aaa securities.
A          Bonds which are rated A possess many favorable investment attributes and are to be
           considered as upper medium grade obligations. Factors giving security to principal
           and interest are considered adequate, but elements may be present which suggest a
           susceptibility to impairment sometime in the future.
Baa        Bonds which are rated Baa are considered as medium grade obligations; i.e., they
           are neither highly protected nor poorly secured. Interest payments and principal
           security appear adequate for the present but certain protective elements may be
           lacking or may be characteristically unreliable over any great length of time. Such
           bonds lack outstanding investment characteristics and in fact have speculative
           characteristics as well.
           Bonds rated Aaa, Aa, A and Baa are considered investment grade bonds.
Ba         Bonds which are rated Ba are judged to have speculative elements; their future
           cannot be considered as well assured. Often the protection of interest and
           principal payments may be very moderate, and therefore not well safeguarded during
           both good and bad times in the future. Uncertainty of position characterizes bonds
           in this class.
B          Bonds which are rated B generally lack characteristics of the desirable investment.
           Assurance of interest and principal payments or of maintenance of other terms of
           the contract over any long period of time may be small.
Caa        Bonds which are rated Caa are of poor standing. Such issues may be in default or
           there may be present elements of danger with respect to principal or interest.
Ca         Bonds which are rated Ca present obligations which are speculative in a high
           degree. Such issues are often in default or have other marked shortcomings.
C          Bonds which are rated C are the lowest rated class of bonds, and issues so rated
           can be regarded as having extremely poor prospects of ever attaining any real
           investment standing.
</TABLE>
 
    RATING REFINEMENTS: Moody's may apply numerical modifiers, 1, 2, and 3 in
each generic rating classification from Aa through B in its municipal bond
rating system. The modifier 1 indicates that the security ranks in the higher
end of its generic rating category; the modifier 2 indicates a mid-range
ranking; and a modifier 3 indicates that the issue ranks in the lower end of its
generic rating category.
 
                            COMMERCIAL PAPER RATINGS
 
    Moody's Commercial Paper ratings are opinions of the ability to repay
punctually promissory obligations not having an original maturity in excess of
nine months. The ratings apply to Municipal Commercial Paper as well as taxable
Commercial Paper. Moody's employs the following three
 
                                       54
<PAGE>
designations, all judged to be investment grade, to indicate the relative
repayment capacity of rated issuers: Prime-1, Prime-2, Prime-3.
 
    Issuers rated Prime-1 have a superior capacity for repayment of short-term
promissory obligations. Issuers rated Prime-2 have a strong capacity for
repayment of short-term promissory obligations; and Issuers rated Prime-3 have
an acceptable capacity for repayment of short-term promissory obligations.
Issuers rated Not Prime do not fall within any of the Prime rating catagories.
 
STANDARD & POOR'S CORPORATION ("STANDARD & POOR'S")
 
                                  BOND RATINGS
 
    A Standard & Poor's bond rating is a current assessment of the
creditworthiness of an obligor with respect to a specific obligation. This
assessment may take into consideration obligors such as guarantors, insurers, or
lessees.
 
    The ratings are based on current information furnished by the issuer or
obtained by Standard & Poor's from other sources it considers reliable. The
ratings are based, in varying degrees, on the following considerations: (1)
likelihood of default-capacity and willingness of the obligor as to the timely
payment of interest and repayment of principal in accordance with the terms of
the obligation; (2) nature of and provisions of the obligation; and (3)
protection afforded by, and relative position of, the obligation in the event of
bankruptcy, reorganization or other arrangement under the laws of bankruptcy and
other laws affecting creditors' rights.
 
    Standard & Poor's does not perform an audit in connection with any rating
and may, on occasion, rely on unaudited financial information. The ratings may
be changed, suspended or withdrawn as a result of changes in, or unavailability
of, such information, or for other reasons.
 
<TABLE>
<S>        <C>
AAA        Debt rated "AAA" has the highest rating assigned by Standard & Poor's. Capacity to
           pay interest and repay principal is extremely strong.
AA         Debt rated "AA" has a very strong capacity to pay interest and repay principal and
           differs from the highest-rated issues only in small degree.
A          Debt rated "A" has a strong capacity to pay interest and repay principal although
           they are somewhat more susceptible to the adverse effects of changes in
           circumstances and economic conditions than debt in higher-rated categories.
BBB        Debt rated "BBB" is regarded as having an adequate capacity to pay interest and
           repay principal. Whereas it normally exhibits adequate protection parameters,
           adverse economic conditions or changing circumstances are more likely to lead to a
           weakened capacity to pay interest and repay principal for debt in this category
           than for debt in higher-rated categories.
           Bonds rated AAA, AA, A and BBB are considered investment grade bonds.
BB         Debt rated "BB" has less near-term vulnerability to default than other speculative
           grade debt. However, it faces major ongoing uncertainties or exposure to adverse
           business, financial or economic conditions which could lead to inadequate capacity
           or willingness to pay interest and repay principal.
B          Debt rated "B" has a greater vulnerability to default but presently has the
           capacity to meet interest payments and principal repayments. Adverse business,
           financial or economic conditions would likely impair capacity or willingness to pay
           interest and repay principal.
CCC        Debt rated "CCC" has a current identifiable vulnerability to default, and is
           dependent upon favorable business, financial and economic conditions to meet timely
           payments of interest and repayments of principal. In the event of adverse business,
           financial or economic conditions, it is not likely to have the capacity to pay
           interest and repay principal.
CC         The rating "CC" is typically applied to debt subordinated to senior debt which is
           assigned an actual or implied "CCC" rating.
</TABLE>
 
                                       55
<PAGE>
<TABLE>
<S>        <C>
C          The rating "C" is typically applied to debt subordinated to senior debt which is
           assigned an actual or implied "CCC-" debt rating.
CI         The rating "CI" is reserved for income bonds on which no interest is being paid.
NR         Indicates that no rating has been requested, that there is insufficient information
           on which to base a rating or that Standard & Poor's does not rate a particular type
           of obligation as a matter of policy.
           Bonds rated "BB", "B", "CCC", "CC" and "C" are regarded as having predominantly
           speculative characteristics with respect to capacity to pay interest and repay
           principal. "BB" indicates the least degree of speculation and "C" the highest
           degree of speculation. While such debt will likely have some quality and protective
           characteristics, these are outweighed by large uncertainties or major risk
           exposures to adverse conditions.
           Plus (+) or minus (-): The rating from "AA" to "CCC" may be modified by the
           addition of a plus or minus sign to show relative standing within the major ratings
           categories.
</TABLE>
 
                            COMMERCIAL PAPER RATINGS
 
    Standard and Poor's commercial paper rating is a current assessment of the
likelihood of timely payment of debt having an original maturity of no more than
365 days. The commercial paper rating is not a recommendation to purchase or
sell a security. The ratings are based upon current information furnished by the
issuer or obtained by Standard and Poor's from other sources it considers
reliable. The ratings may be changed, suspended, or withdrawn as a result of
changes in or unavailability of such information. Ratings are graded into group
categories, ranging from "A" for the highest quality obligations to "D" for the
lowest. Ratings are applicable to both taxable and tax-exempt commercial paper.
The categories are as follows:
 
    Issues assigned A ratings are regarded as having the greatest capacity for
timely payment. Issues in this category are further refined with the designation
1, 2 and 3 to indicate the relative degree of safety.
 
<TABLE>
<S>        <C>
A-1        indicates that the degree of safety regarding timely payment is very strong.
A-2        indicates capacity for timely payment on issues with this designation is strong.
           However, the relative degree of safety is not as overwhelming as for issues
           designated "A-1."
A-3        indicates a satisfactory capacity for timely payment. Obligations carrying this
           designation are, however, somewhat more vulnerable to the adverse effects of
           changes in circumstances than obligations carrying the higher designations.
</TABLE>
 
                                       56


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