MORGAN STANLEY INSTITUTIONAL FUND INC
497, 1996-12-30
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<PAGE>
                       SUPPLEMENT DATED DECEMBER 30, 1996
                      TO THE PROSPECTUS DATED MAY 1, 1996
 
                             FIXED INCOME PORTFOLIO
                         GLOBAL FIXED INCOME PORTFOLIO
                            MUNICIPAL BOND PORTFOLIO
                           MORTGAGE-BACKED SECURITIES
                              HIGH YIELD PORTFOLIO
                             MONEY MARKET PORTFOLIO
                        MUNICIPAL MONEY MARKET PORTFOLIO
 
                               PORTFOLIOS OF THE
 
                    MORGAN STANLEY INSTITUTIONAL FUND, INC.
                                 P.O. BOX 2798
                             BOSTON, MASSACHUSETTS
                                   02208-2798
                                 -------------
 
    The Prospectus as amended and supplemented to date is further amended and
supplemented by replacing:
 
        Under the heading "ADDITIONAL INVESTMENT INFORMATION" on Page 27
    under the subheading "FUTURES CONTRACTS AND OPTIONS ON FUTURES
    CONTRACTS," the first two paragraphs are deleted and replaced with the
    following:
 
        FUTURES CONTRACTS AND OPTIONS ON FUTURES CONTRACTS.  In order to
    remain fully invested and to reduce transaction costs, each Portfolio,
    except the Money Market and Municipal Money Market Portfolios, may
    utilize appropriate futures contracts and options on futures contracts
    to a limited extent. Because transaction costs associated with futures
    and options may be lower than the costs of investing in stocks directly,
    it is expected that the use of futures and options on futures contracts
    to facilitate cash flows may reduce a Portfolio's overall transaction
    costs.
 
        Each Portfolio, except the Money Market and Municipal Money Market
    Portfolios, may enter into futures contracts and options on futures
    provided that not more than 5% of its total assets are required as
    deposit to secure obligations under such contracts, and provided further
    that not more than 20% of its total assets are invested, in the
    aggregate, in futures contracts and options on futures.
                                 --------------
 
    Add the following investment policies with respect to the FIXED INCOME AND
GLOBAL FIXED INCOME PORTFOLIOS under the heading "ADDITIONAL INVESTMENT
INFORMATION" on page 28 before the sub-heading "ADDITIONAL INVESTMENT
INFORMATION -- REPURCHASE AGREEMENTS."
 
        OPTIONS TRANSACTIONS.  The Fixed Income and Global Fixed Income
    Portfolios may write (i.e., sell) covered call options and covered put
    options on portfolio securities. By selling a covered call option, a
    Portfolio would become obligated during the term of the option to
    deliver the securities underlying the option should the option holder
    choose to exercise the option before the option's
<PAGE>
    termination date. In return for the call it has written, the Portfolio
    will receive from the purchaser (or option holder) a premium which is
    the price of the option, less a commission charged by a broker. The
    Portfolio will keep the premium regardless of whether the option is
    exercised. By selling a covered put option, the Portfolio incurs an
    obligation to buy the security underlying the option from the purchaser
    of the put at the option's exercise price at any time during the option
    period, at the purchaser's election (certain options written by the
    Portfolio will be exercisable by the purchaser only on a specific date).
    A call option is "covered" if the Portfolio owns the security underlying
    the option it has written or has an absolute or immediate right to
    acquire the security by holding a call option on such security, or
    maintains a sufficient amount of cash, cash equivalents or liquid assets
    to purchase the underlying security. Generally, a put option is
    "covered" if the Portfolio maintains cash, U.S. Government securities or
    other liquid assets equal to the exercise price of the option, or if the
    Portfolio holds a put option on the same underlying security with a
    similar or higher exercise price.
 
        When a Portfolio writes covered call options, it augments its income
    by the premiums received and is thereby hedged to the extent of that
    amount against a decline in the price of the underlying securities. The
    premiums received will offset a portion of the potential loss incurred
    by the Portfolio if the securities underlying the options are ultimately
    sold by the Portfolio at a loss. However, during the option period, the
    Portfolio has, in return for the premium on the option, given up the
    opportunity for capital appreciation above the exercise price should the
    market price of the underlying security increase, but has retained the
    risk of loss should the price of the underlying security decline.
 
        A Portfolio will write covered put options to receive the premiums
    paid by purchasers (when the Adviser wishes to purchase the security
    underlying the options at a price lower than its current market price,
    in which case the Portfolio will write the covered put at an exercise
    price reflecting the lower purchase price sought) and to close out a
    long put option position. The writer of a covered put option accepts the
    risk of a decline in the price of the underlying security.
 
        A Portfolio may also purchase put or call options. When the
    Portfolio purchases a call option it acquires the right to buy a
    designated security at a designated price (the "exercise price"), and
    when the Portfolio purchases a put option it acquires the right to sell
    a designated security at the exercise price, in each case on or before a
    specified date (the "termination date"), which is usually not more than
    nine months from the date the option is issued. The Portfolio may
    purchase call options to close out a covered call position or to protect
    against an increase in the price of a security it anticipates
    purchasing. The Portfolio may purchase put options on securities to
    protect itself against a decline in the value of the security. If the
    value of the underlying security were to fall below the exercise price
    of the put purchased in an amount greater than the premium paid for the
    option, the Portfolio would incur no additional loss. The Portfolio may
    also purchase put options to close out written put positions in a manner
    similar to call option closing purchase transactions. There are no other
    limits on the Portfolio's ability to purchase call and put options.
 
        Other risks associated with the use of options are (i) imperfect
    correlation between the change in market value of the securities held by
    the Portfolio and the price of options relating to the securities
    purchased or sold by the Portfolio; and (ii) possible lack of a liquid
    secondary market for an option. Options that are not traded on and
    exchange (OTC options) are often considered illiquid and may be
    difficult to value. In the opinion of the Adviser, the risk that the
    Portfolio will be unable to close out an options contract will be
    minimized by only entering into options transactions for which there
    appears to be a liquid secondary market. For more detailed information
    about options transactions, see "Investment Objectives and Policies" in
    the Statement of Additional Information.
                                 --------------
<PAGE>
    Under the heading "PROSPECTUS SUMMARY" under the subheading "HOW TO INVEST,"
the first paragraph is deleted and replaced with the following:
 
    HOW TO INVEST
 
        Class A shares of the Portfolio are offered directly to investors at
    net asset value with no sales commission or 12b-1 charges. Class B
    shares of the Portfolio are offered at net asset value with no sales
    commission, but with a 12b-1 fee, which is accrued daily and paid
    quarterly, equal to 0.25% of the Class B shares' average daily net
    assets on an annualized basis. Share purchases may be made by sending
    investments directly to the Fund or through the Distributor. Shares in a
    Portfolio account opened prior to January 2, 1996 (each, a "Pre-1996
    Account") were designated Class A shares on January 2, 1996. For a
    Portfolio account opened on or after January 2, 1996 (a "New Account"),
    the minimum initial investment is $500,000 for Class A shares and
    $100,000 for Class B shares. Certain exceptions to the foregoing
    minimums apply to (1) shares in a Pre-1996 Account with a value of
    $100,000 or more on March 1, 1996 (a "Grandfathered Class A Account");
    (2) Portfolio accounts held by certain employees of the Adviser and of
    its affiliates; and (3) certain advisory or asset allocation accounts,
    such as Total Funds Management accounts, managed by Morgan Stanley or
    its affiliates, including the Adviser ("Managed Accounts"). The Adviser
    reserves the right in its sole discretion to determine which of such
    advisory or asset allocation accounts shall be Managed Accounts. For
    information regarding Managed Accounts, please contact your Morgan
    Stanley account representative or the Fund at the telephone number
    provided on the cover of this Prospectus. Shares in a Pre-1996 Account
    with a value of less than $100,000 on March 1, 1996 (a "Grandfathered
    Class B Account") converted to Class B shares on March 1, 1996. The
    minimum investment levels may be waived at the discretion of the Adviser
    for (i) certain employees and customers of Morgan Stanley or its
    affiliates and certain trust departments, brokers, dealers, agents,
    financial planners, financial services firms, or investment advisers
    that have entered into an agreement with Morgan Stanley or its
    affiliates; and (ii) retirement and deferred compensation plans and
    trusts used to fund such plans, including, but not limited to, those
    defined in Section 401(a), 403(b) or 457 of the Internal Revenue Code of
    1986, as amended, and "rabbi trusts". See "Purchase of Shares Minimum
    Investment and Account Sizes; Conversion from Class A to Class B
    Shares."
                                 --------------
 
    Under the heading "PURCHASE OF SHARES," under the subheadings "MINIMUM
INVESTMENT AND ACCOUNT SIZES; CONVERSION FROM CLASS A TO CLASS B SHARES" and
"MINIMUM ACCOUNT SIZES AND INVOLUNTARY REDEMPTION OF SHARES," these two sections
are deleted and replaced with the following:
 
    MINIMUM INVESTMENT AND ACCOUNT SIZES; CONVERSION FROM CLASS A TO CLASS B
    SHARES
 
        For a Portfolio account opened on or after January 2, 1996 (a "New
    Account"), the minimum initial investment and minimum account size are
    $500,000 for Class A shares and $100,000 for Class B shares. Managed
    Accounts may purchase Class A shares without being subject to any
    minimum initial investment or minimum account size requirements for a
    Portfolio account. Employees of the Adviser and its affiliates may
    purchase Class A shares subject to conditions, including lower minimum
    initial investment, established by Officers of the Fund.
 
        If the value of a New Account, containing Class A shares falls below
    $500,000 (but remains at or above $100,000) because of shareholder
    redemption(s), the Fund will notify the shareholder, and if the account
    value remains below $500,000 (but remains at or above $100,000) for a
    continuous 60-day period, the Class A shares in such account will
    convert to Class B shares and will be subject to the distribution fee
    and other features applicable to the Class B shares. The Fund, however,
    will not
<PAGE>
    convert Class A shares to Class B shares based solely upon changes in
    the market that reduce the net asset value of shares. Under current tax
    law, conversions between share classes are not a taxable event to the
    shareholder.
 
        Shares in a Portfolio account opened prior to January 2, 1996 (a
    "Pre-1996 Account") were designated Class A shares on January 2, 1996.
    Shares in a Pre-1996 Account with a value of $100,000 or more on March
    1, 1996 (a "Grandfathered Class A Account") remained Class A shares
    regardless of account size thereafter. Except for shares in a Managed
    Account, shares in a Pre-1996 Account with a value of less than $100,000
    on March 1, 1996 (a "Grandfathered Class B Account") converted to Class
    B shares on March 1, 1996. Grandfathered Class A Accounts and Managed
    Accounts are not subject to conversion from Class A shares to Class B
    shares.
 
        Investors may also invest in the Fund by purchasing shares through a
    trust department, broker, dealer, agent, financial planner, financial
    services firm or investment adviser. An investor may be charged an
    additional service or transaction fee by that institution. The minimum
    investment levels may be waived at the discretion of the Adviser for (i)
    certain employees and customers of Morgan Stanley or its affiliates and
    certain trust departments, brokers, dealers, agents, financial planners,
    financial services firms, or investment advisers that have entered into
    an agreement with Morgan Stanley or its affiliates; and (ii) retirement
    and deferred compensation plans and trusts used to fund such plans,
    including, but not limited to, those defined in Section 401(a), 403(b)
    or 457 of the Internal Revenue Code of 1986, as amended, and "rabbi
    trusts". The Fund reserves the right to modify or terminate the
    conversion features of the shares as stated above at any time upon
    60-days' notice to shareholders.
 
    MINIMUM ACCOUNT SIZES AND INVOLUNTARY REDEMPTION OF SHARES
 
        If the value of a New Account falls below $100,000 because of
    shareholder redemption(s), the Fund will notify the shareholder, and if
    the account value remains below $100,000 for a continuous 60-day period,
    the shares in such account are subject to redemption by the Fund and, if
    redeemed, the net asset value of such shares will be promptly paid to
    the shareholder. The Fund, however, will not redeem shares based solely
    upon changes in the market that reduce the net asset value of shares.
 
        Grandfathered Class A Accounts, Grandfathered Class B Accounts and
    Managed Accounts are not subject to involuntary redemption.
 
        The Fund reserves the right to modify or terminate the involuntary
    redemption features of the shares as stated above at any time upon
    60-days' notice to shareholders.
                                 --------------
 
    The Account Registration Form is deleted and replaced with the form enclosed
with this supplement.
<PAGE>
   MORGAN STANLEY INSTITUTIONAL FUND, INC.
          FIXED INCOME, GLOBAL FIXED INCOME, MUNICIPAL BOND, MORTGAGE-BACKED
SECURITIES,
           HIGH YIELD, MONEY MARKET AND MUNICIPAL MONEY MARKET PORTFOLIOS
           P.O. BOX 2798, BOSTON, MA 02208-2798
 
                           ACCOUNT REGISTRATION FORM
 
<TABLE>
<C>   <S>                        <C>
                                 If you need assistance in filling out this form for the
      ACCOUNT INFORMATION        Morgan Stanley Institutional Fund, please contact your
      Fill in where applicable   Morgan Stanley representative or call us toll free
                                 1-(800)-548-7786. Please print all items except signature,
                                 and mail to the Fund at the address above.
 
  A)  REGISTRATION
      1. INDIVIDUAL
      2. JOINT TENANTS
         (RIGHTS OF
      SURVIVORSHIP PRESUMED
      UNLESS
         TENANCY IN COMMON
         IS INDICATED)
</TABLE>
 
1.
                               First
Name                          Initial                               Last Name
 
2.
                               First
Name                          Initial                               Last Name
 
                               First
Name                          Initial                               Last Name
 
<TABLE>
<C>   <S>                        <C>
      3. CORPORATIONS,
         TRUSTS AND OTHERS
         Please call the Fund
      for additional documents
      that may be required to
      set up account and to
      authorize transactions.
</TABLE>
 
3.
 
<TABLE>
<S>                     <C>                 <C>                   <C>               <C>
Type of Registration:   / / INCORPORATED    / / UNINCORPORATED    / / PARTNERSHIP   / / UNIFORM GIFT/TRANSFER TO MINOR
                                            ASSOCIATION                               (ONLY ONE CUSTODIAN AND MINOR PERMITTED)
</TABLE>
 
/ / TRUST ________________________  / / OTHER (Specify) ________________________
 
<TABLE>
<C>   <S>                        <C>
  B)  MAILING ADDRESS
      Please fill in
      completely, including
      telephone number(s).
</TABLE>
 
Street or P.O. Box
City                                                                       State
                                                                             Zip
                                                                              --
Home Telephone No.                                                   Business
Telephone No.                     --            --              --            --
/ / United States Citizen  / / Resident Alien  / / Non-Resident Alien: Indicate
Country of Residence ___________________________________________________________
 
<TABLE>
<C>   <S>                        <C>                             <C>
  C)  TAXPAYER                   Enter your Taxpayer Identification Number. For most individual
      IDENTIFICATION             taxpayers, this is your Social Security Number.
      NUMBER
      1. INDIVIDUAL
      2. JOINT TENANTS
         (RIGHTS OF
      SURVIVORSHIP PRESUMED
      UNLESS
         TENANCY IN COMMON
         IS INDICATED)
      For Custodian account
      of a minor (Uniform
      Gifts/Transfers to Minor
      Acts), give the Social
      Security Number of
      the minor
                                                                 OR
                                 1.         TAXPAYER             SOCIAL SECURITY NUMBER
                                 IDENTIFICATION NUMBER           ("SSN")
                                 ("TIN")
                                                                 OR
                                 2.                                                          TIN                                SSN
</TABLE>
<PAGE>
<TABLE>
<C>   <S>                        <C>                             <C>
                                                                 OR
                                                               TIN                                SSN
 
                                 IMPORTANT TAX INFORMATION
                                 You (as a payee) are required by law to provide us (as  payer)
                                 with  your  correct TIN(s)  or  SSN(s). Accounts  that  have a
                                 missing or  incorrect  TIN(s) or  SSN(s)  will be  subject  to
                                 backup  withholding at a 31%  rate on dividends, distributions
                                 and other  payments. If  you have  not provided  us with  your
                                 correct  TIN(s) or SSN(s), you may be subject to a $50 penalty
                                 imposed by the Internal Revenue Service.
                                 Backup withholding is not an additional tax; the tax liability
                                 of persons subject  to backup withholding  will be reduced  by
                                 the  amount  of tax  withheld.  If withholding  results  in an
                                 overpayment   of   taxes,   a   refund   may   be    obtained.
                                 You may be notified that you are subject to backup withholding
                                 under  Section  3406(a)(1)(C)  of  the  Internal  Revenue Code
                                 because you have  underreported interest or  dividends or  you
                                 were  required to,  but failed to,  file a  return which would
                                 have included a reportable interest or dividend payment.
</TABLE>
 
<PAGE>
 
<TABLE>
<C>   <S>                        <C>                             <C>                   <C>
  D)  PORTFOLIO AND              For Purchase of the following   / / Class A Shares $  / / Class B Shares $
      CLASS SECTION              Portfolio(s):                   / / Class A Shares $
      (Class A shares minimum    Fixed Income Portfolio          / / Class A Shares $  / / Class B Shares $
      $500,000 for each          Global Fixed Income Portfolio   / / Class A Shares $  / / Class B Shares $
      Portfolio and Class B      Municipal Bond Portfolio        / / Class A Shares $  / / Class B Shares $
      shares minimum $100,000    Mortgage-Backed Securities      / / Class A Shares $  / / Class B Shares $
      for the Global Equity,     Portfolio                       / / Class A Shares $  / / Class B Shares $
      International Equity,      High Yield Portfolio
      Asian Equity, European     Money Market Portfolio
      Equity, Japanese Equity    Municipal Money Market
      and Latin American Equity  Portfolio
      Portfolios). Please
      indicate Portfolio, class
      and amount.
                                                                 Total Initial Investment $
</TABLE>
 
<TABLE>
<C>   <S>                        <C>
  E)  METHOD OF
      INVESTMENT
      Please indicate
      portfolio, manner of
      payment.
</TABLE>
 
Payment by:
 
/ / Check (MAKE CHECK PAYABLE TO MORGAN STANLEY INSTITUTIONAL FUND,
INC.--PORTFOLIO NAME)
 
<TABLE>
<S>                                                                                 <C>
/ / Exchange $ From                                                                           - - - - - - - - - - - -- - -
                                                      Name of Portfolio                               Account No.
/ / Account previously established by:  / / Phone exchange  / / Wire on                       - - - - - - - - - - - -- - -
                                                                                            Account No.               (Check
                                                                                      (Previously assigned by the Fund)     Digit)
                                                                            Date
</TABLE>
 
<TABLE>
<C>   <S>                        <C>
  F)  DISTRIBUTION               Income dividends and capital gains distributions (if any) to
      OPTION                     be reinvested in additional shares unless either box below
                                 is checked.
                                 / / Income dividends to be paid in cash, capital gains
                                 distributions (if any) in shares.
                                 / / Income dividends and capital gains distributions (if
                                 any) to be paid in cash.
</TABLE>
 
<TABLE>
<C>   <S>                             <C>                                       <C>
  G)  TELEPHONE                       / / I/we hereby authorize the Fund and
      REDEMPTION                      its agents to honor any telephone         Name of COMMERCIAL Bank (Not Savings
      AND EXCHANGE                    requests to wire redemption proceeds to   Bank)
      OPTION                          the commercial bank indicated at right    Bank Account No.
      Please select at time of        and/or mail redemption proceeds to the
      initial application if you      name and address in which my/our fund
      wish to redeem or exchange      account is registered if such requests                                        Bank
      shares by telephone. A          are believed to be authentic.                                                  ABA
      SIGNATURE GUARANTEE IS          The Fund and the Fund's Transfer Agent                                         No.
      REQUIRED IF BANK ACCOUNT IS     will employ reasonable procedures to
      NOT REGISTERED IDENTICALLY TO   confirm that instructions communicated    Name(s) in which your BANK Account is
      YOUR FUND ACCOUNT.              by telephone are genuine. These           Established
      TELEPHONE REQUESTS FOR          procedures include requiring the
      REDEMPTIONS OR EXCHANGE WILL    investor to provide certain personal      Bank's Street
      NOT BE HONORED UNLESS THE BOX   identification information at the time    Address
      IS CHECKED.                     an account is opened and prior to
                                      effecting each transaction requested by   City          State           Zip
                                      telephone. In addition, all telephone
                                      transaction requests will be recorded
                                      and investors may be required to provide
                                      additional telecopied written
                                      instructions of transaction requests.
                                      Neither the Fund nor the Transfer Agent
                                      will be responsible for any loss,
                                      liability, cost or expense for following
                                      instructions received by telephone that
                                      it reasonably believes to be genuine.
</TABLE>
 
<TABLE>
<C>   <S>                        <C>
  H)  INTERESTED PARTY
      OPTION                                                                                      Name
      In addition to the
      account statement sent to
      my/our registered                                                                          Address
      address, I/we hereby
      authorize the fund to        City                                         State                                         Z
      mail duplicate statements  Code
      to the name and address
      provided at right.
</TABLE>
 
<TABLE>
<C>   <S>                        <C>
  I)  DEALER
      INFORMATION
                                 Representative Name                        Representative
                                 No.                            Branch
                                 No.
</TABLE>
 
<PAGE>
 
<TABLE>
<C>   <S>                        <C>
  J)  SIGNATURE OF
      ALL HOLDERS
      AND TAXPAYER
      CERTIFICATION
      Sign Here ,
</TABLE>
 
<TABLE>
<S>                                  <C>
The undersigned certify that I/we have full authority and legal capacity
to purchase and redeem shares of the Fund and affirm that I/we have
received a current Prospectus of the Morgan Stanley Institutional Fund,
Inc. and agree to be bound by its terms.
  BY SIGNING THIS  APPLICATION, I/WE HEREBY  CERTIFY UNDER PENALTIES  OF
PERJURY THAT THE INFORMATION ON THIS APPLICATION IS COMPLETE AND CORRECT
AND  THAT  AS REQUIRED  BY FEDERAL  LAW  (PLEASE CHECK  APPLICABLE BOXES
BELOW):
/ / U.S. CITIZEN(S)/TAXPAYER(S):
       / / I/WE CERTIFY THAT (1) THE NUMBER(S) SHOWN ABOVE ON THIS  FORM
           IS/ARE  THE CORRECT  SSN(S) OR  TIN(S) AND  (2) I/WE  ARE NOT
           SUBJECT TO ANY BACKUP WITHHOLDING EITHER BECAUSE (A) I/WE ARE
           EXEMPT FROM  BACKUP  WITHHOLDING;  (B)  I/WE  HAVE  NOT  BEEN
           NOTIFIED  BY THE  INTERNAL REVENUE SERVICE  ("IRS") THAT I/WE
           ARE SUBJECT TO BACKUP WITHHOLDING AS A RESULT OF A FAILURE TO
           REPORT ALL INTEREST OR DIVIDENDS; OR (C) THE IRS HAS NOTIFIED
           ME/US  THAT  I  AM/WE  ARE   NO  LONGER  SUBJECT  TO   BACKUP
           WITHHOLDING.
       /  / IF  NO TIN(S) OR  SSN(S) HAS/HAVE BEEN  PROVIDED ABOVE, I/WE
           HAVE APPLIED, OR INTEND  TO APPLY, TO THE  IRS OR THE  SOCIAL
           SECURITY   ADMINISTRATION  FOR  A  TIN  OR  A  SSN  AND  I/WE
           UNDERSTAND THAT IF I/WE DO NOT PROVIDE EITHER NUMBER TO CHASE
           GLOBAL FUNDS SERVICES COMPANY ("CGFSC") WITHIN 60 DAYS OF THE
           DATE OF THIS APPLICATION  OR IF I/WE  FAIL TO FURNISH  MY/OUR
           CORRECT  SSN(S) OR TIN(S),  I/WE MAY BE  SUBJECT TO A PENALTY
           AND A 31% BACKUP WITHHOLDING ON DISTRIBUTIONS AND  REDEMPTION
           PROCEEDS. (PLEASE PROVIDE EITHER NUMBER ON IRS FORM W-9). YOU
           MAY REQUEST SUCH FORM BY CALLING CGFSC AT 800-282-4404.
/ / NON-U.S. CITIZEN(S)/TAXPAYER(S):
  INDICATE COUNTRY OF RESIDENCE FOR TAX PURPOSES:
  UNDER  PENALTIES  OF  PERJURY, I/WE  CERTIFY  THAT I/WE  ARE  NOT U.S.
CITIZENS OR RESIDENTS AND I/WE ARE EXEMPT FOREIGN PERSONS AS DEFINED  BY
THE INTERNAL REVENUE SERVICE.
THE  INTERNAL  REVENUE  SERVICE DOES  NOT  REQUIRE YOUR  CONSENT  TO ANY
PROVISION OF THIS  DOCUMENT OTHER  THAN THE  CERTIFICATIONS REQUIRED  TO
AVOID BACKUP WITHHOLDING.
 
                                     (X)
(X)                                  Signature (if joint account, both
Signature                                                     Date must sign)              Date
</TABLE>
<PAGE>
                       SUPPLEMENT DATED DECEMBER 30, 1996
                      TO THE PROSPECTUS DATED MAY 1, 1996
 
                              TECHNOLOGY PORTFOLIO
 
                                PORTFOLIO OF THE
 
                    MORGAN STANLEY INSTITUTIONAL FUND, INC.
                                 P.O. BOX 2798
                             BOSTON, MASSACHUSETTS
                                   02208-2798
                                 -------------
 
    The Prospectus as amended and supplemented to date is further amended and
supplemented by changing the following:
 
        Under the heading "PROSPECTUS SUMMARY" under the subheading "HOW TO
    INVEST," the first paragraph is deleted and replaced with the following:
 
    HOW TO INVEST
 
        Class A shares of the Portfolio are offered directly to investors at
    net asset value with no sales commission or 12b-1 charges. Class B
    shares of the Portfolio are offered at net asset value with no sales
    commission, but with a 12b-1 fee, which is accrued daily and paid
    quarterly, equal to 0.25%, on an annualized basis, of the Class B
    shares' average daily net assets. Share purchases may be made by sending
    investments directly to the Fund or through the Distributor. The minimum
    initial investment for shares in a Portfolio account is $250,000 for
    Class A shares and $50,000 for Class B shares. Certain exceptions to the
    foregoing minimums apply to (1) Portfolio accounts held by certain
    employees of the Adviser and of its affiliates and (2) certain advisory
    or asset allocation accounts, such as Total Funds Management accounts,
    managed by Morgan Stanley or its affiliates, including the Adviser
    ("Managed Accounts"). The Adviser reserves the right in its sole
    discretion to determine which of such advisory or asset allocation
    accounts shall be Managed Accounts. For information regarding Managed
    Accounts, please contact your Morgan Stanley account representative or
    the Fund at the telephone number provided on the cover of this
    Prospectus. The minimum investment levels may be waived at the
    discretion of the Adviser for (i) certain employees and customers of
    Morgan Stanley or its affiliates and certain trust departments, brokers,
    dealers, agents, financial planners, financial services firms, or
    investment advisers that have entered into an agreement with Morgan
    Stanley or its affiliates; and (ii) retirement and deferred compensation
    plans and trusts used to fund such plans, including, but not limited to,
    those defined in Section 401(a), 403(b) or 457 of the Internal Revenue
    Code of 1986, as amended, and "rabbi trusts". See "Purchase of Shares --
    Minimum Investment and Account Sizes; Conversion from Class A to Class B
    Shares."
                                 --------------
<PAGE>
    Under the heading "PURCHASE OF SHARES," under the subheadings "MINIMUM
INVESTMENT AND ACCOUNT SIZES; CONVERSION FROM CLASS A TO CLASS B SHARES" and
"MINIMUM ACCOUNT SIZES AND INVOLUNTARY REDEMPTION OF SHARES," these two sections
are deleted and replaced with the following:
 
    MINIMUM INVESTMENT AND ACCOUNT SIZES; CONVERSION FROM CLASS A TO CLASS B
    SHARES
 
        For a Portfolio account, the minimum initial investment and minimum
    account size are $250,000 for Class A shares and $50,000 for Class B
    shares. Managed Accounts may purchase Class A shares without being
    subject to such minimum initial investment or minimum account size
    requirements for a Portfolio account. Employees of the Adviser and of
    its affiliates may purchase Class A shares subject to conditions,
    including a lower minimum initial investment established by Officers of
    the Fund.
 
        If the value of a Portfolio account containing Class A shares falls
    below $250,000 (but remains at or above $50,000) because of shareholder
    redemption(s), the Fund will notify the shareholder, and if the account
    value remains below $250,000 (but remains at or above $50,000) for a
    continuous 60-day period, the Class A shares in such account will
    convert to Class B shares and will be subject to the distribution fee
    and other features applicable to the Class B shares. The Fund, however,
    will not convert Class A shares to Class B shares based solely upon
    changes in the market that reduce the net asset value of shares. Under
    current tax law, conversions between share classes are not a taxable
    event to the shareholder. Managed Accounts are not subject to conversion
    from Class A shares to Class B shares.
 
        Investors may also invest in the Portfolio by purchasing shares
    through a trust department, broker, dealer, agent, financial planner,
    financial services firm or investment adviser. An investor may be
    charged an additional service or transaction fee by that institution.
    The minimum investment levels may be waived at the discretion of the
    Adviser for (i) certain employees and customers of Morgan Stanley or its
    affiliates and certain trust departments, brokers, dealers, agents,
    financial planners, financial services firms, or investment advisers
    that have entered into an agreement with Morgan Stanley or its
    affiliates; and (ii) retirement and deferred compensation plans and
    trusts used to fund such plans, including, but not limited to, those
    defined in Section 401(a), 403(b) or 457 of the Internal Revenue Code of
    1986, as amended, and "rabbi trusts". The Fund reserves the right to
    modify or terminate the conversion features of the shares as stated
    above at any time upon 60-days' notice to shareholders.
 
    MINIMUM ACCOUNT SIZES AND INVOLUNTARY REDEMPTION OF SHARES
 
        If the value of a Portfolio account falls below $50,000 because of
    shareholder redemption(s), the Fund will notify the shareholder, and if
    the account value remains below $50,000 for a continuous 60-day period,
    the shares in such account are subject to redemption by the Fund and, if
    redeemed, the net asset value of such shares will be promptly paid to
    the shareholder. The Fund, however, will not redeem shares based solely
    upon changes in the market that reduce the net asset value of shares.
 
        The Fund reserves the right to modify or terminate the involuntary
    redemption features of the shares as stated above at any time upon
    60-days' notice to shareholders.
                                 --------------
 
    The Account Registration Form is deleted and replaced with the form enclosed
with this supplement.
<PAGE>
   MORGAN STANLEY INSTITUTIONAL FUND, INC.
          TECHNOLOGY PORTFOLIO
           P.O. BOX 2798, BOSTON, MA 02208-2798
 
                           ACCOUNT REGISTRATION FORM
 
<TABLE>
<C>   <S>                        <C>
                                 If you need assistance in filling out this form for the
      ACCOUNT INFORMATION        Morgan Stanley Institutional Fund, please contact your
      Fill in where applicable   Morgan Stanley representative or call us toll free
                                 1-(800)-548-7786. Please print all items except signature,
                                 and mail to the Fund at the address above.
 
  A)  REGISTRATION
      1. INDIVIDUAL
      2. JOINT TENANTS
         (RIGHTS OF
      SURVIVORSHIP PRESUMED
      UNLESS
         TENANCY IN COMMON
         IS INDICATED)
</TABLE>
 
1.
                               First
Name                          Initial                               Last Name
 
2.
                               First
Name                          Initial                               Last Name
 
                               First
Name                          Initial                               Last Name
 
<TABLE>
<C>   <S>                        <C>
      3. CORPORATIONS,
         TRUSTS AND OTHERS
         Please call the Fund
      for additional documents
      that may be required to
      set up account and to
      authorize transactions.
</TABLE>
 
3.
 
<TABLE>
<S>                     <C>                 <C>                   <C>               <C>
Type of Registration:   / / INCORPORATED    / / UNINCORPORATED    / / PARTNERSHIP   / / UNIFORM GIFT/TRANSFER TO MINOR
                                            ASSOCIATION                               (ONLY ONE CUSTODIAN AND MINOR PERMITTED)
</TABLE>
 
/ / TRUST ________________________  / / OTHER (Specify) ________________________
 
<TABLE>
<C>   <S>                        <C>
  B)  MAILING ADDRESS
      Please fill in
      completely, including
      telephone number(s).
</TABLE>
 
Street or P.O. Box
City                                                                       State
                                                                             Zip
                                                                              --
Home Telephone No.                                                   Business
Telephone No.                     --            --              --            --
/ / United States Citizen  / / Resident Alien  / / Non-Resident Alien: Indicate
Country of Residence ___________________________________________________________
 
<TABLE>
<C>   <S>                        <C>                             <C>
  C)  TAXPAYER                   Enter your Taxpayer Identification Number. For most individual
      IDENTIFICATION             taxpayers, this is your Social Security Number.
      NUMBER
      1. INDIVIDUAL
      2. JOINT TENANTS
         (RIGHTS OF
      SURVIVORSHIP PRESUMED
      UNLESS
         TENANCY IN COMMON
         IS INDICATED)
      For Custodian account
      of a minor (Uniform
      Gifts/Transfers to Minor
      Acts), give the Social
      Security Number of
      the minor
                                                                 OR
                                 1.         TAXPAYER             SOCIAL SECURITY NUMBER
                                 IDENTIFICATION NUMBER           ("SSN")
                                 ("TIN")
                                                                 OR
                                 2.                                                          TIN                                SSN
</TABLE>
<PAGE>
<TABLE>
<C>   <S>                        <C>                             <C>
                                                                 OR
                                                               TIN                                SSN
 
                                 IMPORTANT TAX INFORMATION
                                 You (as a payee) are required by law to provide us (as  payer)
                                 with  your  correct TIN(s)  or  SSN(s). Accounts  that  have a
                                 missing or  incorrect  TIN(s) or  SSN(s)  will be  subject  to
                                 backup  withholding at a 31%  rate on dividends, distributions
                                 and other  payments. If  you have  not provided  us with  your
                                 correct  TIN(s) or SSN(s), you may be subject to a $50 penalty
                                 imposed by the Internal Revenue Service.
                                 Backup withholding is not an additional tax; the tax liability
                                 of persons subject  to backup withholding  will be reduced  by
                                 the  amount  of tax  withheld.  If withholding  results  in an
                                 overpayment   of   taxes,   a   refund   may   be    obtained.
                                 You may be notified that you are subject to backup withholding
                                 under  Section  3406(a)(1)(C)  of  the  Internal  Revenue Code
                                 because you have  underreported interest or  dividends or  you
                                 were  required to,  but failed to,  file a  return which would
                                 have included a reportable interest or dividend payment.
</TABLE>
 
<PAGE>
 
<TABLE>
<C>   <S>                        <C>                             <C>
  D)  PORTFOLIO AND              For Purchase of the following
      CLASS SECTION              Portfolio(s):                   / / Class A Shares
      (Class A shares minimum    Technology Portfolio            $ / / Class B Shares $
      $500,000 for each                                          Total Initial Investment
      Portfolio and Class B                                      $
      shares minimum $100,000
      for the Global Equity,
      International Equity,
      Asian Equity, European
      Equity, Japanese Equity
      and Latin American Equity
      Portfolios). Please
      indicate Portfolio, class
      and amount.
</TABLE>
 
<TABLE>
<C>   <S>                        <C>
  E)  METHOD OF
      INVESTMENT
      Please indicate
      portfolio, manner of
      payment.
</TABLE>
 
Payment by:
 
/ / Check (MAKE CHECK PAYABLE TO MORGAN STANLEY INSTITUTIONAL FUND,
INC.--PORTFOLIO NAME)
 
<TABLE>
<S>                                                                                 <C>
/ / Exchange $ From                                                                           -- - - - - - - - - - -- - -
                                                      Name of Portfolio                               Account No.
/ / Account previously established by:  / / Phone exchange  / / Wire on                       -- - - - - - - - - - -- - -
                                                                                            Account No.               (Check
                                                                                      (Previously assigned by the Fund)     Digit)
                                                                            Date
</TABLE>
 
<TABLE>
<C>   <S>                        <C>
  F)  DISTRIBUTION               Income dividends and capital gains distributions (if any) to
      OPTION                     be reinvested in additional shares unless either box below
                                 is checked.
                                 / / Income dividends to be paid in cash, capital gains
                                 distributions (if any) in shares.
                                 / / Income dividends and capital gains distributions (if
                                 any) to be paid in cash.
</TABLE>
 
<TABLE>
<C>   <S>                             <C>                                       <C>
  G)  TELEPHONE                       / / I/we hereby authorize the Fund and
      REDEMPTION                      its agents to honor any telephone         Name of COMMERCIAL Bank (Not Savings
      AND EXCHANGE                    requests to wire redemption proceeds to   Bank)
      OPTION                          the commercial bank indicated at right    Bank Account No.
      Please select at time of        and/or mail redemption proceeds to the
      initial application if you      name and address in which my/our fund
      wish to redeem or exchange      account is registered if such requests                                        Bank
      shares by telephone. A          are believed to be authentic.                                                  ABA
      SIGNATURE GUARANTEE IS          The Fund and the Fund's Transfer Agent                                         No.
      REQUIRED IF BANK ACCOUNT IS     will employ reasonable procedures to
      NOT REGISTERED IDENTICALLY TO   confirm that instructions communicated    Name(s) in which your BANK Account is
      YOUR FUND ACCOUNT.              by telephone are genuine. These           Established
      TELEPHONE REQUESTS FOR          procedures include requiring the
      REDEMPTIONS OR EXCHANGE WILL    investor to provide certain personal      Bank's Street
      NOT BE HONORED UNLESS THE BOX   identification information at the time    Address
      IS CHECKED.                     an account is opened and prior to
                                      effecting each transaction requested by   City      State         Zip
                                      telephone. In addition, all telephone
                                      transaction requests will be recorded
                                      and investors may be required to provide
                                      additional telecopied written
                                      instructions of transaction requests.
                                      Neither the Fund nor the Transfer Agent
                                      will be responsible for any loss,
                                      liability, cost or expense for following
                                      instructions received by telephone that
                                      it reasonably believes to be genuine.
</TABLE>
 
<TABLE>
<C>   <S>                        <C>
  H)  INTERESTED PARTY
      OPTION                                                                                      Name
      In addition to the
      account statement sent to
      my/our registered                                                                          Address
      address, I/we hereby
      authorize the fund to        City                                         State                                         Z
      mail duplicate statements  Code
      to the name and address
      provided at right.
</TABLE>
 
<TABLE>
<C>   <S>                        <C>
  I)  DEALER
      INFORMATION
                                 Representative Name                        Representative
                                 No.                            Branch
                                 No.
</TABLE>
 
<PAGE>
 
<TABLE>
<C>   <S>                        <C>
  J)  SIGNATURE OF
      ALL HOLDERS
      AND TAXPAYER
      CERTIFICATION
      Sign Here ,
</TABLE>
 
<TABLE>
<S>                                  <C>
The undersigned certify that I/we have full authority and legal capacity
to purchase and redeem shares of the Fund and affirm that I/we have
received a current Prospectus of the Morgan Stanley Institutional Fund,
Inc. and agree to be bound by its terms.
  BY SIGNING THIS  APPLICATION, I/WE HEREBY  CERTIFY UNDER PENALTIES  OF
PERJURY THAT THE INFORMATION ON THIS APPLICATION IS COMPLETE AND CORRECT
AND  THAT  AS REQUIRED  BY FEDERAL  LAW  (PLEASE CHECK  APPLICABLE BOXES
BELOW):
/ / U.S. CITIZEN(S)/TAXPAYER(S):
       / / I/WE CERTIFY THAT (1) THE NUMBER(S) SHOWN ABOVE ON THIS  FORM
           IS/ARE  THE CORRECT  SSN(S) OR  TIN(S) AND  (2) I/WE  ARE NOT
           SUBJECT TO ANY BACKUP WITHHOLDING EITHER BECAUSE (A) I/WE ARE
           EXEMPT FROM  BACKUP  WITHHOLDING;  (B)  I/WE  HAVE  NOT  BEEN
           NOTIFIED  BY THE  INTERNAL REVENUE SERVICE  ("IRS") THAT I/WE
           ARE SUBJECT TO BACKUP WITHHOLDING AS A RESULT OF A FAILURE TO
           REPORT ALL INTEREST OR DIVIDENDS; OR (C) THE IRS HAS NOTIFIED
           ME/US  THAT  I  AM/WE  ARE   NO  LONGER  SUBJECT  TO   BACKUP
           WITHHOLDING.
       /  / IF  NO TIN(S) OR  SSN(S) HAS/HAVE BEEN  PROVIDED ABOVE, I/WE
           HAVE APPLIED, OR INTEND  TO APPLY, TO THE  IRS OR THE  SOCIAL
           SECURITY   ADMINISTRATION  FOR  A  TIN  OR  A  SSN  AND  I/WE
           UNDERSTAND THAT IF I/WE DO NOT PROVIDE EITHER NUMBER TO CHASE
           GLOBAL FUNDS SERVICES COMPANY ("CGFSC") WITHIN 60 DAYS OF THE
           DATE OF THIS APPLICATION  OR IF I/WE  FAIL TO FURNISH  MY/OUR
           CORRECT  SSN(S) OR TIN(S),  I/WE MAY BE  SUBJECT TO A PENALTY
           AND A 31% BACKUP WITHHOLDING ON DISTRIBUTIONS AND  REDEMPTION
           PROCEEDS. (PLEASE PROVIDE EITHER NUMBER ON IRS FORM W-9). YOU
           MAY REQUEST SUCH FORM BY CALLING CGFSC AT 800-282-4404.
/ / NON-U.S. CITIZEN(S)/TAXPAYER(S):
  INDICATE COUNTRY OF RESIDENCE FOR TAX PURPOSES:
  UNDER  PENALTIES  OF  PERJURY, I/WE  CERTIFY  THAT I/WE  ARE  NOT U.S.
CITIZENS OR RESIDENTS AND I/WE ARE EXEMPT FOREIGN PERSONS AS DEFINED  BY
THE INTERNAL REVENUE SERVICE.
THE  INTERNAL  REVENUE  SERVICE DOES  NOT  REQUIRE YOUR  CONSENT  TO ANY
PROVISION OF THIS  DOCUMENT OTHER  THAN THE  CERTIFICATIONS REQUIRED  TO
AVOID BACKUP WITHHOLDING.
 
                                     (X)
(X)                                  Signature (if joint account, both
Signature                                                                     Date must sign)         Date
</TABLE>
<PAGE>
                       SUPPLEMENT DATED DECEMBER 30, 1996
                      TO THE PROSPECTUS DATED MAY 1, 1996
 
                            EQUITY GROWTH PORTFOLIO
                           EMERGING GROWTH PORTFOLIO
                               MICROCAP PORTFOLIO
                          AGGRESSIVE EQUITY PORTFOLIO
                           EMERGING MARKETS PORTFOLIO
                        EMERGING MARKETS DEBT PORTFOLIO
                           U.S. REAL ESTATE PORTFOLIO
                        SMALL CAP VALUE EQUITY PORTFOLIO
                             VALUE EQUITY PORTFOLIO
                               BALANCED PORTFOLIO
                      ACTIVE COUNTRY ALLOCATION PORTFOLIO
                            GLOBAL EQUITY PORTFOLIO
                         INTERNATIONAL EQUITY PORTFOLIO
                       INTERNATIONAL SMALL CAP PORTFOLIO
                             ASIAN EQUITY PORTFOLIO
                           EUROPEAN EQUITY PORTFOLIO
                           JAPANESE EQUITY PORTFOLIO
                            LATIN AMERICAN PORTFOLIO
                                 GOLD PORTFOLIO
 
                               PORTFOLIOS OF THE
 
                    MORGAN STANLEY INSTITUTIONAL FUND, INC.
                                 P.O. BOX 2798
                             BOSTON, MASSACHUSETTS
                                   02208-2798
                                 -------------
 
    The Prospectus as amended and supplemented to date is further amended and
supplemented by changing the following:
 
        Under the heading "PROSPECTUS SUMMARY," under the subheading "HOW TO
    INVEST," the first paragraph is deleted and replaced with the following:
 
    HOW TO INVEST
 
        Class A shares of the Portfolio are offered directly to investors at
    net asset value with no sales commission or 12b-1 charges. Class B
    shares of the Portfolio are offered at net asset value with no sales
    commission, but with a 12b-1 fee, which is accrued daily and paid
    quarterly, equal to 0.25% of the
<PAGE>
    Class B shares' average daily net assets on an annualized basis. Share
    purchases may be made by sending investments directly to the Fund or
    through the Distributor. Shares in a Portfolio account opened prior to
    January 2, 1996 (each, a "Pre-1996 Account") were designated Class A
    shares on January 2, 1996. For a Portfolio account opened on or after
    January 2, 1996 (a "New Account"), the minimum initial investment is
    $500,000 for Class A shares and $100,000 for Class B shares. Certain
    exceptions to the foregoing minimums apply to (1) shares in a Pre-1996
    Account with a value of $100,000 or more on March 1, 1996 (a
    "Grandfathered Class A Account"); (2) Portfolio accounts held by certain
    employees of the Adviser and of its affiliates; and (3) certain advisory
    or asset allocation accounts, such as Total Funds Management accounts,
    managed by Morgan Stanley or its affiliates, including the Adviser
    ("Managed Accounts"). The Adviser reserves the right in its sole
    discretion to determine which of such advisory or asset allocation
    accounts shall be Managed Accounts. For information regarding Managed
    Accounts, please contact your Morgan Stanley account representative or
    the Fund at the telephone number provided on the cover of this
    Prospectus. Shares in a Pre-1996 Account with a value of less than
    $100,000 on March 1, 1996 (a "Grandfathered Class B Account") converted
    to Class B shares on March 1, 1996. The minimum investment levels may be
    waived at the discretion of the Adviser for (i) certain employees and
    customers of Morgan Stanley or its affiliates and certain trust
    departments, brokers, dealers, agents, financial planners, financial
    services firms, or investment advisers that have entered into an
    agreement with Morgan Stanley or its affiliates; and (ii) retirement and
    deferred compensation plans and trusts used to fund such plans,
    including, but not limited to, those defined in Section 401(a), 403(b)
    or 457 of the Internal Revenue Code of 1986, as amended, and "rabbi
    trusts". See "Purchase of Shares Minimum Investment and Account Sizes;
    Conversion from Class A to Class B Shares."
                                 --------------
 
    Under the heading "PURCHASE OF SHARES," under the subheadings "MINIMUM
INVESTMENT AND ACCOUNT SIZES; CONVERSION FROM CLASS A TO CLASS B SHARES" and
"MINIMUM ACCOUNT SIZES AND INVOLUNTARY REDEMPTION OF SHARES," these two sections
are deleted and replaced with the following:
 
    MINIMUM INVESTMENT AND ACCOUNT SIZES; CONVERSION FROM CLASS A TO CLASS B
    SHARES
 
        For a Portfolio account opened on or after January 2, 1996 (a "New
    Account"), the minimum initial investment and minimum account size are
    $500,000 for Class A shares and $100,000 for Class B shares. Managed
    Accounts may purchase Class A shares without being subject to any
    minimum initial investment or minimum account size requirements for a
    Portfolio account. Employees of the Adviser and certain of its
    affiliates may purchase Class A shares subject to conditions, including
    a lower minimum initial investment, established by Officers of the Fund.
 
        If the value of a New Account containing Class A shares falls below
    $500,000 (but remains at or above $100,000) because of shareholder
    redemption(s), the Fund will notify the shareholder, and if the account
    value remains below $500,000 (but remains at or above $100,000) for a
    continuous 60-day period, the Class A shares in such account will
    convert to Class B shares and will be subject to the distribution fee
    and other features applicable to the Class B shares. The Fund, however,
    will not convert Class A shares to Class B shares based solely upon
    changes in the market that reduce the net asset value of shares. Under
    current tax law, conversions between share classes are not a taxable
    event to the shareholder.
 
        Shares in a Portfolio account opened prior to January 2, 1996 (a
    "Pre-1996 Account") were designated Class A shares on January 2, 1996.
    Shares in a Pre-1996 Account with a value of $100,000 or
<PAGE>
    more on March 1, 1996 (a "Grandfathered Class A Account") remained Class
    A shares regardless of account size thereafter. Except for shares in a
    Managed Account, shares in a Pre-1996 Account with a value of less than
    $100,000 on March 1, 1996 (a "Grandfathered Class B Account") converted
    to Class B shares on March 1, 1996. Grandfathered Class A Accounts and
    Managed Accounts are not subject to conversion from Class A shares to
    Class B shares.
 
        Investors may also invest in the Fund by purchasing shares through a
    trust department, broker, dealer, agent, financial planner, financial
    services firm or investment adviser. An investor may be charged an
    additional service or transaction fee by that institution. The minimum
    investment levels may be waived at the discretion of the Adviser for (i)
    certain employees and customers of Morgan Stanley or its affiliates and
    certain trust departments, brokers, dealers, agents, financial planners,
    financial services firms, or investment advisers that have entered into
    an agreement with Morgan Stanley or its affiliates; and (ii) retirement
    and deferred compensation plans and trusts used to fund such plans,
    including, but not limited to, those defined in Section 401(a), 403(b)
    or 457 of the Internal Revenue Code of 1986, as amended, and "rabbi
    trusts". The Fund reserves the right to modify or terminate the
    conversion features of the shares as stated above at any time upon
    60-days' notice to shareholders.
 
    MINIMUM ACCOUNT SIZES AND INVOLUNTARY REDEMPTION OF SHARES
 
        If the value of a New Account falls below $100,000 because of
    shareholder redemption(s), the Fund will notify the shareholder, and if
    the account value remains below $100,000 for a continuous 60-day period,
    the shares in such account are subject to redemption by the Fund and, if
    redeemed, the net asset value of such shares will be promptly paid to
    the shareholder. The Fund, however, will not redeem shares based solely
    upon changes in the market that reduce the net asset value of shares.
 
        Grandfathered Class A Accounts, Grandfathered Class B Accounts and
    Managed Accounts are not subject to involuntary redemption.
 
        The Fund reserves the right to modify or terminate the involuntary
    redemption features of the shares as stated above at any time upon
    60-days' notice to shareholders.
                                 --------------
 
    The Account Registration Form is deleted and replaced with the form enclosed
with this supplement.
<PAGE>
   MORGAN STANLEY INSTITUTIONAL FUND, INC.
          EQUITY GROWTH, EMERGING GROWTH,
           MICROCAP AND AGGRESSIVE EQUITY PORTFOLIOS
           P.O. BOX 2798, BOSTON, MA 02208-2798
 
                           ACCOUNT REGISTRATION FORM
 
<TABLE>
<C>   <S>                                                           <C>
                                                                    If you need assistance in filling out this form for the
      ACCOUNT INFORMATION                                           Morgan Stanley Institutional Fund, please contact your
      Fill in where applicable                                      Morgan Stanley representative or call us toll free
                                                                    1-(800)-548-7786. Please print all items except signature,
                                                                    and mail to the Fund at the address above.
 
  A)  REGISTRATION
      1. INDIVIDUAL
      2. JOINT TENANTS
         (RIGHTS OF SURVIVORSHIP PRESUMED UNLESS
         TENANCY IN COMMON
         IS INDICATED)
</TABLE>
 
1.
                               First
Name                          Initial                               Last Name
 
2.
                               First
Name                          Initial                               Last Name
 
                               First
Name                          Initial                               Last Name
 
<TABLE>
<C>   <S>                                       <C>
      3. CORPORATIONS,
         TRUSTS AND OTHERS
         Please call the Fund for additional
      documents that may be required to set up
      account and to authorize transactions.
</TABLE>
 
3.
 
<TABLE>
<S>                    <C>               <C>                        <C>               <C>
Type of Registration:  / / INCORPORATED  / / UNINCORPORATED         / / PARTNERSHIP   / / UNIFORM GIFT/TRANSFER TO MINOR
                                         ASSOCIATION                                    (ONLY ONE CUSTODIAN AND MINOR PERMITTED)
</TABLE>
 
/ / TRUST ________________________  / / OTHER (Specify) ________________________
 
<TABLE>
<C>   <S>                                       <C>
                                           Street or P.O. Box
  B)  MAILING ADDRESS
      Please fill in completely, including
      telephone number(s).
</TABLE>
 
                          City                                             State
                                                                             Zip
                                                                              --
                                           Home Telephone
No.                                                   Business Telephone No.
                                                            --  --        --  --
                          / / United States Citizen  / / Resident Alien  / /
Non-Resident Alien: Indicate Country of Residence ______________________________
 
<TABLE>
<C>   <S>                                       <C>                             <C>
  C)  TAXPAYER                                  Enter your Taxpayer Identification Number. For most individual
      IDENTIFICATION                            taxpayers, this is your Social Security Number. OR
      NUMBER                                                                    SOCIAL SECURITY NUMBER
      1. INDIVIDUAL                             1.         TAXPAYER             ("SSN")
      2. JOINT TENANTS                          IDENTIFICATION NUMBER
                                                ("TIN")
                                                --
 
         (RIGHTS OF SURVIVORSHIP PRESUMED       --        --            - - -   ------------- -------------
      UNLESS                                    -- - - - - - - -                ------------- - - - - - - - -
         TENANCY IN COMMON                                                      -
         IS INDICATED)                          2.                              OR                          TINSSN
      For Custodian account
                                                --
 
      of a minor (Uniform                       --        --            - - -   ------------- -------------
      Gifts/Transfers to Minor                  -- - - - - - - -                ------------- - - - - - - - -
                                                                                -
      Acts), give the Social                                                    OR
      Security Number of                                                      TIN                                SSN
      the minor
                                                --
 
                                                --        --            - - -   ------------- -------------
                                                - - - - - - - - -               ------------- - - - - - - - -
                                                                                -
</TABLE>
<PAGE>
 
<TABLE>
<C>   <S>                                       <C>                             <C>
                                                IMPORTANT TAX INFORMATION
                                                You (as a payee) are required by law to provide us (as  payer)
                                                with  your  correct TIN(s)  or  SSN(s). Accounts  that  have a
                                                missing or  incorrect  TIN(s) or  SSN(s)  will be  subject  to
                                                backup  withholding at a 31%  rate on dividends, distributions
                                                and other  payments. If  you have  not provided  us with  your
                                                correct  TIN(s) or SSN(s), you may be subject to a $50 penalty
                                                imposed by the Internal Revenue Service.
                                                Backup withholding is not an additional tax; the tax liability
                                                of persons subject  to backup withholding  will be reduced  by
                                                the  amount  of tax  withheld.  If withholding  results  in an
                                                overpayment   of   taxes,   a   refund   may   be    obtained.
                                                You may be notified that you are subject to backup withholding
                                                under  Section  3406(a)(1)(C)  of  the  Internal  Revenue Code
                                                because you have  underreported interest or  dividends or  you
                                                were  required to,  but failed to,  file a  return which would
                                                have included a reportable interest or dividend payment.
</TABLE>
 
<PAGE>
 
<TABLE>
<C>   <S>                                       <C>                             <C>                   <C>
  D)  PORTFOLIO AND                             For Purchase of the following   / / Class A Shares $  / / Class B Shares $
      CLASS SECTION                             Portfolio(s):                   / / Class A Shares $  / / Class B Shares $
      (Class A shares minimum $500,000 for      Equity Growth Portfolio
      each Portfolio and Class B shares         Emerging Growth Portfolio
      minimum $100,000 for the Global Equity,   MicroCap Portfolio
      International Equity, Asian Equity,       Aggressive Equity Portfolio
      European Equity, Japanese Equity and
      Latin American Equity Portfolios).
      Please indicate Portfolio, class and
      amount.
                                                                                Total Initial Investment $
</TABLE>
 
<TABLE>
<C>   <S>                                       <C>
  E)  METHOD OF
      INVESTMENT
      Please indicate portfolio, manner of
      payment.
</TABLE>
 
Payment by:
 
/ / Check (MAKE CHECK PAYABLE TO MORGAN STANLEY INSTITUTIONAL FUND,
INC.--PORTFOLIO NAME)
 
<TABLE>
<S>                                                                                 <C>
/ / Exchange $ From                                                                           -- - - - - - - - - - -- - -
                                                      Name of Portfolio                               Account No.
/ / Account previously established by:  / / Phone exchange  / / Wire on                       - - - - - - - - - - - -- - -
                                                                                            Account No.               (Check
                                                                                      (Previously assigned by the Fund)     Digit)
                                                                            Date
</TABLE>
 
<TABLE>
<C>   <S>                                       <C>
  F)  DISTRIBUTION                              Income dividends and capital gains distributions (if any) to
      OPTION                                    be reinvested in additional shares unless either box below
                                                is checked.
                                                / / Income dividends to be paid in cash, capital gains
                                                distributions (if any) in shares.
                                                / / Income dividends and capital gains distributions (if
                                                any) to be paid in cash.
</TABLE>
<TABLE>
<C>   <S>                             <C>
  G)  TELEPHONE                       / / I/we hereby authorize the Fund and
      REDEMPTION                      its agents to honor any telephone
      AND EXCHANGE                    requests to wire redemption proceeds to
      OPTION                          the commercial bank indicated at right
      Please select at time of        and/or mail redemption proceeds to the
      initial application if you      name and address in which my/our fund
      wish to redeem or exchange      account is registered if such requests
      shares by telephone. A          are believed to be authentic.
      SIGNATURE GUARANTEE IS          The Fund and the Fund's Transfer Agent
      REQUIRED IF BANK ACCOUNT IS     will employ reasonable procedures to
      NOT REGISTERED IDENTICALLY TO   confirm that instructions communicated
      YOUR FUND ACCOUNT.              by telephone are genuine. These
      TELEPHONE REQUESTS FOR          procedures include requiring the
      REDEMPTIONS OR EXCHANGE WILL    investor to provide certain personal
      NOT BE HONORED UNLESS THE BOX   identification information at the time
      IS CHECKED.                     an account is opened and prior to
                                      effecting each transaction requested by
                                      telephone. In addition, all telephone
                                      transaction requests will be recorded
                                      and investors may be required to provide
                                      additional telecopied written
                                      instructions of transaction requests.
                                      Neither the Fund nor the Transfer Agent
                                      will be responsible for any loss,
                                      liability, cost or expense for following
                                      instructions received by telephone that
                                      it reasonably believes to be genuine.
 
<CAPTION>
  G)
      Name of COMMERCIAL Bank (Not Savings Bank)
      Bank Account No.
                                                   Bank ABA No.
      Name(s) in which your BANK Account is Established
      Bank's Street Address
      City                           State                           Zip
</TABLE>
 
<TABLE>
<C>   <S>                                       <C>
  H)  INTERESTED PARTY                          Name
      OPTION                                    Address
      In addition to the account statement      City         State         Zip Code
      sent to my/our registered address, I/we
      hereby authorize the fund to mail
      duplicate statements to the name and
      address provided at right.
</TABLE>
 
<TABLE>
<C>   <S>                                       <C>
  I)  DEALER
      INFORMATION
                                                Representative Name                        Representative
                                                No.                            Branch
                                                No.
</TABLE>
 
<PAGE>
 
<TABLE>
<C>   <S>                        <C>
  J)  SIGNATURE OF
      ALL HOLDERS
      AND TAXPAYER
      CERTIFICATION
      Sign Here ,
</TABLE>
 
<TABLE>
<S>                                  <C>
The undersigned certify that I/we have full authority and legal capacity
to purchase and redeem shares of the Fund and affirm that I/we have
received a current Prospectus of the Morgan Stanley Institutional Fund,
Inc. and agree to be bound by its terms.
  BY SIGNING THIS  APPLICATION, I/WE HEREBY  CERTIFY UNDER PENALTIES  OF
PERJURY THAT THE INFORMATION ON THIS APPLICATION IS COMPLETE AND CORRECT
AND  THAT  AS REQUIRED  BY FEDERAL  LAW  (PLEASE CHECK  APPLICABLE BOXES
BELOW):
/ / U.S. CITIZEN(S)/TAXPAYER(S):
       / / I/WE CERTIFY THAT (1) THE NUMBER(S) SHOWN ABOVE ON THIS  FORM
           IS/ARE  THE CORRECT  SSN(S) OR  TIN(S) AND  (2) I/WE  ARE NOT
           SUBJECT TO ANY BACKUP WITHHOLDING EITHER BECAUSE (A) I/WE ARE
           EXEMPT FROM  BACKUP  WITHHOLDING;  (B)  I/WE  HAVE  NOT  BEEN
           NOTIFIED  BY THE  INTERNAL REVENUE SERVICE  ("IRS") THAT I/WE
           ARE SUBJECT TO BACKUP WITHHOLDING AS A RESULT OF A FAILURE TO
           REPORT ALL INTEREST OR DIVIDENDS; OR (C) THE IRS HAS NOTIFIED
           ME/US  THAT  I  AM/WE  ARE   NO  LONGER  SUBJECT  TO   BACKUP
           WITHHOLDING.
       /  / IF  NO TIN(S) OR  SSN(S) HAS/HAVE BEEN  PROVIDED ABOVE, I/WE
           HAVE APPLIED, OR INTEND  TO APPLY, TO THE  IRS OR THE  SOCIAL
           SECURITY   ADMINISTRATION  FOR  A  TIN  OR  A  SSN  AND  I/WE
           UNDERSTAND THAT IF I/WE DO NOT PROVIDE EITHER NUMBER TO CHASE
           GLOBAL FUNDS SERVICES COMPANY ("CGFSC") WITHIN 60 DAYS OF THE
           DATE OF THIS APPLICATION  OR IF I/WE  FAIL TO FURNISH  MY/OUR
           CORRECT  SSN(S) OR TIN(S),  I/WE MAY BE  SUBJECT TO A PENALTY
           AND A 31% BACKUP WITHHOLDING ON DISTRIBUTIONS AND  REDEMPTION
           PROCEEDS. (PLEASE PROVIDE EITHER NUMBER ON IRS FORM W-9). YOU
           MAY REQUEST SUCH FORM BY CALLING CGFSC AT 800-282-4404.
/ / NON-U.S. CITIZEN(S)/TAXPAYER(S):
  INDICATE COUNTRY OF RESIDENCE FOR TAX PURPOSES:
  UNDER  PENALTIES  OF  PERJURY, I/WE  CERTIFY  THAT I/WE  ARE  NOT U.S.
CITIZENS OR RESIDENTS AND I/WE ARE EXEMPT FOREIGN PERSONS AS DEFINED  BY
THE INTERNAL REVENUE SERVICE.
THE  INTERNAL  REVENUE  SERVICE DOES  NOT  REQUIRE YOUR  CONSENT  TO ANY
PROVISION OF THIS  DOCUMENT OTHER  THAN THE  CERTIFICATIONS REQUIRED  TO
AVOID BACKUP WITHHOLDING.
 
                                     (X)
(X)                                  Signature (if joint account, both
Signature                                                     Date must sign)              Date
</TABLE>
<PAGE>
   MORGAN STANLEY INSTITUTIONAL FUND, INC.
          EMERGING MARKETS AND EMERGING MARKETS DEBT PORTFOLIOS
           P.O. BOX 2798, BOSTON, MA 02208-2798
 
                           ACCOUNT REGISTRATION FORM
 
<TABLE>
<C>   <S>                                       <C>
                                                If you need assistance in filling out
                                                this form for the Morgan Stanley
      ACCOUNT INFORMATION                       Institutional Fund, please contact your
      Fill in where applicable                  Morgan Stanley representative or call us
                                                toll free 1-(800)-548-7786. Please print
                                                all items except signature, and mail to
                                                the Fund at the address above.
</TABLE>
 
<TABLE>
<C>   <S>                                       <C>
  A)  REGISTRATION
</TABLE>
 
                            1.
<TABLE>
<C>   <S>                                       <C>
      1. INDIVIDUAL
</TABLE>
 
                                                              First
Name                      Initial                          Last Name
<TABLE>
<C>   <S>                                       <C>
      2. JOINT TENANTS
</TABLE>
 
<TABLE>
<C>   <S>                                       <C>
        (RIGHTS OF SURVIVORSHIP
</TABLE>
 
                            2.
<TABLE>
<C>   <S>                                       <C>
        PRESUMED UNLESS
</TABLE>
 
                                                              First
Name                      Initial                          Last Name
<TABLE>
<C>   <S>                                       <C>
        TENANCY IN COMMON
</TABLE>
 
<TABLE>
<C>   <S>                                       <C>
        IS INDICATED)
</TABLE>
 
                                                              First
Name                      Initial                          Last Name
 
<TABLE>
<C>   <S>                                       <C>
 
                            3.
 
      3. CORPORATIONS,
        TRUSTS AND OTHERS
        Please call the Fund for additional
      documents that may be required to set up
      account and to authorize transactions.
</TABLE>
 
<TABLE>
<S>                    <C>               <C>                        <C>               <C>
Type of Registration:  / / INCORPORATED  / / UNINCORPORATED         / / PARTNERSHIP   / / UNIFORM GIFT/TRANSFER TO MINOR
                                         ASSOCIATION                                    (ONLY ONE CUSTODIAN AND MINOR PERMITTED)
</TABLE>
 
                            / / TRUST __________  / / OTHER (Specify) __________
 
<TABLE>
<C>   <S>                                       <C>
                                    Street or P.O. Box
 
  B)  MAILING ADDRESS
      Please fill in completely, including
      telephone number(s).
</TABLE>
 
                            City                                           State
                                                                             Zip
                                                                              --
                                           Home Telephone
No.                                                   Business Telephone No.
                                                         --       -- --       --
                            / / United States Citizen  / / Resident Alien  / /
Non-Resident Alien: Indicate Country of Residence ______________________________
 
<TABLE>
<C>   <S>                                       <C>                                       <C>
  C)  TAXPAYER                                  PART 1. Enter your Taxpayer               IMPORTANT TAX INFORMATION
      IDENTIFICATION                            Identification Number. For most           You  (as a payee) are required by law to
      NUMBER                                    individual taxpayers, this is your        provide us (as payer) with your  correct
      If the account is in more than one name,  Social Security Number.                   Taxpayer Identification Number. Accounts
      CIRCLE THE                                TAXPAYER IDENTIFICATION NUMBER            that   have   a  missing   or  incorrect
                                                                                          Taxpayer Identification  Number will  be
                                                                                          subject  to backup withholding  at a 31%
                                                                                          rate on
</TABLE>
 
                          --
 
<TABLE>
<C>   <S>                                       <C>                                       <C>
      NAME OF THE PERSON WHOSE TAXPAYER         -- -- -- -- -- -- -- -- -- -- -- --       dividends,   distributions   and   other
      IDENTIFICATION NUMBER IS PROVIDED IN      OR                                        payments.  If you  have not  provided us
      SECTION A) ABOVE. If no name is circled,  SOCIAL SECURITY NUMBER                    with your correct taxpayer
      the number                                                                          identification  number,   you   may   be
                                                                                          subject  to a $50 penalty imposed by the
                                                                                          Internal Revenue Service.
                                                                                          Backup withholding is not an  additional
                                                                                          tax;   the  tax   liability  of  persons
                                                                                          subject to  backup withholding  will  be
                                                                                          reduced  by the amount  of tax withheld.
                                                                                          If withholding
</TABLE>
 
                           --        --
 
<TABLE>
<C>   <S>                                       <C>                                       <C>
      will be considered to be that of the      -- -- -- -- -- -- -- -- -- -- -- --       results in  an overpayment  of taxes,  a
      last name listed. For Custodian account   PART 2. BACKUP WITHHOLDING                refund may be obtained.
      of a minor (Uniform Gift/Transfer to      / / Check this box if you are NOT         You may be notified that you are subject
      Minor Act), give the Social Security      subject to Backup Withholding under the   to   backup  withholding  under  Section
      Number of the minor.                      provisions of Section 3406(a)(1)(C) of    3406(a)(1)(C) of  the  Internal  Revenue
                                                the Internal Revenue Code.                Code   because  you  have  underreported
                                                                                          interest  or  dividends   or  you   were
                                                                                          required  to but failed to file a return
                                                                                          which would have  included a  reportable
                                                                                          interest  or  dividend  payment.  IF YOU
                                                                                          HAVE NOT BEEN SO NOTIFIED, CHECK THE BOX
                                                                                          IN PART 2 AT LEFT.
</TABLE>
 
<TABLE>
<C>   <S>                                       <C>                             <C>                   <C>
  D)  PORTFOLIO AND                             For Purchase of the following   / / Class A Shares $  / / Class B Shares $
      CLASS SELECTION                           Portfolio(s):                   / / Class A Shares $  / / Class B Shares $
      (Class A shares minimum $500,000 and      Emerging Markets Portfolio
      Class B shares minimum $100,000). Please  Emerging Markets Debt
      indicate Portfolio, class and amount.     Portfolio
                                                                                Total Initial Investment $
</TABLE>
 
                                    Payment by:
 
<TABLE>
<C>   <S>                                       <C>
                                    / / Check (MAKE CHECK PAYABLE TO MORGAN
STANLEY INSTITUTIONAL FUND, INC.--PORTFOLIO NAME)
  E)  METHOD OF
      INVESTMENT
      Please indicate manner of payment.
</TABLE>
 
<TABLE>
<S>                                                           <C>
/ / Exchange $ From                                            -- - - - - - - - - - -- - -
                                           Name of Portfolio           Account No.
/ / Account previously established by:  / / Phone
exchange  / / Wire on                                          -- - - - - - - - - - -- - -
                                                              Account No.            (Check
                                                               (Previously assigned by the
                                                                      Fund)   Digit)
                                                              Date
</TABLE>
 
<PAGE>
 
<TABLE>
<S>                                                           <C>                             <C>
  F)  DISTRIBUTION                              Income dividends and capital gains distributions (if any)
      OPTION                                    will be reinvested in additional shares unless either box
                                                below is checked.
                                                / / Income dividends to be paid in cash, capital gains
                                                distributions (if any) in shares.
                                                / / Income dividends and capital gains distributions (if
                                                any) to be paid in cash.
</TABLE>
<TABLE>
<C>   <S>                             <C>
  G)  TELEPHONE                       / / I/we hereby authorize the Fund and
      REDEMPTION                      its agents to honor any telephone
      Please select at time of        requests to wire redemption proceeds to
      initial application if you      the commercial bank indicated at right
      wish to redeem shares by        and/or mail redemption proceeds to the
      telephone. A SIGNATURE          name and address in which my/our fund
      GUARANTEE IS REQUIRED IF BANK   account is registered if such requests
      ACCOUNT IS NOT REGISTERED       are believed to be authentic.
      IDENTICALLY TO YOUR FUND        The Fund and the Fund's Transfer Agent
      ACCOUNT.                        will employ reasonable procedures to
      TELEPHONE REQUESTS FOR          confirm that instructions communicated
      REDEMPTIONS WILL NOT BE         by telephone are genuine. These
      HONORED UNLESS THE BOX IS       procedures include requiring the
      CHECKED.                        investor to provide certain personal
                                      identification information at the time
                                      an account is opened and prior to
                                      effecting each transaction requested by
                                      telephone. In addition, all telephone
                                      transaction requests will be recorded
                                      and investors may be required to provide
                                      additional telecopied written
                                      instructions of transaction requests.
                                      Neither the Fund nor the Transfer Agent
                                      will be responsible for any loss,
                                      liability, cost or expense for following
                                      instructions received by telephone that
                                      it reasonably believes to be genuine.
 
<CAPTION>
  G)
      Name of COMMERCIAL Bank (Not Savings Bank)
      Bank Account No.
                                                   Bank ABA No.
      Name(s) in which your BANK Account is Established
      Bank's Street Address
      City                           State                           Zip
</TABLE>
 
<TABLE>
<C>   <S>                                       <C>
  H)  INTERESTED PARTY
      OPTION                                    Name
      In addition to the account statement
      sent to my/our registered address, I/we
      hereby authorize the fund to mail         Address
      duplicate statements to the name and
      address provided at right.                City        State        Zip Code
</TABLE>
 
<TABLE>
<C>   <S>                                       <C>
  I)  DEALER
      INFORMATION
                                                Representative
                                                Name                  Representative
                                                No.                     Branch
                                                No.
 
</TABLE>
<TABLE>
<C>        <S>                    <C>
       J)  SIGNATURE OF
           ALL HOLDERS
           AND TAXPAYER
           CERTIFICATION
 
</TABLE>
 
<TABLE>
<S>                                  <C>
The undersigned certify(ies)  that I/we  have full  authority and  legal
capacity  to purchase and redeem shares of the Fund and affirm that I/we
have received a current Prospectus  of the Morgan Stanley  Institutional
Fund,  Inc. and agree to  be bound by its  terms. UNDER THE PENALTIES OF
PERJURY, I/WE CERTIFY THAT THE INFORMATION PROVIDED IN SECTION C)  ABOVE
IS TRUE, CORRECT AND COMPLETE.
 
THE  INTERNAL  REVENUE  SERVICE DOES  NOT  REQUIRE YOUR  CONSENT  TO ANY
PROVISION OF THIS  DOCUMENT OTHER  THAN THE  CERTIFICATIONS REQUIRED  TO
AVOID BACKUP WITHHOLDING.
 
(X)                                  (X)
Signature                                           Date Signature                                           Date
                                     Sign Here ,
</TABLE>
<PAGE>
   MORGAN STANLEY INSTITUTIONAL FUND, INC.
          U.S. REAL ESTATE PORTFOLIO
           P.O. BOX 2798, BOSTON, MA 02208-2798
 
                           ACCOUNT REGISTRATION FORM
 
<TABLE>
<C>   <S>                                       <C>
                                                If you need assistance in filling out this form for the
      ACCOUNT INFORMATION                       Morgan Stanley Institutional Fund, please contact your
      Fill in where applicable                  Morgan Stanley representative or call us toll free
                                                1-(800)-548-7786. Please print all items except signature,
                                                and mail to the Fund at the address above.
 
  A)  REGISTRATION
      1. INDIVIDUAL
      2. JOINT TENANTS
         (RIGHTS OF SURVIVORSHIP PRESUMED
      UNLESS
         TENANCY IN COMMON
         IS INDICATED)
</TABLE>
 
1.
                               First
Name                          Initial                               Last Name
 
2.
                               First
Name                          Initial                               Last Name
 
                               First
Name                          Initial                               Last Name
 
<TABLE>
<C>   <S>                                       <C>
      3. CORPORATIONS,
         TRUSTS AND OTHERS
         Please call the Fund for additional
      documents that may be required to set up
      account and to authorize transactions.
</TABLE>
 
3.
 
<TABLE>
<S>                     <C>                 <C>                   <C>               <C>
Type of Registration:   / / INCORPORATED    / / UNINCORPORATED    / / PARTNERSHIP   / / UNIFORM GIFT/TRANSFER TO MINOR
                                            ASSOCIATION                               (ONLY ONE CUSTODIAN AND MINOR PERMITTED)
</TABLE>
 
/ / TRUST ________________________  / / OTHER (Specify) ________________________
 
<TABLE>
<C>   <S>                                       <C>
  B)  MAILING ADDRESS
      Please fill in completely, including
      telephone number(s).
</TABLE>
 
Street or P.O. Box
City                                                                       State
                                                                             Zip
                                                                              --
Home Telephone No.                                                   Business
Telephone No.                     --            --              --            --
/ / United States Citizen  / / Resident Alien  / / Non-Resident Alien: Indicate
Country of Residence ___________________________________________________________
 
<TABLE>
<C>   <S>                                       <C>                                       <C>
  C)  TAXPAYER                                  Enter  your Taxpayer Identification Number. For most individual taxpayers, this is
      IDENTIFICATION                            your Social Security Number.
      NUMBER
      1. INDIVIDUAL
      2. JOINT TENANTS
         (RIGHTS OF SURVIVORSHIP PRESUMED
      UNLESS
         TENANCY IN COMMON
         IS INDICATED)
      For Custodian account
      of a minor (Uniform
      Gifts/Transfers to Minor
      Acts), give the Social
      Security Number of
      the minor
                                                                                          OR
                                                1.         TAXPAYER IDENTIFICATION        SOCIAL SECURITY NUMBER
                                                NUMBER ("TIN")                            ("SSN")
                                                                                          OR
                                                2.                                                          TIN SSN
</TABLE>
<PAGE>
<TABLE>
<C>   <S>                                       <C>                                       <C>
                                                                                          OR
                                                TIN                                       SSN
 
                                                IMPORTANT TAX INFORMATION
                                                You  (as a payee) are required  by law to provide us  (as payer) with your correct
                                                TIN(s) or SSN(s). Accounts that have a missing or incorrect TIN(s) or SSN(s)  will
                                                be  subject to backup  withholding at a  31% rate on  dividends, distributions and
                                                other payments. If you have  not provided us with  your correct TIN(s) or  SSN(s),
                                                you  may be  subject to  a $50  penalty imposed  by the  Internal Revenue Service.
                                                Backup withholding is not an additional tax; the tax liability of persons  subject
                                                to  backup  withholding  will  be  reduced  by  the  amount  of  tax  withheld. If
                                                withholding results  in  an  overpayment  of taxes,  a  refund  may  be  obtained.
                                                You  may be  notified that  you are  subject to  backup withholding  under Section
                                                3406(a)(1)(C) of the Internal Revenue Code because you have underreported interest
                                                or dividends or you  were required to,  but failed to, file  a return which  would
                                                have included a reportable interest or dividend payment.
</TABLE>
 
<PAGE>
 
<TABLE>
<C>   <S>                                       <C>                             <C>                   <C>
  D)  PORTFOLIO AND                             For Purchase of the following   / / Class A Shares $  / / Class B Shares $
      CLASS SECTION                             Portfolio:
      (Class A shares minimum $500,000 for      U.S. Real Estate Portfolio
      each Portfolio and Class B shares
      minimum $100,000 for the Global Equity,
      International Equity, Asian Equity,
      European Equity, Japanese Equity and
      Latin American Equity Portfolios).
      Please indicate Portfolio, class and
      amount.
                                                                                Total Initial Investment $
</TABLE>
 
<TABLE>
<C>   <S>                                       <C>
  E)  METHOD OF
      INVESTMENT
      Please indicate portfolio, manner of
      payment.
</TABLE>
 
Payment by:
 
/ / Check (MAKE CHECK PAYABLE TO MORGAN STANLEY INSTITUTIONAL FUND,
INC.--PORTFOLIO NAME)
 
<TABLE>
<S>                                                                                 <C>
/ / Exchange $ From                                                                           -- - - - - - - - - - -- - -
                                                      Name of Portfolio                               Account No.
/ / Account previously established by:  / / Phone exchange  / / Wire on                       -- - - - - - - - - - -- - -
                                                                                            Account No.               (Check
                                                                                      (Previously assigned by the Fund)     Digit)
                                                                            Date
</TABLE>
 
<TABLE>
<C>   <S>                                       <C>
  F)  DISTRIBUTION                              Income dividends and capital gains distributions (if any) to
      OPTION                                    be reinvested in additional shares unless either box below
                                                is checked.
                                                / / Income dividends to be paid in cash, capital gains
                                                distributions (if any) in shares.
                                                / / Income dividends and capital gains distributions (if
                                                any) to be paid in cash.
</TABLE>
<TABLE>
<C>   <S>                             <C>
  G)  TELEPHONE                       / / I/we hereby authorize the Fund and
      REDEMPTION                      its agents to honor any telephone
      AND EXCHANGE                    requests to wire redemption proceeds to
      OPTION                          the commercial bank indicated at right
      Please select at time of        and/or mail redemption proceeds to the
      initial application if you      name and address in which my/our fund
      wish to redeem or exchange      account is registered if such requests
      shares by telephone. A          are believed to be authentic.
      SIGNATURE GUARANTEE IS          The Fund and the Fund's Transfer Agent
      REQUIRED IF BANK ACCOUNT IS     will employ reasonable procedures to
      NOT REGISTERED IDENTICALLY TO   confirm that instructions communicated
      YOUR FUND ACCOUNT.              by telephone are genuine. These
      TELEPHONE REQUESTS FOR          procedures include requiring the
      REDEMPTIONS OR EXCHANGE WILL    investor to provide certain personal
      NOT BE HONORED UNLESS THE BOX   identification information at the time
      IS CHECKED.                     an account is opened and prior to
                                      effecting each transaction requested by
                                      telephone. In addition, all telephone
                                      transaction requests will be recorded
                                      and investors may be required to provide
                                      additional telecopied written
                                      instructions of transaction requests.
                                      Neither the Fund nor the Transfer Agent
                                      will be responsible for any loss,
                                      liability, cost or expense for following
                                      instructions received by telephone that
                                      it reasonably believes to be genuine.
 
<CAPTION>
  G)
      Name of COMMERCIAL Bank (Not Savings Bank)
      Bank Account No.
                                                   Bank ABA No.
      Name(s) in which your BANK Account is Established
      Bank's Street Address
      City                           State                           Zip
</TABLE>
 
<TABLE>
<C>   <S>                        <C>
  H)  INTERESTED PARTY
      OPTION                                                                                      Name
      In addition to the
      account statement sent to
      my/our registered                                                                          Address
      address, I/we hereby
      authorize the fund to      City         State         Zip Code
      mail duplicate statements
      to the name and address
      provided at right.
</TABLE>
 
<TABLE>
<C>   <S>                                       <C>
  I)  DEALER
      INFORMATION
                                                Representative Name                        Representative
                                                No.                            Branch
                                                No.
</TABLE>
 
<PAGE>
 
<TABLE>
<C>   <S>                                       <C>
  J)  SIGNATURE OF
      ALL HOLDERS
      AND TAXPAYER
      CERTIFICATION
      Sign Here ,
</TABLE>
 
<TABLE>
<S>                                                           <C>
The undersigned certify that I/we have full authority and legal capacity to purchase and redeem shares of the Fund and
affirm that I/we have received a current Prospectus of the Morgan Stanley Institutional Fund, Inc. and agree to be bound
by its terms.
  BY  SIGNING THIS APPLICATION, I/WE HEREBY CERTIFY UNDER PENALTIES OF PERJURY THAT THE INFORMATION ON THIS APPLICATION IS
COMPLETE AND CORRECT AND THAT AS REQUIRED BY FEDERAL LAW (PLEASE CHECK APPLICABLE BOXES BELOW):
/ / U.S. CITIZEN(S)/TAXPAYER(S):
       / / I/WE CERTIFY THAT (1) THE NUMBER(S) SHOWN ABOVE ON  THIS FORM IS/ARE THE CORRECT SSN(S) OR TIN(S) AND (2)  I/WE
           ARE  NOT SUBJECT TO ANY BACKUP WITHHOLDING EITHER BECAUSE (A) I/WE ARE EXEMPT FROM BACKUP WITHHOLDING; (B) I/WE
           HAVE NOT BEEN NOTIFIED BY THE INTERNAL REVENUE SERVICE ("IRS") THAT I/WE ARE SUBJECT TO BACKUP WITHHOLDING AS A
           RESULT OF A FAILURE TO REPORT ALL INTEREST OR DIVIDENDS; OR (C) THE IRS HAS NOTIFIED ME/US THAT I AM/WE ARE  NO
           LONGER SUBJECT TO BACKUP WITHHOLDING.
       /  / IF NO TIN(S) OR SSN(S) HAS/HAVE BEEN PROVIDED ABOVE, I/WE  HAVE APPLIED, OR INTEND TO APPLY, TO THE IRS OR THE
           SOCIAL SECURITY ADMINISTRATION FOR A TIN OR A SSN AND I/WE UNDERSTAND THAT IF I/WE DO NOT PROVIDE EITHER NUMBER
           TO CHASE GLOBAL FUNDS SERVICES COMPANY ("CGFSC") WITHIN 60 DAYS OF THE DATE OF THIS APPLICATION OR IF I/WE FAIL
           TO FURNISH MY/OUR CORRECT SSN(S) OR TIN(S),  I/WE MAY BE SUBJECT TO A  PENALTY AND A 31% BACKUP WITHHOLDING  ON
           DISTRIBUTIONS  AND REDEMPTION PROCEEDS.  (PLEASE PROVIDE EITHER NUMBER  ON IRS FORM W-9).  YOU MAY REQUEST SUCH
           FORM BY CALLING CGFSC AT 800-282-4404.
/ / NON-U.S. CITIZEN(S)/TAXPAYER(S):
  INDICATE COUNTRY OF RESIDENCE FOR TAX PURPOSES:
  UNDER PENALTIES OF  PERJURY, I/WE CERTIFY  THAT I/WE  ARE NOT U.S.  CITIZENS OR  RESIDENTS AND I/WE  ARE EXEMPT  FOREIGN
PERSONS AS DEFINED BY THE INTERNAL REVENUE SERVICE.
THE INTERNAL REVENUE SERVICE DOES NOT REQUIRE YOUR CONSENT TO ANY PROVISION OF THIS DOCUMENT OTHER THAN THE CERTIFICATIONS
REQUIRED TO AVOID BACKUP WITHHOLDING.
 
(X)                                                           (X)
Signature                                                     Date Signature (if joint account, both must sign)   Date
</TABLE>
<PAGE>
   MORGAN STANLEY INSTITUTIONAL FUND, INC.
          SMALL CAP VALUE EQUITY, VALUE EQUITY AND BALANCED PORTFOLIOS
           P.O. BOX 2798, BOSTON, MA 02208-2798
 
                           ACCOUNT REGISTRATION FORM
 
<TABLE>
<C>   <S>                                                           <C>
                                                                    If you need assistance in filling out this form for the
      ACCOUNT INFORMATION                                           Morgan Stanley Institutional Fund, please contact your
      Fill in where applicable                                      Morgan Stanley representative or call us toll free
                                                                    1-(800)-548-7786. Please print all items except signature,
                                                                    and mail to the Fund at the address above.
 
  A)  REGISTRATION
      1. INDIVIDUAL
      2. JOINT TENANTS
         (RIGHTS OF SURVIVORSHIP PRESUMED UNLESS
         TENANCY IN COMMON
         IS INDICATED)
</TABLE>
 
1.
                  First Name                  Initial                  Last Name
 
2.
                  First Name                  Initial                  Last Name
 
                  First Name                  Initial                  Last Name
 
<TABLE>
<C>   <S>                                       <C>
      3. CORPORATIONS,
         TRUSTS AND OTHERS
         Please call the Fund for additional
      documents that may be required to set up
      account and to authorize transactions.
</TABLE>
 
3.
 
<TABLE>
<S>                     <C>                 <C>                   <C>               <C>
Type of Registration:   / / INCORPORATED    / /UNINCORPORATED     / / PARTNERSHIP   / /UNIFORM GIFT/TRANSFER TO MINOR
                                            ASSOCIATION                               (ONLY ONE CUSTODIAN AND MINOR PERMITTED)
</TABLE>
 
/ / TRUST ________________________  / / OTHER (Specify) ________________________
 
<TABLE>
<C>   <S>                                       <C>
  B)  MAILING ADDRESS
      Please fill in completely, including
      telephone number(s).
</TABLE>
 
Street or P.O. Box
City                                                                       State
                                                                             Zip
                                                                              --
Home Telephone No.                                                   Business
Telephone No.                     --            --              --            --
/ / United States Citizen  / / Resident Alien  / / Non-Resident Alien: Indicate
Country of Residence ___________________________________________________________
 
<TABLE>
<C>   <S>                                                           <C>                             <C>
  C)  TAXPAYER                                                      Enter your Taxpayer Identification Number. For most individual
      IDENTIFICATION                                                taxpayers, this is your Social Security Number.
      NUMBER
      1. INDIVIDUAL
      2.JOINT TENANTS
         (RIGHTS OF SURVIVORSHIP PRESUMED UNLESS
         TENANCY IN COMMON
         IS INDICATED)
      For Custodian account
      of a minor (Uniform
      Gifts/Transfers to Minor
      Acts), give the Social
      Security Number of
      the minor
                                                                                                    OR
                                                                    1.         TAXPAYER             SOCIAL SECURITY NUMBER
                                                                    IDENTIFICATION NUMBER           ("SSN")
                                                                    ("TIN")
                                                                                                    OR
                                                                    2.         TIN                  SSN
</TABLE>
<PAGE>
<TABLE>
<C>   <S>                                                           <C>                             <C>
                                                                                                    OR
                                                                    TIN                             SSN
 
                                                                    IMPORTANT TAX INFORMATION
                                                                    You  (as a payee) are required by law to provide us (as payer)
                                                                    with your  correct  TIN(s) or  SSN(s).  Accounts that  have  a
                                                                    missing  or  incorrect TIN(s)  or  SSN(s) will  be  subject to
                                                                    backup withholding at a  31% rate on dividends,  distributions
                                                                    and  other payments.  If you  have not  provided us  with your
                                                                    correct TIN(s) or SSN(s), you may be subject to a $50  penalty
                                                                    imposed by the Internal Revenue Service.
                                                                    Backup withholding is not an additional tax; the tax liability
                                                                    of  persons subject to  backup withholding will  be reduced by
                                                                    the amount  of  tax withheld.  If  withholding results  in  an
                                                                    overpayment    of   taxes,   a   refund   may   be   obtained.
                                                                    You may be notified that you are subject to backup withholding
                                                                    under Section  3406(a)(1)(C)  of  the  Internal  Revenue  Code
                                                                    because  you have  underreported interest or  dividends or you
                                                                    were required to,  but failed  to, file a  return which  would
                                                                    have included a reportable interest or dividend payment.
</TABLE>
 
<PAGE>
 
<TABLE>
<C>   <S>                                       <C>                             <C>                   <C>
  D)  PORTFOLIO AND                             For Purchase of the following   / / Class A Shares $  / / Class B Shares $
      CLASS SECTION                             Portfolio(s):                   / / Class A Shares $  / / Class B Shares $
      (Class A shares minimum $500,000 for      Small Cap Value Equity          / / Class A Shares $  / / Class B Shares $
      each Portfolio and Class B shares         Portfolio
      minimum $100,000 for the Global Equity,   Value Equity Portfolio
      International Equity, Asian Equity,       Balanced Portfolio
      European Equity, Japanese Equity and
      Latin American Equity Portfolios).
      Please indicate Portfolio, class and
      amount.
                                                                                Total Initial Investment $
</TABLE>
 
<TABLE>
<C>   <S>                                       <C>
  E)  METHOD OF
      INVESTMENT
      Please indicate portfolio, manner of
      payment.
</TABLE>
 
Payment by:
 
/ / Check (MAKE CHECK PAYABLE TO MORGAN STANLEY INSTITUTIONAL FUND,
INC.--PORTFOLIO NAME)
 
<TABLE>
<S>                                                                                 <C>
/ / Exchange $ From                                                                           -- - - - - - - - - - -- - -
                                                      Name of Portfolio                               Account No.
/ / Account previously established by:  / / Phone exchange  / / Wire on                       -- - - - - - - - - - -- - -
                                                                                            Account No.               (Check
                                                                                      (Previously assigned by the Fund)     Digit)
                                                                            Date
</TABLE>
 
<TABLE>
<C>   <S>                                       <C>
  F)  DISTRIBUTION                              Income dividends and capital gains distributions (if any) to
      OPTION                                    be reinvested in additional shares unless either box below
                                                is checked.
                                                / / Income dividends to be paid in cash, capital gains
                                                distributions (if any) in shares.
                                                / / Income dividends and capital gains distributions (if
                                                any) to be paid in cash.
</TABLE>
<TABLE>
<C>   <S>                             <C>
  G)  TELEPHONE                       / / I/we hereby authorize the Fund and
      REDEMPTION                      its agents to honor any telephone
      AND EXCHANGE                    requests to wire redemption proceeds to
      OPTION                          the commercial bank indicated at right
      Please select at time of        and/or mail redemption proceeds to the
      initial application if you      name and address in which my/our fund
      wish to redeem or exchange      account is registered if such requests
      shares by telephone. A          are believed to be authentic.
      SIGNATURE GUARANTEE IS          The Fund and the Fund's Transfer Agent
      REQUIRED IF BANK ACCOUNT IS     will employ reasonable procedures to
      NOT REGISTERED IDENTICALLY TO   confirm that instructions communicated
      YOUR FUND ACCOUNT.              by telephone are genuine. These
      TELEPHONE REQUESTS FOR          procedures include requiring the
      REDEMPTIONS OR EXCHANGE WILL    investor to provide certain personal
      NOT BE HONORED UNLESS THE BOX   identification information at the time
      IS CHECKED.                     an account is opened and prior to
                                      effecting each transaction requested by
                                      telephone. In addition, all telephone
                                      transaction requests will be recorded
                                      and investors may be required to provide
                                      additional telecopied written
                                      instructions of transaction requests.
                                      Neither the Fund nor the Transfer Agent
                                      will be responsible for any loss,
                                      liability, cost or expense for following
                                      instructions received by telephone that
                                      it reasonably believes to be genuine.
 
<CAPTION>
  G)
      Name of COMMERCIAL Bank (Not Savings Bank)
      Bank Account No.
                                                   Bank ABA No.
      Name(s) in which your BANK Account is Established
      Bank's Street Address
      City                           State                           Zip
</TABLE>
 
<TABLE>
<C>   <S>                                       <C>
  H)  INTERESTED PARTY
      OPTION                                                                                                     Name
      In addition to the account statement
      sent to my/our registered address, I/we
      hereby authorize the fund to mail                                                                         Address
      duplicate statements to the name and
      address provided at right.                City         State         Zip Code
</TABLE>
 
<TABLE>
<C>   <S>                                       <C>
  I)  DEALER
      INFORMATION
                                                Representative Name                        Representative
                                                No.                            Branch
                                                No.
</TABLE>
 
<PAGE>
 
<TABLE>
<C>   <S>                                       <C>
  J)  SIGNATURE OF
      ALL HOLDERS
      AND TAXPAYER
      CERTIFICATION
      Sign Here ,
</TABLE>
 
<TABLE>
<S>                                  <C>
The undersigned certify that I/we have full authority and legal capacity
to purchase and redeem shares of the Fund and affirm that I/we have
received a current Prospectus of the Morgan Stanley Institutional Fund,
Inc. and agree to be bound by its terms.
  BY  SIGNING THIS APPLICATION,  I/WE HEREBY CERTIFY  UNDER PENALTIES OF
PERJURY THAT THE INFORMATION ON THIS APPLICATION IS COMPLETE AND CORRECT
AND THAT  AS REQUIRED  BY  FEDERAL LAW  (PLEASE CHECK  APPLICABLE  BOXES
BELOW):
/ / U.S. CITIZEN(S)/TAXPAYER(S):
       /  / I/WE CERTIFY THAT (1) THE NUMBER(S) SHOWN ABOVE ON THIS FORM
           IS/ARE THE  CORRECT SSN(S)  OR TIN(S)  AND (2)  I/WE ARE  NOT
           SUBJECT TO ANY BACKUP WITHHOLDING EITHER BECAUSE (A) I/WE ARE
           EXEMPT  FROM  BACKUP  WITHHOLDING;  (B)  I/WE  HAVE  NOT BEEN
           NOTIFIED BY THE  INTERNAL REVENUE SERVICE  ("IRS") THAT  I/WE
           ARE SUBJECT TO BACKUP WITHHOLDING AS A RESULT OF A FAILURE TO
           REPORT ALL INTEREST OR DIVIDENDS; OR (C) THE IRS HAS NOTIFIED
           ME/US   THAT  I  AM/WE  ARE   NO  LONGER  SUBJECT  TO  BACKUP
           WITHHOLDING.
       / / IF  NO TIN(S) OR  SSN(S) HAS/HAVE BEEN  PROVIDED ABOVE,  I/WE
           HAVE  APPLIED, OR INTEND  TO APPLY, TO THE  IRS OR THE SOCIAL
           SECURITY  ADMINISTRATION  FOR  A  TIN  OR  A  SSN  AND   I/WE
           UNDERSTAND THAT IF I/WE DO NOT PROVIDE EITHER NUMBER TO CHASE
           GLOBAL FUNDS SERVICES COMPANY ("CGFSC") WITHIN 60 DAYS OF THE
           DATE  OF THIS APPLICATION  OR IF I/WE  FAIL TO FURNISH MY/OUR
           CORRECT SSN(S) OR TIN(S),  I/WE MAY BE  SUBJECT TO A  PENALTY
           AND  A 31% BACKUP WITHHOLDING ON DISTRIBUTIONS AND REDEMPTION
           PROCEEDS. (PLEASE PROVIDE EITHER NUMBER ON IRS FORM W-9). YOU
           MAY REQUEST SUCH FORM BY CALLING CGFSC AT 800-282-4404.
/ / NON-U.S. CITIZEN(S)/TAXPAYER(S):
  INDICATE COUNTRY OF RESIDENCE FOR TAX PURPOSES:
  UNDER PENALTIES  OF  PERJURY, I/WE  CERTIFY  THAT I/WE  ARE  NOT  U.S.
CITIZENS  OR RESIDENTS AND I/WE ARE EXEMPT FOREIGN PERSONS AS DEFINED BY
THE INTERNAL REVENUE SERVICE.
THE INTERNAL  REVENUE  SERVICE DOES  NOT  REQUIRE YOUR  CONSENT  TO  ANY
PROVISION  OF THIS  DOCUMENT OTHER  THAN THE  CERTIFICATIONS REQUIRED TO
AVOID BACKUP WITHHOLDING.
 
                                     (X)
(X)                                  Signature (if joint account, both
Signature                                                     Date must sign)              Date
</TABLE>
<PAGE>
   MORGAN STANLEY INSTITUTIONAL FUND, INC.
          ACTIVE COUNTRY ALLOCATION PORTFOLIO
           P.O. BOX 2798, BOSTON, MA 02208-2798
 
                           ACCOUNT REGISTRATION FORM
 
<TABLE>
<C>   <S>                                                           <C>
                                                                    If you need assistance in filling out this form for the
      ACCOUNT INFORMATION                                           Morgan Stanley Institutional Fund, please contact your
      Fill in where applicable                                      Morgan Stanley representative or call us toll free
                                                                    1-(800)-548-7786. Please print all items except signature,
                                                                    and mail to the Fund at the address above.
 
  A)  REGISTRATION
      1. INDIVIDUAL
      2. JOINT TENANTS
         (RIGHTS OF SURVIVORSHIP PRESUMED UNLESS
         TENANCY IN COMMON
         IS INDICATED)
</TABLE>
 
1.
                  First Name                  Initial                  Last Name
 
2.
                  First Name                  Initial                  Last Name
 
                  First Name                  Initial                  Last Name
 
<TABLE>
<C>   <S>                                       <C>
      3. CORPORATIONS,
         TRUSTS AND OTHERS
         Please call the Fund for additional
      documents that may be required to set up
      account and to authorize transactions.
</TABLE>
 
3.
 
<TABLE>
<S>                     <C>                 <C>                   <C>               <C>
Type of Registration:   / / INCORPORATED    / / UNINCORPORATED    / / PARTNERSHIP   / / UNIFORM GIFT/TRANSFER TO MINOR
                                            ASSOCIATION                               (ONLY ONE CUSTODIAN AND MINOR PERMITTED)
</TABLE>
 
/ / TRUST ________________________  / / OTHER (Specify) ________________________
 
<TABLE>
<C>   <S>                                       <C>
  B)  MAILING ADDRESS
      Please fill in completely, including
      telephone number(s).
</TABLE>
 
Street or P.O. Box
City                                                                       State
                                                                             Zip
                                                                              --
Home Telephone No.                                                   Business
Telephone No.                     --            --              --            --
/ / United States Citizen  / / Resident Alien  / / Non-Resident Alien: Indicate
Country of Residence ___________________________________________________________
 
<TABLE>
<C>   <S>                                                           <C>                             <C>
  C)  TAXPAYER                                                      Enter your Taxpayer Identification Number. For most individual
      IDENTIFICATION                                                taxpayers, this is your Social Security Number.
      NUMBER
      1. INDIVIDUAL
      2. JOINT TENANTS
         (RIGHTS OF SURVIVORSHIP PRESUMED UNLESS
         TENANCY IN COMMON
         IS INDICATED)
      For Custodian account
      of a minor (Uniform
      Gifts/Transfers to Minor
      Acts), give the Social
      Security Number of
      the minor
                                                                                                    OR
                                                                    1.         TAXPAYER             SOCIAL SECURITY NUMBER
                                                                    IDENTIFICATION NUMBER           ("SSN")
                                                                    ("TIN")
                                                                                                    OR
                                                                    2.         TIN                  SSN
                                                                                                    OR
                                                                    TIN                             SSN
</TABLE>
<PAGE>
 
<TABLE>
<C>   <S>                                                           <C>                             <C>
                                                                    IMPORTANT TAX INFORMATION
                                                                    You  (as a payee) are required by law to provide us (as payer)
                                                                    with your  correct  TIN(s) or  SSN(s).  Accounts that  have  a
                                                                    missing  or  incorrect TIN(s)  or  SSN(s) will  be  subject to
                                                                    backup withholding at a  31% rate on dividends,  distributions
                                                                    and  other payments.  If you  have not  provided us  with your
                                                                    correct TIN(s) or SSN(s), you may be subject to a $50  penalty
                                                                    imposed by the Internal Revenue Service.
                                                                    Backup withholding is not an additional tax; the tax liability
                                                                    of  persons subject to  backup withholding will  be reduced by
                                                                    the amount  of  tax withheld.  If  withholding results  in  an
                                                                    overpayment    of   taxes,   a   refund   may   be   obtained.
                                                                    You may be notified that you are subject to backup withholding
                                                                    under Section  3406(a)(1)(C)  of  the  Internal  Revenue  Code
                                                                    because  you have  underreported interest or  dividends or you
                                                                    were required to,  but failed  to, file a  return which  would
                                                                    have included a reportable interest or dividend payment.
</TABLE>
 
<PAGE>
 
<TABLE>
<C>   <S>                        <C>                             <C>                   <C>
  D)  PORTFOLIO AND              For Purchase of the following
      CLASS SECTION              Portfolio(s):                   / / Class A Shares $  / / Class B Shares $
      (Class A shares minimum    Active Country Allocation
      $500,000 for each          Portfolio
      Portfolio and Class B
      shares minimum $100,000
      for the Global Equity,
      International Equity,
      Asian Equity, European
      Equity, Japanese Equity
      and Latin American Equity
      Portfolios). Please
      indicate Portfolio, class
      and amount.
                                                                 Total Initial Investment $
</TABLE>
 
<TABLE>
<C>   <S>                        <C>
  E)  METHOD OF
      INVESTMENT
      Please indicate
      portfolio, manner of
      payment.
</TABLE>
 
Payment by:
 
/ / Check (MAKE CHECK PAYABLE TO MORGAN STANLEY INSTITUTIONAL FUND,
INC.--PORTFOLIO NAME)
 
<TABLE>
<S>                                                                                 <C>
/ / Exchange $ From                                                                           -- - - - - - - - - - -- - -
                                                      Name of Portfolio                               Account No.
/ / Account previously established by:  / / Phone exchange  / / Wire on                       -- - - - - - - - - - -- - -
                                                                                            Account No.               (Check
                                                                                      (Previously assigned by the Fund)     Digit)
                                                                            Date
</TABLE>
 
<TABLE>
<C>   <S>                        <C>
  F)  DISTRIBUTION               Income dividends and capital gains distributions (if any) to
      OPTION                     be reinvested in additional shares unless either box below
                                 is checked.
                                 / / Income dividends to be paid in cash, capital gains
                                 distributions (if any) in shares.
                                 / / Income dividends and capital gains distributions (if
                                 any) to be paid in cash.
</TABLE>
 
<TABLE>
<C>   <S>                             <C>                                       <C>
  G)  TELEPHONE                       / / I/we hereby authorize the Fund and
      REDEMPTION                      its agents to honor any telephone         Name of COMMERCIAL Bank (Not Savings
      AND EXCHANGE                    requests to wire redemption proceeds to   Bank)
      OPTION                          the commercial bank indicated at right    Bank Account No.
      Please select at time of        and/or mail redemption proceeds to the
      initial application if you      name and address in which my/our fund
      wish to redeem or exchange      account is registered if such requests                                        Bank
      shares by telephone. A          are believed to be authentic.                                                  ABA
      SIGNATURE GUARANTEE IS          The Fund and the Fund's Transfer Agent                                         No.
      REQUIRED IF BANK ACCOUNT IS     will employ reasonable procedures to
      NOT REGISTERED IDENTICALLY TO   confirm that instructions communicated    Name(s) in which your BANK Account is
      YOUR FUND ACCOUNT.              by telephone are genuine. These           Established
      TELEPHONE REQUESTS FOR          procedures include requiring the
      REDEMPTIONS OR EXCHANGE WILL    investor to provide certain personal      Bank's Street
      NOT BE HONORED UNLESS THE BOX   identification information at the time    Address
      IS CHECKED.                     an account is opened and prior to
                                      effecting each transaction requested by   City                   State                   Zip
                                      telephone. In addition, all telephone
                                      transaction requests will be recorded
                                      and investors may be required to provide
                                      additional telecopied written
                                      instructions of transaction requests.
                                      Neither the Fund nor the Transfer Agent
                                      will be responsible for any loss,
                                      liability, cost or expense for following
                                      instructions received by telephone that
                                      it reasonably believes to be genuine.
</TABLE>
 
<TABLE>
<C>   <S>                        <C>
  H)  INTERESTED PARTY
      OPTION                                                                                      Name
      In addition to the
      account statement sent to
      my/our registered                                                                          Address
      address, I/we hereby
      authorize the fund to      City         State         Zip Code
      mail duplicate statements
      to the name and address
      provided at right.
</TABLE>
 
<TABLE>
<C>   <S>                        <C>
  I)  DEALER
      INFORMATION
                                 Representative Name                        Representative
                                 No.                            Branch
                                 No.
</TABLE>
 
<TABLE>
<C>   <S>                        <C>
  J)  SIGNATURE OF
      ALL HOLDERS
      AND TAXPAYER
      CERTIFICATION
      Sign Here ,
</TABLE>
 
<TABLE>
<S>                                  <C>
The undersigned certify that I/we have full authority and legal capacity
to purchase and redeem shares of the Fund and affirm that I/we have
received a current Prospectus of the Morgan Stanley Institutional Fund,
Inc. and agree to be bound by its terms.
  BY  SIGNING THIS APPLICATION,  I/WE HEREBY CERTIFY  UNDER PENALTIES OF
PERJURY THAT THE INFORMATION ON THIS APPLICATION IS COMPLETE AND CORRECT
AND THAT  AS REQUIRED  BY  FEDERAL LAW  (PLEASE CHECK  APPLICABLE  BOXES
BELOW):
/ / U.S. CITIZEN(S)/TAXPAYER(S):
       /  / I/WE CERTIFY THAT (1) THE NUMBER(S) SHOWN ABOVE ON THIS FORM
           IS/ARE THE  CORRECT SSN(S)  OR TIN(S)  AND (2)  I/WE ARE  NOT
           SUBJECT TO ANY BACKUP WITHHOLDING EITHER BECAUSE (A) I/WE ARE
           EXEMPT  FROM  BACKUP  WITHHOLDING;  (B)  I/WE  HAVE  NOT BEEN
           NOTIFIED BY THE  INTERNAL REVENUE SERVICE  ("IRS") THAT  I/WE
           ARE SUBJECT TO BACKUP WITHHOLDING AS A RESULT OF A FAILURE TO
           REPORT ALL INTEREST OR DIVIDENDS; OR (C) THE IRS HAS NOTIFIED
           ME/US   THAT  I  AM/WE  ARE   NO  LONGER  SUBJECT  TO  BACKUP
           WITHHOLDING.
       / / IF  NO TIN(S) OR  SSN(S) HAS/HAVE BEEN  PROVIDED ABOVE,  I/WE
           HAVE  APPLIED, OR INTEND  TO APPLY, TO THE  IRS OR THE SOCIAL
           SECURITY  ADMINISTRATION  FOR  A  TIN  OR  A  SSN  AND   I/WE
           UNDERSTAND THAT IF I/WE DO NOT PROVIDE EITHER NUMBER TO CHASE
           GLOBAL FUNDS SERVICES COMPANY ("CGFSC") WITHIN 60 DAYS OF THE
           DATE  OF THIS APPLICATION  OR IF I/WE  FAIL TO FURNISH MY/OUR
           CORRECT SSN(S) OR TIN(S),  I/WE MAY BE  SUBJECT TO A  PENALTY
           AND  A 31% BACKUP WITHHOLDING ON DISTRIBUTIONS AND REDEMPTION
           PROCEEDS. (PLEASE PROVIDE EITHER NUMBER ON IRS FORM W-9). YOU
           MAY REQUEST SUCH FORM BY CALLING CGFSC AT 800-282-4404.
/ / NON-U.S. CITIZEN(S)/TAXPAYER(S):
  INDICATE COUNTRY OF RESIDENCE FOR TAX PURPOSES:
  UNDER PENALTIES  OF  PERJURY, I/WE  CERTIFY  THAT I/WE  ARE  NOT  U.S.
CITIZENS  OR RESIDENTS AND I/WE ARE EXEMPT FOREIGN PERSONS AS DEFINED BY
THE INTERNAL REVENUE SERVICE.
THE INTERNAL  REVENUE  SERVICE DOES  NOT  REQUIRE YOUR  CONSENT  TO  ANY
PROVISION  OF THIS  DOCUMENT OTHER  THAN THE  CERTIFICATIONS REQUIRED TO
AVOID BACKUP WITHHOLDING.
 
                                     (X)
(X)                                  Signature (if joint account, both
Signature                                                                     Date must sign)         Date
</TABLE>
 
<PAGE>
<PAGE>
   MORGAN STANLEY INSTITUTIONAL FUND, INC.
          GLOBAL EQUITY, INTERNATIONAL EQUITY, INTERNATIONAL SMALL CAP,
           ASIAN EQUITY, EUROPEAN EQUITY, JAPANESE EQUITY AND LATIN AMERICAN
PORTFOLIOS
           P.O. BOX 2798, BOSTON, MA 02208-2798
 
                           ACCOUNT REGISTRATION FORM
 
<TABLE>
<C>   <S>                        <C>
                                 If you need assistance in filling out this form for the
      ACCOUNT INFORMATION        Morgan Stanley Institutional Fund, please contact your
      Fill in where applicable   Morgan Stanley representative or call us toll free
                                 1-(800)-548-7786. Please print all items except signature,
                                 and mail to the Fund at the address above.
 
  A)  REGISTRATION
      1. INDIVIDUAL
      2. JOINT TENANTS
         (RIGHTS OF
      SURVIVORSHIP PRESUMED
      UNLESS
         TENANCY IN COMMON
         IS INDICATED)
</TABLE>
 
1.
                               First
Name                          Initial                               Last Name
 
2.
                               First
Name                          Initial                               Last Name
 
                               First
Name                          Initial                               Last Name
 
<TABLE>
<C>   <S>                        <C>
      3. CORPORATIONS,
         TRUSTS AND OTHERS
         Please call the Fund
      for additional documents
      that may be required to
      set up account and to
      authorize transactions.
</TABLE>
 
3.
 
<TABLE>
<S>                     <C>                 <C>                   <C>               <C>
Type of Registration:   / / INCORPORATED    / / UNINCORPORATED    / / PARTNERSHIP   / / UNIFORM GIFT/TRANSFER TO MINOR
                                            ASSOCIATION                               (ONLY ONE CUSTODIAN AND MINOR PERMITTED)
</TABLE>
 
/ / TRUST ________________________  / / OTHER (Specify) ________________________
 
<TABLE>
<C>   <S>                        <C>
  B)  MAILING ADDRESS
      Please fill in
      completely, including
      telephone number(s).
</TABLE>
 
Street or P.O. Box
City                                                                       State
                                                                             Zip
                                                                              --
Home Telephone No.                                                   Business
Telephone No.                     --            --              --            --
/ / United States Citizen  / / Resident Alien  / / Non-Resident Alien: Indicate
Country of Residence ___________________________________________________________
 
<TABLE>
<C>   <S>                        <C>                             <C>
  C)  TAXPAYER                   Enter your Taxpayer Identification Number. For most individual
      IDENTIFICATION             taxpayers, this is your Social Security Number.
      NUMBER
      1. INDIVIDUAL
      2.JOINT TENANTS
         (RIGHTS OF
      SURVIVORSHIP PRESUMED
      UNLESS
         TENANCY IN COMMON
         IS INDICATED)
      For Custodian account
      of a minor (Uniform
      Gifts/Transfers to Minor
      Acts), give the Social
      Security Number of
      the minor
                                                                 OR
                                 1.         TAXPAYER             SOCIAL SECURITY NUMBER
                                 IDENTIFICATION NUMBER           ("SSN")
                                 ("TIN")
                                                                 OR
                                 2.                             TIN                                SSN
                                                                 OR
                                                               TIN                                SSN
</TABLE>
<PAGE>
 
<TABLE>
<C>   <S>                        <C>                             <C>
                                 IMPORTANT TAX INFORMATION
                                 You (as a payee) are required by law to provide us (as payer)
                                 with your correct TIN(s) or SSN(s). Accounts that have a
                                 missing or incorrect TIN(s) or SSN(s) will be subject to
                                 backup withholding at a 31% rate on dividends, distributions
                                 and other payments. If you have not provided us with your
                                 correct TIN(s) or SSN(s), you may be subject to a $50 penalty
                                 imposed by the Internal Revenue Service.
                                 Backup withholding is not an additional tax; the tax liability
                                 of persons subject to backup withholding will be reduced by
                                 the amount of tax withheld. If withholding results in an
                                 overpayment of taxes, a refund may be obtained.
                                 You may be notified that you are subject to backup withholding
                                 under Section 3406(a)(1)(C) of the Internal Revenue Code
                                 because you have underreported interest or dividends or you
                                 were required to, but failed to, file a return which would
                                 have included a reportable interest or dividend payment.
</TABLE>
 
<PAGE>
 
<TABLE>
<C>   <S>                        <C>                             <C>                   <C>
  D)  PORTFOLIO AND              For Purchase of the following   / / Class A Shares $  / / Class B Shares $
      CLASS SECTION              Portfolio(s):                   / / Class A Shares $
      (Class A shares minimum    Global Equity Portfolio         / / Class A Shares $  / / Class B Shares $
      $500,000 for each          International Small Cap         / / Class A Shares $  / / Class B Shares $
      Portfolio and Class B      Portfolio                       / / Class A Shares $  / / Class B Shares $
      shares minimum $100,000    European Equity Portfolio       / / Class A Shares $  / / Class B Shares $
      for the Global Equity,     Latin American Portfolio        / / Class A Shares $  / / Class B Shares $
      International Equity,      International Equity Portfolio
      Asian Equity, European     Asian Equity Portfolio
      Equity, Japanese Equity    Japanese Equity Portfolio
      and Latin American Equity
      Portfolios). Please
      indicate Portfolio, class
      and amount.
                                                                 Total Initial Investment $
</TABLE>
 
<TABLE>
<C>   <S>                        <C>
  E)  METHOD OF
      INVESTMENT
      Please indicate
      portfolio, manner of
      payment.
</TABLE>
 
Payment by:
 
/ / Check (MAKE CHECK PAYABLE TO MORGAN STANLEY INSTITUTIONAL FUND,
INC.--PORTFOLIO NAME)
 
<TABLE>
<S>                                                                                 <C>
/ / Exchange $ From                                                                           -- - - - - - - - - - -- - -
                                                      Name of Portfolio                               Account No.
/ / Account previously established by:  / / Phone exchange  / / Wire on                       - - - - - - - - - - - -- - -
                                                                                            Account No.               (Check
                                                                                      (Previously assigned by the Fund)     Digit)
                                                                            Date
</TABLE>
 
<TABLE>
<C>   <S>                        <C>
  F)  DISTRIBUTION               Income dividends and capital gains distributions (if any) to
      OPTION                     be reinvested in additional shares unless either box below
                                 is checked.
                                 / / Income dividends to be paid in cash, capital gains
                                 distributions (if any) in shares.
                                 / / Income dividends and capital gains distributions (if
                                 any) to be paid in cash.
</TABLE>
 
<TABLE>
<C>   <S>                             <C>                                       <C>
  G)  TELEPHONE                       / / I/we hereby authorize the Fund and
      REDEMPTION                      its agents to honor any telephone         Name of COMMERCIAL Bank (Not Savings
      AND EXCHANGE                    requests to wire redemption proceeds to   Bank)
      OPTION                          the commercial bank indicated at right    Bank Account No.
      Please select at time of        and/or mail redemption proceeds to the
      initial application if you      name and address in which my/our fund
      wish to redeem or exchange      account is registered if such requests                                        Bank
      shares by telephone. A          are believed to be authentic.                                                  ABA
      SIGNATURE GUARANTEE IS          The Fund and the Fund's Transfer Agent                                         No.
      REQUIRED IF BANK ACCOUNT IS     will employ reasonable procedures to
      NOT REGISTERED IDENTICALLY TO   confirm that instructions communicated    Name(s) in which your BANK Account is
      YOUR FUND ACCOUNT.              by telephone are genuine. These           Established
      TELEPHONE REQUESTS FOR          procedures include requiring the
      REDEMPTIONS OR EXCHANGE WILL    investor to provide certain personal      Bank's Street
      NOT BE HONORED UNLESS THE BOX   identification information at the time    Address
      IS CHECKED.                     an account is opened and prior to
                                      effecting each transaction requested by   City       State       Zip
                                      telephone. In addition, all telephone
                                      transaction requests will be recorded
                                      and investors may be required to provide
                                      additional telecopied written
                                      instructions of transaction requests.
                                      Neither the Fund nor the Transfer Agent
                                      will be responsible for any loss,
                                      liability, cost or expense for following
                                      instructions received by telephone that
                                      it reasonably believes to be genuine.
</TABLE>
 
<TABLE>
<C>   <S>                        <C>
  H)  INTERESTED PARTY
      OPTION                                                                                      Name
      In addition to the
      account statement sent to
      my/our registered                                                                          Address
      address, I/we hereby
      authorize the fund to        City                                         State                                         Z
      mail duplicate statements  Code
      to the name and address
      provided at right.
</TABLE>
 
<TABLE>
<C>   <S>                        <C>
  I)  DEALER
      INFORMATION
                                 Representative Name                        Representative
                                 No.                            Branch
                                 No.
</TABLE>
 
<PAGE>
 
<TABLE>
<C>   <S>                        <C>
  J)  SIGNATURE OF
      ALL HOLDERS
      AND TAXPAYER
      CERTIFICATION
      Sign Here ,
</TABLE>
 
<TABLE>
<S>                                  <C>
The undersigned certify that I/we have full authority and legal capacity
to purchase and redeem shares of the Fund and affirm that I/we have
received a current Prospectus of the Morgan Stanley Institutional Fund,
Inc. and agree to be bound by its terms.
  BY SIGNING THIS APPLICATION, I/WE HEREBY CERTIFY UNDER PENALTIES OF
PERJURY THAT THE INFORMATION ON THIS APPLICATION IS COMPLETE AND CORRECT
AND THAT AS REQUIRED BY FEDERAL LAW (PLEASE CHECK APPLICABLE BOXES
BELOW):
/ / U.S. CITIZEN(S)/TAXPAYER(S):
       / / I/WE CERTIFY THAT (1) THE NUMBER(S) SHOWN ABOVE ON THIS FORM
           IS/ARE THE CORRECT SSN(S) OR TIN(S) AND (2) I/WE ARE NOT
           SUBJECT TO ANY BACKUP WITHHOLDING EITHER BECAUSE (A) I/WE ARE
           EXEMPT FROM BACKUP WITHHOLDING; (B) I/WE HAVE NOT BEEN
           NOTIFIED BY THE INTERNAL REVENUE SERVICE ("IRS") THAT I/WE
           ARE SUBJECT TO BACKUP WITHHOLDING AS A RESULT OF A FAILURE TO
           REPORT ALL INTEREST OR DIVIDENDS; OR (C) THE IRS HAS NOTIFIED
           ME/US THAT I AM/WE ARE NO LONGER SUBJECT TO BACKUP
           WITHHOLDING.
       / / IF NO TIN(S) OR SSN(S) HAS/HAVE BEEN PROVIDED ABOVE, I/WE
           HAVE APPLIED, OR INTEND TO APPLY, TO THE IRS OR THE SOCIAL
           SECURITY ADMINISTRATION FOR A TIN OR A SSN AND I/WE
           UNDERSTAND THAT IF I/WE DO NOT PROVIDE EITHER NUMBER TO CHASE
           GLOBAL FUNDS SERVICES COMPANY ("CGFSC") WITHIN 60 DAYS OF THE
           DATE OF THIS APPLICATION OR IF I/WE FAIL TO FURNISH MY/OUR
           CORRECT SSN(S) OR TIN(S), I/WE MAY BE SUBJECT TO A PENALTY
           AND A 31% BACKUP WITHHOLDING ON DISTRIBUTIONS AND REDEMPTION
           PROCEEDS. (PLEASE PROVIDE EITHER NUMBER ON IRS FORM W-9). YOU
           MAY REQUEST SUCH FORM BY CALLING CGFSC AT 800-282-4404.
/ / NON-U.S. CITIZEN(S)/TAXPAYER(S):
  INDICATE COUNTRY OF RESIDENCE FOR TAX PURPOSES:
  UNDER PENALTIES OF PERJURY, I/WE CERTIFY THAT I/WE ARE NOT U.S.
CITIZENS OR RESIDENTS AND I/WE ARE EXEMPT FOREIGN PERSONS AS DEFINED BY
THE INTERNAL REVENUE SERVICE.
THE INTERNAL REVENUE SERVICE DOES NOT REQUIRE YOUR CONSENT TO ANY
PROVISION OF THIS DOCUMENT OTHER THAN THE CERTIFICATIONS REQUIRED TO
AVOID BACKUP WITHHOLDING.
 
                                     (X)
(X)                                  Signature (if joint account, both
Signature                                                         Date must sign)         Date
</TABLE>
<PAGE>
   MORGAN STANLEY INSTITUTIONAL FUND, INC.
          GOLD PORTFOLIO
           P.O. BOX 2798, BOSTON, MA 02208-2798
 
                           ACCOUNT REGISTRATION FORM
 
<TABLE>
<C>   <S>                        <C>
                                 If you need assistance in filling out this form for the
      ACCOUNT INFORMATION        Morgan Stanley Institutional Fund, please contact your
      Fill in where applicable   Morgan Stanley representative or call us toll free
                                 1-(800)-548-7786. Please print all items except signature,
                                 and mail to the Fund at the address above.
 
  A)  REGISTRATION
      1. INDIVIDUAL
      2. JOINT TENANTS
         (RIGHTS OF
      SURVIVORSHIP PRESUMED
      UNLESS
         TENANCY IN COMMON
         IS INDICATED)
</TABLE>
 
1.
                               First
Name                          Initial                               Last Name
 
2.
                               First
Name                          Initial                               Last Name
 
                               First
Name                          Initial                               Last Name
 
<TABLE>
<C>   <S>                        <C>
      3. CORPORATIONS,
         TRUSTS AND OTHERS
         Please call the Fund
      for additional documents
      that may be required to
      set up account and to
      authorize transactions.
</TABLE>
 
3.
 
<TABLE>
<S>                     <C>                 <C>                   <C>               <C>
Type of Registration:   / / INCORPORATED    / / UNINCORPORATED    / / PARTNERSHIP   / / UNIFORM GIFT/TRANSFER TO MINOR
                                            ASSOCIATION                               (ONLY ONE CUSTODIAN AND MINOR PERMITTED)
</TABLE>
 
/ / TRUST ________________________  / / OTHER (Specify) ________________________
 
<TABLE>
<C>   <S>                        <C>
  B)  MAILING ADDRESS
      Please fill in
      completely, including
      telephone number(s).
</TABLE>
 
Street or P.O. Box
City                                                                       State
                                                                             Zip
                                                                              --
Home Telephone No.                                                   Business
Telephone No.                     --            --              --            --
/ / United States Citizen  / / Resident Alien  / / Non-Resident Alien: Indicate
Country of Residence ___________________________________________________________
 
<TABLE>
<C>   <S>                        <C>                             <C>
  C)  TAXPAYER                   Enter your Taxpayer Identification Number. For most individual
      IDENTIFICATION             taxpayers, this is your Social Security Number.
      NUMBER
      1. INDIVIDUAL
      2. JOINT TENANTS
         (RIGHTS OF
      SURVIVORSHIP PRESUMED
      UNLESS
         TENANCY IN COMMON
         IS INDICATED)
      For Custodian account
      of a minor (Uniform
      Gifts/Transfers to Minor
      Acts), give the Social
      Security Number of
      the minor
                                                                 OR
                                 1.         TAXPAYER             SOCIAL SECURITY NUMBER
                                 IDENTIFICATION NUMBER           ("SSN")
                                 ("TIN")
                                                                 OR
                                 2.                                                          TIN                                SSN
</TABLE>
<PAGE>
<TABLE>
<C>   <S>                        <C>                             <C>
                                                                 OR
                                                               TIN                                SSN
 
                                 IMPORTANT TAX INFORMATION
                                 You (as a payee) are required by law to provide us (as  payer)
                                 with  your  correct TIN(s)  or  SSN(s). Accounts  that  have a
                                 missing or  incorrect  TIN(s) or  SSN(s)  will be  subject  to
                                 backup  withholding at a 31%  rate on dividends, distributions
                                 and other  payments. If  you have  not provided  us with  your
                                 correct  TIN(s) or SSN(s), you may be subject to a $50 penalty
                                 imposed by the Internal Revenue Service.
                                 Backup withholding is not an additional tax; the tax liability
                                 of persons subject  to backup withholding  will be reduced  by
                                 the  amount  of tax  withheld.  If withholding  results  in an
                                 overpayment   of   taxes,   a   refund   may   be    obtained.
                                 You may be notified that you are subject to backup withholding
                                 under  Section  3406(a)(1)(C)  of  the  Internal  Revenue Code
                                 because you have  underreported interest or  dividends or  you
                                 were  required to,  but failed to,  file a  return which would
                                 have included a reportable interest or dividend payment.
</TABLE>
 
<PAGE>
 
<TABLE>
<C>   <S>                        <C>                             <C>                   <C>
  D)  PORTFOLIO AND              For Purchase of the following   / / Class A Shares $  / / Class B Shares $
      CLASS SECTION              Portfolio:
      (Class A shares minimum    Gold Portfolio
      $500,000 for each
      Portfolio and Class B
      shares minimum $100,000
      for the Global Equity,
      International Equity,
      Asian Equity, European
      Equity, Japanese Equity
      and Latin American Equity
      Portfolios). Please
      indicate Portfolio, class
      and amount.
                                                                 Total Initial Investment $
</TABLE>
 
<TABLE>
<C>   <S>                        <C>
  E)  METHOD OF
      INVESTMENT
      Please indicate
      portfolio, manner of
      payment.
</TABLE>
 
Payment by:
 
/ / Check (MAKE CHECK PAYABLE TO MORGAN STANLEY INSTITUTIONAL FUND,
INC.--PORTFOLIO NAME)
 
<TABLE>
<S>                                                                                 <C>
/ / Exchange $ From                                                                           -- - - - - - - - - - -- - -
                                                      Name of Portfolio                               Account No.
/ / Account previously established by:  / / Phone exchange  / / Wire on                       - - - - - - - - - - - -- - -
                                                                                            Account No.               (Check
                                                                                      (Previously assigned by the Fund)     Digit)
                                                                            Date
</TABLE>
 
<TABLE>
<C>   <S>                        <C>
  F)  DISTRIBUTION               Income dividends and capital gains distributions (if any) to
      OPTION                     be reinvested in additional shares unless either box below
                                 is checked.
                                 / / Income dividends to be paid in cash, capital gains
                                 distributions (if any) in shares.
                                 / / Income dividends and capital gains distributions (if
                                 any) to be paid in cash.
</TABLE>
 
<TABLE>
<C>   <S>                             <C>                                       <C>
  G)  TELEPHONE                       / / I/we hereby authorize the Fund and
      REDEMPTION                      its agents to honor any telephone         Name of COMMERCIAL Bank (Not Savings
      AND EXCHANGE                    requests to wire redemption proceeds to   Bank)
      OPTION                          the commercial bank indicated at right    Bank Account No.
      Please select at time of        and/or mail redemption proceeds to the
      initial application if you      name and address in which my/our fund
      wish to redeem or exchange      account is registered if such requests                                        Bank
      shares by telephone. A          are believed to be authentic.                                                  ABA
      SIGNATURE GUARANTEE IS          The Fund and the Fund's Transfer Agent                                         No.
      REQUIRED IF BANK ACCOUNT IS     will employ reasonable procedures to
      NOT REGISTERED IDENTICALLY TO   confirm that instructions communicated    Name(s) in which your BANK Account is
      YOUR FUND ACCOUNT.              by telephone are genuine. These           Established
      TELEPHONE REQUESTS FOR          procedures include requiring the
      REDEMPTIONS OR EXCHANGE WILL    investor to provide certain personal      Bank's Street
      NOT BE HONORED UNLESS THE BOX   identification information at the time    Address
      IS CHECKED.                     an account is opened and prior to
                                      effecting each transaction requested by   City      State     Zip
                                      telephone. In addition, all telephone
                                      transaction requests will be recorded
                                      and investors may be required to provide
                                      additional telecopied written
                                      instructions of transaction requests.
                                      Neither the Fund nor the Transfer Agent
                                      will be responsible for any loss,
                                      liability, cost or expense for following
                                      instructions received by telephone that
                                      it reasonably believes to be genuine.
</TABLE>
 
<TABLE>
<C>   <S>                        <C>
  H)  INTERESTED PARTY
      OPTION                                                                                      Name
      In addition to the
      account statement sent to
      my/our registered                                                                          Address
      address, I/we hereby
      authorize the fund to        City                                         State                                         Z
      mail duplicate statements  Code
      to the name and address
      provided at right.
</TABLE>
 
<TABLE>
<C>   <S>                        <C>
  I)  DEALER
      INFORMATION
                                 Representative Name                        Representative
                                 No.                            Branch
                                 No.
</TABLE>
 
<PAGE>
 
<TABLE>
<C>   <S>                        <C>
  J)  SIGNATURE OF
      ALL HOLDERS
      AND TAXPAYER
      CERTIFICATION
      Sign Here ,
</TABLE>
 
<TABLE>
<S>                                  <C>
The undersigned certify that I/we have full authority and legal capacity
to purchase and redeem shares of the Fund and affirm that I/we have
received a current Prospectus of the Morgan Stanley Institutional Fund,
Inc. and agree to be bound by its terms.
  BY SIGNING THIS  APPLICATION, I/WE HEREBY  CERTIFY UNDER PENALTIES  OF
PERJURY THAT THE INFORMATION ON THIS APPLICATION IS COMPLETE AND CORRECT
AND  THAT  AS REQUIRED  BY FEDERAL  LAW  (PLEASE CHECK  APPLICABLE BOXES
BELOW):
/ / U.S. CITIZEN(S)/TAXPAYER(S):
       / / I/WE CERTIFY THAT (1) THE NUMBER(S) SHOWN ABOVE ON THIS  FORM
           IS/ARE  THE CORRECT  SSN(S) OR  TIN(S) AND  (2) I/WE  ARE NOT
           SUBJECT TO ANY BACKUP WITHHOLDING EITHER BECAUSE (A) I/WE ARE
           EXEMPT FROM  BACKUP  WITHHOLDING;  (B)  I/WE  HAVE  NOT  BEEN
           NOTIFIED  BY THE  INTERNAL REVENUE SERVICE  ("IRS") THAT I/WE
           ARE SUBJECT TO BACKUP WITHHOLDING AS A RESULT OF A FAILURE TO
           REPORT ALL INTEREST OR DIVIDENDS; OR (C) THE IRS HAS NOTIFIED
           ME/US  THAT  I  AM/WE  ARE   NO  LONGER  SUBJECT  TO   BACKUP
           WITHHOLDING.
       /  / IF  NO TIN(S) OR  SSN(S) HAS/HAVE BEEN  PROVIDED ABOVE, I/WE
           HAVE APPLIED, OR INTEND  TO APPLY, TO THE  IRS OR THE  SOCIAL
           SECURITY   ADMINISTRATION  FOR  A  TIN  OR  A  SSN  AND  I/WE
           UNDERSTAND THAT IF I/WE DO NOT PROVIDE EITHER NUMBER TO CHASE
           GLOBAL FUNDS SERVICES COMPANY ("CGFSC") WITHIN 60 DAYS OF THE
           DATE OF THIS APPLICATION  OR IF I/WE  FAIL TO FURNISH  MY/OUR
           CORRECT  SSN(S) OR TIN(S),  I/WE MAY BE  SUBJECT TO A PENALTY
           AND A 31% BACKUP WITHHOLDING ON DISTRIBUTIONS AND  REDEMPTION
           PROCEEDS. (PLEASE PROVIDE EITHER NUMBER ON IRS FORM W-9). YOU
           MAY REQUEST SUCH FORM BY CALLING CGFSC AT 800-282-4404.
/ / NON-U.S. CITIZEN(S)/TAXPAYER(S):
  INDICATE COUNTRY OF RESIDENCE FOR TAX PURPOSES:
  UNDER  PENALTIES  OF  PERJURY, I/WE  CERTIFY  THAT I/WE  ARE  NOT U.S.
CITIZENS OR RESIDENTS AND I/WE ARE EXEMPT FOREIGN PERSONS AS DEFINED  BY
THE INTERNAL REVENUE SERVICE.
THE  INTERNAL  REVENUE  SERVICE DOES  NOT  REQUIRE YOUR  CONSENT  TO ANY
PROVISION OF THIS  DOCUMENT OTHER  THAN THE  CERTIFICATIONS REQUIRED  TO
AVOID BACKUP WITHHOLDING.
 
                                     (X)
(X)                                  Signature (if joint account, both
Signature                                                                     Date must sign)         Date
</TABLE>
<PAGE>
                       SUPPLEMENT DATED DECEMBER 30, 1996
                      TO THE PROSPECTUS DATED MAY 1, 1996
 
                         INTERNATIONAL MAGNUM PORTFOLIO
 
                                PORTFOLIO OF THE
 
                    MORGAN STANLEY INSTITUTIONAL FUND, INC.
                                 P.O. BOX 2798
                             BOSTON, MASSACHUSETTS
                                   02208-2798
                                 -------------
 
    The Prospectus as amended and supplemented to date is further amended and
supplemented by changing the following:
 
        Under the heading "PROSPECTUS SUMMARY" under the subheading "HOW TO
    INVEST," the first paragraph is deleted and replaced with the following:
 
    HOW TO INVEST
 
        Class A shares of the Portfolio are offered directly to investors at
    net asset value with no sales commission or 12b-1 charges. Class B
    shares of the Portfolio are offered at net asset value with no sales
    commission, but with a 12b-1 fee, which is accrued daily and paid
    quarterly, equal to 0.25%, on an annualized basis, of the Class B
    shares' average daily net assets. Share purchases may be made by sending
    investments directly to the Fund or through the Distributor. The minimum
    initial investment for shares in a Portfolio account is $500,000 for
    Class A shares and $100,000 for Class B shares. Certain exceptions to
    the foregoing minimums apply to (1) Portfolio accounts held by certain
    employees of the Adviser and of its affiliates and (2) certain advisory
    or asset allocation accounts, such as Total Funds Management accounts,
    managed by Morgan Stanley or its affiliates, including the Adviser
    ("Managed Accounts"). The Adviser reserves the right in its sole
    discretion to determine which of such advisory or asset allocation
    accounts shall be Managed Accounts. For information regarding Managed
    Accounts, please contact your Morgan Stanley account representative or
    the Fund at the telephone number provided on the cover of this
    Prospectus. The minimum investment levels may be waived at the
    discretion of the Adviser for (i) certain employees and customers of
    Morgan Stanley or its affiliates and certain trust departments, brokers,
    dealers, agents, financial planners, financial services firms, or
    investment advisers that have entered into an agreement with Morgan
    Stanley or its affiliates; and (ii) retirement and deferred compensation
    plans and trusts used to fund such plans, including, but not limited to,
    those defined in Section 401(a), 403(b) or 457 of the Internal Revenue
    Code of 1986, as amended, and "rabbi trusts". See "Purchase of Shares --
    Minimum Investment and Account Sizes; Conversion from Class A to Class B
    Shares."
                                 --------------
<PAGE>
    Under the heading "PURCHASE OF SHARES," under the subheadings "MINIMUM
INVESTMENT AND ACCOUNT SIZES; CONVERSION FROM CLASS A TO CLASS B SHARES" and
"MINIMUM ACCOUNT SIZES AND INVOLUNTARY REDEMPTION OF SHARES," these two sections
are deleted and replaced with the following:
 
    MINIMUM INVESTMENT AND ACCOUNT SIZES; CONVERSION FROM CLASS A TO CLASS B
    SHARES
 
        For a Portfolio account, the minimum initial investment and minimum
    account size are $500,000 for Class A shares and $100,000 for Class B
    shares. Managed Accounts may purchase Class A shares without being
    subject to such minimum initial investment or minimum account size
    requirements for a Portfolio account. Employees of the Adviser and of
    its affiliates may purchase Class A shares subject to conditions,
    including a lower minimum initial investment established by Officers of
    the Fund.
 
        If the value of a Portfolio account containing Class A shares falls
    below $500,000 (but remains at or above $100,000) because of shareholder
    redemption(s), the Fund will notify the shareholder, and if the account
    value remains below $500,000 (but remains at or above $100,000) for a
    continuous 60-day period, the Class A shares in such account will
    convert to Class B shares and will be subject to the distribution fee
    and other features applicable to the Class B shares. The Fund, however,
    will not convert Class A shares to Class B shares based solely upon
    changes in the market that reduce the net asset value of shares. Under
    current tax law, conversions between share classes are not a taxable
    event to the shareholder. Managed Accounts are not subject to conversion
    from Class A shares to Class B shares.
 
        Investors may also invest in the Portfolio by purchasing shares
    through a trust department, broker, dealer, agent, financial planner,
    financial services firm or investment adviser. An investor may be
    charged an additional service or transaction fee by that institution.
    The minimum investment levels may be waived at the discretion of the
    Adviser for (i) certain employees and customers of Morgan Stanley or its
    affiliates and certain trust departments, brokers, dealers, agents,
    financial planners, financial services firms, or investment advisers
    that have entered into an agreement with Morgan Stanley or its
    affiliates; and (ii) retirement and deferred compensation plans and
    trusts used to fund such plans, including, but not limited to, those
    defined in Section 401(a), 403(b) or 457 of the Internal Revenue Code of
    1986, as amended, and "rabbi trusts". The Fund reserves the right to
    modify or terminate the conversion features of the shares as stated
    above at any time upon 60-days' notice to shareholders.
 
    MINIMUM ACCOUNT SIZES AND INVOLUNTARY REDEMPTION OF SHARES
 
        If the value of a Portfolio account falls below $100,000 because of
    shareholder redemption(s), the Fund will notify the shareholder, and if
    the account value remains below $100,000 for a continuous 60-day period,
    the shares in such account are subject to redemption by the Fund and, if
    redeemed, the net asset value of such shares will be promptly paid to
    the shareholder. The Fund, however, will not redeem shares based solely
    upon changes in the market that reduce the net asset value of shares.
 
        The Fund reserves the right to modify or terminate the involuntary
    redemption features of the shares as stated above at any time upon
    60-days' notice to shareholders.
                                 --------------
 
    The Account Registration Form is deleted and replaced with the form enclosed
with this supplement.
<PAGE>
<TABLE>
<S>                                                                 <C>
   MORGAN STANLEY INSTITUTIONAL FUND, INC.
          INTERNATIONAL MAGNUM PORTFOLIO
           P.O. BOX 2798, BOSTON, MA 02208-2798
 
                           ACCOUNT REGISTRATION FORM
 
                                                                     If you need assistance in filling out this form for the
      ACCOUNT INFORMATION                                            Morgan Stanley Institutional Fund, please contact your
      Fill in where applicable                                       Morgan Stanley representative or call us toll free 1 (800)
                                                                     548-7786. Please print all items except signature, and mail
                                                                     to the Fund at the address above.
 
 A)   REGISTRATION
 
                            1.

      1. INDIVIDUAL
 
                                                              First
Name                      Initial                          Last Name

      2. JOINT TENANTS
 
        (RIGHTS OF SURVIVORSHIP
 
                            2.

        PRESUMED UNLESS
 
                                                              First
Name                      Initial                          Last Name

        TENANCY IN COMMON
 
        IS INDICATED)
 
                                                              First
Name                      Initial                          Last Name
 
                            3.
 
      3. CORPORATIONS,
        TRUSTS AND OTHERS
        Please call the Fund for additional documents that may be
      required to set up account and to authorize transactions
</TABLE>

<TABLE>
<S>                    <C>               <C>                 <C>              <C>
Type of Registration:  / / INCORPORATED  / / UNINCORPORATED  / / PARTNERSHIP  / / UNIFORM GIFT/TRANSFER TO MINOR
                                         ASSOCIATION                            (ONLY ONE CUSTODIAN AND MINOR PERMITTED)
 
                            / / TRUST __________  / / OTHER (Specify) __________
 
                                    Street or P.O. Box
 
 B)   MAILING ADDRESS
      Please fill in completely, including telephone number(s).
 
                            City                                           State
                                                                             Zip
                                                                              --
                                           Home Telephone
No.                                                   Business Telephone No.
                                                         --       -- --       --
                            / / United States Citizen  / / Resident Alien  / /
Non-Resident Alien: Indicate Country of Residence ______________________________
 
 C)  TAXPAYER                                  PART 1. Enter your Taxpayer               IMPORTANT TAX INFORMATION
     IDENTIFICATION                            Identification Number. For most           You  (as a payee) are required by law to
     NUMBER                                    individual taxpayers, this is your        provide us (as payer) with your  correct
     If the account is in more than one name,  Social Security Number.                   taxpayer identification number. Accounts
     CIRCLE THE                                TAXPAYER IDENTIFICATION NUMBER            that   have   a  missing   or  incorrect
                                                                                         taxpayer identification  number will  be
                                                                                         subject  to backup withholding  at a 31%
                                                                                         rate on
 
                          --
 
     NAME OF THE PERSON WHOSE TAXPAYER         -- -- -- -- -- -- -- -- -- -- -- --       dividends,   distributions   and   other
     IDENTIFICATION NUMBER IS PROVIDED IN      OR                                        payments.  If you  have not  provided us
     SECTION A) ABOVE. If no name is circled,  SOCIAL SECURITY NUMBER                    with your correct taxpayer
     the number                                                                          identification  number,   you   may   be
                                                                                         subject  to a $50 penalty imposed by the
                                                                                         Internal Revenue Service.
                                                                                         Backup withholding is not an  additional
                                                                                         tax;   the  tax   liability  of  persons
                                                                                         subject to  backup withholding  will  be
                                                                                         reduced  by the amount  of tax withheld.
                                                                                         If withholding
 
                           --        --
 
     will be considered to be that of the      -- -- -- -- -- -- -- -- -- -- -- --       results in  an overpayment  of taxes,  a
     last name listed. For Custodian account   PART 2. BACKUP WITHHOLDING                refund  may be  obtained.    You  may be
     of a minor (Uniform Gifts/ Transfers to   / / Check this box if you are NOT         notified that you are subject to  backup
     Minors Acts), give the Social Security    subject to Backup Withholding under the   withholding  under Section 3406(a)(1)(C)
     Number of the minor.                      provisions of Section 3406(a)(1)(C) of    of the Internal Revenue Code because you
                                               the Internal Revenue Code.                have underreported interest or dividends
                                                                                         or you were  required to  but failed  to
                                                                                         file  a return which would have included
                                                                                         a  reportable   interest   or   dividend
                                                                                         payment.   IF  YOU  HAVE   NOT  BEEN  SO
                                                                                         NOTIFIED, CHECK  THE BOX  IN PART  2  AT
                                                                                         LEFT.
 D)  PORTFOLIO AND                  For Purchase of the following  / / Class A Shares
     CLASS SELECTION                Portfolio:
     (Class A shares minimum        International Magnum
     $500,000 and Class B shares    Portfolio
     minimum $100,000). Please
     indicate class and amount.
                                                                   Total Initial Investment $
 
 D)  / / Class B Shares
 
 
 
                                    Payment by:
 
                                    / / Check (MAKE CHECK PAYABLE TO MORGAN
STANLEY INSTITUTIONAL FUND, INC.--INTERNATIONAL MAGNUM PORTFOLIO)
 E)   METHOD OF
      INVESTMENT
      Please indicate manner of payment.
 
/ / Exchange $ From                                                                             -- - - - - - - - - - -- - -
                                           Name of Portfolio                                            Account No.
/ / Account previously established by:
/ / Phone exchange  / / Wire on                                                                 -- - - - - - - - - - -- - -
                                                                                               Account No.            (Check
                                                                                                 Previously assigned by the
                                                                                                       Fund   Digit)
                                                           Date
</TABLE>
 
<PAGE>
 
<TABLE>
<S>                                                                                       <C>
                                                                                          DISTRIBUTION
                                                                                    F)    OPTION
                                                                     Income
                                                                     dividends
                                                                     and
                                                                     capital
                                                                     gains
                                                                     distributions
                                                                     (if any) will
                                                                     be reinvested
                                                                     in additional
                                                                     shares unless
                                                                     either box
                                                                     below is
                                                                     checked.
                                                                     / /
                                                                     Income
                                                                     dividends
                                                                     to be
                                                                     paid in
                                                                     cash,
                                                                     capital
                                                                     gains
                                                                     distributions
                                                                     (if any) in
                                                                     shares.
                                                                     / /
                                                                     Income
                                                                     dividends
                                                                     and
                                                                     capital
                                                                     gains
                                                                     distributions
                                                                     (if any) to
                                                                     be paid in
                                                                     cash.
 
 G)  TELEPHONE                                 / / I/we hereby authorize the Fund and
     REDEMPTION                                its agents to honor any telephone         Name of COMMERCIAL Bank (Not Savings
     OPTION                                        requests to wire redemption proceeds  Bank)
     Please select at time of initial              to the commercial bank indicated at   Bank Account No.
     application if you wish to redeem shares      right and/or mail redemption
     by telephone. A SIGNATURE GUARANTEE IS                                    proceeds
     REQUIRED IF BANK ACCOUNT IS NOT                                                 to                                      Bank
     REGISTERED IDENTICALLY TO YOUR FUND                                            the                                       ABA
     ACCOUNT.                                                                      name                                       No.
     TELEPHONE REQUESTS FOR REDEMPTIONS OR                                          and
     EXCHANGES WILL NOT BE HONORED UNLESS THE                                   address  Name(s) in which your BANK Account is
     APPLICABLE BOX IS CHECKED.                                                      in  Established
                                                                                  which
                                                                                 my/our  Bank's Street
                                                                                   fund  Address
                                                                                account
                                                                                     is  City         State         Zip
                                                                             registered
                                                                                     if
                                                                                   such
                                                                               requests
                                                                                    are
                                                                               believed
                                                                                     to
                                                                                     be
                                                authentic.
                                               The Fund and the Fund's Transfer Agent
                                               will employ reasonable procedures to
                                               confirm that instructions communicated
                                               by telephone are genuine. These
                                               procedures include requiring the
                                               investor to provide certain personal
                                               identification information at the time
                                               an account is opened and prior to
                                               effecting each transaction requested by
                                               telephone. In addition, all telephone
                                               transaction requests will be recorded
                                               and investors may be required to provide
                                               additional telecopied written
                                               instructions of transaction requests.
                                               Neither the Fund nor the Transfer Agent
                                               will be responsible for any loss,
                                               liability, cost or expense for following
                                               instructions received by telephone that
                                               it reasonably believes to be genuine.
 
      In addition to the account statement sent to my/our
      registered address, I/we hereby authorize the fund to mail
      duplicate statements to the name and address provided at       Address
      right.                                                           City    State        Z
                                                                     Code
 
 I)   DEALER
      INFORMATION
                                                                     Representative Name                  Representative
                                                                     No.                     Branch No.
 
The  undersigned certify that I/we have full  authority and legal capacity to purchase and  redeem shares of the Fund and affirm
that I/we have
                                                            J)    SIGNATURE OF
received a current Prospectus  of the Morgan  Stanley Institutional Fund,  Inc. and agree to  be bound by  its terms. UNDER  THE
PENALTIES OF                                                      ALL HOLDERS
PERJURY, I/WE CERTIFY THAT THE INFORMATION PROVIDED IN SECTION C) ABOVE IS TRUE, CORRECT AND COMPLETE.
                                                                  AND TAXPAYER
The  Internal Revenue Service  does not require  your consent to  any provision of  this document other  than the certifications
required to                                                       CERTIFICATION
avoid backup withholding.
                                                                  Sign Here ,
</TABLE>

<PAGE>
- --------------------------------------------------------------------------------
                              P R O S P E C T U S
   -------------------------------------------------------------------------
 
                            EQUITY GROWTH PORTFOLIO
                           EMERGING GROWTH PORTFOLIO
                               MICROCAP PORTFOLIO
                          AGGRESSIVE EQUITY PORTFOLIO
 
                               PORTFOLIOS OF THE
                    MORGAN STANLEY INSTITUTIONAL FUND, INC.
 
                P.O. BOX 2798, BOSTON, MASSACHUSETTS 02208-2798
                      FOR INFORMATION CALL 1-800-548-7786
                                ----------------
 
    Morgan  Stanley Institutional Fund, Inc. (the "Fund") is a no-load, open-end
management investment company, or mutual fund, which offers redeemable shares in
a   series   of   diversified   and   non-diversified   investment    portfolios
("portfolios").   The  Fund   currently  consists   of  twenty-eight  portfolios
representing a  broad range  of  investment choices.  The  Fund is  designed  to
provide clients with attractive alternatives for meeting their investment needs.
This  prospectus (the  "Prospectus") pertains  to the  Class A  and the  Class B
shares of the  Equity Growth,  Emerging Growth, MicroCap  and Aggressive  Equity
Portfolios (the "Portfolios"). On January 2, 1996, the Portfolios began offering
two classes of shares, the Class A shares and the Class B shares, except for the
Money  Market,  Municipal Money  Market and  International Small  Cap Portfolios
which only offer Class  A Shares. All  shares of the  Portfolios owned prior  to
January 2, 1996 were redesignated Class A shares on January 2, 1996. The Class A
and  Class B shares  currently offered by the  Portfolios have different minimum
investment requirements and fund expenses. Shares of the portfolios are  offered
with  no sales charge or  exchange or redemption fee  (with the exception of the
International Small Cap Portfolio).
 
    The  EQUITY  GROWTH  PORTFOLIO  seeks  long-term  capital  appreciation   by
investing  primarily in  growth-oriented equity  securities of  medium and large
capitalization corporations.
 
    The EMERGING  GROWTH  PORTFOLIO  seeks  long-term  capital  appreciation  by
investing  primarily  in  growth-oriented equity  securities  of small-to-medium
sized corporations.
 
    The MICROCAP  PORTFOLIO seeks  long-term capital  appreciation by  investing
primarily in growth-oriented equity securities of small corporations.
 
    The  AGGRESSIVE EQUITY PORTFOLIO  is a non-diversified  portfolio that seeks
long-term capital appreciation  by investing primarily  in corporate equity  and
equity-linked securities.
 
    INVESTORS  SHOULD NOTE THAT EACH OF  THE EQUITY GROWTH AND AGGRESSIVE EQUITY
PORTFOLIOS MAY INVEST UP  TO 10% OF ITS  TOTAL ASSETS IN RESTRICTED  SECURITIES.
INVESTMENTS  IN RESTRICTED  SECURITIES IN  EXCESS OF  5% OF  A PORTFOLIO'S TOTAL
ASSETS MAY BE CONSIDERED  A SPECULATIVE ACTIVITY, MAY  INVOLVE GREATER RISK  AND
MAY INCREASE THE PORTFOLIO'S EXPENSES.
 
    The  Fund is designed  to meet the investment  needs of discerning investors
who place a premium on quality  and personal service. With Morgan Stanley  Asset
Management   Inc.  as   Adviser  and   Administrator  (the   "Adviser"  and  the
"Administrator"), and with Morgan Stanley & Co. Incorporated ("Morgan  Stanley")
as Distributor, the Fund makes available to institutional investors and high net
worth  individual  investors  a  series of  portfolios  which  benefit  from the
investment expertise and commitment to excellence associated with Morgan Stanley
and its affiliates.
 
    This Prospectus is designed to set forth concisely the information about the
Fund that a prospective investor should  know before investing and it should  be
retained  for future reference. The Fund  offers additional portfolios which are
described in other prospectuses and  under "Prospectus Summary" below. The  Fund
currently  offers the following portfolios:  (i) GLOBAL AND INTERNATIONAL EQUITY
- -- Active Country Allocation, Asian  Equity, Emerging Markets, European  Equity,
Global  Equity, Gold, International  Equity, International Magnum, International
Small Cap, Japanese Equity  and Latin American Portfolios;  (ii) U.S. EQUITY  --
Aggressive  Equity, Emerging  Growth, Equity  Growth, MicroCap,  Small Cap Value
Equity, Value Equity  and U.S. Real  Estate Portfolios; (iii)  EQUITY AND  FIXED
INCOME  -- Balanced Portfolio; (iv) FIXED INCOME -- Emerging Markets Debt, Fixed
Income,  Global  Fixed  Income,  High  Yield,  Mortgage-Backed  Securities   and
Municipal  Bond Portfolios; and  (v) MONEY MARKET --  Money Market and Municipal
Money Market Portfolios. Additional information about the Fund is contained in a
"Statement of Additional Information" dated  May 1, 1996, which is  incorporated
herein   by  reference.  The   Statement  of  Additional   Information  and  the
prospectuses pertaining to the other portfolios  of the Fund are available  upon
request  and without charge  by writing or  calling the Fund  at the address and
telephone number set forth above.
 
  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.
 
                  THE DATE OF THIS PROSPECTUS IS MAY 1, 1996.
                    SUPPLEMENTED THROUGH DECEMBER 30, 1996.
<PAGE>
                                 FUND EXPENSES
 
    The  following table illustrates the expenses and fees that a shareholder of
the Portfolios indicated below will incur:
 
<TABLE>
<CAPTION>
                                                           EQUITY      EMERGING                 AGGRESSIVE
                                                           GROWTH       GROWTH      MICROCAP      EQUITY
SHAREHOLDER TRANSACTION EXPENSES                          PORTFOLIO    PORTFOLIO    PORTFOLIO    PORTFOLIO
- -------------------------------------------------------  -----------  -----------  -----------  -----------
<S>                                                      <C>          <C>          <C>          <C>
Maximum Sales Load Imposed on Purchases
  Class A..............................................        None         None         None         None
  Class B..............................................        None         None         None         None
Maximum Sales Load Imposed on Reinvested Dividends
  Class A..............................................        None         None         None         None
  Class B..............................................        None         None         None         None
Deferred Sales Load
  Class A..............................................        None         None         None         None
  Class B..............................................        None         None         None         None
Redemption Fees
  Class A..............................................        None         None         None         None
  Class B..............................................        None         None         None         None
Exchange Fees
  Class A..............................................        None         None         None         None
  Class B..............................................        None         None         None         None
</TABLE>
 
<TABLE>
<CAPTION>
                                                           EQUITY      EMERGING                 AGGRESSIVE
                                                           GROWTH       GROWTH      MICROCAP      EQUITY
ANNUAL FUND OPERATING EXPENSES                            PORTFOLIO    PORTFOLIO    PORTFOLIO    PORTFOLIO
- -------------------------------------------------------  -----------  -----------  -----------  -----------
<S>                                                      <C>          <C>          <C>          <C>
 (AS A PERCENTAGE OF AVERAGE NET ASSETS)
Management Fee (Net of Fee Waivers)*
  Class A..............................................       0.52%        0.99%        1.05%+       0.21%
  Class B..............................................       0.52%        0.99%        1.05%+       0.21%
12b-1 Fees
  Class A..............................................        None         None         None         None
  Class B..............................................       0.25%        0.25%        0.25%+       0.25%
Other Expenses
  Class A..............................................       0.28%        0.26%        0.45%+       0.79%
  Class B..............................................       0.28%        0.26%        0.45%+       0.79%
                                                         -----------  -----------  -----------  -----------
Total Operating Expenses (Net of Fee Waivers)*
  Class A..............................................       0.80%        1.25%        1.50%+       1.00%
  Class B..............................................       1.05%        1.50%        1.75%+       1.25%
                                                         -----------  -----------  -----------  -----------
                                                         -----------  -----------  -----------  -----------
</TABLE>
 
- ------------------------
*The Adviser  has agreed  to waive  its management  fees and/or  reimburse  each
 Portfolio,  if necessary,  if such  fees would  cause any  of the  total annual
 operating expenses of the Portfolios to exceed a specified percentage of  their
 respective  average daily net assets. Set  forth below, for each Portfolio, are
 the management fees and total operating expenses absent such fee waivers and/or
 expense reimbursements as a percent of average daily net assets of the Class  A
 shares and Class B shares, respectively, of each Portfolio.
 
                                       2
<PAGE>
 
<TABLE>
<CAPTION>
                                                                                           TOTAL OPERATING
                                                                                         EXPENSES ABSENT FEE
                                                                                               WAIVERS
                                                              MANAGEMENT FEES ABSENT    ----------------------
PORTFOLIO                                                           FEE WAIVERS          CLASS A    CLASS B+
- -----------------------------------------------------------  -------------------------  ---------  -----------
<S>                                                          <C>                        <C>        <C>
Equity Growth..............................................              0.60%              0.88%       1.13%
Emerging Growth............................................              1.00%              1.26%       1.51%
MicroCap...................................................              1.25%              1.50%+      1.75%
Aggressive Equity..........................................              0.80%              1.59%       1.84%
</TABLE>
 
- ------------------------------
+  Estimated.
 
These  reductions became or  will become effective  as of the  inception of each
Portfolio. As a result of these reductions, the Management Fees stated above are
lower than  the contractual  fees stated  under "Management  of the  Fund."  For
further information on Fund expenses, see "Management of the Fund."
 
    The  purpose of the table  above is to assist  the investor in understanding
the various expenses that  an investor in the  Portfolios will bear directly  or
indirectly.  The Class A  expenses and fees  for the Equity  Growth and Emerging
Growth Portfolios are based on actual figures for the fiscal year ended December
31, 1995. The Class A expenses and fees for the MicroCap Portfolio are based  on
estimates,  assuming that the average daily net  assets of the Class A shares of
the MicroCap Portfolio will  be $50,000,000. The Class  B expenses and fees  for
each  Portfolio  are based  on estimates,  assuming that  the average  daily net
assets of  the Class  B shares  of each  Portfolio will  be $50,000,000.  "Other
Expenses"  include  Board  of  Directors'  fees  and  expenses,  amortization of
organizational costs, filing fees, professional  fees and costs for  shareholder
reports.  Due to  the continuous nature  of Rule  12b-1 fees, long  term Class B
shareholders may pay more than the  equivalent of the maximum front-end  charges
otherwise permitted by the Rules of Fair Practice of the National Association of
Securities Dealers, Inc. ("NASD").
 
                                       3
<PAGE>
    The  following  example illustrates  the expenses  that you  would pay  on a
$1,000 investment assuming (1) a 5% annual rate of return and (2) redemption  at
the  end of each time period. As noted in the table above, the Portfolios charge
no redemption fees of any kind. The example is based on total operating expenses
of the Portfolios after fee waivers.
 
<TABLE>
<CAPTION>
                                                                       1 YEAR       3 YEARS      5 YEARS     10 YEARS
                                                                     -----------  -----------  -----------  -----------
<S>                                                                  <C>          <C>          <C>          <C>
Equity Growth Portfolio
  Class A..........................................................   $       8    $      26    $      44    $      99
  Class B..........................................................          11           33           58          128
Emerging Growth Portfolio
  Class A..........................................................          13           40           69          151
  Class B..........................................................          15           47           82          179
MicroCap Portfolio
  Class A..........................................................          15           47        *            *
  Class B..........................................................          18           55        *            *
Aggressive Equity Portfolio
  Class A..........................................................          10           32           55          122
  Class B..........................................................          13           40           69          151
</TABLE>
 
- ------------------------------
*  Because the MicroCap Portfolio has not yet commenced operations the Fund  has
   not projected expenses beyond the 3-year period shown for the Portfolio.
 
    THIS  EXAMPLE SHOULD  NOT BE CONSIDERED  A REPRESENTATION OF  PAST OR FUTURE
EXPENSES OR  PERFORMANCE. ACTUAL  EXPENSES MAY  BE GREATER  OR LESS  THAN  THOSE
SHOWN.
 
    The  Fund intends  to comply  with all  state laws  that restrict investment
company expenses. Currently, the  most restrictive state  law requires that  the
aggregate  annual expenses  of an  investment company  shall not  exceed two and
one-half percent (2 1/2%) of  the first $30 million  of average net assets,  two
percent (2%) of the next $70 million of average net assets, and one and one-half
percent (1 1/2%) of the remaining net assets of such investment company.
 
    The  Adviser has agreed to a reduction in  the amounts payable to it, and to
reimburse the Portfolios, if  necessary, if in  any fiscal year  the sum of  the
Portfolios' expenses exceeds the limit set by applicable state law.
 
                                       4
<PAGE>
                              FINANCIAL HIGHLIGHTS
 
    The  following table provides financial highlights for the Class A shares of
the Equity Growth, Emerging Growth and Aggressive Equity Portfolios for each  of
the  periods presented. The audited financial  highlights for the Class A shares
for the fiscal year  ended December 31,  1995 are part  of the Fund's  financial
statements  which  appear  in the  Fund's  December  31, 1995  Annual  Report to
Shareholders and  which  are included  in  the Fund's  Statement  of  Additional
Information. The Portfolios' financial highlights for each of the periods in the
five  years ended December 31,  1995 have been audited  by Price Waterhouse LLP,
whose unqualified report thereon is also included in the Statement of Additional
Information. Additional  performance  information  for the  Class  A  shares  is
included  in the Annual  Report. The Annual Report  and the financial statements
therein, along with the Statement of Additional Information, are available at no
cost from the Fund at the address  and telephone number noted on the cover  page
of  this Prospectus.  Financial highlights  are not  available for  the MicroCap
Portfolio nor for  the new  Class B  shares since they  were not  offered as  of
December  31, 1995. Subsequent to October 31, 1992 (the Fund's prior fiscal year
end), the  Fund  changed its  fiscal  year end  to  December 31.  The  following
information  should be  read in  conjunction with  the financial  statements and
notes thereto.
 
                                       5
<PAGE>
                            EQUITY GROWTH PORTFOLIO
 
<TABLE>
<CAPTION>
                                       APRIL 2,                  TWO MONTHS
                                       1991* TO    YEAR ENDED       ENDED       YEAR ENDED     YEAR ENDED     YEAR ENDED
                                      OCTOBER 31,  OCTOBER 31,  DECEMBER 31,   DECEMBER 31,   DECEMBER 31,   DECEMBER 31,
                                         1991         1992          1992           1993           1994           1995
                                      -----------  -----------  -------------  -------------  -------------  -------------
<S>                                   <C>          <C>          <C>            <C>            <C>            <C>
NET ASSET VALUE, BEGINNING OF
 PERIOD.............................   $   10.00    $   10.66     $   11.44      $   11.88      $   12.14      $   12.02
                                      -----------  -----------  -------------  -------------  -------------  -------------
INCOME FROM INVESTMENT OPERATIONS
  Net Investment Income (1).........        0.05         0.16          0.03           0.22           0.17           0.22
  Net Realized and Unrealized Gain
   on Investments...................        0.61         0.82          0.41           0.28           0.21           4.93
                                      -----------  -----------  -------------  -------------  -------------  -------------
  Total from Investment
   Operations.......................        0.66         0.98          0.44           0.50           0.38           5.15
                                      -----------  -----------  -------------  -------------  -------------  -------------
DISTRIBUTIONS
  Net Investment Income.............          --        (0.20)           --          (0.23)         (0.13)         (0.28)
  In Excess of Net Investment
   Income...........................          --           --            --          (0.01)            --             --
  Net Realized Gain.................          --           --            --             --          (0.37)         (2.75)
                                      -----------  -----------  -------------  -------------  -------------  -------------
  Total Distributions...............          --        (0.20)           --          (0.24)         (0.50)         (3.03)
                                      -----------  -----------  -------------  -------------  -------------  -------------
NET ASSET VALUE, END OF PERIOD......   $   10.66    $   11.44     $   11.88      $   12.14      $   12.02      $   14.14
                                      -----------  -----------  -------------  -------------  -------------  -------------
                                      -----------  -----------  -------------  -------------  -------------  -------------
TOTAL RETURN........................        6.60%        9.26%         3.85%          4.33%          3.26%         45.02%
                                      -----------  -----------  -------------  -------------  -------------  -------------
                                      -----------  -----------  -------------  -------------  -------------  -------------
RATIOS AND SUPPLEMENTAL DATA:
Net Assets, End of Period
 (Thousands)........................   $  18,139    $  36,558     $  45,985      $  73,789      $  97,259      $ 158,112
Ratio of Expenses to Average Net
 Assets (1)(2)......................        0.80%**       0.80%        0.80%**        0.80%          0.80%          0.80%
Ratio of Net Investment Income to
 Average Net Assets (1)(2)..........        2.34%**       1.73%        1.93%**        1.59%          1.44%          1.57%
Portfolio Turnover Rate.............           3%          38%            1%           172%           146%           186%
- ------------------------------
(1) Effect of voluntary expense
    limitation during the period:
     Per share benefit to net
      investment income.............   $    0.03    $    0.02     $    0.01      $    0.02      $    0.01      $    0.01
   Ratios before expense limitation:
     Expenses to Average Net
      Assets........................        1.37%**       1.01%        1.11%**        0.93%          0.89%          0.88%
     Net Investment Income to
      Average Net Assets............        1.77%**       1.52%        1.62%**        1.46%          1.35%          1.49%
</TABLE>
 
(2) Under the terms of an Investment Advisory Agreement, the Adviser is entitled
    to receive a management  fee calculated at  an annual rate  of 0.60% of  the
    average  daily net  assets of the  Equity Growth Portfolio.  The Adviser has
    agreed to  waive a  portion of  this fee  and/or reimburse  expenses of  the
    Equity  Growth Portfolio to the extent  that the total operating expenses of
    the Equity Growth Portfolio exceed 0.80% of the average daily net assets  of
    the  Class A shares and 1.05% of the average daily net assets of the Class B
    shares. In the  period ended October  31, 1991, the  year ended October  31,
    1992,  the two months ended December 31,  1992, the years ended December 31,
    1993, 1994 and 1995,  the Adviser waived  management fees and/or  reimbursed
    expenses totalling $23,000, $51,000, $22,000, $68,000, $83,000 and $105,000,
    respectively, for the Equity Growth Portfolio.
 
 * Commencement of Operations.
** Annualized.
 
                                       6
<PAGE>
                           EMERGING GROWTH PORTFOLIO
<TABLE>
<CAPTION>
                                 NOVEMBER 1,                                     TWO MONTHS
                                  1989* TO       YEAR ENDED      YEAR ENDED         ENDED        YEAR ENDED      YEAR ENDED
                                 OCTOBER 31,     OCTOBER 31,     OCTOBER 31,    DECEMBER 31,    DECEMBER 31,    DECEMBER 31,
                                    1990           1991++           1992            1992            1993            1994
                                -------------   -------------   -------------   -------------   -------------   -------------
<S>                             <C>             <C>             <C>             <C>             <C>             <C>
NET ASSET VALUE, BEGINNING OF
 PERIOD.......................  $     10.00     $      9.03     $     16.18     $     14.97     $     16.22     $     16.22
                                -------------   -------------   -------------   -------------   -------------   -------------
INCOME FROM INVESTMENT
 OPERATIONS
  Net Investment Income/
   (Loss) (1).................         0.08              --           (0.09)          (0.01)          (0.11)          (0.09)
  Net Realized and Unrealized
   Gain/(Loss) on
   Investments................        (1.00)           7.19           (1.12)           1.26            0.11           (0.01)
                                -------------   -------------   -------------   -------------   -------------   -------------
  Total from Investment
   Operations.................        (0.92)           7.19           (1.21)           1.25            0.00           (0.10)
                                -------------   -------------   -------------   -------------   -------------   -------------
DISTRIBUTIONS
  Net Investment Income.......        (0.05)          (0.04)             --              --              --              --
                                -------------   -------------   -------------   -------------   -------------   -------------
NET ASSET VALUE, END OF
 PERIOD.......................  $      9.03     $     16.18     $     14.97     $     16.22     $     16.22     $     16.12
                                -------------   -------------   -------------   -------------   -------------   -------------
                                -------------   -------------   -------------   -------------   -------------   -------------
TOTAL RETURN..................        (9.27)%         79.84%          (7.48)%          8.35%           0.00%          (0.62)%
                                -------------   -------------   -------------   -------------   -------------   -------------
                                -------------   -------------   -------------   -------------   -------------   -------------
RATIO AND SUPPLEMENTAL DATA:
Net Assets, End of Period
 (Thousands)..................  $    11,261     $    54,364     $    80,156     $    94,161     $   103,621     $   117,669
Ratio of Expenses to Average
 Net Assets (1)(2)............         1.26%**         1.25%           1.25%           1.25%**         1.25%           1.25%
Ratio of Net Investment
 Income/ (Loss) to Average Net
 Assets (1)(2)................         0.64%**         0.00%          (0.66)%         (0.68)%**       (0.77)%         (0.61)%
Portfolio Turnover Rate.......           19%              2%             17%              1%             25%             24%
- ------------------------------
(1) Effect of voluntary expense limitation during the period:
     Per share benefit to net
      investment income.......  $      0.01     $      0.02     $      0.01     $      0.00     $      0.01     $     0.002
   Ratios before expense
    limitation:
     Expenses to Average Net
      Assets..................         1.64%           1.39%           1.29%           1.36%**         1.31%           1.26%
     Net Investment Income
      (Loss) to Average Net
      Assets..................         0.24%          (0.14)%         (0.71)%         (0.79)%**       (0.83)%         (0.62)%
 
<CAPTION>
 
                                 YEAR ENDED
                                DECEMBER 31,
                                    1995
                                -------------
<S>                             <C>
NET ASSET VALUE, BEGINNING OF
 PERIOD.......................  $     16.12
                                -------------
INCOME FROM INVESTMENT
 OPERATIONS
  Net Investment Income/
   (Loss) (1).................        (0.18)
  Net Realized and Unrealized
   Gain/(Loss) on
   Investments................         5.55
                                -------------
  Total from Investment
   Operations.................         5.37
                                -------------
DISTRIBUTIONS
  Net Investment Income.......           --
                                -------------
NET ASSET VALUE, END OF
 PERIOD.......................  $     21.49
                                -------------
                                -------------
TOTAL RETURN..................        33.31%
                                -------------
                                -------------
RATIO AND SUPPLEMENTAL DATA:
Net Assets, End of Period
 (Thousands)..................  $   119,378
Ratio of Expenses to Average
 Net Assets (1)(2)............         1.25%
Ratio of Net Investment
 Income/ (Loss) to Average Net
 Assets (1)(2)................        (0.76)%
Portfolio Turnover Rate.......           25%
- ------------------------------
(1) Effect of voluntary expens
     Per share benefit to net
      investment income.......  $     0.003
   Ratios before expense
    limitation:
     Expenses to Average Net
      Assets..................         1.26%
     Net Investment Income
      (Loss) to Average Net
      Assets..................        (0.77)%
</TABLE>
 
(2) Under the terms of an Investment Advisory Agreement, the Adviser is entitled
    to  receive a management  fee calculated at  an annual rate  of 1.00% of the
    average daily net assets of the  Emerging Growth Portfolio. The Adviser  has
    agreed  to waive  a portion  of this  fee and/or  reimburse expenses  of the
    Emerging Growth Portfolio to the extent that the total operating expenses of
    the Emerging Growth Portfolio exceed 1.25%  of the average daily net  assets
    of the Class A shares and 1.50% of the average daily net assets of the Class
    B  shares. In the period ended October 31, 1990, the years ended October 31,
    1991 and  1992, the  two months  ended December  31, 1992,  the years  ended
    December  31, 1993, 1994, and 1995 the Adviser waived management fees and/or
    reimbursed expenses totalling $28,000,  $41,000, $31,000, $18,000,  $51,000,
    $16,000 and $18,000, respectively, for the Emerging Growth Portfolio.
 
 * Commencement of Operations.
 
++ Per  share amounts for the  year ended October 31,  1991 are based on average
   outstanding shares.
 
** Annualized.
 
                                       7
<PAGE>
                          AGGRESSIVE EQUITY PORTFOLIO
 
<TABLE>
<CAPTION>
                                                                                                   PERIOD FROM
                                                                                                MARCH 8, 1995* TO
                                                                                                DECEMBER 31, 1995
                                                                                                ------------------
<S>                                                                                             <C>
NET ASSET VALUE, BEGINNING OF PERIOD..........................................................      $    10.00
                                                                                                       -------
INCOME FROM INVESTMENT OPERATIONS
  Net Investment Income (1)...................................................................            0.15
  Net Realized and Unrealized Gain on Investments.............................................            3.95
                                                                                                       -------
    Total from Investment Operations..........................................................            4.10
                                                                                                       -------
DISTRIBUTIONS
  Net Investment Income.......................................................................           (0.15)
  Net Realized Gain...........................................................................           (1.78)
                                                                                                       -------
  Total Distributions.........................................................................           (1.93)
                                                                                                       -------
NET ASSET VALUE, END OF PERIOD................................................................      $    12.17
                                                                                                       -------
                                                                                                       -------
TOTAL RETURN..................................................................................           41.25%
                                                                                                       -------
                                                                                                       -------
RATIO AND SUPPLEMENTAL DATA:
Net Assets, End of Period (Thousands).........................................................      $   28,548
Ratio of Expenses to Average Net Assets (1)(2)................................................            1.00%**
Ratio of Net Investment Income to Average Net Assets (1)(2)...................................            1.64%**
Portfolio Turnover Rate.......................................................................             309%
- ------------------------
(1) Effect of voluntary expense limitation during the period:
     Per share benefit to net investment income...............................................      $     0.06
   Ratios before expense limitation:
     Expenses to Average Net Assets...........................................................            1.59%**
     Net Investment Income to Average Net Assets..............................................            1.05%**
</TABLE>
 
(2) Under the terms of an Investment Advisory Agreement, the Adviser is entitled
    to receive a management  fee calculated at  an annual rate  of 0.80% of  the
    average daily net assets of the Aggressive Equity Portfolio. The Adviser has
    agreed  to waive  a portion  of this  fee and/or  reimburse expenses  of the
    Aggressive Equity Portfolio to the extent that the total operating  expenses
    of  the Aggressive  Equity Portfolio exceed  1.00% of the  average daily net
    assets of the Class A  Shares and 1.25% of the  average daily net assets  of
    the  Class B  Shares. In  the period  ended December  31, 1995,  the Adviser
    waived management fees and/or reimbursed expenses totalling $96,000 for  the
    Aggressive Equity Portfolio.
 
 * Commencement of Operations
 
** Annualized
 
                                       8
<PAGE>
                               PROSPECTUS SUMMARY
 
THE FUND
 
    The   Fund  consists  of  twenty-eight  portfolios,  offering  institutional
investors and high net  worth individual investors a  broad range of  investment
choices coupled with the advantages of a no-load mutual fund with Morgan Stanley
and  its affiliates providing customized  services as Adviser, Administrator and
Distributor. Each portfolio offers Class  A shares and except the  International
Small  Cap, Money Market  and Municipal Money Market  Portfolios, offers Class B
shares. Each portfolio has its own investment objective and policies designed to
meet its specific goals. The investment objective of each Portfolio described in
this Prospectus is as follows:
 
    - The EQUITY  GROWTH  PORTFOLIO  seeks  long-term  capital  appreciation  by
      investing  primarily in  growth-oriented equity  securities of  medium and
      large capitalization companies.
 
    - The EMERGING  GROWTH PORTFOLIO  seeks  long-term capital  appreciation  by
      investing  primarily  in growth-oriented  equity  securities of  small- to
      medium-sized corporations.
 
    - The MICROCAP PORTFOLIO seeks  long-term capital appreciation by  investing
      primarily in growth-oriented equity securities of small corporations.
 
    - The  AGGRESSIVE EQUITY PORTFOLIO is a non-diversified portfolio that seeks
      capital appreciation  by  investing  primarily  in  corporate  equity  and
      equity-linked securities.
 
    The  other portfolios of the Fund  are described in other Prospectuses which
may be obtained from the Fund at the address and phone number noted on the cover
page of this  Prospectus. The objectives  of these other  portfolios are  listed
below:
 
    GLOBAL AND INTERNATIONAL EQUITY:
 
    - The   ACTIVE   COUNTRY  ALLOCATION   PORTFOLIO  seeks   long-term  capital
      appreciation by investing in accordance with country weightings determined
      by the Adviser  in equity  securities of  non-U.S. issuers  which, in  the
      aggregate, replicate broad country indices.
 
    - The  ASIAN  EQUITY  PORTFOLIO  seeks  long-term  capital  appreciation  by
      investing primarily in equity securities of Asian issuers.
 
    - The CHINA GROWTH PORTFOLIO seeks to provide long-term capital appreciation
      by investing primarily  in equity  securities of issuers  in The  People's
      Republic of China, Hong Kong and Taiwan.
 
    - The  EMERGING MARKETS  PORTFOLIO seeks  long-term capital  appreciation by
      investing primarily in equity securities of emerging country issuers.
 
    - The EUROPEAN  EQUITY PORTFOLIO  seeks  long-term capital  appreciation  by
      investing primarily in equity securities of European issuers.
 
    - The  GLOBAL  EQUITY  PORTFOLIO  seeks  long-term  capital  appreciation by
      investing primarily in equity securities of issuers throughout the  world,
      including U.S. issuers.
 
    - The  GOLD  PORTFOLIO  seeks long-term  capital  appreciation  by investing
      primarily in equity securities of foreign and domestic issuers engaged  in
      gold-related activities.
 
    - The INTERNATIONAL EQUITY PORTFOLIO seeks long-term capital appreciation by
      investing primarily in equity securities of non-U.S. issuers.
 
                                       9
<PAGE>
    - The INTERNATIONAL SMALL CAP PORTFOLIO seeks long-term capital appreciation
      by  investing  primarily in  equity  securities of  non-U.S.  issuers with
      equity market capitalizations of less than $1 billion.
 
    - The JAPANESE  EQUITY PORTFOLIO  seeks  long-term capital  appreciation  by
      investing primarily in equity securities of Japanese issuers.
 
    - The  LATIN  AMERICAN  PORTFOLIO seeks  long-term  capital  appreciation by
      investing primarily in  equity securities  of Latin  American issuers  and
      debt  securities  issued or  guaranteed by  Latin American  governments or
      governmental entities.
 
    - The INTERNATIONAL MAGNUM PORTFOLIO seeks long-term capital appreciation by
      investing primarily in equity securities of non-U.S. issuers in accordance
      with EAFE  country  (as defined  in  "Investment Objective  and  Policies"
      below) weightings determined by the Adviser.
 
    U.S. EQUITY:
 
    - The  SMALL CAP VALUE EQUITY PORTFOLIO seeks high long-term total return by
      investing in  undervalued  equity  securities of  small-  to  medium-sized
      companies.
 
    - The  U. S.  REAL ESTATE PORTFOLIO  seeks to provide  above average current
      income and long-term capital appreciation by investing primarily in equity
      securities of companies in the  U.S. real estate industry, including  real
      estate investment trusts.
 
    - The  VALUE EQUITY PORTFOLIO seeks high total return by investing in equity
      securities which the Adviser  believes to be  undervalued relative to  the
      stock market in general at the time of purchase.
 
    EQUITY AND FIXED INCOME:
    - The BALANCED PORTFOLIO seeks high total return while preserving capital by
      investing  in  a combination  of undervalued  equity securities  and fixed
      income securities.
 
    FIXED INCOME:
 
    - The EMERGING MARKETS DEBT PORTFOLIO  seeks high total return by  investing
      primarily   in  debt  securities  of  government,  government-related  and
      corporate issuers located in emerging countries.
 
    - The FIXED INCOME PORTFOLIO seeks to produce a high total return consistent
      with the preservation of capital  by investing in a diversified  portfolio
      of fixed income securities.
 
    - The GLOBAL FIXED INCOME PORTFOLIO seeks to produce an attractive real rate
      of return while preserving capital by investing in fixed income securities
      of issuers throughout the world, including U.S. issuers.
 
    - The  HIGH YIELD PORTFOLIO seeks to maximize total return by investing in a
      diversified portfolio of high yield  fixed income securities that offer  a
      yield  above  that generally  available on  debt  securities in  the three
      highest rating categories of the recognized rating services.
 
    - The MORTGAGE-BACKED SECURITIES Portfolio seeks to produce as high a  level
      of  current income  as is consistent  with the preservation  of capital by
      investing primarily  in  a  variety  of  investment-grade  mortgage-backed
      securities.
 
    - The  MUNICIPAL BOND  PORTFOLIO seeks  to produce  a high  level of current
      income  consistent  with  preservation  of  principal  through  investment
      primarily  in municipal obligations, the interest  on which is exempt from
      federal income tax.
 
                                       10
<PAGE>
    MONEY MARKET:
 
    - The MONEY MARKET PORTFOLIO seeks  to maximize current income and  preserve
      capital  while maintaining high  levels of liquidity  through investing in
      high quality money  market instruments  with remaining  maturities of  one
      year or less.
 
    - The  MUNICIPAL MONEY MARKET PORTFOLIO seeks to maximize current tax-exempt
      income and preserve  capital while  maintaining high  levels of  liquidity
      through  investing in high quality money market instruments with remaining
      maturities of one year or less which are exempt from federal income tax.
 
INVESTMENT MANAGEMENT
 
    Morgan Stanley Asset Management  Inc., a wholly  owned subsidiary of  Morgan
Stanley  Group  Inc.,  which,  together  with  its  affiliated  asset management
companies, at December 31, 1995 had approximately $57.4 billion in assets  under
management  as  an  investment  manager  or  as  a  fiduciary  adviser,  acts as
investment adviser to the  Fund and each of  its portfolios. See "Management  of
the Fund -- Investment Adviser" and "Management of the Fund -- Administrator."
 
HOW TO INVEST
 
    Class  A shares of each  Portfolio are offered directly  to investors at net
asset value with no sales  commission or 12b-1 charges.  Class B shares of  each
Portfolio  are offered at net  asset value with no  sales commission, but with a
12b-1 fee, which  is accrued daily  and paid  quarterly, equal to  0.25% of  the
Class B shares' average daily net assets on an annualized basis. Share purchases
may  be  made  by  sending  investments directly  to  the  Fund  or  through the
Distributor. Shares  in a  Portfolio account  opened prior  to January  2,  1996
(each,  a "Pre-1996 Account") were designated Class A shares on January 2, 1996.
For a Portfolio account opened  on or after January  2, 1996 (a "New  Account"),
the  minimum initial investment is $500,000 for  Class A shares and $100,000 for
Class B shares. Certain exceptions to the foregoing minimums apply to (1) shares
in a Pre-1996  Account with  a value of  $100,000 or  more on March  1, 1996  (a
"Grandfathered  Class  A  Account");  (2)  Portfolio  accounts  held  by certain
employees of the  Adviser and  of its affiliates;  and (3)  certain advisory  or
asset  allocation accounts, such as Total  Funds Management accounts, managed by
Morgan Stanley or  its affiliates, including  the Adviser ("Managed  Accounts").
The Adviser reserves the right in its sole discretion to determine which of such
advisory or asset allocation accounts shall be Managed Accounts. For information
regarding   Managed  Accounts,  please  contact   your  Morgan  Stanley  account
representative or the Fund at the telephone number provided on the cover of this
Prospectus. Shares in a Pre-1996 Account with  a value of less than $100,000  on
March 1, 1996 (a "Grandfathered Class B Account") converted to Class B shares on
March  1, 1996. The minimum investment levels may be waived at the discretion of
the Adviser for  (i) certain employees  and customers of  Morgan Stanley or  its
affiliates  and certain  trust departments, brokers,  dealers, agents, financial
planners, financial services  firms, or  investment advisers  that have  entered
into an agreement with Morgan Stanley or its affiliates; and (ii) retirement and
deferred  compensation plans and trusts used  to fund such plans, including, but
not limited to, those defined in Section  401(a), 403(b) or 457 of the  Internal
Revenue Code of 1986, as amended, and "rabbi trusts". See "Purchase of Shares --
Minimum  Investment  and  Account Sizes;  Conversion  from  Class A  to  Class B
Shares."
 
                                       11
<PAGE>
    The minimum  subsequent  investment for  each  Portfolio account  is  $1,000
(except  for automatic reinvestment of dividends and capital gains distributions
for which there is no minimum).  Such subsequent investments will be applied  to
purchase  additional  shares  in the  same  class  held by  a  shareholder  in a
Portfolio account. See "Purchase of Shares -- Additional Investments."
 
HOW TO REDEEM
 
    Class A shares or Class  B shares of each Portfolio  may be redeemed at  any
time, without cost, at the net asset value per share of shares of the applicable
class  next determined after  receipt of the  redemption request. The redemption
price may be more or less than the purchase price. Certain redemptions may cause
involuntary redemption or automatic conversion. Class  A or Class B shares  held
in   New  Accounts  are   subject  to  involuntary   redemption  if  shareholder
redemption(s) of such  shares reduces  the value of  such account  to less  than
$100,000  for a continuous 60-day period.  Involuntary redemption does not apply
to Managed Accounts, Grandfathered  Class A Accounts  and Grandfathered Class  B
Accounts,  regardless of  the value of  such accounts.  Class A shares  in a New
Account will convert  to Class  B shares  if shareholder  redemption(s) of  such
shares  reduces the value of such account to less than $500,000 for a continuous
60-day period. Class B shares in a New Account will convert to Class A shares if
shareholder purchases of additional Class B shares or market activity cause  the
value  of Class B shares in the New Account to increase to $500,000 or more. See
"Purchase of  Shares --  Minimum  Account Sizes  and Involuntary  Redemption  of
Shares" and "Redemption of Shares."
 
RISK FACTORS
 
    The   investment  policies  of  the  Portfolios  entail  certain  risks  and
considerations of which an investor should be aware. Because the Emerging Growth
and  MicroCap  Portfolios  seek  long-term  capital  appreciation  by  investing
primarily in small- to medium-sized companies and small companies, respectively,
both  of which  types of  companies are more  vulnerable to  financial and other
risks than larger, more established  companies, investments in these  Portfolios
may involve a higher degree of risk and price volatility than the general equity
markets.  The Aggressive  Equity Portfolio  may invest  in small-to medium-sized
companies to a lesser extent. The  Equity Growth, Emerging Growth, MicroCap  and
Aggressive  Equity Portfolios may invest in securities of foreign issuers, which
are subject to certain risks not typically associated with domestic  securities.
See   "Investment   Objectives   and   Policies"   and   "Additional  Investment
Information." In addition, the Portfolios  may invest in repurchase  agreements,
lend  their portfolio  securities and may  purchase securities  on a when-issued
basis. The Equity Growth and Aggressive Equity Portfolios may invest in  covered
call  options and may also invest in  stock options, stock futures contracts and
options on stock futures contracts, and  may invest in forward foreign  currency
exchange contracts to hedge currency risk associated with investment in non-U.S.
dollar-denominated  securities. The  Aggressive Equity  Portfolio may  invest in
convertible debentures and  specialty equity-linked securities,  such as  PERCS,
ELKS  or LYONs,  of U.S., and  to a  limited extent, foreign  issuers, which may
involve risks  in  addition to  those  associated with  equity  securities.  The
Aggressive  Equity Portfolio is a non-diversified portfolio under the Investment
Company Act of  1940, as amended  (the "1940  Act") and therefore  may invest  a
greater  proportion  of its  assets in  the  securities of  a smaller  number of
issuers and may, as  a result, be  subject to greater risk  with respect to  its
portfolio  securities. See "Investment  Limitations." See "Additional Investment
Information." Each of these investment strategies involves specific risks  which
are  described  under  "Investment  Objectives  and  Policies"  and  "Additional
Investment Information" herein and under "Investment Objectives and Policies" in
the Statement of Additional Information.
 
                                       12
<PAGE>
                       INVESTMENT OBJECTIVES AND POLICIES
 
    The investment objective of each Portfolio is described below, together with
the policies the Fund employs in  its efforts to achieve these objectives.  Each
Portfolio's  investment  objective  is a  fundamental  policy which  may  not be
changed without the approval of a majority of the Portfolio's outstanding voting
securities. There  is  no  assurance  that  the  Portfolios  will  attain  their
objectives. The investment policies described below are not fundamental policies
and may be changed without shareholder approval.
 
THE EQUITY GROWTH PORTFOLIO
 
    The  Portfolio's  investment  objective  is  to  provide  long-term  capital
appreciation by  investing primarily  in  growth-oriented equity  securities  of
medium  and large capitalization U.S. corporations  and, to a limited extent, as
described below, foreign  corporations. With  respect to  the Portfolio,  equity
securities  include  common and  preferred  stocks, convertible  securities, and
rights and warrants to purchase  common stocks. Under normal circumstances,  the
Portfolio  will invest at least  65% of the value of  its total assets in equity
securities.
 
    The Adviser employs a flexible and eclectic investment process in pursuit of
the Portfolio's investment  objectives. In selecting  stocks for the  Portfolio,
the  Adviser  concentrates  on  a  universe  of  rapidly  growing,  high quality
companies and lower, but accelerating, earnings growth situations. The Adviser's
universe of  potential investments  generally  comprises companies  with  market
capitalizations  of $750  million or  more. The  Portfolio is  not restricted to
investments  in  specific  market  sectors.   The  Adviser  uses  its   research
capabilities, analytical resources and judgment to assess economic, industry and
market  trends, as well as individual  company developments, to select promising
growth investments for the Portfolio. The Adviser concentrates on companies with
strong, communicative managements and clearly defined strategies for growth.  In
addition,  the  Adviser  rigorously  assesses  company  developments,  including
changes in strategic direction, management  focus and current and likely  future
earnings  results. Valuation is  important to the  Adviser but is  viewed in the
context of  prospects for  sustainable  earnings growth  and the  potential  for
positive  earnings surprises vis-a-vis consensus  expectations. The Portfolio is
free to invest in any equity security that, in the Adviser's judgment,  provides
above average potential for capital appreciation.
 
    In   selecting  investments  for  the   Portfolio,  the  Adviser  emphasizes
individual security  selection. The  Portfolio's investments  will generally  be
diversified  by number  of issues but  concentrated sector  positions may result
from  the  investment  process.  The   Portfolio  has  a  long-term   investment
perspective; however, the Adviser may take advantage of short-term opportunities
that are consistent with the Portfolio's objective by selling recently purchased
securities which have increased in value.
 
    The  Portfolio may  invest up  to 25%  of its  total assets  at the  time of
purchase in  securities  of  foreign  companies. The  Portfolio  may  invest  in
securities  of foreign issuers  directly or in the  form of Depositary Receipts.
Investors should recognize that investing in foreign companies involves  certain
special considerations which are not typically associated with investing in U.S.
companies.  See  "Additional  Investment  Information"  herein  and  "Investment
Objectives and Policies -- Forward  Foreign Currency Exchange Contracts" in  the
Statement of Additional Information.
 
    The  Portfolio may invest in convertible securities of domestic and, subject
to the above  restrictions, foreign  issuers on  occasions when,  due to  market
conditions,  it  is  more  advantageous  to  purchase  such  securities  than to
 
                                       13
<PAGE>
purchase common stock.  Since the Portfolio  invests in both  common stocks  and
convertible securities, the risks of investing in the general equity markets may
be tempered to a degree by the Portfolio's investments in convertible securities
which are often not as volatile as common stock.
 
    Any  remaining assets may be invested  in certain securities or obligations,
including  derivative  securities,  as  set  forth  in  "Additional   Investment
Information" below.
 
THE EMERGING GROWTH PORTFOLIO
 
    The  Portfolio's  investment  objective  is  to  provide  long-term  capital
appreciation by  investing primarily  in  growth-oriented equity  securities  of
small-  to  medium-sized  domestic  corporations and,  to  a  limited  extent as
described below, foreign corporations. The  production of any current income  is
incidental  to  this  objective.  Such  companies  generally  have  annual gross
revenues ranging  from  $10  million  to  $750  million.  With  respect  to  the
Portfolio,  equity securities  include common and  preferred stocks, convertible
securities, and rights and warrants to  purchase common stocks, and any  similar
equity  interest, such as trust or partnership interests. Such equity securities
may not pay dividends or distributions and may or may not carry voting rights.
 
    The Adviser  employs  a  flexible  investment  program  in  pursuit  of  the
Portfolio's investment objective. The Portfolio is not restricted to investments
in  specific market sectors. The Portfolio will invest in small- to medium-sized
companies that are early in their life  cycle, but which have the potential,  in
the  Adviser's  judgment,  to become  major  enterprises. The  Adviser  uses its
judgment and  research capabilities  to assess  economic, industry,  market  and
company   developments  to  select  investments  in  promising  emerging  growth
companies that are expected  to benefit from new  technology or new products  or
services.  In  addition, the  Adviser looks  for  special developments,  such as
research discoveries,  changes in  customer  demand, rejuvenated  management  or
basic   changes  in  the   economic  environment.  These   situations  are  only
illustrative of the types of investments  the Portfolio may make. The  Portfolio
is  free to invest in any common  stock which in the Adviser's judgment provides
above-average potential for capital appreciation.
 
    The Portfolio intends to manage  its investments actively to accomplish  its
investment   objective.  Since   the  Portfolio   has  a   long-term  investment
perspective, the  Adviser  does  not  intend to  respond  to  short-term  market
fluctuations  or to  acquire securities for  the purpose  of short-term trading;
however, the Adviser  may take  advantage of short-term  opportunities that  are
consistent with its objective.
 
    The  Portfolio may  invest up  to 25%  of its  total assets  at the  time of
purchase in  securities  of  foreign  companies. The  Portfolio  may  invest  in
securities  of foreign issuers  directly or in the  form of Depositary Receipts.
See "Additional  Investment Information"  below. The  Portfolio may  enter  into
forward  foreign currency exchange  contracts which provide  for the purchase or
sale of  foreign  currencies  in  connection  with  the  settlement  of  foreign
securities  transactions or to hedge the underlying currency exposure related to
foreign investments. The  Portfolio will  not enter into  these commitments  for
speculative  purposes.  Investors  should recognize  that  investing  in foreign
companies involves  certain  special  considerations  which  are  not  typically
associated   with  investing  in  U.S.  companies.  See  "Additional  Investment
Information" herein and "Investment Objectives and Policies -- Forward  Currency
Exchange Contracts" in the Statement of Additional Information.
 
    The  Portfolio may  also invest in  convertible securities  of domestic and,
subject to the  above restrictions, foreign  issuers on occasions  when, due  to
market  conditions, it is more advantageous  to purchase such securities than to
purchase common stock. The Portfolio will not invest in debt securities that are
not rated at least
 
                                       14
<PAGE>
investment grade by either Standard & Poor's Ratings Group or Moody's  Investors
Service,  Inc. Since the Portfolio invests in both common stocks and convertible
securities, the risks of investing in the general equity markets may be tempered
to a degree by the Portfolio's investments in convertible securities, which  are
often not as volatile as equity securities.
 
    Any  remaining assets may be invested  in certain securities or obligations,
including derivative securities,  that are set  forth in "Additional  Investment
Information" below.
 
THE MICROCAP PORTFOLIO
 
    The  Portfolio's  investment  objective  is  to  provide  long-term  capital
appreciation by  investing primarily  in  growth-oriented equity  securities  of
small domestic corporations and, to a limited extent as described below, foreign
corporations.  The  production  of  any current  income  is  incidental  to this
objective. Such  companies generally  have, at  time of  purchase, annual  gross
revenues  of $150 million or  less or market capitalizations  of $250 million or
less. With  respect  to the  Portfolio,  equity securities  include  common  and
preferred stocks, convertible securities, rights and warrants to purchase common
stocks, and any similar equity interest, such as trust or partnership interests.
Such  equity securities may or may not pay dividends or distributions and may or
may not carry voting rights.
 
    The Adviser  employs  a  flexible  investment  program  in  pursuit  of  the
Portfolio's investment objective. The Portfolio is not restricted to investments
in  specific market  sectors. The  Portfolio will  invest in  equity securities,
including securities purchased in initial  public offerings, of small  companies
that  are  early in  their  life cycle,  but which  have  the potential,  in the
Adviser's judgement, to achieve long-term capital appreciation. The Adviser uses
its judgment and research capabilities to assess economic, industry, market  and
company  developments  to select  investments  in promising  companies  that are
expected to  benefit  from  new  technology or  new  products  or  services.  In
addition,   the  Adviser  looks  for  special  developments,  such  as  research
discoveries, changes in customer demand, rejuvenated management or basic changes
in the economic environment. These situations are only illustrative of the types
of investments the Portfolio may  make. The Portfolio is  free to invest in  any
equity security which in the Adviser's judgment provides above-average potential
for capital appreciation.
 
    The  Portfolio intends to manage its  investments actively to accomplish its
investment  objective.   Since  the   Portfolio  has   a  long-term   investment
perspective,  the  Adviser  does  not intend  to  respond  to  short-term market
fluctuations or to  acquire securities  for the purpose  of short-term  trading;
however,  the Adviser  may take advantage  of short-term  opportunities that are
consistent with its objective.
 
    The Portfolio  may invest  up to  25% of  its total  assets at  the time  of
purchase  in securities of  foreign companies. The Portfolio  may invest in such
securities of foreign issuers  directly or in the  form of Depositary  Receipts.
See  "Additional  Investment Information"  below. The  Portfolio may  enter into
forward foreign currency exchange  contracts which provide  for the purchase  or
sale  of  foreign  currencies  in  connection  with  the  settlement  of foreign
securities transactions or to hedge the underlying currency exposure related  to
foreign  investments. The  Portfolio will not  enter into  these commitments for
speculative purposes.  Investors  should  recognize that  investing  in  foreign
companies  involves  certain  special  considerations  which  are  not typically
associated  with  investing  in  U.S.  companies.  See  "Additional   Investment
Information"  herein and "Investment Objectives and Policies -- Forward Currency
Exchange Contracts" in the Statement of Additional Information.
 
                                       15
<PAGE>
    The Portfolio may invest in convertible securities of domestic and,  subject
to  the above  restrictions, foreign  issuers on  occasions when,  due to market
conditions, it is more advantageous to purchase such securities than to purchase
common stock. The  Portfolio will  not invest in  debt securities  that are  not
rated  at least investment  grade by either  Standard & Poor's  Ratings Group or
Moody's Investors  Service, Inc.  Since  the Portfolio  invests in  both  common
stocks  and convertible securities, the risks of investing in the general equity
markets  may  be  tempered  to  a  degree  by  the  Portfolio's  investments  in
convertible  securities, which are  often not as  volatile as equity securities.
See "Additional Investment Information".
 
    Any remaining assets may be  invested in certain securities or  obligations,
including   derivative  securities,  as  set  forth  in  "Additional  Investment
Information" below.
 
THE AGGRESSIVE EQUITY PORTFOLIO
 
    The Portfolio's investment objective is  to provide capital appreciation  by
investing  primarily  in a  non-diversified  portfolio of  corporate  equity and
equity-linked  securities.   With  respect   to   the  Portfolio,   equity   and
equity-linked  securities  include  common  and  preferred  stocks,  convertible
securities, rights and warrants to purchase common stocks, options, futures, and
specialty securities,  such as  ELKS, LYONs,  PERCS of  U.S., and  to a  limited
extent,  as described  below, foreign issuers.  The Aggressive Equity  Fund is a
non-diversified portfolio and thus can be more heavily weighted in fewer  stocks
than  the  Equity  Growth  Portfolio,  which  is  a  diversified  portfolio. See
"Investment Limitations." Under normal circumstances, the Portfolio will  invest
at  least  65% of  the value  of its  total assets  in equity  and equity-linked
securities.
 
    The Adviser employs a flexible and eclectic investment process in pursuit of
the Portfolio's investment objective. In selecting securities for the Portfolio,
the Adviser  concentrates  on  a  universe  of  rapidly  growing,  high  quality
companies and lower, but accelerating, earnings growth situations. The Adviser's
universe  of  potential investments  generally  comprises companies  with market
capitalizations of  $500  million  or more  but  smaller  market  capitalization
securities  may be purchased from time to  time. The Portfolio is not restricted
to investments  in  specific  market  sectors. The  Adviser  uses  its  research
capabilities, analytical resources and judgment to assess economic, industry and
market  trends, as well as individual  company developments, to select promising
investments for  the  Portfolio.  The Adviser  concentrates  on  companies  with
strong,  communicative managements and clearly defined strategies for growth. In
addition, the Adviser  rigorously assesses earnings  results. The Adviser  seeks
companies  which will deliver surprisingly  strong earnings growth. Valuation is
of secondary importance to the Adviser and is viewed in the context of prospects
for  sustainable  earnings  growth  and  the  potential  for  positive  earnings
surprises in relation to consensus expectations. The Portfolio is free to invest
in  any  equity  or  equity-linked security  that,  in  the  Adviser's judgment,
provides above average potential for capital appreciation.
 
    The Portfolio may  from time to  time and consistent  with applicable  legal
requirements  sell securities  short that it  owns (i.e., "against  the box") or
borrows. See "Additional Investment Information".
 
    In  selecting  investments  for   the  Portfolio,  the  Adviser   emphasizes
individual   security  selection.  Overweighted   sector  positions  and  issuer
positions may result from the investment process. See "Investment  Limitations."
The  Portfolio has a long-term investment  perspective; however, the Adviser may
take  advantage  of  short-term  opportunities  that  are  consistent  with  the
Portfolio's  objective  by  selling  recently  purchased  securities  which have
increased in value.
 
                                       16
<PAGE>
    The Portfolio may invest in equity and equity-linked securities of  domestic
and  foreign corporations. However, the Portfolio does not expect to invest more
than 25% of its total  assets at the time of  purchase in securities of  foreign
companies. The Portfolio may invest in securities of foreign issuers directly or
in the form of American Depositary Receipts ("ADRs"). Investors should recognize
that  investing  in foreign  companies  involves certain  special considerations
which are  not  typically  associated  with investing  in  U.S.  companies.  See
"Additional  Investment  Information"  herein  and  "Investment  Objectives  and
Policies -- Forward  Foreign Currency  Exchange Contracts" in  the Statement  of
Additional Information.
 
    Any  remaining assets may be invested  in certain securities or obligations,
including  derivative  securities,  as  set  forth  in  "Additional   Investment
Information" below.
 
                       ADDITIONAL INVESTMENT INFORMATION
 
CONVERTIBLE SECURITIES, WARRANTS AND EQUITY-LINKED SECURITIES
 
    The  Portfolios  may invest  in securities  such as  convertible securities,
preferred  stock,  warrants  or  other  securities  exchangeable  under  certain
circumstances  for  shares  of  common stock.  Warrants  are  instruments giving
holders the right, but not the obligation, to buy shares of a company at a given
price during a specified period.
 
    The Aggressive  Equity Portfolio  may  invest in  equity-linked  securities,
including,  among others,  PERCS, ELKS or  LYONs, which are  securities that are
convertible into  or the  value of  which is  based upon  the value  of,  equity
securities upon certain terms and conditions. The amount received by an investor
at  maturity of such  securities is not fixed  but is based on  the price of the
underlying common stock. It  is impossible to predict  whether the price of  the
underlying  common stock  will rise  or fall.  Trading prices  of the underlying
common stock will be influenced by the issuer's operational results, by complex,
interrelated political,  economic, financial,  or  other factors  affecting  the
capital  markets, the  stock exchanges on  which the underlying  common stock is
traded and the market segment of which the issuer is a part. In addition, it  is
not possible to predict how equity-linked securities will trade in the secondary
market, which is fairly developed and liquid. The market for such securities may
be  shallow,  however,  and  high  volume  trades  may  be  possible  only  with
discounting. In addition to the foregoing  risks, the return on such  securities
depends  on the creditworthiness of  the issuer of the  securities, which may be
the issuer of the  underlying securities or a  third party investment banker  or
other  lender. The creditworthiness of such  third party issuer of equity-linked
securities may, and often does, exceed the creditworthiness of the issuer of the
underlying securities.  The advantage  of  using equity-linked  securities  over
traditional  equity and debt securities is  that the former are income producing
vehicles that  may provide  a higher  income  than the  dividend income  on  the
underlying  equity securities while  allowing some participation  in the capital
appreciation of the  underlying equity  securities. Another  advantage of  using
equity-linked securities is that they may be used for hedging to reduce the risk
of investing in the generally more volatile underlying equity securities.
 
    The  following are three examples of equity-linked securities. The Portfolio
may invest  in the  securities described  below or  other similar  equity-linked
securities.
 
    PERCS.   Preferred Equity Redemption  Cumulative Stock ("PERCS") technically
are preferred  stock  with  some  characteristics of  common  stock.  PERCS  are
mandatorily  convertible into common stock after a period of time, usually three
years, during which  the investors' capital  gains are capped,  usually at  30%.
 
                                       17
<PAGE>
Commonly,  PERCS may be  redeemed by the issuer  at any time  or if the issuer's
common stock is  trading at a  specified price level  or better. The  redemption
price  starts at the beginning  of the PERCS duration period  at a price that is
above the cap by the amount of the extra dividends the PERCS holder is  entitled
to  receive relative  to the  common stock  over the  duration of  the PERCS and
declines to the cap price shortly before maturity of the PERCS. In exchange  for
having  the cap on capital gains and giving  the issuer the option to redeem the
PERCS at any time or  at the specified common  stock price level, the  Portfolio
may  be compensated with a substantially higher  dividend yield than that on the
underlying common stock.  Investors, such  as the Portfolio,  that seek  current
income,  find PERCS attractive because a PERCS provides a higher dividend income
than that paid with respect to a company's common stock.
 
    ELKS.    Equity-Linked  Securities   ("ELKS")  differ  from  ordinary   debt
securities,  in that the principal amount received  at maturity is not fixed but
is based on the  price of the  issuer's common stock.  ELKS are debt  securities
commonly  issued in  fully registered form  for a  term of three  years under an
indenture trust. At maturity, the holder of  ELKS will be entitled to receive  a
principal  amount equal to the lesser of a  cap amount, commonly in the range of
30% to 55% greater than the current  price of the issuer's common stock, or  the
average  closing  price  per share  of  the  issuer's common  stock,  subject to
adjustment as  a result  of certain  dilution events,  for the  10 trading  days
immediately  prior to maturity.  Unlike PERCS, ELKS are  commonly not subject to
redemption prior to maturity. ELKS  usually bear interest during the  three-year
term  at a substantially higher  rate than the dividend  yield on the underlying
common stock. In exchange for having the cap on the return that might have  been
received  as capital gains on the underlying  common stock, the Portfolio may be
compensated with the higher yield, contingent on how well the underlying  common
stock  does. Investors,  such as the  Portfolio, that seek  current income, find
ELKS attractive because  ELKS provide a  higher dividend income  than that  paid
with respect to a company's common stock.
 
    LYONS.    Liquid  Yield Option  Notes  ("LYONs") differ  from  ordinary debt
securities, in that the amount  received prior to maturity  is not fixed but  is
based  on the price  of the issuer's  common stock. LYONs  are zero-coupon notes
that sell at a large discount from  face value. For an investment in LYONs,  the
Portfolio  will  not  receive  any interest  payments  until  the  notes mature,
typically in 15 to 20 years, when the notes are redeemed at face, or par, value.
The yield on LYONs, typically, is lower-than-market rate for debt securities  of
the  same maturity, due in part to the  fact that the LYONs are convertible into
common stock of the issuer at any time at the option of the holder of the LYONs.
Commonly, the LYONs are redeemable  by the issuer at  any time after an  initial
period  or if the issuer's common stock is trading at a specified price level or
better, or,  at  the  option  of  the holder,  upon  certain  fixed  dates.  The
redemption  price  typically is  the purchase  price of  the LYONs  plus accrued
original issue  discount  to  the  date of  redemption,  which  amounts  to  the
lower-than-market  yield. The Portfolio will  receive only the lower-than-market
yield unless the  underlying common stock  increases in value  at a  substantial
rate.  LYONs are  attractive to investors,  like the Portfolio,  when it appears
that they will  increase in value  due to the  rise in value  of the  underlying
common stock.
 
    DEPOSITARY  RECEIPTS.  The Portfolios may invest indirectly in securities of
foreign companies through sponsored or unsponsored American Depositary  Receipts
("ADRs"),  Global  Depositary Receipts  ("GDRs") and  other types  of Depositary
Receipts (which,  together  with ADRs  and  GDRs, are  hereinafter  collectively
referred  to as "Depositary  Receipts"), to the  extent such Depositary Receipts
are or become available. Depositary Receipts are not necessarily denominated  in
the  same currency as the underlying securities. In addition, the issuers of the
securities underlying  unsponsored  Depositary  Receipts are  not  obligated  to
disclose material
 
                                       18
<PAGE>
information  in the U.S. and, therefore, there may be less information available
regarding such  issuers  and  there  may  not  be  a  correlation  between  such
information and the market value of the Depositary Receipts. ADRs are Depositary
Receipts  typically  issued  by  a  U.S.  financial  institution  which evidence
ownership interests in  a security  or pool of  securities issued  by a  foreign
issuer.  GDRs and  other types  of Depositary  Receipts are  typically issued by
foreign banks  or trust  companies, although  they also  may be  issued by  U.S.
financial  institutions, and evidence ownership interests  in a security or pool
of securities  issued by  either a  foreign or  a U.S.  corporation.  Generally,
Depositary  Receipts  in  registered  form  are designed  for  use  in  the U.S.
securities market and Depositary Receipts in bearer form are designed for use in
securities markets outside  the U.S.  For purposes of  a Portfolio's  investment
policies,  the Portfolio's investments in Depositary  Receipts will be deemed to
be investments in the underlying securities.
 
    FOREIGN INVESTMENT.   The Portfolios may  invest in U.S.  dollar-denominated
securities  of foreign issuers  trading in U.S. markets  and the Emerging Growth
and Aggressive  Equity  Portfolios  may invest  in  non-U.S.  dollar-denominated
securities  of foreign issuers. Investment in  securities of foreign issuers and
in foreign branches  of domestic  banks involves  somewhat different  investment
risks  than those  affecting securities of  U.S. domestic issuers.  There may be
limited publicly  available information  with respect  to foreign  issuers,  and
foreign  issuers are not  generally subject to  uniform accounting, auditing and
financial standards  and requirements  comparable to  those applicable  to  U.S.
companies.  There  may also  be less  government  supervision and  regulation of
foreign securities exchanges, brokers and listed companies than in the U.S. Many
foreign securities markets  have substantially  less volume  than U.S.  national
securities exchanges, and securities of some foreign issuers are less liquid and
more   volatile  than  securities  of  comparable  domestic  issuers.  Brokerage
commissions and  other transaction  costs on  foreign securities  exchanges  are
generally higher than in the U.S. Dividends and interest paid by foreign issuers
may  be subject to withholding  and other foreign taxes,  which may decrease the
net return on foreign investments as compared to dividends and interest paid  to
the  Portfolio by domestic companies. It is not expected that a Portfolio or its
shareholders would be able to claim a credit for U.S. tax purposes with  respect
to  any  such  foreign  taxes.  See  "Taxes."  Additional  risks  include future
political and economic developments, the possibility that a foreign jurisdiction
might impose  or change  withholding taxes  on income  payable with  respect  to
foreign  securities, possible  seizure, nationalization or  expropriation of the
foreign issuer  or  foreign  deposits  and  the  possible  adoption  of  foreign
governmental restrictions such as exchange controls.
 
    Investments  in securities of foreign  issuers are frequently denominated in
foreign  currencies  and,  since  the  Emerging  Growth  and  Aggressive  Equity
Portfolios  may also  temporarily hold uninvested  reserves in  bank deposits in
foreign currencies, the value of the Portfolios' assets measured in U.S. dollars
may be affected favorably or unfavorably  by changes in currency exchange  rates
and  in  exchange control  regulations, and  the Portfolios  may incur  costs in
connection with conversions between various currencies.
 
    FORWARD FOREIGN  CURRENCY  EXCHANGE  CONTRACTS.   The  Emerging  Growth  and
Aggressive  Equity Portfolios may  enter into forward  foreign currency exchange
contracts ("forward contracts"),  that provide for  the purchase or  sale of  an
amount of a specified foreign currency at a future date. Purposes for which such
contracts may be used include protecting against a decline in a foreign currency
against  the U.S.  dollar between  the trade date  and settlement  date when the
Portfolio purchases or sells non-U.S. dollar denominated securities, locking  in
 
                                       19
<PAGE>
the  U.S. dollar value of dividends declared on securities held by the Portfolio
and generally  protecting  the U.S.  dollar  value  of securities  held  by  the
Portfolio  against exchange rate fluctuation. Such contracts may also be used as
a protective  measure  against the  effects  of fluctuating  rates  of  currency
exchange  and  exchange control  regulations. While  such forward  contracts may
limit losses to the Portfolio against exchange rate fluctuations, they will also
limit any gains that  may otherwise have been  realized. Such forward  contracts
are  derivative  securities,  in  which the  Portfolio  may  invest  for hedging
purposes. See "Investment Objectives and  Policies -- Forward Currency  Exchange
Contracts" in the Statement of Additional Information.
 
    LOANS  OF PORTFOLIO SECURITIES.  The Portfolios may lend their securities to
brokers, dealers, domestic and foreign banks or other financial institutions for
the purpose of increasing its net investment income. These loans must be secured
continuously by cash or equivalent collateral, or by a letter of credit at least
equal to the  market value  of the securities  loaned plus  accrued interest  or
income.  There may be a risk of delay in recovery of the securities or even loss
of rights  in  the  collateral  should  the  borrower  of  the  securities  fail
financially.  A  Portfolio  will  not enter  into  securities  loan transactions
exceeding, in the aggregate, 33  1/3% of the market  value of its total  assets.
For   more  detailed  information  about  securities  lending,  see  "Investment
Objectives and Policies" in the Statement of Additional Information.
 
    MONEY MARKET INSTRUMENTS.   Each Portfolio is permitted  to invest in  money
market   instruments,  although  the  Portfolios  intend  to  stay  invested  in
securities  satisfying  their  primary   investment  objective  to  the   extent
practical.  Each  Portfolio  may  make money  market  investments  pending other
investment or settlement  for liquidity,  or in adverse  market conditions.  The
money market investments permitted for the Portfolios include obligations of the
United  States  Government and  its agencies  and instrumentalities;  other debt
securities; commercial paper including bank obligations; certificates of deposit
(including Eurodollar certificates of  deposit); and repurchase agreements.  For
more detailed information about these money market investments, see "Description
of Securities and Ratings" in the Statement of Additional Information.
 
    NON-PUBLICLY   TRADED   SECURITIES,   PRIVATE   PLACEMENTS   AND  RESTRICTED
SECURITIES.  The Equity  Growth and Aggressive Equity  Portfolios may invest  in
securities  that are  neither listed  on a  stock exchange  nor traded  over the
counter. Such unlisted equity securities may involve a higher degree of business
and financial risk that  can result in  substantial losses. As  a result of  the
absence of a public trading market for these securities, they may be less liquid
than  publicly traded  securities. Although  these securities  may be  resold in
privately negotiated transactions, the prices realized from these sales could be
less than those  originally paid by  such Portfolios  or less than  what may  be
considered   the  fair  value  of  such  securities.  Further,  companies  whose
securities are not  publicly traded  may not be  subject to  the disclosure  and
other  investor  protection  requirements  which might  be  applicable  if their
securities  were  publicly  traded.  If  such  securities  are  required  to  be
registered  under the securities laws of  one or more jurisdictions before being
resold, the Portfolio may be required to bear the expenses of registration. As a
general matter, the Portfolio may not invest more than 15% of its net assets  in
illiquid  securities,  including  securities  for  which  there  is  no  readily
available secondary  market.  Securities  that  are  not  registered  under  the
Securities  Act  of  1933, as  amended,  but that  can  be offered  and  sold to
qualified institutional  buyers under  Rule  144A under  that  Act will  not  be
included  within the foregoing 15% restriction  if the securities are determined
to be liquid. The Board of Directors has adopted guidelines and delegated to the
Adviser, subject  to  the supervision  of  the  Board of  Directors,  the  daily
function  of determining and  monitoring the liquidity  of Rule 144A securities.
Rule 144A securities may become  illiquid if qualified institutional buyers  are
not interested in acquiring the securities.
 
                                       20
<PAGE>
    REPURCHASE  AGREEMENTS.  The Portfolios may enter into repurchase agreements
with brokers, dealers or  banks that meet the  credit guidelines established  by
the  Fund's Board of Directors. In a  repurchase agreement, the Portfolio buys a
security from a seller  that has agreed  to repurchase it  at a mutually  agreed
upon  date and price, reflecting the interest rate effective for the term of the
agreement. The term of these agreements  is usually from overnight to one  week,
and  never exceeds  one year.  Repurchase agreements  may be  viewed as  a fully
collateralized loan  of money  by the  Portfolio to  the seller.  The  Portfolio
always  receives securities, with a market value  at least equal to the purchase
price (including accrued interest)  as collateral and  this value is  maintained
during  the term  of the  agreement. If the  seller defaults  and the collateral
value declines, the Portfolio might incur a loss. If bankruptcy proceedings  are
commenced  with  respect to  the seller,  the  Portfolio's realization  upon the
collateral may  be  delayed or  limited.  The aggregate  of  certain  repurchase
agreements  and  certain  other  investments  is  limited  as  set  forth  under
"Investment Limitations."
 
    SHORT SALES.   The Aggressive Equity  Portfolio may from  time to time  sell
securities  short consistent with applicable legal requirements. A short sale is
a transaction in which the Portfolio would sell securities it either owns or has
the right to acquire at no added cost (i.e., "against the box") or does not  own
(but  has borrowed)  in anticipation  of a  decline in  the market  price of the
securities. When the Portfolio  makes a short sale  of borrowed securities,  the
proceeds  it receives from the sale will be held on behalf of a broker until the
Portfolio replaces the  borrowed securities.  To deliver the  securities to  the
buyer,  the  Portfolio will  need  to arrange  through  a broker  to  borrow the
securities and, in so doing, the Portfolio will become obligated to replace  the
securities  borrowed  at their  market  price at  the  time of  the replacement,
whatever that price may be.  The Portfolio may have to  pay a premium to  borrow
the  securities and must pay any dividends or interest payable on the securities
until they are replaced.
 
    The Portfolio's obligation to replace the securities borrowed in  connection
with  a short sale will be secured  by collateral deposited with the broker that
consists of cash, U.S.  Government securities or other  liquid, high grade  debt
obligations.  In  addition, if  the short  sale  is not  "against the  box", the
Portfolio will place  in a segregated  account with the  Custodian an amount  of
cash,  U.S. Government securities  or other liquid,  high grade debt obligations
equal to the difference, if any, between (1) the market value of the  securities
sold  at  the  time they  were  sold short  and  (2) any  cash,  U.S. Government
securities or other liquid, high grade debt obligations deposited as  collateral
with the broker in connection with the short sale (not including the proceeds of
the  short sale). Short sales by the Portfolio involve certain risks and special
considerations. Possible losses from short  sales differ from losses that  could
be  incurred from a purchase of a  security, because losses from short sales may
be unlimited, whereas  losses from  purchases can  equal only  the total  amount
invested.
 
    SMALL  AND MEDIUM-SIZED COMPANIES.  Because the Emerging Growth and MicroCap
Portfolios seek long-term capital appreciation by investing primarily in  small-
to medium-sized companies and small companies, respectively, both of which types
of  companies are more vulnerable to financial and other risks than larger, more
established companies,  investments in  these Portfolios  may involve  a  higher
degree  of  risk  and price  volatility  than  the general  equity  markets. The
Aggressive Equity Portfolio may invest in small- to medium-sized companies to  a
lesser extent.
 
    STOCK  OPTIONS, FUTURES  CONTRACTS AND  OPTIONS IN  FUTURES CONTRACTS.   The
Equity Growth and Aggressive  Equity Portfolios may  write (i.e., sell)  covered
call  options on portfolio  securities. The Equity  Growth and Aggressive Equity
Portfolios may write covered put options  on portfolio securities. By selling  a
covered call option, the Portfolio would become obligated during the term of the
option to deliver the securities underlying
 
                                       21
<PAGE>
the  option should the  option holder choose  to exercise the  option before the
option's termination date. In return for the call it has written, the  Portfolio
will  receive from the purchaser (or option holder) a premium which is the price
of the option, less a  commission charged by a  broker. The Portfolio will  keep
the  premium regardless of whether the option is exercised. By selling a covered
put option, the Portfolio  incurs an obligation to  buy the security  underlying
the  option from the purchaser of the put  at the option's exercise price at any
time during  the option  period, at  the purchaser's  election (certain  options
written by the Portfolio will be exercisable by the purchaser only on a specific
date).  A call option is "covered" if the Portfolio owns the security underlying
the option it has written or has  an absolute or immediate right to acquire  the
security  by holding a call  option on such security,  or maintains a sufficient
amount of cash, cash equivalents or liquid securities to purchase the underlying
security.
 
    Generally, a  put option  is  "covered" if  the  Fund maintains  cash,  U.S.
Government securities or other high grade debt obligations equal to the exercise
price  of the option, or if  the Fund holds a put  option on the same underlying
security with a similar or higher exercise price.
 
    When the Portfolio writes  covered call options, it  augments its income  by
the premiums received and is thereby hedged to the extent of that amount against
a  decline in the price of the underlying securities. The premiums received will
offset a  portion  of  the potential  loss  incurred  by the  Portfolio  if  the
securities  underlying the  options are  ultimately sold  by the  Portfolio at a
loss. However, during the  option period, the Portfolio  has, in return for  the
premium  on the option, given up  the opportunity for capital appreciation above
the exercise price should the market price of the underlying security  increase,
but  has retained the risk  of loss should the  price of the underlying security
decline.
 
    The Equity Growth and the Aggressive Equity Portfolios may write put options
to receive the premiums paid by purchasers (when the Adviser wishes to  purchase
the  security underlying  the option  at a price  lower than  its current market
price, in which case  the Portfolio will  write the covered  put at an  exercise
price  reflecting the lower purchase  price sought) and to  close out a long put
option position.
 
    The Equity Growth and the Aggressive Equity Portfolios may also purchase put
options on  their  portfolio securities  or  call options.  When  the  Portfolio
purchases  a call option it acquires the right to buy a designated security at a
designated price (the "exercise price"), and when the Portfolio purchases a  put
option  it acquires  the right  to sell  a designated  security at  the exercise
price, in each  case on  or before a  specified date  (the "termination  date"),
which  is usually not more than nine months  from the date the option is issued.
The Portfolio may purchase call options to close out a covered call position  or
to  protect  against an  increase  in the  price  of a  security  it anticipates
purchasing. The Portfolio may purchase put options on securities which it  holds
in its portfolio to protect itself against decline in the value of the security.
If the value of the underlying security were to fall below the exercise price of
the put purchased in an amount greater than the premium paid for the option, the
Portfolio  would incur no  additional loss. The Portfolio  may also purchase put
options to close out written  put positions in a  manner similar to call  option
closing  purchase transactions.  There are  no other  limits on  the Portfolio's
ability to purchase call and put options.
 
    The Equity  Growth  and the  Aggressive  Equity Portfolios  may  enter  into
futures  contracts and options on futures contracts to remain fully invested and
to  reduce  transaction  costs.  The  Portfolio  may  also  enter  into  futures
transactions as a hedge against fluctuations in the price of a security it holds
or  intends to acquire, but  not for speculation or  for achieving leverage. The
Portfolio  may   enter   into  futures   contracts   and  options   on   futures
 
                                       22
<PAGE>
contracts  provided that not more than 5% of the Portfolio's total assets at the
time of entering into the  contract or option is  required as deposit to  secure
obligations  under such contracts  and options, and provided  that not more than
20% of the  Portfolio's total  assets in the  aggregate is  invested in  futures
contracts  and options on futures  contracts (and in options  in the case of the
Equity Growth and the Aggressive Equity Portfolios).
 
    The Equity  Growth and  the Aggressive  Equity Portfolios  may purchase  and
write  call  and  put  options  on futures  contracts  that  are  traded  on any
international exchange, traded over-the-counter  or which are synthetic  options
or futures or equity swaps, and may enter into closing transactions with respect
to  such  options to  terminate an  existing  position. An  option on  a futures
contract gives  the purchaser  the right  (in return  for the  premium paid)  to
assume a position in a futures contract (a long position if the option is a call
and  a short position if the  option is a put) at  a specified exercise price at
any time during the term  of the option. The  Portfolio will purchase and  write
options on futures contracts for identical purposes to those set forth above for
the  purchase of a futures contract (purchase of  a call option or sale of a put
option) and the sale of a futures contract (purchase of a put option or sale  of
a call option), or to close out a long or short position in future contracts.
 
    Options,  futures and options on futures are derivative securities, in which
the Portfolio  may invest  for hedging  purposes,  as well  as to  remain  fully
invested  and to reduce transaction costs. Investing for the latter two purposes
may be considered  speculative. The  primary risks  associated with  the use  of
options,  futures and options  on futures are  (i) imperfect correlation between
the change in market value of the stocks held by the Portfolio and the prices of
futures and options relating to the  stocks purchased or sold by the  Portfolio;
and  (ii) possible lack of a liquid secondary  market for an option or a futures
contract and the  resulting inability to  close a futures  position which  could
have  an adverse impact on  the Portfolio's ability to  hedge. In the opinion of
the Board of Directors, the risk that the Portfolio will be unable to close  out
a  futures position or options contract will  be minimized by only entering into
futures contracts or options transactions for which there appears to be a liquid
secondary market.
 
    TEMPORARY INVESTMENTS.  During periods in which the Adviser believes changes
in economic, financial or political conditions make it advisable, the Portfolios
may reduce their holdings in equity and other securities for temporary defensive
purposes and the Portfolios may invest  in certain short-term (less than  twelve
months  to maturity) and  medium-term (not greater than  five years to maturity)
debt securities or may hold cash. The short-term and medium-term debt securities
in which  the Portfolio  may invest  consist of  (a) obligations  of the  United
States   or   foreign  country   governments,   their  respective   agencies  or
instrumentalities;  (b)   bank   deposits  and   bank   obligations   (including
certificates  of  deposit, time  deposits  and bankers'  acceptances)  of United
States or foreign country banks denominated  in any currency; (c) floating  rate
securities   and  other  instruments  denominated  in  any  currency  issued  by
international development agencies; (d) finance company and corporate commercial
paper and  other short-term  corporate  debt obligations  of United  States  and
foreign  country corporations meeting the  Portfolio's credit quality standards;
and (e) repurchase agreements with banks and broker-dealers with respect to such
securities. For temporary  defensive purposes, the  Portfolios intend to  invest
only  in short-term and medium-term debt securities that the Adviser believes to
be of high quality, i.e., subject to relatively low risk of loss of interest  or
principal  (there  is currently  no rating  system for  debt securities  to most
foreign countries).
 
    WHEN-ISSUED AND DELAYED  DELIVERY SECURITIES.   The Portfolios may  purchase
securities  on a  when-issued or delayed  delivery basis.  In such transactions,
instruments are bought with payment and  delivery taking place in the future  in
order  to secure what is considered to be  an advantageous yield or price at the
time of the
 
                                       23
<PAGE>
transaction. Delivery of and payment for these securities may take as long as  a
month  or more after the date of the purchase commitment, but will take place no
more than 120 days after  the trade date. The  Portfolio will maintain with  the
Custodian  a separate  account with  a segregated  portfolio of  high-grade debt
securities or cash in an amount at least equal to these commitments. The payment
obligation and the interest rates  that will be received  are each fixed at  the
time  a Portfolio  enters into  the commitment  and no  interest accrues  to the
Portfolio until settlement. Thus,  it is possible that  the market value at  the
time  of settlement  could be  higher or  lower than  the purchase  price if the
general level of  interest rates  has changed.  It is  a current  policy of  the
Portfolios   not  to  enter  into  when-issued  commitments  exceeding,  in  the
aggregate, 15% of the Portfolio's net assets other than the obligations  created
by these commitments.
 
                             INVESTMENT LIMITATIONS
 
    Except  for the MicroCap and Aggressive Equity Portfolios, each Portfolio is
a diversified  investment company  and  is therefore  subject to  the  following
fundamental  limitations: (a) as to 75% of its total assets, a Portfolio may not
invest more than 5%  of its total  assets in the securities  of any one  issuer,
except   obligations   of   the   U.S.   Government   and   its   agencies   and
instrumentalities, and  (b)  a  Portfolio may  not  own  more than  10%  of  the
outstanding voting securities of any one issuer.
 
    The MicroCap and Aggressive Equity Portfolios are non-diversified portfolios
under  the 1940 Act, which means that the Portfolios are not limited by the 1940
Act in the proportion of their assets that may be invested in the obligations of
a single issuer. Thus, the Portfolios  may invest a greater proportion of  their
assets  in the securities of a  small number of issuers and  as a result will be
subject to greater risk with respect to their portfolio securities. However, the
Portfolios intend to  comply with  diversification requirements  imposed by  the
Internal  Revenue Code  of 1986, as  amended (the "Code"),  for qualification as
regulated investment companies. See "Investment Limitations" in the Statement of
Additional Information.
 
    Each Portfolio also operates under certain investment restrictions that  are
deemed  fundamental limitations and may be changed only with the approval of the
holders of a majority  of such Portfolio's  outstanding shares. See  "Investment
Limitations"  in  the Statement  of  Additional Information.  In  addition, each
Portfolio operates  under  certain  non-fundamental  investment  limitations  as
described  below and in the Statement  of Additional Information. Each Portfolio
may not:  (i) enter  into repurchase  agreements with  more than  seven days  to
maturity  if, as a result, more than 15%  of the market value of the Portfolio's
net assets would be invested in such repurchase agreements and other investments
for which market  quotations are not  readily available or  which are  otherwise
illiquid;  (ii) borrow money,  except from banks  for extraordinary or emergency
purposes, and then only  in amounts up  to 10% of the  value of the  Portfolio's
total  assets, taken at  cost at the  time of borrowing;  or purchase securities
while borrowings  exceed 5%  of  its total  assets;  (iii) mortgage,  pledge  or
hypothecate  any assets except in connection  with any such borrowing in amounts
up to 10% of the value of the  Portfolio's net assets at the time of  borrowing;
(iv)  invest in fixed time deposits with a duration of over seven calendar days;
or (v) invest in fixed time deposits  with a duration of from two business  days
to seven calendar days if more than 10% of the Portfolio's total assets would be
invested in these deposits.
 
                             MANAGEMENT OF THE FUND
 
    INVESTMENT  ADVISER.  Morgan Stanley Asset Management Inc. is the Investment
Adviser and Administrator of  the Fund and each  of its portfolios. The  Adviser
provides investment advice and portfolio management
 
                                       24
<PAGE>
services  pursuant  to  an Investment  Advisory  Agreement and,  subject  to the
supervision of the  Fund's Board  of Directors,  makes each  of the  Portfolio's
day-to-day  investment  decisions,  arranges  for  the  execution  of  portfolio
transactions and  generally manages  each of  the Portfolio's  investments.  The
Adviser  is entitled  to receive from  each Portfolio an  annual management fee,
payable quarterly, equal to the percentage of average daily net assets set forth
in the table below. However, the Adviser  has agreed to a reduction in the  fees
payable  to it and to reimburse the Portfolios, if necessary, if such fees would
cause the total  annual operating  expenses of  either Portfolio  to exceed  the
respective percentage of average daily net assets set forth below.
 
<TABLE>
<CAPTION>
                                                                  MAXIMUM TOTAL OPERATING
                                                                     EXPENSES AFTER FEE
                                                                           WAIVER
                                                                  ------------------------
                  PORTFOLIO                     MANAGEMENT FEE      CLASS A      CLASS B
- ---------------------------------------------  -----------------  -----------  -----------
<S>                                            <C>                <C>          <C>
Equity Growth Portfolio                                0.60%           0.80%        1.05%
Emerging Growth Portfolio                              1.00%           1.25%        1.50%
MicroCap Portfolio                                     1.25%           1.50%        1.75%
Aggressive Equity Portfolio                            0.80%           1.00%        1.25%
</TABLE>
 
    The  fees payable  by the  Emerging Growth,  MicroCap and  Aggressive Equity
Portfolios  are  higher  than  the  management  fees  paid  by  most  investment
companies,  but  the  Adviser  believes  the fees  are  comparable  to  those of
investment companies with similar investment objectives.
 
    The Adviser, with  principal offices  at 1221  Avenue of  the Americas,  New
York,  New  York  10020,  conducts a  worldwide  portfolio  management business,
providing a broad  range of portfolio  management services to  customers in  the
United  States and abroad. At December 31,  1995, the Adviser, together with its
affiliated   asset   management   companies,   managed   investments    totaling
approximately  $57.4 billion, including approximately $41.9 billion under active
management and  $15.5  billion as  Named  Fiduciary or  Fiduciary  Adviser.  See
"Management of the Fund" in the Statement of Additional Information.
 
    PORTFOLIO  MANAGERS.  The following  persons have primary responsibility for
managing the Portfolios indicated.
 
    EQUITY GROWTH PORTFOLIO  -- KURT  FEUERMAN AND  MARGARET K.  JOHNSON.   Kurt
Feuerman  joined  Morgan Stanley  Asset Management  in July  1993 as  a Managing
Director in  the  Institutional Equity  Group.  Previously Mr.  Feuerman  was  a
Managing  Director of Morgan Stanley  & Co., Incorporated's Research Department,
where he was  responsible for  emerging growth stocks,  gaming and  restaurants.
Before  joining Morgan Stanley,  Mr. Feuerman was a  Managing Director of Drexel
Burnham Lambert, where he had been an equity analyst since 1984. Over the years,
he has been highly  ranked in the Institutional  Investor All American  Research
Poll  in four separate  categories: packaged food,  tobacco, emerging growth and
gaming. Mr. Feuerman earned an M.B.A. from Columbia University in 1982, an  M.A.
from  Syracuse University in  1980, and a  B.A. from McGill  University in 1977.
Margaret Johnson is a Principal  of the Adviser and  a Portfolio Manager in  the
Institutional  Equity Group.  She joined  the Adviser in  1984 and  worked as an
Analyst in the  Marketing and  Fiduciary Advisor  areas. Ms.  Johnson became  an
Equity  Analyst in 1986 and a Portfolio Manager in 1989. Prior to joining Morgan
Stanley, she worked for the New York  City PBS affiliate, WNET, Channel 13.  She
holds  a B.A. degree from Yale College and is a Chartered Financial Analyst. Mr.
Feuerman and  Ms.  Johnson have  had  primary responsibility  for  managing  the
Portfolio's assets since July 1993 and April 1991, respectively.
 
                                       25
<PAGE>
    EMERGING  GROWTH PORTFOLIO -- DENNIS G. SHERVA.  Dennis Sherva is a Managing
Director of Morgan Stanley & Co., Incorporated and head of emerging growth stock
investments at the Adviser. He has  had primary responsibility for managing  the
Portfolio's  assets since November  1989. Prior to joining  the Adviser in 1988,
Mr. Sherva was Morgan  Stanley's Director of  Worldwide Research activities  for
five  years  and  maintained  direct responsibility  for  emerging  growth stock
strategy and analysis. As  an analyst following emerging  growth stocks for  the
past  decade, he was rated  number one in the  small growth company category six
times by  Institutional  Investor  magazine's All-America  Research  Team  poll.
Before joining Morgan Stanley in 1977, Mr. Sherva had twelve years of industrial
and investment experience. He serves on the Board of Directors of Morgan Stanley
Venture  Capital Inc. and Morgan Stanley R&D Ventures, Inc. Mr. Sherva graduated
from the  University  of  Minnesota  and  received  an  M.A.  from  Wayne  State
University. He is also a Chartered Financial Analyst.
 
    MICROCAP  PORTFOLIO --  DENNIS G. SHERVA.   Information about  Mr. Sherva is
included under the Emerging Growth Portfolio above.
 
    AGGRESSIVE EQUITY  PORTFOLIO  --  KURT  FEUERMAN.    Information  about  Mr.
Feuerman is included under the Equity Growth Portfolio above.
 
    ADMINISTRATOR.    The Adviser  also  provides the  Fund  with administrative
services pursuant to  an Administration Agreement.  The services provided  under
the  Administration Agreement are subject to the supervision of the Officers and
the Board of  Directors of  the Fund  and include  day-to-day administration  of
matters  related  to the  corporate existence  of the  Fund, maintenance  of its
records, preparation of reports, supervision of the Fund's arrangements with its
custodian,  and  assistance  in  the  preparation  of  the  Fund's  registration
statements  under  Federal and  State  laws. The  Administration  Agreement also
provides that the Administrator,  through its agents, will  provide to the  Fund
dividend  disbursing and  transfer agent  services. For  its services  under the
Administration Agreement, the Fund  pays the Adviser a  monthly fee which on  an
annual basis equals 0.15% of the average daily net assets of the Portfolio.
 
    Under  an agreement between  the Adviser and The  Chase Manhattan Bank, N.A.
("Chase"), Chase  provides certain  administrative services  to the  Fund. In  a
merger  completed on September 1, 1995, Chase succeeded to all of the rights and
obligations under the  U.S. Trust Administration  Agreement between the  Adviser
and  the United  States Trust  Company of New  York ("U.S.  Trust"), pursuant to
which U.S. Trust had  agreed to provide certain  administrative services to  the
Fund.  Pursuant  to  a  delegation  clause  in  the  U.S.  Trust  Administration
Agreement, U.S.  Trust delegated  its administration  responsibilities to  Chase
Global  Funds Services Company ("CGFSC"), formerly known as Mutual Funds Service
Company, which after the  merger with Chase  is a subsidiary  of Chase and  will
continue  to provide  certain administrative services  to the  Fund. The Adviser
supervises and  monitors such  administrative services  provided by  CGFSC.  The
services  provided  under  the  Administration  Agreement  and  the  U.S.  Trust
Administration Agreement are  also subject to  the supervision of  the Board  of
Directors  of the  Fund. The  Board of  Directors of  the Fund  has approved the
provision of services described above  pursuant to the Administration  Agreement
and  the U.S. Trust Administration  Agreement as being in  the best interests of
the Fund. CGFSC's business address  is 73 Tremont Street, Boston,  Massachusetts
02108-3913. For additional information regarding the Administration Agreement or
the  U.S. Trust  Administration Agreement, see  "Management of the  Fund" in the
Statement of Additional Information.
 
                                       26
<PAGE>
    DIRECTORS AND OFFICERS.  Pursuant  to the Fund's Articles of  Incorporation,
the  Board of Directors decides  upon matters of general  policy and reviews the
actions of the Fund's  Adviser, Administrator and  Distributor. The Officers  of
the Fund conduct and supervise its daily business operations.
 
    DISTRIBUTOR.   Morgan  Stanley serves  as the  exclusive Distributor  of the
shares of  the Fund.  Under its  Distribution Agreement  with the  Fund,  Morgan
Stanley  sells  shares of  each  Portfolio upon  the  terms and  at  the current
offering price described in this Prospectus. Morgan Stanley is not obligated  to
sell any certain number of shares of any Portfolio.
 
    The  Portfolios currently offer  only the classes of  shares offered by this
Prospectus. The Portfolios may in the future offer one or more classes of shares
with features, distribution expenses or  other expenses that are different  from
those  of  the  classes  currently  offered. The  Fund  has  adopted  a  Plan of
Distribution with respect to the Class B shares pursuant to Rule 12b-1 under the
1940 Act (the "Plan").  Under the Plan, the  Distributor is entitled to  receive
from  the  Portfolios  a  distribution  fee, which  is  accrued  daily  and paid
quarterly, of  0.25% of  the Class  B shares'  average daily  net assets  on  an
annualized  basis. The Distributor expects to reallocate  most of its fee to its
investment representatives. The Distributor may, in its discretion,  voluntarily
waive  from time to time all or any  portion of its distribution fee and each of
the Distributor and the Adviser if free  to make additional payments out of  its
own  assets  to  promote  the  sale  of  Fund  shares,  including  payments that
compensate financial  institutions  for  distribution  services  or  shareholder
services.
 
    The  Plan is designed to compensate the Distributor for its services, not to
reimburse the Distributor for its expenses,  and the Distributor may retain  any
portion  of the fee that it does not expend in fulfillment of its obligations to
the Fund.
 
    EXPENSES.  Each Portfolio is responsible  for payment of certain other  fees
and  expenses  (including legal  fees,  accountants' fees,  custodial  fees, and
printing and mailing  costs) specified  in the  Administration and  Distribution
Agreements.
 
                               PURCHASE OF SHARES
 
    Class A and Class B shares of each Portfolio may be purchased, without sales
commission,  at the net asset  value per share next  determined after receipt of
the purchase order by the Portfolio. See "Valuation of Shares."
 
MINIMUM INVESTMENT AND ACCOUNT SIZES; CONVERSION FROM CLASS A TO CLASS B SHARES
 
    For a  Portfolio  account  opened  on  or after  January  2,  1996  (a  "New
Account"),  the minimum initial investment and minimum account size are $500,000
for Class  A  shares and  $100,000  for Class  B  shares. Managed  Accounts  may
purchase Class A shares without being subject to such minimum initial investment
or  minimum account size requirements for  a Portfolio account. Employees of the
Adviser and of its affiliates may purchase Class A Shares subject to conditions,
including a lower  minimum initial  investment, established by  Officers of  the
Fund.
 
    If the value of a New Account containing Class A shares falls below $500,000
(but  remains at  or above $100,000)  because of  shareholder redemption(s), the
Fund will  notify  the shareholder,  and  if  the account  value  remains  below
$500,000  (but remains at or above $100,000) for a continuous 60-day period, the
Class A  shares in  such account  will convert  to Class  B shares  and will  be
subject to the distribution fee and other features
 
                                       27
<PAGE>
applicable  to the Class B  shares. The Fund, however,  will not convert Class A
shares to Class B shares based solely upon changes in the market that reduce the
net asset value  of shares.  Under current  tax law,  conversions between  share
classes are not a taxable event to the shareholder.
 
    Shares  in a Portfolio account opened prior  to January 2, 1996 (a "Pre-1996
Account") were  designated  Class A  shares  on January  2,  1996. Shares  in  a
Pre-1996  Account  with  a  value  of  $100,000 or  more  on  March  1,  1996 (a
"Grandfathered Class A Account") remained  Class A shares regardless of  account
size  thereafter. Except for shares  in a Managed Account,  shares in a Pre-1996
Account with a value of  less than $100,000 on  March 1, 1996 (a  "Grandfathered
Class  B Account") converted to  Class B shares on  March 1, 1996. Grandfathered
Class A Accounts and Managed Accounts are not subject to conversion from Class A
shares to Class B shares.
 
    Investors may also invest in the  Fund by purchasing shares through a  trust
department, broker, dealer, agent, financial planner, financial services firm or
investment  adviser.  An  investor  may  be  charged  an  additional  service or
transaction fee by that institution. The minimum investment levels may be waived
at the discretion  of the  Adviser for (i)  certain employees  and customers  of
Morgan  Stanley  or  its  affiliates  and  certain  trust  departments, brokers,
dealers, agents,  financial planners,  financial services  firms, or  investment
advisers  that  have  entered  into  an agreement  with  Morgan  Stanley  or its
affiliates; and (ii) retirement and deferred compensation plans and trusts  used
to  fund such  plans, including,  but not limited  to, those  defined in Section
401(a), 403(b) or  457 of the  Internal Revenue  Code of 1986,  as amended,  and
"rabbi  trusts".  The  Fund  reserves  the  right  to  modify  or  terminate the
conversion features of  the shares  as stated above  at any  time upon  60-days'
notice to shareholders.
 
MINIMUM ACCOUNT SIZES AND INVOLUNTARY REDEMPTION OF SHARES
 
    If  the value of a  New Account falls below  $100,000 because of shareholder
redemption(s), the Fund will  notify the shareholder, and  if the account  value
remains  below  $100,000 for  a  continuous 60-day  period,  the shares  in such
account are subject to redemption  by the Fund and,  if redeemed, the net  asset
value  of  such shares  will  be promptly  paid  to the  shareholder.  The Fund,
however, will not  redeem shares based  solely upon changes  in the market  that
reduce the net asset value of shares.
 
    Grandfathered  Class A Accounts, Grandfathered  Class B Accounts and Managed
Accounts are not subject to involuntary redemption.
 
    The  Fund  reserves  the  right  to  modify  or  terminate  the  involuntary
redemption  features of  the shares  as stated above  at any  time upon 60-days'
notice to shareholders.
 
CONVERSION FROM CLASS B TO CLASS A SHARES
 
    If the value of Class B shares in a Portfolio account increases, whether due
to shareholder share  purchases or  market activity,  to $500,000  or more,  the
Class  B shares  will convert  to Class  A shares.  Under current  tax law, such
conversion is not a taxable event  to the shareholder. Class A shares  converted
from  Class B shares are  subject to the same  minimum account size requirements
that are applicable to New Accounts containing Class A shares, as stated  above.
The  Fund reserves the right  to modify or terminate  this conversion feature at
any time upon 60-days' notice to shareholders.
 
                                       28
<PAGE>
INITIAL PURCHASES DIRECTLY FROM THE FUND
 
    The Fund's determination of an investor's eligibility to purchase shares  of
a  given class will  take precedence over  the investor's selection  of a class.
Assuming the investor is eligible for the  class, the Fund will select the  most
favorable class for the investor, if the investor has not done so.
 
1) BY  CHECK.   An account may  be opened  by completing and  signing an Account
   Registration Form and mailing it, together with a check ($500,000 minimum for
   Class A shares  of the  Portfolios and  $100,000 for  Class B  shares of  the
   Portfolios,  with certain exceptions for  Morgan Stanley employees and select
   customers) payable to "Morgan Stanley Institutional Fund, Inc. --  [portfolio
   name]", to:
 
      Morgan Stanley Institutional Fund, Inc.
     P.O. Box 2798
     Boston, Massachusetts 02208-2798
 
     Payment will  be accepted only  in U.S. dollars,  unless prior approval for
  payment by other currencies is given by the Fund. The Classes of shares of the
  Portfolio(s) to be purchased should be designated on the Account  Registration
  Form.  For purchases  by check, the  Fund is ordinarily  credited with Federal
  Funds within  one business  day. Thus,  your purchase  of shares  by check  is
  ordinarily  credited to your account at the  net asset value per share of each
  of the relevant Portfolios determined on the next business day after receipt.
 
2) BY FEDERAL  FUNDS WIRE.   Purchases  may be  made by  having your  bank  wire
   Federal  Funds to the Fund's bank account.  In order to ensure prompt receipt
   of your Federal Funds Wire, it is important that you follow these steps:
 
A.  Telephone  the Fund  (toll free: 1-800-548-7786)  and provide  us with  your
    name,  address,  telephone  number, Social  Security  or  Tax Identification
    Number, the  portfolio(s) selected,  the class  selected, the  amount  being
    wired,  and by  which bank.  We will  then provide  you with  a Fund account
    number. (Investors with existing accounts should also notify the Fund  prior
    to wiring funds.)
 
B.    Instruct  your  bank to  wire  the  specified amount  to  the  Fund's Wire
    Concentration Bank Account (be  sure to have your  bank include the name  of
    the  portfolio(s)  selected,  the  class  selected  and  the  account number
    assigned to you) as follows:
 
    Chase Manhattan Bank, N.A.
    One Manhattan Plaza
    New York, NY 10081-1000
    ABA #021000021
    DDA #91-02-733293
    Attn: Morgan Stanley Institutional Fund, Inc.
    Ref: (Portfolio name, your account number, your account name)
 
    Please call the Fund at 1-800-548-7786 prior to wiring funds.
 
C.  Complete  the Account Registration  Form and  mail it to  the address  shown
    thereon.
 
                                       29
<PAGE>
  Purchase  orders for shares of the Portfolios  which are received prior to the
  regular close of the NYSE (currently 4:00 p.m. Eastern Time) will be  executed
  at  the price computed  on the date of  receipt as long  as the Transfer Agent
  receives payment by check or  in Federal Funds prior  to the regular close  of
  the NYSE on such day.
 
  Federal Funds purchase orders will be accepted only on a day on which the Fund
  and Chase (the "Custodian Bank") are open for business. Your bank may charge a
  service fee for wiring Federal Funds.
 
3) BY  BANK WIRE.   The  same procedure outlined  under "By  Federal Funds Wire"
   above must be  followed in  purchasing shares  by bank  wire. However,  money
   transferred  by bank wire may or may  not be converted into Federal Funds the
   same day, depending on the time the  money is received and the bank  handling
   the wire. Prior to such conversion, an investor's money will not be invested.
   Your bank may charge a service fee for wiring funds.
 
ADDITIONAL INVESTMENTS
 
    You  may  add to  your account  at any  time (minimum  additional investment
$1,000  except  for  automatic  reinvestment  of  dividends  and  capital  gains
distributions for which there are no minimums) by purchasing shares at net asset
value  by mailing a check to the  Fund (payable to "Morgan Stanley Institutional
Fund, Inc. -- [portfolio name]") at the above address or by wiring monies to the
Custodian Bank as outlined above. It  is very important that your account  name,
the  portfolio name and the class selected be specified in the letter or wire to
assure proper  crediting to  your account.  In order  to insure  that your  wire
orders  are invested  promptly, you  are requested to  notify one  of the Fund's
representatives (toll free: 1-800-548-7786) prior  to the wire date.  Additional
investments will be applied to purchase additional shares in the same class held
by a shareholder in a Portfolio account.
 
OTHER PURCHASE INFORMATION
 
    The  purchase price of the  Class A and Class B  shares of each Portfolio is
the net asset value next determined after the order is received. See  "Valuation
of  Shares." An order received prior to the close of the New York Stock Exchange
("NYSE"), which is  currently 4:00 p.m.  Eastern Time, will  be executed at  the
price  computed on the date of receipt; an order received after the close of the
NYSE will be executed at the price computed on the next day the NYSE is open  as
long  as the Transfer Agent receives payment  by check or in Federal Funds prior
to the regular close of the NYSE on such day.
 
    Although the legal rights of Class A  and Class B shares will be  identical,
the  different expenses borne by  each class will result  in different net asset
values and dividends. The net  asset value of Class  B shares will generally  be
lower than the net asset value of Class A shares as a result of the distribution
expense  charged to Class B shares. It  is expected, however, that the net asset
value per share of the two classes  will tend to converge immediately after  the
recording  of dividends  which will  differ by  approximately the  amount of the
distribution expense accrual differential between the classes.
 
    In the interest  of economy and  convenience, and because  of the  operating
procedures  of the Fund, certificates representing shares of the Portfolios will
not be issued. All shares  purchased are confirmed to  you and credited to  your
account  on the Fund's books  maintained by the Adviser  or its agents. You will
have  the  same  rights  and  ownership  with  respect  to  such  shares  as  if
certificates had been issued.
 
                                       30
<PAGE>
    To  ensure that checks are collected by the Fund, withdrawals of investments
made by check  are not presently  permitted until payment  for the purchase  has
been  received,  which may  take up  to eight  business days  after the  date of
purchase. As a condition  of this offering,  if a purchase  is cancelled due  to
nonpayment or because your check does not clear, you will be responsible for any
loss  the Fund or its  agents incur. If you are  already a shareholder, the Fund
may redeem shares from your account(s) to  reimburse the Fund or its agents  for
any  loss. In addition, you  may be prohibited or  restricted from making future
investments in the Fund.
 
    Investors may  also invest  in the  Fund by  purchasing shares  through  the
Distributor.
 
EXCESSIVE TRADING
 
    Frequent   trades  involving  either  substantial   portfolio  assets  or  a
substantial portion of your  account or accounts controlled  by you can  disrupt
management  of a Portfolio and raise its expenses. Consequently, in the interest
of all the stockholders  of the Portfolio and  the Portfolio's performance,  the
Fund  may in its discretion bar a  stockholder that engages in excessive trading
of shares of a  Portfolio from further  purchases of shares of  the Fund for  an
indefinite  period. The  Fund considers  excessive trading  to be  more than one
purchase and sale  involving shares  of the  same Portfolio  within any  120-day
period. For example, exchanging shares of Portfolio A for shares of Portfolio B,
then  exchanging shares of Portfolio B for shares of Portfolio C of the Fund and
again exchanging the shares of  Portfolio C for shares  of Portfolio B within  a
120-day  period  amounts to  excessive trading.  Two  types of  transactions are
exempt from these excessive trading restrictions: (1) trades exclusively between
money market  portfolios,  and (2)  trades  done  in connection  with  an  asset
allocation service managed or advised by MSAM and/or any of its affiliates.
 
                              REDEMPTION OF SHARES
 
    You  may  withdraw all  or  any portion  of the  amount  in your  account by
redeeming shares at any time. Please note  that purchases made by check are  not
permitted to be redeemed until payment of the purchase price has been collected,
which  may take up to  eight business days after  purchase. The Fund will redeem
Class A shares or Class B shares of a Portfolio at the next determined net asset
value of shares  of the applicable  class. On days  that both the  NYSE and  the
Custodian  Bank are open for business, the net  asset value per share of each of
the Portfolios is determined at the close of trading of the NYSE (currently 4:00
p.m. Eastern  Time).  Shares  of the  Portfolios  may  be redeemed  by  mail  or
telephone.  No charge is made for redemption. Any redemption may be more or less
than the purchase price  of your shares depending  on, among other factors,  the
market value of the investment securities held by the Portfolios.
 
BY MAIL
 
    Each  Portfolio will redeem its Class A shares  or Class B shares at the net
asset value determined on the  date the request is  received, if the request  is
received  in "good  order" before  the regular close  of the  NYSE. Your request
should be addressed to Morgan Stanley  Institutional Fund, Inc., P.O. Box  2798,
Boston,  Massachusetts 02208-2798,  except that deliveries  by overnight courier
should be addressed to Morgan Stanley Institutional Fund, Inc., c/o Chase Global
Funds Services Company, 73 Tremont Street, Boston, Massachusetts 02108-3913.
 
                                       31
<PAGE>
    "Good order"  means that  the  request to  redeem  shares must  include  the
following documentation:
 
        (a)   A letter of instruction or a stock assignment specifying the class
    and number  of  shares  or dollar  amount  to  be redeemed,  signed  by  all
    registered  owners  of the  shares  in the  exact  names in  which  they are
    registered;
 
        (b)  Any  required   signature  guarantees   (see  "Further   Redemption
    Information" below); and
 
        (c)    Other supporting  legal documents,  if required,  in the  case of
    estates, trusts,  guardianships, custodianships,  corporations, pension  and
    profit sharing plans and other organizations.
 
    Shareholders who are uncertain of requirements for redemption should consult
with a Morgan Stanley Institutional Fund representative.
 
BY TELEPHONE
 
    Provided  you have previously elected the Telephone Redemption Option on the
Account Registration  Form, you  can  request a  redemption  of your  shares  by
calling  the Fund  and requesting  the redemption proceeds  be mailed  to you or
wired to your bank.  Please contact one of  Morgan Stanley Institutional  Fund's
representatives  for further details. In times of drastic market conditions, the
telephone redemption option  may be  difficult to implement.  If you  experience
difficulty in making a telephone redemption, your request may be made by mail or
overnight courier and will be implemented at the net asset value next determined
after  it is received. Redemption requests sent to the Fund through express mail
must be mailed  to the  address of the  Dividend Disbursing  and Transfer  Agent
listed  under "General Information". The Fund and the Fund's transfer agent (the
"Transfer  Agent")  will  employ  reasonable  procedures  to  confirm  that  the
instructions  communicated by  telephone are  genuine. These  procedures include
requiring the investor to provide certain personal identification information at
the time an account is opened and prior to effecting each transaction  requested
by  telephone. In addition, all telephone  transaction requests will be recorded
and  investors  may  be  required  to  provide  additional  telecopied   written
instructions  regarding transaction requests. Neither  the Fund nor the Transfer
Agent will be responsible for any loss, liability, cost or expense for following
instructions received by telephone that either of them reasonably believes to be
genuine.
 
    To change the commercial  bank or account  designated to receive  redemption
proceeds,  a written  request must  be sent  to the  Fund at  the address above.
Requests to change the bank  or account must be  signed by each shareholder  and
each signature must be guaranteed.
 
FURTHER REDEMPTION INFORMATION
 
    Normally  the  Fund will  make payment  for all  shares redeemed  within one
business day of receipt  of the request,  but in no event  will payment be  made
more  than  seven days  after receipt  of  a redemption  request in  good order.
However, payments to investors  redeeming shares which  were purchased by  check
will  not be made until  payment for the purchase  has been collected, which may
take up to eight days after the date of purchase. The Fund may suspend the right
of redemption or postpone the date upon which redemptions are effected at  times
when  the NYSE is closed, or under  any emergency circumstances as determined by
the Securities and Exchange Commission (the "Commission").
 
    If the Board  of Directors determines  that it would  be detrimental to  the
best  interests of  the remaining  shareholders of  a Portfolio  to make payment
wholly  or  partly  in   cash,  the  Fund  may   pay  the  redemption   proceeds
 
                                       32
<PAGE>
in  whole  or  in part  by  a distribution  in-kind  of securities  held  by the
Portfolio in lieu of cash in conformity with applicable rules of the Commission.
Distributions-in-kind will be made  in readily marketable securities.  Investors
may  incur brokerage charges on the sale  of portfolio securities so received in
payment of redemptions.
 
    To protect  your account,  the Fund  and its  agents from  fraud,  signature
guarantees  are required for  certain redemptions to verify  the identity of the
person who has  authorized a redemption  from your account.  Please contact  the
Fund  for further  information. See "Redemption  of Shares" in  the Statement of
Additional Information.
 
                              SHAREHOLDER SERVICES
 
EXCHANGE FEATURES
 
    You may exchange shares  that you own  in the Portfolios  for shares of  any
other  available  portfolio of  the Fund  (other  than the  International Equity
Portfolio, which is  closed to  new investors). In  exchanging for  shares of  a
portfolio  with more  than one  class, the  class of  shares you  receive in the
exchange will be determined in the same  manner as any other purchase of  shares
and  will not  be based  on the  class of  shares surrendered  for the exchange.
Consequently, the same minimum initial  investment and minimum account size  for
determining  the  class  of shares  received  in  the exchange  will  apply. See
"Purchase of  Shares." Shares  of the  portfolios may  be exchanged  by mail  or
telephone.  The privilege to exchange shares  by telephone is automatic and made
available without shareholder election. Before you make an exchange, you  should
read  the prospectus of the portfolio(s) in which you seek to invest. Because an
exchange transaction  is treated  as a  redemption followed  by a  purchase,  an
exchange  would be considered  a taxable event for  shareholders subject to tax.
The exchange privilege  is only available  with respect to  portfolios that  are
registered  for  sale  in  a  shareholder's  state  of  residence.  The exchange
privilege may be modified or  terminated by the Fund  at any time upon  60-days'
notice to shareholders.
 
BY MAIL
 
    In  order to  exchange shares  by mail, you  should include  in the exchange
request the name, class of shares and account number of your current  portfolio,
the  name of the  portfolio(s) and the  class(es) of shares  of the portfolio(s)
into which you intend to exchange  shares, and the signatures of all  registered
account holders. Send the exchange request to Morgan Stanley Institutional Fund,
P.O. Box 2798, Boston, Massachusetts 02208-2798.
 
BY TELEPHONE
 
    When  exchanging shares by  telephone, have ready the  name, class of shares
and account number of the current Portfolio, the name(s) of the portfolio(s) and
class(es) of  shares into  which  you intend  to  exchange shares,  your  Social
Security  number  or Tax  I.D. number,  and your  account address.  Requests for
telephone exchanges received prior to 4:00 p.m. (Eastern Time) are processed  at
the  close  of business  that  same day  based  on the  net  asset value  of the
class(es) of the portfolios  at the close of  business. Requests received  after
4:00  p.m. (Eastern Time) are  processed the next business  day based on the net
asset value determined  at the  close of business  on such  day. For  additional
information   regarding  responsibility  for   the  authenticity  of  telephoned
instructions, see "Redemption of Shares -- By Telephone" above.
 
TRANSFER OF REGISTRATION
 
    You may transfer  the registration  of any of  your Fund  shares to  another
person  by writing  to Morgan Stanley  Institutional Fund, Inc.,  P.O. Box 2798,
Boston,  Massachusetts  02208-2798.   As  in  the   case  of  redemptions,   the
 
                                       33
<PAGE>
written  request must be received in good order before any transfer can be made.
Transferring the  registration of  shares  may affect  the eligibility  of  your
account  for a given class of a Portfolio's shares and may result in involuntary
conversion or redemption of your shares. See "Purchase of Shares" above.
 
                              VALUATION OF SHARES
 
    The net asset value per share of a class of shares of each of the Portfolios
is determined by dividing the total market value of the Portfolio's  investments
and  other assets attributable to such  class, less any liabilities attributable
to such class, by the  total number of outstanding shares  of such class of  the
Portfolio.  Net  asset  value  is  calculated separately  for  each  class  of a
Portfolio. Net asset value per share is  determined as of the close of the  NYSE
on  each day  that the NYSE  is open  for business. Price  information on listed
securities is taken from  the exchange where the  security is primarily  traded.
Securities  listed on a U.S. securities exchange for which market quotations are
available are valued at the last quoted  sale price on the day the valuation  is
made. Securities listed on a foreign exchange are valued at their closing price.
Unlisted  securities and listed securities not  traded on the valuation date for
which market quotations are not readily available are valued at a price that  is
considered  to best  represent fair value  within a  range not in  excess of the
current asked price nor  less than the  current bid price.  The current bid  and
asked  prices are determined  based on the  bid and asked  prices quoted on such
valuation date by reputable brokers.
 
    Bonds and other fixed income securities are valued according to the broadest
and most representative  market, which will  ordinarily be the  over-the-counter
market.  Net asset value includes interest  on fixed income securities, which is
accrued daily.  In addition,  bonds and  other fixed  income securities  may  be
valued on the basis of prices provided by a pricing service when such prices are
believed  to  reflect  the fair  market  value  of such  securities.  The prices
provided by a pricing service are determined without regard to bid or last  sale
prices,  but take into  account institutional-size trading  in similar groups of
securities and any developments related  to the specific securities.  Securities
not  priced in this manner are valued at the most recently quoted sale price, or
when securities exchange valuations are used, at the latest quoted bid price  on
the  day of valuation. If there is no  such reported sale, the latest quoted bid
price will be used. Securities purchased with remaining maturities of 60 days or
less are valued at amortized cost, if it approximates market value. In the event
that amortized  cost  does  not  approximate  market  value,  market  prices  as
determined above will be used.
 
    The value of other assets and securities for which no quotations are readily
available  (including  restricted  and unlisted  foreign  securities)  and those
securities for which it is inappropriate to determine prices in accordance  with
the  above-stated procedures  are determined in  good faith at  fair value using
methods determined by the  Board of Directors. For  purposes of calculating  net
asset value per share, all assets and liabilities initially expressed in foreign
currencies will be translated into U.S. dollars at the mean of the bid price and
asked  price of  such currencies against  the U.S.  dollar as quoted  by a major
bank.
 
    Although the legal rights of Class A  and Class B shares will be  identical,
the  different expenses borne by  each class will result  in different net asset
values and dividends for the class.  Dividends will differ by approximately  the
amount  of the distribution expense accrual  differential among the classes. The
net asset value of  Class B shares  will generally be lower  than the net  asset
value  of the Class A shares as a  result of the distribution expense charged to
Class B shares.
 
                                       34
<PAGE>
                            PERFORMANCE INFORMATION
 
    The Fund may from time to time advertise total return for each class of  the
Portfolios.  THESE FIGURES ARE BASED ON HISTORICAL EARNINGS AND ARE NOT INTENDED
TO INDICATE FUTURE PERFORMANCE. The "total return" shows what an investment in a
class of a Portfolio would have earned over a specified period of time (such  as
one,  five or ten years),  assuming that all distributions  and dividends by the
Portfolio were reinvested in the same class on the reinvestment dates during the
period. Total return  does not  take into account  any federal  or state  income
taxes that may be payable on dividends and distributions or upon redemption. The
Fund  may  also include  comparative performance  information in  advertising or
marketing  the  Portfolio's  shares,  including  data  from  Lipper   Analytical
Services,  Inc.,  other  industry  publications,  business  periodicals,  rating
services and market indices.
 
    The performance figures  for Class  B shares  will generally  be lower  than
those  for Class  A shares because  of the  distribution fee charged  to Class B
shares.
 
                   DIVIDENDS AND CAPITAL GAINS DISTRIBUTIONS
 
    All income dividends and capital gains  distributions for a class of  shares
will be automatically reinvested in additional shares of such class at net asset
value,  except that,  upon written  notice to  the Fund  or by  checking off the
appropriate box in the Distribution  Option Section on the Account  Registration
Form,  a shareholder  may elect  to receive  income dividends  and capital gains
distributions in cash.
 
    The Emerging  Growth  and  the  MicroCap  Portfolios  expect  to  distribute
substantially all of their net investment income in the form of annual dividends
and  the Equity Growth and the Aggressive Equity Portfolios expect to distribute
substantially all  of their  net  investment income  in  the form  of  quarterly
dividends.  Net realized gains  for each Portfolio, if  any, after reduction for
any  available  tax  loss  carryforwards  will  also  be  distributed  annually.
Confirmations  of the purchase of shares of each Portfolio through the automatic
reinvestment of  income  dividends  and  capital  gains  distributions  will  be
provided,  pursuant to Rule 10b-10(b) under the Securities Exchange Act of 1934,
as amended, on  the next  monthly client  statement following  such purchase  of
shares.  Consequently, confirmations of  such purchases will  not be provided at
the time of completion of such purchases, as might otherwise be required by Rule
10b-10.
 
    Undistributed net  investment income  is included  in each  Portfolio's  net
assets  for the purpose of calculating net  asset value per share. Therefore, on
the "ex-dividend" date,  the net  asset value  per share  excludes the  dividend
(i.e.,  is reduced  by the  per share  amount of  the dividend).  Dividends paid
shortly after the purchase of shares by an investor, although in effect a return
of capital, are taxable to shareholders subject to income tax.
 
    Because of  the  distribution  fee  and  any  other  expenses  that  may  be
attributable  to the  Class B  shares, the  net income  attributable to  and the
dividends payable  on  Class  B  shares  will  be  lower  than  the  net  income
attributable  to and the dividends  payable on Class A  shares. As a result, the
net asset value per share of the classes of the Portfolios will differ at times.
Expenses of the Portfolio allocated to a particular class of shares thereof will
be borne on a pro rata basis by each outstanding share of that class.
 
                                     TAXES
 
    The following summary of certain federal income tax consequences is based on
current tax laws and regulations, which may be changed by legislative, judicial,
or administrative action.
 
                                       35
<PAGE>
    No attempt has been made to  present a detailed explanation of the  federal,
state,  or  local  income tax  treatment  of  a Portfolio  or  its shareholders.
Accordingly, shareholders  are urged  to consult  their tax  advisors  regarding
specific questions as to federal, state and local income taxes.
 
    Each  Portfolio  is treated  as  a separate  entity  for federal  income tax
purposes and  is not  combined with  the  Fund's other  portfolios. It  is  each
Portfolio's intent to continue to qualify for the special tax treatment afforded
regulated  investment  companies  under the  Code,  so that  the  Portfolio will
continue to be relieved of federal income tax on that part of its net investment
income and net capital gain that is distributed to shareholders.
 
    Each Portfolio distributes  substantially all of  its net investment  income
(including, for this purpose, the excess of net short-term capital gain over net
long-term  capital  loss)  to  shareholders. Dividends  from  a  Portfolio's net
investment income  are  taxable  to shareholders  as  ordinary  income,  whether
received  in cash or  in additional shares.  Such dividends paid  by a Portfolio
will generally qualify  for the 70%  dividends-received deduction for  corporate
shareholders  to  the  extent  of qualifying  dividend  income  received  by the
Portfolio from U.S.  corporations. Each  Portfolio will report  annually to  its
shareholders the amount of dividend income qualifying for such treatment.
 
    Distributions  of net capital gain (the excess of net long-term capital gain
over net  short-term capital  loss)  are taxable  to shareholders  as  long-term
capital  gain, regardless of how long  shareholders have held their shares. Each
Portfolio sends reports annually to its  shareholders of the federal income  tax
status of all distributions made during the preceding year.
 
    Each   Portfolio  intends   to  make  sufficient   distributions  or  deemed
distributions of its ordinary income and capital gain net income (the excess  of
short-term  and long-term  capital gains  over short-term  and long-term capital
losses), prior to the end of each  calendar year to avoid liability for  federal
excise tax.
 
    Dividends  and  other  distributions  declared by  a  Portfolio  in October,
November or December of any year and payable to shareholders of record on a date
in such month will be deemed to have been paid by the Portfolio and received  by
the  shareholders on December 31  of that year if  the distributions are paid by
the Portfolio at any time during the following January.
 
    The sale, redemption, or  exchange of shares may  result in taxable gain  or
loss to the selling, exchanging or redeeming shareholder, depending upon whether
the fair market value of the sale, exchange or redemption proceeds exceeds or is
less  than the shareholder's  adjusted basis in the  sold, exchanged or redeemed
shares. Any such  taxable gain or  loss generally will  be treated as  long-term
capital  gain or loss  if the shares have  been held for more  than one year and
otherwise generally  will be  treated as  short-term capital  gain or  loss.  If
capital  gain distributions have been made with  respect to shares that are sold
at a loss after  being held for six  months or less, however,  then the loss  is
treated  as  a  long-term  capital  loss  to  the  extent  of  the  capital gain
distributions.
 
    Investment income  received  by  a Portfolio  from  sources  within  foreign
countries  may be subject to foreign income taxes withheld at the source. To the
extent that a Portfolio is  liable for foreign income  taxes so withheld, it  is
not  expected that  a Portfolio  or its  shareholders would  be able  to claim a
credit for U.S. tax purposes with respect to any such foreign taxes.
 
    The conversion of Class A shares to  Class B shares should not be a  taxable
event to the shareholder.
 
                                       36
<PAGE>
    Shareholders  are urged  to consult with  their tax  advisors concerning the
application of state and local income taxes to investments in a Portfolio, which
may differ from the federal income tax consequences described above.
 
    THE  TAX  DISCUSSION  SET  FORTH  ABOVE  IS  INCLUDED  HEREIN  FOR   GENERAL
INFORMATION  ONLY. PROSPECTIVE INVESTORS  SHOULD CONSULT THEIR  OWN TAX ADVISERS
WITH RESPECT TO THE TAX CONSEQUENCES TO THEM OF AN INVESTMENT IN A PORTFOLIO.
 
                             PORTFOLIO TRANSACTIONS
 
    The Investment  Advisory  Agreement authorizes  the  Adviser to  select  the
brokers  or  dealers that  will execute  the purchases  and sales  of investment
securities for the Portfolios and directs the Adviser to use its best efforts to
obtain the best available price and most favorable execution with respect to all
transactions for the  Portfolios. The  Fund has  authorized the  Adviser to  pay
higher commissions in recognition of brokerage services which, in the opinion of
the Adviser, are necessary for the achievement of better execution, provided the
Adviser believes this to be in the best interest of the Fund.
 
    Since shares of the Portfolios are not marketed through intermediary brokers
or  dealers, it is  not the Fund's  practice to allocate  brokerage or principal
business on the basis of sales of  shares which may be made through such  firms.
However,  the Adviser may  place portfolio orders  with qualified broker-dealers
who recommend the  Fund's portfolios or  who act  as agents in  the purchase  of
shares of the Fund's portfolios for their clients.
 
    In  purchasing and selling  securities for the Portfolios,  it is the Fund's
policy to seek to obtain quality execution at the most favorable prices  through
responsible   broker-dealers.  In   selecting  broker-dealers   to  execute  the
securities transactions for the Portfolios, consideration will be given to  such
factors  as the price of the security, the  rate of the commission, the size and
difficulty of  the  order,  the  reliability,  integrity,  financial  condition,
general  execution and operational capabilities of competing broker-dealers, and
the brokerage  and  research services  which  they  provide to  the  Fund.  Some
securities  considered for investment by the  Portfolios may also be appropriate
for other clients served by the Adviser.  If the purchase or sale of  securities
consistent  with the investment  policies of the  Portfolios and one  or more of
these other clients served  by the Adviser  is considered at  or about the  same
time, transactions in such securities will be allocated among the Portfolios and
such  other  clients in  a manner  deemed  fair and  reasonable by  the Adviser.
Although there is  no specified  formula for allocating  such transactions,  the
various  allocation  methods  used  by  the Adviser,  and  the  results  of such
allocations, are subject to periodic review by the Fund's Board of Directors.
 
    Subject to the overriding objective of obtaining the best possible execution
of orders,  the Adviser  may allocate  a portion  of the  Portfolio's  brokerage
transactions  to Morgan Stanley or broker affiliates of Morgan Stanley. In order
for Morgan Stanley or  its affiliates to effect  any portfolio transactions  for
the Fund, the commissions, fees or other remuneration received by Morgan Stanley
or such affiliates 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   a
securities  exchange during a comparable period  of time. Furthermore, the Board
of   Directors    of    the    Fund,   including    a    majority    of    those
 
                                       37
<PAGE>
Directors  who are not  "interested persons," as  defined in the  1940 Act, have
adopted  procedures  which   are  reasonably  designed   to  provide  that   any
commissions,  fees  or  other  remuneration  paid  to  Morgan  Stanley  or  such
affiliates are consistent with the foregoing standard.
 
    Portfolio securities will not  be purchased from or  through, or sold to  or
through,  the Adviser or Morgan Stanley  or any "affiliated persons," as defined
in the 1940 Act of Morgan Stanley  when such entities are acting as  principals,
except to the extent permitted by law.
 
    Although none of the Portfolios will invest for short-term trading purposes,
investment securities may be sold from time to time without regard to the length
of time they have been held. For the Equity Growth, Emerging Growth and MicroCap
Portfolios,  it  is anticipated  that,  under normal  circumstances,  the annual
portfolio turnover  rate will  not exceed  100%. However,  the annual  portfolio
turnover  rate of the Equity Growth Portfolio for the fiscal year ended December
31, 1994 was  146%. For the  Aggressive Equity Portfolio,  the annual  portfolio
turnover  rate  is expected  to exceed  100%.  High portfolio  turnover involves
correspondingly greater transaction costs  which will be  borne directly by  the
respective  Portfolio. In addition,  high portfolio turnover  may result in more
capital gains  which would  be taxable  to the  shareholders of  the  respective
Portfolio.   The  tables  set  forth   in  "Financial  Highlights"  present  the
Portfolios' historical turnover rates.
 
                              GENERAL INFORMATION
 
DESCRIPTION OF COMMON STOCK
 
    The Fund  was organized  as a  Maryland corporation  on June  16, 1988.  The
Articles  of Incorporation, as amended and restated, permit the Fund to issue up
to 34 billion shares of common stock,  with $.001 par value per share.  Pursuant
to the Fund's Articles of Incorporation, the Board of Directors may increase the
number  of shares the  Fund is authorized  to issue without  the approval of the
shareholders of the  Fund. Subject  to the  notice period  to shareholders  with
respect to shares held by the shareholders, the Board of Directors has the power
to  designate one or more classes of shares  of common stock and to classify and
reclassify any  unissued shares  with respect  to such  classes. The  shares  of
common  stock of each  portfolio are currently classified  into two classes, the
Class A shares and the Class B  shares, except for the International Small  Cap,
Money  Market and  Municipal Money Market  Portfolios, which only  offer Class A
shares.
 
    The  shares  of   the  Portfolios,   when  issued,  will   be  fully   paid,
nonassessable,  fully transferable and  redeemable at the  option of the holder.
The shares have no preference as to conversion, exchange, dividends,  retirement
or  other features and have no pre-emptive  rights. The shares of each portfolio
have non-cumulative voting rights, which means that the holders of more than 50%
of the  shares voting  for  the election  of Directors  can  elect 100%  of  the
Directors  if they choose to do so.  Persons or organizations owning 25% or more
of the  outstanding shares  of a  Portfolio  may be  presumed to  "control"  (as
defined  in the 1940  Act) such Portfolio.  Under Maryland law,  the Fund is not
required to hold an annual meeting of its shareholders unless required to do  so
under the 1940 Act.
 
REPORTS TO SHAREHOLDERS
 
    The  Fund will send to its  shareholders annual and semi-annual reports; the
financial statements  appearing in  annual reports  are audited  by  independent
accountants.  Monthly unaudited portfolio  data is also  available from the Fund
upon request.
 
                                       38
<PAGE>
    In addition, the Adviser or its agent, as Transfer Agent, will send to  each
shareholder having an account directly with the Fund a monthly statement showing
transactions in the account, the total number of shares owned, and any dividends
or distributions paid.
 
CUSTODIAN
 
    As  of September 1,  1995, domestic securities  and cash are  held by Chase,
which replaced U.S.  Trust as  the Fund's domestic  custodian. Chase  is not  an
affiliate  of  the Adviser  or the  Distributor.  Morgan Stanley  Trust Company,
Brooklyn, New York ("MSTC"),  an affiliate of the  Adviser and the  Distributor,
acts  as the Fund's custodian for foreign  assets held outside the United States
and employs subcustodians  approved by  the Board of  Directors of  the Fund  in
accordance  with regulations of  the Securities and  Exchange Commission for the
purpose of providing  custodial services  for such  assets. MSTC  may also  hold
certain  domestic assets for  the Fund. For more  information on the custodians,
see "General Information -- Custody Arrangements" in the Statement of Additional
Information.
 
DIVIDEND DISBURSING AND TRANSFER AGENT
 
    Chase  Global   Funds  Services   Company,   73  Tremont   Street,   Boston,
Massachusetts 02108-3913, acts as Dividend Disbursing and Transfer Agent for the
Fund.
 
INDEPENDENT ACCOUNTANTS
 
    Price  Waterhouse LLP  serves as  independent accountants  for the  Fund and
audits the annual financial statements of each Portfolio.
 
LITIGATION
 
    The Fund is not involved in any litigation.
 
                                       39
<PAGE>
                 (This page has been left blank intentionally.)
<PAGE>
   MORGAN STANLEY INSTITUTIONAL FUND, INC.
          EQUITY GROWTH, EMERGING GROWTH,
           MICROCAP AND AGGRESSIVE EQUITY PORTFOLIOS
           P.O. BOX 2798, BOSTON, MA 02208-2798
 
                           ACCOUNT REGISTRATION FORM
 
<TABLE>
<C>   <S>                                                           <C>
                                                                    If you need assistance in filling out this form for the
      ACCOUNT INFORMATION                                           Morgan Stanley Institutional Fund, please contact your
      Fill in where applicable                                      Morgan Stanley representative or call us toll free
                                                                    1-(800)-548-7786. Please print all items except signature,
                                                                    and mail to the Fund at the address above.
 
  A)  REGISTRATION
      1. INDIVIDUAL
      2. JOINT TENANTS
         (RIGHTS OF SURVIVORSHIP PRESUMED UNLESS
         TENANCY IN COMMON
         IS INDICATED)
</TABLE>
 
1.
                               First
Name                          Initial                               Last Name
 
2.
                               First
Name                          Initial                               Last Name
 
                               First
Name                          Initial                               Last Name
 
<TABLE>
<C>   <S>                                       <C>
      3. CORPORATIONS,
         TRUSTS AND OTHERS
         Please call the Fund for additional
      documents that may be required to set up
      account and to authorize transactions.
</TABLE>
 
3.
 
<TABLE>
<S>                    <C>               <C>                        <C>               <C>
Type of Registration:  / / INCORPORATED  / / UNINCORPORATED         / / PARTNERSHIP   / / UNIFORM GIFT/TRANSFER TO MINOR
                                         ASSOCIATION                                    (ONLY ONE CUSTODIAN AND MINOR PERMITTED)
</TABLE>
 
/ / TRUST ________________________  / / OTHER (Specify) ________________________
 
<TABLE>
<C>   <S>                                       <C>
                                           Street or P.O. Box
  B)  MAILING ADDRESS
      Please fill in completely, including
      telephone number(s).
</TABLE>
 
                          City                                             State
                                                                             Zip
                                                                              --
                                           Home Telephone
No.                                                   Business Telephone No.
                                                            --  --        --  --
                          / / United States Citizen  / / Resident Alien  / /
Non-Resident Alien: Indicate Country of Residence ______________________________
 
<TABLE>
<C>   <S>                                       <C>                             <C>
  C)  TAXPAYER                                  Enter your Taxpayer Identification Number. For most individual
      IDENTIFICATION                            taxpayers, this is your Social Security Number. OR
      NUMBER                                                                    SOCIAL SECURITY NUMBER
      1. INDIVIDUAL                             1.         TAXPAYER             ("SSN")
      2. JOINT TENANTS                          IDENTIFICATION NUMBER
                                                ("TIN")
                                                --
 
         (RIGHTS OF SURVIVORSHIP PRESUMED       --        --            - - -   ------------- -------------
      UNLESS                                    -- - - - - - - -                ------------- - - - - - - - -
         TENANCY IN COMMON                                                      -
         IS INDICATED)                          2.                              OR                          TINSSN
      For Custodian account
                                                --
 
      of a minor (Uniform                       --        --            - - -   ------------- -------------
      Gifts/Transfers to Minor                  -- - - - - - - -                ------------- - - - - - - - -
                                                                                -
      Acts), give the Social                                                    OR
      Security Number of                                                      TIN                                SSN
      the minor
                                                --
 
                                                --        --            - - -   ------------- -------------
                                                - - - - - - - - -               ------------- - - - - - - - -
                                                                                -
</TABLE>
<PAGE>
 
<TABLE>
<C>   <S>                                       <C>                             <C>
                                                IMPORTANT TAX INFORMATION
                                                You (as a payee) are required by law to provide us (as  payer)
                                                with  your  correct TIN(s)  or  SSN(s). Accounts  that  have a
                                                missing or  incorrect  TIN(s) or  SSN(s)  will be  subject  to
                                                backup  withholding at a 31%  rate on dividends, distributions
                                                and other  payments. If  you have  not provided  us with  your
                                                correct  TIN(s) or SSN(s), you may be subject to a $50 penalty
                                                imposed by the Internal Revenue Service.
                                                Backup withholding is not an additional tax; the tax liability
                                                of persons subject  to backup withholding  will be reduced  by
                                                the  amount  of tax  withheld.  If withholding  results  in an
                                                overpayment   of   taxes,   a   refund   may   be    obtained.
                                                You may be notified that you are subject to backup withholding
                                                under  Section  3406(a)(1)(C)  of  the  Internal  Revenue Code
                                                because you have  underreported interest or  dividends or  you
                                                were  required to,  but failed to,  file a  return which would
                                                have included a reportable interest or dividend payment.
</TABLE>
 
<PAGE>
 
<TABLE>
<C>   <S>                                       <C>                             <C>                   <C>
  D)  PORTFOLIO AND                             For Purchase of the following   / / Class A Shares $  / / Class B Shares $
      CLASS SECTION                             Portfolio(s):                   / / Class A Shares $  / / Class B Shares $
      (Class A shares minimum $500,000 for      Equity Growth Portfolio
      each Portfolio and Class B shares         Emerging Growth Portfolio
      minimum $100,000 for the Global Equity,   MicroCap Portfolio
      International Equity, Asian Equity,       Aggressive Equity Portfolio
      European Equity, Japanese Equity and
      Latin American Equity Portfolios).
      Please indicate Portfolio, class and
      amount.
                                                                                Total Initial Investment $
</TABLE>
 
<TABLE>
<C>   <S>                                       <C>
  E)  METHOD OF
      INVESTMENT
      Please indicate portfolio, manner of
      payment.
</TABLE>
 
Payment by:
 
/ / Check (MAKE CHECK PAYABLE TO MORGAN STANLEY INSTITUTIONAL FUND,
INC.--PORTFOLIO NAME)
 
<TABLE>
<S>                                                                                 <C>
/ / Exchange $ From                                                                           -- - - - - - - - - - -- - -
                                                      Name of Portfolio                               Account No.
/ / Account previously established by:  / / Phone exchange  / / Wire on                       - - - - - - - - - - - -- - -
                                                                                            Account No.               (Check
                                                                                      (Previously assigned by the Fund)     Digit)
                                                                            Date
</TABLE>
 
<TABLE>
<C>   <S>                                       <C>
  F)  DISTRIBUTION                              Income dividends and capital gains distributions (if any) to
      OPTION                                    be reinvested in additional shares unless either box below
                                                is checked.
                                                / / Income dividends to be paid in cash, capital gains
                                                distributions (if any) in shares.
                                                / / Income dividends and capital gains distributions (if
                                                any) to be paid in cash.
</TABLE>
<TABLE>
<C>   <S>                             <C>
  G)  TELEPHONE                       / / I/we hereby authorize the Fund and
      REDEMPTION                      its agents to honor any telephone
      AND EXCHANGE                    requests to wire redemption proceeds to
      OPTION                          the commercial bank indicated at right
      Please select at time of        and/or mail redemption proceeds to the
      initial application if you      name and address in which my/our fund
      wish to redeem or exchange      account is registered if such requests
      shares by telephone. A          are believed to be authentic.
      SIGNATURE GUARANTEE IS          The Fund and the Fund's Transfer Agent
      REQUIRED IF BANK ACCOUNT IS     will employ reasonable procedures to
      NOT REGISTERED IDENTICALLY TO   confirm that instructions communicated
      YOUR FUND ACCOUNT.              by telephone are genuine. These
      TELEPHONE REQUESTS FOR          procedures include requiring the
      REDEMPTIONS OR EXCHANGE WILL    investor to provide certain personal
      NOT BE HONORED UNLESS THE BOX   identification information at the time
      IS CHECKED.                     an account is opened and prior to
                                      effecting each transaction requested by
                                      telephone. In addition, all telephone
                                      transaction requests will be recorded
                                      and investors may be required to provide
                                      additional telecopied written
                                      instructions of transaction requests.
                                      Neither the Fund nor the Transfer Agent
                                      will be responsible for any loss,
                                      liability, cost or expense for following
                                      instructions received by telephone that
                                      it reasonably believes to be genuine.
 
<CAPTION>
  G)
      Name of COMMERCIAL Bank (Not Savings Bank)
      Bank Account No.
                                                   Bank ABA No.
      Name(s) in which your BANK Account is Established
      Bank's Street Address
      City                           State                           Zip
</TABLE>
 
<TABLE>
<C>   <S>                                       <C>
  H)  INTERESTED PARTY                          Name
      OPTION                                    Address
      In addition to the account statement      City         State         Zip Code
      sent to my/our registered address, I/we
      hereby authorize the fund to mail
      duplicate statements to the name and
      address provided at right.
</TABLE>
 
<TABLE>
<C>   <S>                                       <C>
  I)  DEALER
      INFORMATION
                                                Representative Name                        Representative
                                                No.                            Branch
                                                No.
</TABLE>
 
<PAGE>
 
<TABLE>
<C>   <S>                        <C>
  J)  SIGNATURE OF
      ALL HOLDERS
      AND TAXPAYER
      CERTIFICATION
      Sign Here ,
</TABLE>
 
<TABLE>
<S>                                  <C>
The undersigned certify that I/we have full authority and legal capacity
to purchase and redeem shares of the Fund and affirm that I/we have
received a current Prospectus of the Morgan Stanley Institutional Fund,
Inc. and agree to be bound by its terms.
  BY SIGNING THIS  APPLICATION, I/WE HEREBY  CERTIFY UNDER PENALTIES  OF
PERJURY THAT THE INFORMATION ON THIS APPLICATION IS COMPLETE AND CORRECT
AND  THAT  AS REQUIRED  BY FEDERAL  LAW  (PLEASE CHECK  APPLICABLE BOXES
BELOW):
/ / U.S. CITIZEN(S)/TAXPAYER(S):
       / / I/WE CERTIFY THAT (1) THE NUMBER(S) SHOWN ABOVE ON THIS  FORM
           IS/ARE  THE CORRECT  SSN(S) OR  TIN(S) AND  (2) I/WE  ARE NOT
           SUBJECT TO ANY BACKUP WITHHOLDING EITHER BECAUSE (A) I/WE ARE
           EXEMPT FROM  BACKUP  WITHHOLDING;  (B)  I/WE  HAVE  NOT  BEEN
           NOTIFIED  BY THE  INTERNAL REVENUE SERVICE  ("IRS") THAT I/WE
           ARE SUBJECT TO BACKUP WITHHOLDING AS A RESULT OF A FAILURE TO
           REPORT ALL INTEREST OR DIVIDENDS; OR (C) THE IRS HAS NOTIFIED
           ME/US  THAT  I  AM/WE  ARE   NO  LONGER  SUBJECT  TO   BACKUP
           WITHHOLDING.
       /  / IF  NO TIN(S) OR  SSN(S) HAS/HAVE BEEN  PROVIDED ABOVE, I/WE
           HAVE APPLIED, OR INTEND  TO APPLY, TO THE  IRS OR THE  SOCIAL
           SECURITY   ADMINISTRATION  FOR  A  TIN  OR  A  SSN  AND  I/WE
           UNDERSTAND THAT IF I/WE DO NOT PROVIDE EITHER NUMBER TO CHASE
           GLOBAL FUNDS SERVICES COMPANY ("CGFSC") WITHIN 60 DAYS OF THE
           DATE OF THIS APPLICATION  OR IF I/WE  FAIL TO FURNISH  MY/OUR
           CORRECT  SSN(S) OR TIN(S),  I/WE MAY BE  SUBJECT TO A PENALTY
           AND A 31% BACKUP WITHHOLDING ON DISTRIBUTIONS AND  REDEMPTION
           PROCEEDS. (PLEASE PROVIDE EITHER NUMBER ON IRS FORM W-9). YOU
           MAY REQUEST SUCH FORM BY CALLING CGFSC AT 800-282-4404.
/ / NON-U.S. CITIZEN(S)/TAXPAYER(S):
  INDICATE COUNTRY OF RESIDENCE FOR TAX PURPOSES:
  UNDER  PENALTIES  OF  PERJURY, I/WE  CERTIFY  THAT I/WE  ARE  NOT U.S.
CITIZENS OR RESIDENTS AND I/WE ARE EXEMPT FOREIGN PERSONS AS DEFINED  BY
THE INTERNAL REVENUE SERVICE.
THE  INTERNAL  REVENUE  SERVICE DOES  NOT  REQUIRE YOUR  CONSENT  TO ANY
PROVISION OF THIS  DOCUMENT OTHER  THAN THE  CERTIFICATIONS REQUIRED  TO
AVOID BACKUP WITHHOLDING.
 
                                     (X)
(X)                                  Signature (if joint account, both
Signature                                                     Date must sign)              Date
</TABLE>
<PAGE>
- -------------------------------------------
- -------------------------------------------
- -------------------------------------------
- -------------------------------------------
 
  NO  DEALER, SALES  REPRESENTATIVE OR ANY  OTHER PERSON HAS  BEEN AUTHORIZED TO
GIVE ANY INFORMATION OR TO MAKE ANY REPRESENTATIONS, OTHER THAN THOSE  CONTAINED
IN THIS PROSPECTUS, IN CONNECTION WITH THE OFFER MADE BY THIS PROSPECTUS AND, IF
GIVEN OR MADE, SUCH OTHER INFORMATION OR REPRESENTATIONS MUST NOT BE RELIED UPON
AS  HAVING BEEN AUTHORIZED BY THE FUND  OR THE DISTRIBUTOR. THIS PROSPECTUS DOES
NOT CONSTITUTE AN OFFER BY THE FUND OR THE DISTRIBUTOR TO SELL OR A SOLICITATION
OF AN OFFER TO BUY ANY OF  THE SECURITIES OFFERED HEREBY IN ANY JURISDICTION  TO
ANY  PERSON TO WHOM  IT IS UNLAWFUL TO  MAKE SUCH OFFER  OR SOLICITATION IN SUCH
JURISDICTION.
 
                           --------------------------
 
                               TABLE OF CONTENTS
 
<TABLE>
<S>                                                 <C>
                                                    PAGE
                                                    ----
Fund Expenses.....................................    2
Financial Highlights..............................    5
Prospectus Summary................................    9
Investment Objectives and Policies................   13
Additional Investment Information.................   17
Investment Limitations............................   24
Management of the Fund............................   25
Purchase of Shares................................   27
Redemption of Shares..............................   31
Shareholder Services..............................   33
Valuation of Shares...............................   34
Performance Information...........................   35
Dividends and Capital Gains Distributions.........   35
Taxes.............................................   36
Portfolio Transactions............................   37
General Information...............................   38
Account Registration Form
</TABLE>
 
                            EQUITY GROWTH PORTFOLIO
                           EMERGING GROWTH PORTFOLIO
                               MICROCAP PORTFOLIO
                          AGGRESSIVE EQUITY PORTFOLIO
                               PORTFOLIOS OF THE
                                 MORGAN STANLEY
                            INSTITUTIONAL FUND, INC.
 
                                  Common Stock
                               ($.001 PAR VALUE)
 
                                 -------------
                                   PROSPECTUS
                                 -------------
 
                               Investment Adviser
                                 Morgan Stanley
                             Asset Management Inc.
 
                                  Distributor
                              Morgan Stanley & Co.
                                  Incorporated
 
- ---------------------------------
- ---------------------------------
- ---------------------------------
- ---------------------------------
<PAGE>
- --------------------------------------------------------------------------------
                              P R O S P E C T U S
     ----------------------------------------------------------------------
 
                           EMERGING MARKETS PORTFOLIO
                        EMERGING MARKETS DEBT PORTFOLIO
 
                               PORTFOLIOS OF THE
                    MORGAN STANLEY INSTITUTIONAL FUND, INC.
 
                P.O. BOX 2798, BOSTON, MASSACHUSETTS 02208-2798
                      FOR INFORMATION CALL 1-800-548-7786
                                ----------------
 
    Morgan  Stanley Institutional Fund, Inc. (the "Fund") is a no-load, open-end
management investment company, or mutual fund, which offers redeemable shares in
a   series   of   diversified   and   non-diversified   investment    portfolios
("portfolios").   The  Fund   currently  consists   of  twenty-eight  portfolios
representing a  broad range  of  investment choices.  The  Fund is  designed  to
provide clients with attractive alternatives for meeting their investment needs.
This  prospectus (the  "Prospectus") pertains  to the  Class A  and the  Class B
shares of the Emerging Markets Portfolio and the Emerging Markets Debt Portfolio
(the "Portfolios").  On  January 2,  1996,  the Portfolios  began  offering  two
classes  of shares, the  Class A shares and  the Class B  shares, except for the
Money Market,  Municipal Money  Market and  International Small  Cap  Portfolios
which  only offer Class  A shares. All  shares of the  Portfolios owned prior to
January 2, 1996 were redesignated Class A shares on January 2, 1996. The Class A
and Class B shares  currently offered by the  Portfolios have different  minimum
investment  requirements and fund expenses. Shares of the portfolios are offered
with no sales charge or  exchange or redemption fee  (with the exception of  the
International Small Cap Portfolio).
 
    The  EMERGING  MARKETS  PORTFOLIO seeks  long-term  capital  appreciation by
investing primarily in equity securities of emerging country issuers.
 
    The EMERGING MARKETS  DEBT PORTFOLIO  seeks high total  return by  investing
primarily  in debt  securities of  government, government-related  and corporate
issuers located in emerging countries.
 
    Emerging markets  securities  are subject  to  special risks.  See  "Foreign
Investment Risk Factors."
 
    INVESTORS  SHOULD NOTE THAT EACH PORTFOLIO MAY INVEST UP TO 10% OF ITS TOTAL
ASSETS IN RESTRICTED SECURITIES AND  UP TO 25% OF  ITS NET ASSETS IN  RESTRICTED
SECURITIES THAT ARE RULE 144A SECURITIES. SEE "ADDITIONAL INVESTMENT INFORMATION
- --   NON-PUBLICLY   TRADED   SECURITIES,  PRIVATE   PLACEMENTS   AND  RESTRICTED
SECURITIES."  INVESTMENTS  IN  RESTRICTED  SECURITIES  IN  EXCESS  OF  5%  OF  A
PORTFOLIO'S  TOTAL ASSETS MAY BE CONSIDERED  A SPECULATIVE ACTIVITY, MAY INVOLVE
GREATER RISK AND MAY INCREASE THE PORTFOLIO'S EXPENSES.
 
    THE EMERGING MARKETS PORTFOLIO  MAY INVEST IN  EQUITY SECURITIES OF  RUSSIAN
COMPANIES.  RUSSIA'S SYSTEM OF  SHARE REGISTRATION AND  CUSTODY INVOLVES CERTAIN
RISKS OF  LOSS  THAT ARE  NOT  NORMALLY  ASSOCIATED WITH  INVESTMENTS  IN  OTHER
SECURITIES MARKETS. SEE "ADDITIONAL INVESTMENT INFORMATION -- RUSSIAN SECURITIES
TRANSACTIONS."
 
    The  Fund is designed  to meet the investment  needs of discerning investors
who place a premium on quality  and personal service. With Morgan Stanley  Asset
Management   Inc.  as   Adviser  and   Administrator  (the   "Adviser"  and  the
"Administrator") and with Morgan Stanley  & Co. Incorporated ("Morgan  Stanley")
as Distributor, the Fund makes available to institutional investors and high net
worth  individual  investors  a  series of  portfolios  which  benefit  from the
investment expertise and commitment to excellence associated with Morgan Stanley
and its affiliates.
 
    This Prospectus is designed to set forth concisely the information about the
Fund that a prospective investor should  know before investing and it should  be
retained  for future reference. The Fund  offers additional Portfolios which are
described in other prospectuses and under the Prospectus Summary section herein.
The Fund currently offers the following portfolios: (i) GLOBAL AND INTERNATIONAL
EQUITY -- Active  Country Allocation, Asian  Equity, Emerging Markets,  European
Equity,  Global  Equity, Gold,  International  Equity, International  Small Cap,
Japanese Equity and Latin  American Portfolios; (ii)  U.S. EQUITY --  Aggressive
Equity,  Emerging Growth, Equity Growth, MicroCap,  Small Cap Value Equity, U.S.
Real Estate and Value Equity  Portfolios; (iii) BALANCED -- Balanced  Portfolio;
(iv)  FIXED INCOME -- Emerging Markets  Debt, Fixed Income, Global Fixed Income,
High Yield, Mortgage-Backed  Securities and Municipal  Bond Portfolios; and  (v)
MONEY  MARKET -- Money Market and  Municipal Money Market Portfolios. Additional
information  about  the  Fund  is  contained  in  a  "Statement  of   Additional
Information,"  dated May 1, 1996, which is incorporated herein by reference. The
Statement of Additional Information and the prospectuses pertaining to the other
portfolios of the Fund are available upon request and without charge by  writing
or calling the Fund at the address and telephone number set forth above.
 
 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.
 
                  THE DATE OF THIS PROSPECTUS IS MAY 1, 1996.
                    SUPPLEMENTED THROUGH DECEMBER 30, 1996.
<PAGE>
                                 FUND EXPENSES
 
    The  following table illustrates the expenses and fees that a shareholder of
the Portfolios indicated below will incur:
<TABLE>
<CAPTION>
                                                                                              EMERGING
                                                                                 EMERGING      MARKETS
                                                                                  MARKETS       DEBT
SHAREHOLDER TRANSACTION EXPENSES                                                 PORTFOLIO    PORTFOLIO
- ------------------------------------------------------------------------------  -----------  -----------
<S>                                                                             <C>          <C>
Maximum Sales Load Imposed on Purchases
  Class A.....................................................................        None         None
  Class B.....................................................................        None         None
Maximum Sales Load Imposed on Reinvested Dividends
  Class A.....................................................................        None         None
  Class B.....................................................................        None         None
Deferred Sales Load
  Class A.....................................................................        None         None
  Class B.....................................................................        None         None
Redemption Fees
  Class A.....................................................................        None         None
  Class B.....................................................................        None         None
Exchange Fees
  Class A.....................................................................        None         None
  Class B.....................................................................        None         None
 
<CAPTION>
 
ANNUAL FUND OPERATING EXPENSES
- ------------------------------------------------------------------------------
 (AS A PERCENTAGE OF AVERAGE NET ASSETS)
<S>                                                                             <C>          <C>
Management Fee*
  Class A.....................................................................       1.25%        1.00%
  Class B.....................................................................       1.25%        1.00%
12b-1 Fees
  Class A.....................................................................        None         None
  Class B.....................................................................       0.25%        0.25%
Other Expenses
  Class A.....................................................................       0.47%        0.75%
  Class B.....................................................................       0.47%        0.75%
                                                                                -----------  -----------
Total Operating Expenses*
  Class A.....................................................................       1.72%        1.75%
  Class B.....................................................................       1.97%        2.00%
                                                                                -----------  -----------
                                                                                -----------  -----------
</TABLE>
 
- ------------------------------
*The Adviser has  agreed to waive  its management fees  and/or to reimburse  the
 Portfolios, if necessary, if such fees would cause the Portfolios' total annual
 operating  expenses, as  a percentage  of average  daily net  assets, to exceed
 1.75% for the Class A shares and  2.00% for the Class B shares. The  management
 fees  are 1.25% for the  Emerging Markets Portfolio and  1.00% for the Emerging
 Markets Debt Portfolio. The Adviser reserves the right to terminate any of  its
 fee  waivers and/or expense reimbursements at  any time in its sole discretion.
 For further information on Fund expenses, see "Management of the Fund."
 
                                       2
<PAGE>
    The purpose of the  table above is to  assist the investor in  understanding
the  various expenses that an  investor in the Portfolios  will bear directly or
indirectly. The Class A expenses and fees for the Portfolios are based on actual
figures for the fiscal year  ended December 31, 1995.  The Class B expenses  and
fees  for each Portfolio are based on estimates, assuming that the average daily
net assets of the Class B shares  of each Portfolio will be $50,000,000.  "Other
Expenses"  include  Board  of  Directors'  fees  and  expenses,  amortization of
organizational costs, filing fees, professional  fees and costs for  shareholder
reports.  Due to  the continuous nature  of Rule  12b-1 fees, long  term Class B
shareholders may pay  more than the  equivalent of the  maximum front-end  sales
charges  otherwise  permitted by  the  Rules of  Fair  Practice of  the National
Association of Securities Dealers, Inc. ("NASD").
 
    The following  example illustrates  the expenses  that you  would pay  on  a
$1,000  investment assuming (1) a 5% annual rate of return and (2) redemption at
the end of each time period. As noted in the table above, the Portfolios  charge
no  redemption  fees  of any  kind.  The  following example  is  based  on total
operating expenses of the Portfolios after fee waivers.
 
<TABLE>
<CAPTION>
                                                                       1 YEAR       3 YEARS      5 YEARS     10 YEARS
                                                                     -----------  -----------  -----------  -----------
<S>                                                                  <C>          <C>          <C>          <C>
Emerging Markets Portfolio
  Class A..........................................................   $      17    $      54    $      93    $     203
  Class B..........................................................          20           62          106          230
Emerging Markets Debt Portfolio
  Class A..........................................................          18           55           95          206
  Class B..........................................................          20           63          108          233
</TABLE>
 
    THIS EXAMPLE SHOULD  NOT BE CONSIDERED  A REPRESENTATION OF  PAST OR  FUTURE
EXPENSES  OR  PERFORMANCE. ACTUAL  EXPENSES MAY  BE GREATER  OR LESS  THAN THOSE
SHOWN.
 
    The Fund intends  to continue to  comply with all  state laws that  restrict
investment  company expenses. Currently, the most restrictive state law requires
that the aggregate annual expenses of an investment company shall not exceed two
and one-half percent (2 1/2%)  of the first $30  million of average net  assets,
two  percent (2%)  of the next  $70 million of  average net assets,  and one and
one-half percent  (1  1/2%) of  the  remaining  net assets  of  such  investment
company.
 
    The  Adviser has agreed to a reduction in  the amounts payable to it, and to
reimburse the Portfolios, if  necessary, if in  any fiscal year  the sum of  the
Portfolio's expenses exceeds the limit set by applicable state laws.
 
                                       3
<PAGE>
                              FINANCIAL HIGHLIGHTS
 
    The following table provides financial highlights for the Class A shares for
the  Emerging  Markets and  Emerging  Markets Debt  Portfolios  for each  of the
periods presented. The audited financial highlights  for the Class A shares  for
the  fiscal  year ended  December  31, 1995  are  part of  the  Fund's financial
statements which  appear  in the  Fund's  December  31, 1995  Annual  Report  to
Shareholders  and  which  are included  in  the Fund's  Statement  of Additional
Information. The  Portfolios'  financial  highlights for  each  of  the  periods
presented  have been audited  by Price Waterhouse  LLP, whose unqualified report
thereon is also included in the Statement of Additional Information.  Additional
performance  information for the Class A shares of the Portfolios is included in
the Annual Report. The Annual Report and the financial statements therein, along
with the Statement of Additional Information, are available at no cost from  the
Fund  at  the address  and  telephone number  noted on  the  cover page  of this
Prospectus. Financial highlights are  not available for the  new Class B  shares
since  they were not offered as of  December 31, 1995. Subsequent to October 31,
1992 (the Fund's prior fiscal year end), the Fund changed its fiscal year end to
December 31. The following  information should be read  in conjunction with  the
financial statements and notes thereto.
 
                                       4
<PAGE>
                           EMERGING MARKETS PORTFOLIO
 
<TABLE>
<CAPTION>
                                                                      TWO
                                                       SEPTEMBER    MONTHS       YEAR        YEAR
                                                          25,        ENDED       ENDED       ENDED       YEAR
                                                       1992* TO    DECEMBER    DECEMBER    DECEMBER      ENDED
                                                        OCTOBER       31,         31,         31,      DECEMBER
                                                       31, 1992      1992        1993        1994      31, 1995
                                                       ---------   ---------   ---------   ---------   ---------
<S>                                                    <C>         <C>         <C>         <C>         <C>
NET ASSET VALUE, BEGINNING OF PERIOD.................  $ 10.00     $ 10.11     $ 10.22     $ 19.00     $ 16.30
                                                       ---------   ---------   ---------   ---------   ---------
INCOME FROM INVESTMENT OPERATIONS
  Net Investment Income/(Loss) (1)...................       --          --       (0.01)      (0.04)       0.08
  Net Realized and Unrealized Gain/ (Loss) on
   Investments.......................................     0.11        0.11        8.79       (1.69)      (2.05)
                                                       ---------   ---------   ---------   ---------   ---------
  Total from Investment Operations...................     0.11        0.11        8.78       (1.73)      (1.97)
                                                       ---------   ---------   ---------   ---------   ---------
DISTRIBUTIONS
  Net Investment Income..............................       --          --          --          --       (0.06)
  Net Realized Gain..................................       --          --          --       (0.97)      (1.13)
                                                       ---------   ---------   ---------   ---------   ---------
  Total Distributions................................       --          --          --       (0.97)      (1.19)
                                                       ---------   ---------   ---------   ---------   ---------
NET ASSET VALUE, END OF PERIOD.......................  $ 10.11     $ 10.22     $ 19.00     $ 16.30     $ 13.14
                                                       ---------   ---------   ---------   ---------   ---------
TOTAL RETURN.........................................     1.10%       1.09%      85.91%      (9.63)%    (12.77)%
                                                       ---------   ---------   ---------   ---------   ---------
                                                       ---------   ---------   ---------   ---------   ---------
RATIOS AND SUPPLEMENTAL DATA:
Net Assets, End of Period (Thousands)................  $28,806     $74,219     $735,352    $929,638    $876,591
Ratio of Expenses to Average Net
 Assets (1)(2).......................................     1.75%**     1.75%**     1.75%       1.75%       1.72%
Ratio of Net Investment Gain/(Loss) to Average Net
 Assets (1)(2).......................................    (0.53)%**   (0.33)%**   (0.06)%     (0.26)%      0.60%
Portfolio Turnover Rate..............................        0%          2%         52%         32%         54%
- ------------------------
</TABLE>
 
<TABLE>
<S> <C>                                                 <C>         <C>         <C>         <C>         <C>
(1) Effect of voluntary expense limitation during the period:
    Per share benefit to net investment income........  $  0.02     $  0.00     $  0.01         N/A         N/A
    Ratios before expense limitation:
    Expenses to Average Net Assets....................     4.82%**     2.48%**     1.79%        N/A         N/A
    Net Investment Gain/(Loss) to Average
       Net Assets.....................................    (3.60)%**   (1.06)%**   (0.10)%       N/A         N/A
</TABLE>
 
(2) Under the terms of an Investment Advisory Agreement, the Adviser is entitled
    to  receive a management  fee calculated at  an annual rate  of 1.25% of the
    average daily net assets of the Emerging Markets Portfolio. The Adviser  has
    agreed  to waive  a portion  of this  fee and/or  reimburse expenses  of the
    Portfolio to the extent that the  total operating expenses of the  Portfolio
    exceed 1.75% of the average daily net assets of the Class A shares and 2.00%
    of  the average net assets of the Class  B shares. The Adviser did not waive
    fees or reimburse expenses for the  years ended December 31, 1994 and  1995.
    In  the period ended October  31, 1992, the two  month period ended December
    31, 1992 and the year ended  December 31, 1993, the Adviser waived  advisory
    fees  and/or reimbursed  expenses totalling  $58,000, $50,000  and $122,000,
    respectively, for the Emerging Markets Portfolio.
 
 * Commencement of Operations.
 
** Annualized.
 
                                       5
<PAGE>
                        EMERGING MARKETS DEBT PORTFOLIO
 
<TABLE>
<CAPTION>
                                                                                     PERIOD FROM
                                                                                  FEBRUARY 1, 1994*   YEAR ENDED
                                                                                   TO DECEMBER 31,   DECEMBER 31,
                                                                                        1994             1995
                                                                                  -----------------  -------------
<S>                                                                               <C>                <C>
NET ASSET VALUE, BEGINNING OF PERIOD............................................     $     10.00      $      8.59
                                                                                        --------     -------------
INCOME FROM INVESTMENT OPERATIONS
  Net Investment Income.........................................................            0.50             1.36
  Net Realized and Unrealized Gain/(Loss) on Investments........................           (1.91)            0.91
                                                                                        --------     -------------
  Total from Investment Operations..............................................           (1.41)            2.27
                                                                                        --------     -------------
DISTRIBUTIONS
  Net Investment Income.........................................................              --            (1.86)
  Net Realized Gain.............................................................                            (0.41)
                                                                                        --------     -------------
    Total Distributions.........................................................              --            (2.27)
                                                                                        --------     -------------
NET ASSET VALUE, END OF PERIOD..................................................     $      8.59      $      8.59
                                                                                        --------     -------------
                                                                                        --------     -------------
TOTAL RETURN....................................................................          (14.10)%          28.23%
                                                                                        --------     -------------
                                                                                        --------     -------------
RATIOS AND SUPPLEMENTAL DATA:
Net Assets, End of Period (Thousands)...........................................     $   144,949      $   181,878
Ratio of Expenses to Average Net Assets.........................................            1.49%**          1.75%
Ratio of Net Investment Income to Average Net Assets............................            9.97%**         14.70%
Portfolio Turnover Rate.........................................................             273%             406%
- ------------------------
</TABLE>
 
 * Commencement of Operations.
** Annualized.
 
                                       6
<PAGE>
                               PROSPECTUS SUMMARY
 
THE FUND
 
    The  Fund  consists  of  twenty-eight  portfolios,  offering   institutional
investors  and high net  worth individual investors a  broad range of investment
choices coupled with the advantages of a no-load mutual fund with Morgan Stanley
and its affiliates providing customized  services as Adviser, Administrator  and
Distributor.   Each  portfolio  offers  Class  A  shares  and,  except  for  the
International Small Cap,  Money Market  and Municipal  Money Market  Portfolios,
also  offers Class B shares. Each portfolio has its own investment objective and
policies designed to meet its specific  goals. The investment objective of  each
Portfolio described in this Prospectus is as follows:
 
    -The  EMERGING  MARKETS PORTFOLIO  seeks  long-term capital  appreciation by
     investing primarily in equity securities of emerging country issuers.
 
    -The EMERGING MARKETS DEBT  PORTFOLIO seeks high  total return by  investing
     primarily   in  debt  securities   of  government,  government-related  and
     corporate issuers located  in emerging countries.  The other portfolios  of
     the Fund are described in other prospectuses which may be obtained from the
     Fund  at the address and  telephone number noted on  the cover page of this
     Prospectus. The objectives of these other portfolios are listed below:
 
    GLOBAL AND INTERNATIONAL EQUITY:
 
    -The  ACTIVE   COUNTRY   ALLOCATION  PORTFOLIO   seeks   long-term   capital
     appreciation  by investing in accordance with country weightings determined
     by the  Adviser in  equity securities  of non-U.S.  issuers which,  in  the
     aggregate, replicate broad country indices.
 
    -The   ASIAN  EQUITY  PORTFOLIO  seeks  long-term  capital  appreciation  by
     investing primarily in equity securities of Asian issuers.
 
    -The CHINA GROWTH PORTFOLIO seeks to provide long-term capital  appreciation
     by  investing primarily in the equity securities of issuers in The People's
     Republic of China, Hong Kong and Taiwan.
 
    -The EUROPEAN  EQUITY  PORTFOLIO  seeks long-term  capital  appreciation  by
     investing primarily in equity securities of European issuers.
 
    -The  GLOBAL  EQUITY  PORTFOLIO  seeks  long-term  capital  appreciation  by
     investing primarily in equity securities  of issuers throughout the  world,
     including U.S. issuers.
 
    -The  GOLD  PORTFOLIO  seeks  long-term  capital  appreciation  by investing
     primarily in equity securities of  foreign and domestic issuers engaged  in
     gold-related activities.
 
    -The  INTERNATIONAL EQUITY PORTFOLIO seeks long-term capital appreciation by
     investing primarily in equity securities of non-U.S. issuers.
 
    -The INTERNATIONAL MAGNUM PORTFOLIO seeks long-term capital appreciation  by
     investing  primarily in equity securities of non-U.S. issuers in accordance
     with EAFE  country  (as defined  in  "Investment Objectives  and  Policies"
     below) weightings determined by the Adviser.
 
    -The  INTERNATIONAL SMALL CAP PORTFOLIO seeks long-term capital appreciation
     by investing primarily in equity securities of non-U.S. issuers with equity
     market capitalizations of under $1 billion.
 
                                       7
<PAGE>
    -The JAPANESE  EQUITY  PORTFOLIO  seeks long-term  capital  appreciation  by
     investing primarily in equity securities of Japanese issuers.
 
    -The  LATIN  AMERICAN  PORTFOLIO  seeks  long-term  capital  appreciation by
     investing primarily in equity securities of Latin American issuers and debt
     securities  issued  or   guaranteed  by  Latin   American  governments   or
     governmental entities.
 
    U.S. EQUITY:
 
    -The  AGGRESSIVE EQUITY  PORTFOLIO seeks  capital appreciation  by investing
     primarily in corporate equity and equity-linked securities.
 
    -The EMERGING  GROWTH  PORTFOLIO  seeks long-term  capital  appreciation  by
     investing  primarily  in  growth-oriented equity  securities  of  small- to
     medium-sized corporations.
 
    -The  EQUITY  GROWTH  PORTFOLIO  seeks  long-term  capital  appreciation  by
     investing   in  growth-oriented  equity  securities  of  medium  and  large
     capitalization companies.
 
    -The MICROCAP PORTFOLIO  seeks long-term capital  appreciation by  investing
     primarily in growth-oriented equity securities of small corporations.
 
    -The  SMALL  CAP  VALUE EQUITY  PORTFOLIO  seeks long-term  total  return by
     investing in  undervalued  equity  securities  of  small-  to  medium-sized
     companies.
 
    -The  U.S.  REAL ESTATE  PORTFOLIO seeks  to  provide above  average current
     income and long-term capital appreciation by investing primarily in  equity
     securities  of companies in  the U.S. real  estate industry, including real
     estate investment trusts.
 
    -The VALUE EQUITY PORTFOLIO seeks high  total return by investing in  equity
     securities  which the  Adviser believes to  be undervalued  relative to the
     stock market in general at the time of purchase.
 
    BALANCED:
 
    -The BALANCED PORTFOLIO seeks high total return while preserving capital  by
     investing  in  a combination  of  undervalued equity  securities  and fixed
     income securities.
 
    FIXED INCOME:
 
    -The FIXED INCOME PORTFOLIO seeks to produce a high total return  consistent
     with the preservation of capital by investing in a diversified portfolio of
     fixed income securities.
 
    -The  GLOBAL FIXED INCOME PORTFOLIO seeks to produce an attractive real rate
     of return while preserving capital by investing in fixed income  securities
     of issuers throughout the world, including U.S. issuers.
 
    -The  HIGH YIELD PORTFOLIO seeks to maximize  total return by investing in a
     diversified portfolio of high  yield fixed income  securities that offer  a
     yield  above  that  generally available  on  debt securities  in  the three
     highest rating categories of the recognized rating services.
 
    -The MORTGAGE-BACKED SECURITIES PORTFOLIO seeks  to produce as high a  level
     of  current income  as is  consistent with  the preservation  of capital by
     investing  primarily  in  a  variety  of  investment-grade  mortgage-backed
     securities.
 
                                       8
<PAGE>
    -The  MUNICIPAL  BOND PORTFOLIO  seeks to  produce a  high level  of current
     income  consistent  with  preservation  of  principal  through   investment
     primarily  in municipal obligations,  the interest on  which is exempt from
     federal income tax.
 
    MONEY MARKET:
 
    -The MONEY MARKET PORTFOLIO  seeks to maximize  current income and  preserve
     capital  while maintaining  high levels  of liquidity  through investing in
     high quality money market instruments with remaining maturities of one year
     or less.
 
    -The MUNICIPAL MONEY MARKET PORTFOLIO  seeks to maximize current  tax-exempt
     income  and  preserve capital  while maintaining  high levels  of liquidity
     through investing in high quality  money market instruments with  remaining
     maturities of one year or less which are exempt from federal income tax.
 
INVESTMENT MANAGEMENT
 
    Morgan  Stanley Asset Management  Inc., a wholly  owned subsidiary of Morgan
Stanley Group  Inc.,  which,  together  with  its  affiliated  asset  management
companies,  at December 31, 1995 had approximately $57.4 billion in assets under
management as  an  investment  manager  or  as  a  fiduciary  adviser,  acts  as
investment  adviser to the Fund  and each of its  portfolios. See "Management of
the Fund -- Investment Adviser" and "Management of the Fund -- Administrator."
 
HOW TO INVEST
 
    Class A shares of  each Portfolio are offered  directly to investors at  net
asset  value with no sales  commission or 12b-1 charges.  Class B shares of each
Portfolio are offered at net  asset value with no  sales commission, but with  a
12b-1  fee, which  is accrued daily  and paid  quarterly, equal to  0.25% of the
Class B shares' average daily net assets on an annualized basis. Share purchases
may be  made  by  sending  investments  directly to  the  Fund  or  through  the
Distributor.  Shares  in a  Portfolio account  opened prior  to January  2, 1996
(each, a "Pre-1996 Account") were designated Class A shares on January 2,  1996.
For  a Portfolio account opened  on or after January  2, 1996 (a "New Account"),
the minimum initial investment is $500,000  for Class A shares and $100,000  for
Class B shares. Certain exceptions to the foregoing minimums apply to (1) shares
in  a Pre-1996  Account with a  value of  $100,000 or more  on March  1, 1996 (a
"Grandfathered Class  A  Account");  (2)  Portfolio  accounts  held  by  certain
employees  of the  Adviser and  of its affiliates;  and (3)  certain advisory or
asset allocation accounts, such as  Total Funds Management accounts, managed  by
Morgan  Stanley or its  affiliates, including the  Adviser ("Managed Accounts").
The Adviser reserves the right in its sole discretion to determine which of such
advisory or asset allocation accounts shall be Managed Accounts. For information
regarding  Managed  Accounts   please  contact  your   Morgan  Stanley   account
representative or the Fund at the telephone number provided on the cover of this
Prospectus.  Shares in a Pre-1996 Account with  a value of less than $100,000 on
March 1, 1996 (a "Grandfathered Class B Account") converted to Class B shares on
March 1, 1996. The minimum investment levels may be waived at the discretion  of
the  Adviser for (i)  certain employees and  customers of Morgan  Stanley or its
affiliates and certain  trust departments, brokers,  dealers, agents,  financial
planers,  financial services firms or investment advisers that have entered into
an agreement with  Morgan Stanley  or its  affiliates; and  (ii) retirement  and
deferred  compensation plans and trusts, used to fund such plans, including, but
not limited
 
                                       9
<PAGE>
to, those defined in Section 401(a), 403(b) or 457 of the Internal Revenue  Code
of  1986, as  amended, and  "rabbi trusts". See  "Purchase of  Shares -- Minimum
Investment and Account Sizes; Conversion from Class A to Class B Shares."
 
    The minimum  subsequent  investment for  each  Portfolio account  is  $1,000
(except  for automatic reinvestment of dividends and capital gains distributions
for which there is no minimum).  Such subsequent investments will be applied  to
purchase  additional  shares  in the  same  class  held by  a  shareholder  in a
Portfolio account. See "Purchase of Shares -- Additional Investments."
 
HOW TO REDEEM
 
    Class A shares or Class  B shares of each Portfolio  may be redeemed at  any
time, without cost, at the net asset value per share of shares of the applicable
class  next determined after  receipt of the  redemption request. The redemption
price may be more or less than the purchase price. Certain redemptions may cause
involuntary redemption or  conversion. Class  A or Class  B shares  held in  New
Accounts  are subject to involuntary  redemption if shareholder redemption(s) of
such shares  reduces the  value of  such account  to less  than $100,000  for  a
continuous  60-day  period. Involuntary  redemption  does not  apply  to Managed
Accounts, Grandfathered Class  A Accounts  and Grandfathered  Class B  Accounts,
regardless  of the value of such accounts. Class  A shares in a New Account will
convert to Class B  shares if shareholder redemption(s)  of such shares  reduces
the  value of such account to less than $500,000 for a continuous 60-day period.
Class B shares in a  New Account will convert to  Class A shares if  shareholder
purchases of additional Class B shares or market activity cause the value of the
Class B shares in the New Account to increase to $500,000 or more. See "Purchase
of  Shares --  Minimum Account Sizes  and Involuntary Redemption  of Shares" and
"Redemption of Shares."
 
RISK FACTORS
 
    Investing in emerging country securities involves certain considerations not
typically associated with investing in  securities of U.S. companies,  including
(1)  restrictions on foreign investment and  on repatriation of capital invested
in emerging countries,  (2) currency  fluctuations, (3) the  cost of  converting
foreign  currency into U.S.  dollars, (4) potential  price volatility and lesser
liquidity of shares traded on emerging  country securities markets or lack of  a
secondary  trading market  for such  securities and  (5) political  and economic
risks, including the risk of nationalization or expropriation of assets and  the
risk  of war. In  addition, accounting, auditing,  financial and other reporting
standards in  emerging  countries  are  not equivalent  to  U.S.  standards  and
therefore,  disclosure of certain material information  may not be made and less
information may be available to  investors investing in emerging countries  than
in  the  U.S.  There  is  also generally  less  governmental  regulation  of the
securities industry in emerging countries  than in the United States.  Moreover,
it  may be more difficult to  obtain a judgment in a  court outside the U.S. See
"Investment Objectives and Policies" and "Additional Investment Information." In
addition, each Portfolio may invest in repurchase agreements, lend its portfolio
securities and purchase securities  on a when-issued  basis. Each Portfolio  may
invest  in foreign currency futures contracts and options to hedge currency risk
associated with investment  in non-U.S. dollar  denominated securities. Each  of
these  investment strategies involves  specific risks which  are described under
"Investment Objectives  and Policies"  and "Additional  Investment  Information"
herein  and  under  "Investment Objectives  and  Policies" in  the  Statement of
Additional Information.
 
                                       10
<PAGE>
    The Emerging Markets Portfolio  may invest in  equity securities of  Russian
companies.  The registration, clearing and settlement of securities transactions
in Russia  are  subject  to  significant  risks  not  normally  associated  with
securities  transactions in the United States  and other more developed markets.
See "Additional Investment Information -- Russian Securities Transactions."
 
                                       11
<PAGE>
                       INVESTMENT OBJECTIVES AND POLICIES
 
    The investment objective of each Portfolio is described below, together with
the policies the Fund employs in its efforts to achieve these objectives.  There
is  no assurance that each Portfolio will attain its objective. Each Portfolio's
investment objective is a  fundamental policy which may  not be changed  without
the approval of a majority of the Portfolio's outstanding voting securities. The
investment  policies described  below are  not fundamental  policies and  may be
changed without shareholder approval.
 
THE EMERGING MARKETS PORTFOLIO
 
    The investment objective of  the Portfolio is  to provide long-term  capital
appreciation  by investing  primarily in  equity securities  of emerging country
issuers. With respect  to the  Portfolio, equity securities  include common  and
preferred stocks, convertible securities, rights and warrants to purchase common
stocks.  Under normal conditions,  at least 65% of  the Portfolio's total assets
will be  invested  in  emerging  country equity  securities.  As  used  in  this
Prospectus,  the term  "emerging country" applies  to any country  which, in the
opinion of the Adviser, is generally considered to be an emerging or  developing
country   by  the   international  financial   community,  which   includes  the
International Bank for  Reconstruction and Development  (more commonly known  as
the  World Bank) and the International  Finance Corporation. There are currently
over 130  countries  which,  in  the  opinion  of  the  Adviser,  are  generally
considered to be emerging or developing countries by the international financial
community,  approximately  40  of  which  currently  have  stock  markets. These
countries generally include every nation in the world except the United  States,
Canada,  Japan,  Australia,  New Zealand  and  most nations  located  in Western
Europe. Currently, investing in many emerging  countries is not feasible or  may
involve  unacceptable political risks. The  Portfolio will focus its investments
on those  emerging market  countries  in which  it  believes the  economies  are
developing  strongly and in  which the markets  are becoming more sophisticated.
The Portfolio  intends to  invest primarily  in  some or  all of  the  following
countries:
 
<TABLE>
<S>                     <C>                     <C>                     <C>
Argentina               Botswana                Brazil                  Chile
China                   Colombia                Greece                  Hong Kong
Hungary                 India                   Indonesia               Jamaica
Jordan                  Kenya                   Malaysia                Mexico
Nigeria                 Pakistan                Peru                    Philippines
Poland                  Portugal                Russia                  South Africa
South Korea             Sri Lanka               Taiwan                  Thailand
Turkey                  Venezuela               Zimbabwe
</TABLE>
 
As  markets  in other  countries develop,  the Portfolio  expects to  expand and
further diversify the emerging countries in which it invests. The Portfolio does
not intend to  invest in any  security in a  country where the  currency is  not
freely  convertible  to  U.S. dollars,  unless  the Portfolio  has  obtained the
necessary governmental licensing to convert such currency or other appropriately
licensed or sanctioned contractual guarantees to protect such investment against
loss of  that currency's  external  value, or  the  Portfolio has  a  reasonable
expectation  at the time the investment is made that such governmental licensing
or other appropriately licensed  or sanctioned guarantees  would be obtained  or
that the currency in which the security is quoted would be freely convertible at
the time of any proposed sale of the security by the Portfolio.
 
    An emerging country security is one issued by a company that, in the opinion
of  the  Adviser, has  one or  more  of the  following characteristics:  (i) its
principal   securities   trading   market    is   in   an   emerging    country,
 
                                       12
<PAGE>
(ii)  alone, or on a consolidated basis, the  company derives 50% or more of its
annual revenue from either goods produced,  sales made or services performed  in
emerging countries; or (iii) the company is organized under the laws of, and has
a principal office in, an emerging country. The Adviser will base determinations
as  to eligibility on  publicly available information and  inquiries made to the
companies. (See "Foreign Investment Risk Factors" for a discussion of the nature
of information publicly available for non-U.S. companies.)
 
    To the  extent that  the Portfolio's  assets are  not invested  in  emerging
country  equity securities, the remainder  of the assets may  be invested in (i)
debt securities denominated in the currency of an emerging country or issued  or
guaranteed  by  an emerging  country company  or the  government of  an emerging
country, (ii) equity  or debt  securities of corporate  or governmental  issuers
located  in industrialized countries, and  (iii) short-term and medium-term debt
securities of  the  type  described below  under  "Temporary  Instruments."  The
Portfolio's  assets  may  be  invested in  debt  securities  when  the Portfolio
believes that, based  upon factors  such as  relative interest  rate levels  and
foreign  exchange rates, such debt  securities offer opportunities for long-term
capital appreciation. It is likely that many of the debt securities in which the
Portfolio will invest will be unrated, and whether or not rated, such securities
may have speculative  characteristics. When deemed  appropriate by the  Adviser,
the  Portfolio may invest up to 10% of its total assets (measured at the time of
the investment) in lower quality debt securities. Lower quality debt securities,
also known as "junk bonds," are  often considered to be speculative and  involve
greater  risk  of  default or  price  changes  due to  changes  in  the issuer's
creditworthiness. As  of  the date  of  this prospectus,  less  than 5%  of  the
Portfolio's total assets were invested in junk bonds. The market prices of these
securities  may fluctuate more  than those of higher  quality securities and may
decline significantly  in  periods of  general  economic difficulty,  which  may
follow  periods  of  rising interest  rates.  Securities in  the  lowest quality
category may present the risk  of default, or may  be in default. For  temporary
defensive  purposes, the Portfolio may invest less  than 65% of its total assets
in emerging country equity securities, in which case the Portfolio may invest in
other equity securities or may invest  in debt securities of the kind  described
under "Temporary Investments" below.
 
    The  Portfolio  may  invest  indirectly in  securities  of  emerging country
issuers through sponsored or unsponsored American Depositary Receipts  ("ADRs").
ADRs  may not necessarily be denominated in  the same currency as the underlying
securities into which  they may be  converted. In addition,  the issuers of  the
stock  of unsponsored ADRs are not obligated to disclose material information in
the U.S. and, therefore, there may not be a correlation between such information
and the market value of the ADR.
 
THE EMERGING MARKETS DEBT PORTFOLIO
 
    The investment objective of the Portfolio  is to seek high total return.  In
seeking  to achieve this objective,  the Portfolio will seek  to invest at least
65% of its total assets in debt securities of government and  government-related
issuers located in emerging countries (including participations in loans between
governments   and  financial   institutions),  and  of   entities  organized  to
restructure outstanding debt  of such  issuers. In addition,  the Portfolio  may
invest  up to 35%  of its total  assets in debt  securities of corporate issuers
located in or organized under the laws of emerging countries. See "The  Emerging
Markets Portfolio" above for a definition of emerging countries.
 
    The  Adviser intends  to invest the  Portfolio's assets  in emerging country
debt securities that provide a high level  of current income, while at the  same
time   holding  the  potential   for  capital  appreciation   if  the  perceived
 
                                       13
<PAGE>
creditworthiness of the  issuer improves due  to improving economic,  financial,
political,  social or  other conditions  in the country  in which  the issuer is
located. Currently,  investing  in  many  emerging  country  securities  is  not
feasible  or may involve unacceptable  political risks. Initially, the Portfolio
expects that its investments  in emerging country debt  securities will be  made
primarily in some or all of the following emerging countries:
 
<TABLE>
<S>                     <C>                     <C>
Algeria                 India                   Philippines
Argentina               Indonesia               Poland
Brazil                  Ivory Coast             Portugal
Bulgaria                Jamaica                 Russia
Chile                   Jordan                  Slovakia
China                   Malaysia                South Africa
Colombia                Mexico                  Thailand
Costa Rica              Morocco                 Trinidad & Tobago
Czech Republic          Nicaragua               Tunisia
Dominican Republic      Nigeria                 Turkey
Ecuador                 Pakistan                Uruguay
Egypt                   Panama                  Venezuela
Greece                  Paraguay                Zaire
Hungary                 Peru
</TABLE>
 
In  selecting emerging country debt securities  for investment by the Investment
Fund, the Adviser will apply a market risk analysis contemplating assessment  of
factors   such  as  liquidity,  volatility,   tax  implications,  interest  rate
sensitivity, counterparty risks and technical market considerations.  Currently,
investing  in many  emerging country securities  is not feasible  or may involve
unacceptable political risks. As opportunities  to invest in debt securities  in
other  countries develop, the Portfolio expects  to expand and further diversify
the emerging countries in which it invests. While the Portfolio generally is not
restricted in  the portion  of its  assets which  may be  invested in  a  single
country  or  region,  it  is  anticipated  that,  under  normal  conditions, the
Portfolio's assets will be invested in issuers in at least three countries.
 
    The  Portfolio's   investments   in   government,   government-related   and
restructured  debt securities will consist of (i) debt securities or obligations
issued or guaranteed by governments, governmental agencies or  instrumentalities
and   political   subdivisions   located   in   emerging   countries  (including
participations in loans  between governments and  financial institutions),  (ii)
debt  securities  or  obligations  issued  by  government  owned,  controlled or
sponsored entities located in emerging countries, and (iii) interests in issuers
organized  and  operated  for  the  purpose  of  restructuring  the   investment
characteristics  of instruments issued  by any of  the entities described above.
Such type of restructuring involves the deposit with or purchase by an entity of
specific instruments and the issuance by that  entity of one or more classes  of
securities  backed by, or representing interests in, the underlying instruments.
Certain issuers of such  structured securities may be  deemed to be  "investment
companies" as defined in the Investment Company Act of 1940 (the "1940 Act"). As
a  result,  the Portfolio's  investment  in such  securities  may be  limited by
certain investment  restrictions  contained in  the  1940 Act.  See  "Additional
Investment Information -- Structured Securities."
 
    The  Portfolio's  investments in  debt  securities of  corporate  issuers in
emerging countries  may include  debt securities  or obligations  issued (i)  by
banks  located in  emerging countries or  by branches of  emerging country banks
located outside the country or (ii) by companies organized under the laws of  an
emerging country.
 
                                       14
<PAGE>
Determinations  as to eligibility will be made  by the Adviser based on publicly
available information and inquiries made to the issuer. (See "Foreign Investment
Risk Factors" for a discussion of  the nature of information publicly  available
for non-U.S. issuers.) The Portfolio may also invest in certain debt obligations
customarily referred to as "Brady Bonds," which are created through the exchange
of  existing commercial  bank loans to  foreign entities for  new obligations in
connection with  debt restructurings  under  a plan  introduced by  former  U.S.
Secretary  of the  Treasury Nicholas  F. Brady.  See "Investment  Objectives and
Policies -- Emerging  Country Equity and  Debt Securities" in  the Statement  of
Additional Information for further information about Brady Bonds.
 
    Emerging country debt securities held by the Portfolio will take the form of
bonds,  notes, bills,  debentures, convertible  securities, warrants,  bank debt
obligations, short-term paper, mortgage and other asset-backed securities,  loan
participations,  loan assignments and interests issued by entities organized and
operated for  the purpose  of restructuring  the investment  characteristics  of
instruments issued by emerging country issuers. U.S. dollar-denominated emerging
country  debt securities held by the Portfolio  will generally be listed but not
traded on a securities exchange, and non-U.S. dollar-denominated securities held
by the Portfolio may or  may not be listed or  traded on a securities  exchange.
Investments in emerging country debt securities entail special investment risks.
See  "Additional Investment Information -- Foreign Investment Risk Factors." The
Portfolio will be subject to no  restrictions on the maturities of the  emerging
country  debt securities it holds; those  maturities may range from overnight to
30 years.
 
    The Portfolio is not restricted  in the portion of  its assets which may  be
invested  in securities denominated  in a particular  currency and a substantial
portion of the Portfolio's assets may be invested in non-U.S. dollar-denominated
securities. The  portion  of  the  Portfolio's  assets  invested  in  securities
denominated  in currencies  other than  the U.S.  dollar will  vary depending on
market conditions.  Although the  Portfolio is  permitted to  engage in  a  wide
variety of investment practices designed to hedge against currency exchange rate
risks   with  respect  to  its  holdings  of  non-U.S.  dollar-denominated  debt
securities, the Portfolio may be limited  in its ability to hedge against  these
risks.  See  "Additional  Investment  Information  --  Forward  Foreign Currency
Exchange Contracts" and "Foreign Currency Futures Contracts and Options" in  the
Statement of Additional Information.
 
    In  selecting particular emerging country  debt securities for investment by
the Portfolio,  the Adviser  will  apply a  market risk  analysis  contemplating
assessment  of factors such as liquidity, volatility, tax implications, interest
rate  sensitivity,  counterparty  risks  and  technical  market  considerations.
Emerging  country  debt securities  in which  the Portfolio  may invest  will be
subject to high risk and will not be required to meet a minimum rating  standard
and  may not  be rated  for creditworthiness  by any  internationally recognized
credit rating organization. The Portfolio's investments are expected to be rated
in the lower and lowest  rating categories of internationally recognized  credit
rating  organizations or  are expected  to be  unrated securities  of comparable
quality. These  types of  debt obligations  are predominantly  speculative  with
respect  to the capacity to pay interest  and repay principal in accordance with
their terms and generally involve a greater risk of default and of volatility in
price than securities in  higher rating categories. Ratings  of a non-U.S.  debt
instrument,  to the  extent that  those ratings  are undertaken,  are related to
evaluations of the  country in which  the issuer of  the instrument is  located.
Ratings  generally  take into  account  the currency  in  which a  non-U.S. debt
instrument is denominated. Instruments issued  by a foreign government in  other
than  the local currency, for example, typically  have a lower rating than local
currency instruments  due  to the  existence  of  an additional  risk  that  the
government will be unable to obtain the required foreign currency to service its
foreign currency-denominated debt. In general, the
 
                                       15
<PAGE>
ratings of debt securities or obligations issued by a non-U.S. public or private
entity  will  not be  higher  than the  rating of  the  currency or  the foreign
currency debt of the central  government of the country  in which the issuer  is
located, regardless of the intrinsic creditworthiness of the issuer.
 
    The  Portfolio is  authorized to borrow  up to  33 1/3% of  its total assets
(including the amount  borrowed), less  all liabilities  and indebtedness  other
than  the borrowing,  for investment  purposes to  increase the  opportunity for
greater return and for  payment of dividends.  Such borrowings would  constitute
leverage,  which  is  a  speculative  characteristic.  Leveraging  will  magnify
declines as well as increases in the  net asset value of the Portfolio's  shares
and  increases  in the  yield on  the  Portfolio's investments.  See "Additional
Investment Information -- Borrowing and Other Forms of Leverage."
 
    The Portfolio  may  also invest  in  zero coupon,  pay-in-kind  or  deferred
payment  securities and in securities that  may be collateralized by zero coupon
securities (such as Brady Bonds). Zero coupon securities are securities that are
sold at a  discount to par  value and on  which interest payments  are not  made
during  the  life of  the security.  Upon  maturity, the  holder is  entitled to
receive the par value of the security.  While interest payments are not made  on
such securities, holders of such securities are deemed to have received annually
"phantom  income." Because the Portfolio will distribute its "phantom income" to
shareholders, to the extent that shareholders elect to receive dividends in cash
rather than reinvesting such dividends in additional shares, the Portfolio  will
have  fewer  assets  with which  to  purchase income  producing  securities. The
Portfolio accrues income with respect to  these securities prior to the  receipt
of  cash  payments. Pay-in-kind  securities  are securities  that  have interest
payable by  delivery of  additional  securities. Upon  maturity, the  holder  is
entitled  to receive the aggregate par value of the securities. Deferred payment
securities  are  securities   that  remain  zero   coupon  securities  until   a
predetermined  date, at which time the  stated coupon rate becomes effective and
interest becomes  payable at  regular intervals.  Zero coupon,  pay-in-kind  and
deferred  payment securities may be subject  to greater fluctuation in value and
lesser liquidity in the event of adverse market conditions than comparably rated
securities paying cash interest at regular interest payment periods.
 
    The  Portfolio  may  also   invest  up  to  5%   of  its  total  assets   in
mortgage-backed  securities  and  in  other  asset-backed  securities  issued by
non-governmental entities,  such  as  banks and  other  financial  institutions.
Mortgage-backed   securities  include   mortgage  pass-through   securities  and
collateralized mortgage obligations. Asset-backed securities are  collateralized
by  such assets  as automobile  or credit  card receivables  and are securitized
either in a pass-through  structure or in a  pay-through structure similar to  a
CMO.
 
    The   Portfolio's   investments   in   government,   government-related  and
restructured debt  instruments  are  subject to  special  risks,  including  the
inability  or  unwillingness  to  repay  principal  and  interest,  requests  to
reschedule or restructure  outstanding debt  and requests  to extend  additional
loan amounts. The Portfolio may have limited recourse in the event of default on
such  debt instruments. The Portfolio may  invest in loans, assignments of loans
and participations in loans. See "Additional Investment Information."
 
                       ADDITIONAL INVESTMENT INFORMATION
 
    AMERICAN DEPOSITARY  RECEIPTS.   The Portfolios  may on  occasion invest  in
American  Depositary Receipts ("ADRs"). ADRs are securities, typically issued by
a U.S. financial institution (a "depositary"), that evidence ownership interests
in a  security  or  a  pool  of securities  issued  by  a  foreign  issuer  (the
"underlying  issuer") and deposited  with the depositary.  ADRs include American
Depositary Shares and New York Shares and may be
 
                                       16
<PAGE>
"sponsored" or  "unsponsored."  Sponsored  ADRs are  established  jointly  by  a
depositary   and  the  underlying  issuer,   whereas  unsponsored  ADRs  may  be
established by  a depositary  without participation  by the  underlying  issuer.
Holders  of  an unsponsored  ADR generally  bear all  the costs  associated with
establishing the unsponsored ADR. The depositary of an unsponsored ADR is  under
no  obligation  to  distribute  shareholder  communications  received  from  the
underlying issuer  or to  pass through  to the  holders of  the unsponsored  ADR
voting  rights with respect  to the deposited securities  or pool of securities.
The Portfolios may invest in sponsored and unsponsored ADRs.
 
    BORROWING AND OTHER FORMS OF LEVERAGE.  The Emerging Markets Debt  Portfolio
is  authorized to borrow money from banks  and other entities in an amount equal
to up to 33 1/3% of the Portfolio's total assets (including the amount borrowed)
less all liabilities and indebtedness other than the borrowing, and may use  the
proceeds  of  the  borrowing  for  investment  purposes  or  to  pay  dividends.
Borrowings create leverage, which is a speculative characteristic. Although  the
Portfolio  is authorized to borrow, it will do so only when the Adviser believes
that  borrowing  will   benefit  the   Portfolio  after   taking  into   account
considerations  such as  the costs  of the  borrowing and  the likely investment
returns on  the securities  purchased  with borrowed  monies. Borrowing  by  the
Portfolio  will create the opportunity for increased net income but, at the same
time, will  involve  special  risk  considerations.  Leveraging  resulting  from
borrowing  will magnify  declines as  well as  increases in  the Portfolio's net
asset value per  share and  net yield.  The Portfolio  expects that  all of  its
borrowing will be made on a secured basis. The Portfolio's Custodian will either
segregate  the assets securing the  borrowing for the benefit  of the lenders or
arrangements will  be made  with a  suitable sub-custodian.  If assets  used  to
secure  the borrowing decrease in value, the Portfolio may be required to pledge
additional collateral to the lender in the  form of cash or securities to  avoid
liquidation of those assets.
 
    FOREIGN  INVESTMENT.   Investment in obligations  of foreign  issuers and in
foreign branches of domestic banks involves somewhat different investment  risks
than  those affecting obligations of U.S. issuers. There may be limited publicly
available information with respect to  foreign issuers, and foreign issuers  are
not  generally subject to  uniform accounting, auditing  and financial standards
and requirements comparable  to those  applicable to U.S.  companies. There  may
also  be  less  government  supervision  and  regulation  of  foreign securities
exchanges, brokers and listed companies than in the U.S. Many foreign securities
markets have substantially less volume than U.S. national securities  exchanges,
and  securities of some foreign  issuers are less liquid  and more volatile than
securities of  comparable  domestic  issuers. Brokerage  commissions  and  other
transaction  costs on foreign securities exchanges  are generally higher than in
the U.S.  Dividends and  interest paid  by  foreign issuers  may be  subject  to
withholding  and  other foreign  taxes,  which may  decrease  the net  return on
foreign  investments  as  compared  to  dividends  and  interest  paid  by  U.S.
companies.  Additional risks include future political and economic developments,
the possibility that a foreign  jurisdiction might impose or change  withholding
taxes  on income  payable with respect  to foreign securities,  and the possible
adoption of foreign governmental restrictions such as exchange controls.
 
    Prior governmental approval  for foreign investments  may be required  under
certain  circumstances in  some emerging  countries, and  the extent  of foreign
investment in certain debt securities and  domestic companies may be subject  to
limitation  in other emerging countries.  Foreign ownership limitations also may
be imposed by  the charters  of individual  companies in  emerging countries  to
prevent, among other concerns, violation of foreign investment limitations.
 
                                       17
<PAGE>
    Repatriation  of investment  income, capital  and the  proceeds of  sales by
foreign investors may require governmental registration and/or approval in  some
emerging  countries. The Portfolios could be adversely affected by delays in, or
a refusal to grant, any required governmental registration or approval for  such
repatriation.  Any  investment subject  to  such repatriation  controls  will be
considered illiquid if it appears reasonably likely that this process will  take
more than seven days.
 
    The  economies  of individual  emerging  countries may  differ  favorably or
unfavorably from the U.S. economy in  such respects as growth of gross  domestic
product,   rate  of  inflation,  currency  depreciation,  capital  reinvestment,
resource  self-sufficiency  and  balance  of  payments  position.  Further,  the
economies   of  developing  countries  generally   are  heavily  dependent  upon
international trade  and,  accordingly,  have  been, and  may  continue  to  be,
adversely  affected by trade barriers, exchange controls, managed adjustments in
relative currency values and other protectionist measures imposed or  negotiated
by  the countries with which they trade. These economies also have been, and may
continue to be, adversely affected by economic conditions in the countries  with
which they trade.
 
    With   respect  to  any  emerging  country,  there  is  the  possibility  of
nationalization, expropriation  or  confiscatory  taxation,  political  changes,
government  regulation, social instability or diplomatic developments (including
war) which could affect adversely the  economies of such countries or the  value
of  each  Portfolio's investments  in those  countries. In  addition, it  may be
difficult to obtain and enforce a judgment in a court outside of the U.S.
 
    Investments in securities of foreign  issuers are frequently denominated  in
foreign  currencies, and because each  Portfolio may temporarily hold uninvested
reserves in bank deposits in foreign  currencies, the value of each  Portfolio's
assets, as measured in U.S. dollars, may be affected favorably or unfavorably by
changes in currency rates and in exchange control regulations and the Portfolios
may incur costs in connection with conversions between various currencies.
 
    FORWARD  FOREIGN CURRENCY EXCHANGE CONTRACTS.  The Portfolios may enter into
forward foreign currency  exchange contracts  that provide for  the purchase  or
sale of an amount of a specified foreign currency at a future date. Purposes for
which  such contracts  may be  used include  protecting against  a decline  in a
foreign currency against the U.S. dollar  between the trade date and  settlement
date  when  the Portfolio  purchases or  sells securities,  locking in  the U.S.
dollar value  of  dividends declared  on  securities  held by  a  Portfolio  and
generally  protecting the U.S. dollar value  of securities held by the Portfolio
against exchange  rate  fluctuation.  Such  contracts may  also  be  used  as  a
protective measure against the effects of fluctuating rates of currency exchange
and  exchange control regulations. While such forward contracts may limit losses
to the Portfolio as a result of exchange rate fluctuation, they will also  limit
any  gains that may otherwise have been realized. See "Investment Objectives and
Policies -- Forward  Foreign Currency  Exchange Contracts" in  the Statement  of
Additional Information.
 
    As  another  means  of  reducing  the  risks  associated  with  investing in
securities denominated  in foreign  currencies, the  Portfolios may  enter  into
contracts  for the future acquisition or  delivery of foreign currencies and may
purchase foreign  currency options.  These  investment techniques  are  designed
primarily  to hedge against anticipated future  changes in currency prices, that
otherwise  might  adversely  affect  the  value  of  the  Portfolio's  portfolio
securities.  A Portfolio  will incur brokerage  fees when it  purchases or sells
futures contracts  or  options, and  it  will  be required  to  maintain  margin
deposits.  As set forth  below, futures contracts and  options entail risks, but
the Adviser believes  that use  of such contracts  and options  may benefit  the
Portfolio by diminishing currency
 
                                       17
<PAGE>
risks.  A  Portfolio will  not  enter into  any  futures contract  or  option if
immediately thereafter the value  of all the  foreign currencies underlying  its
futures  contracts and foreign currency options would exceed 10% of the value of
its total assets.  In addition, a  Portfolio may enter  into a futures  contract
only if immediately thereafter not more than 5% of its total assets are required
as deposit to secure obligations under such contracts.
 
    The  primary risks associated  with the use  of futures and  options are (i)
failure to  predict accurately  the  direction of  currency movements  and  (ii)
market  risks (e.g., lack of liquidity or lack of correlation between the change
in value  of underlying  currencies and  that of  the value  of the  Portfolio's
futures or options contracts). The risk that a Portfolio will be unable to close
out  a futures position or  options contract will be  minimized by the Portfolio
only entering into  futures contracts  or options transactions  for which  there
appears  to be  a liquid secondary  market. For more  detailed information about
futures transactions, see "Investment Objectives and Policies" in the  Statement
of Additional Information.
 
    The  Emerging Markets  Debt Portfolio  may attempt  to accomplish objectives
similar to those described above with  respect to forward and futures  contracts
for currency by means of purchasing put or call options on foreign currencies on
exchanges.  A put option gives the Portfolio the right to sell a currency at the
exercise price  until the  expiration of  the option.  A call  option gives  the
Portfolio  the right  to purchase  a currency  at the  exercise price  until the
expiration of the option.
 
    The Portfolio's Custodian  will place  cash, U.S.  government securities  or
high-grade debt securities into a segregated account of a Portfolio in an amount
equal   to  the  value  of  such  Portfolio's  total  assets  committed  to  the
consummation of forward foreign currency exchange contracts. If the value of the
securities placed  in  the  segregated  account  declines,  additional  cash  or
securities  will be placed in the account on  a daily basis so that the value of
the account will be at least equal to the amount of such Portfolio's commitments
with respect  to such  contracts.  See "Investment  Objectives and  Policies  --
Forward Currency Exchange Contracts" in the Statement of Additional Information.
 
    INVESTMENT  FUNDS.  Some  emerging countries have  laws and regulations that
currently  preclude  direct  foreign  investment  in  the  securities  of  their
companies.  However, indirect foreign investment  in the securities of companies
listed and traded  on the  stock exchanges in  these countries  is permitted  by
certain emerging countries through investment funds which have been specifically
authorized.  The Portfolios may invest in  these investment funds subject to the
provisions of the 1940 Act, and  other applicable laws as discussed below  under
"Investment  Restrictions." If a Portfolio invests in such investment funds, the
Portfolio's shareholders will  bear not  only their proportionate  share of  the
expenses  of the  Portfolio (including  operating expenses  and the  fees of the
Adviser), but  also will  indirectly  bear similar  expenses of  the  underlying
investment funds.
 
    Certain  of the investment funds referred  to in the preceding paragraph are
advised by the Adviser. These Portfolios may, to the extent permitted under  the
1940  Act  and other  applicable law,  invest  in these  investment funds.  If a
Portfolio does elect to make an investment  in such an investment fund, it  will
only purchase the securities of such investment fund in the secondary market.
 
    LOAN  PARTICIPATIONS  AND ASSIGNMENTS.   The  Emerging Markets  and Emerging
Markets Debt  Portfolios  may invest  in  fixed  rate and  floating  rate  loans
("Loans")  arranged through private negotiations  between an issuer of sovereign
debt obligations  and  one  or  more  financial  institutions  ("Lenders").  The
Portfolio's  investments in Loans  are expected in  most instances to  be in the
form of participation in  Loans ("Participations") and assignments  of all or  a
portion of Loans ("Assignments") from third parties. The Portfolio will have the
right to
 
                                       18
<PAGE>
receive  payments of principal,  interest and any  fees to which  it is entitled
only from the  Lender selling  the Participation and  only upon  receipt by  the
Lender  of the payments from the borrower. In the event of the insolvency of the
Lender selling  a Participation,  the  Portfolio may  be  treated as  a  general
creditor  of the Lender and may not  benefit from any set-off between the Lender
and the borrower. Certain Participations may be structured in a manner  designed
to  avoid purchasers of Participations  being subject to the  credit risk of the
Lender with respect to  the Participation. Even under  such a structure, in  the
event  of the Lender's  insolvency, the Lender's  servicing of the Participation
may be delayed and the assignability  of the Participation may be impaired.  The
Portfolio will acquire Participations only if the Lender interpositioned between
the Portfolio and the borrower is determined by the Adviser to be creditworthy.
 
    When the Portfolio purchases Assignments from Lenders it will acquire direct
rights  against  the  borrower on  the  Loan. However,  because  Assignments are
arranged through private negotiations between potential assignees and  potential
assignors, the rights and obligations acquired by the Portfolio as the purchaser
of  an Assignment may differ  from, and be more limited  than, those held by the
assigning Lender. Because  there is no  liquid market for  such securities,  the
Portfolio  anticipates  that such  securities could  be sold  only to  a limited
number of institutional  investors. The lack  of a liquid  secondary market  may
have  an adverse  impact on  the value  of such  securities and  the Portfolio's
ability to dispose of particular Assignments or Participations when necessary to
meet the Portfolio's liquidity needs or in response to a specific economic event
such as a deterioration in the creditworthiness  of the borrower. The lack of  a
liquid secondary market for Assignments and Participations also may make it more
difficult  for the Portfolio to assign a  value to these securities for purposes
of valuing the Portfolio's portfolio and calculating its net asset value.
 
    LOANS OF  PORTFOLIO  SECURITIES.   The  Portfolios may  lend  securities  to
brokers, dealers, domestic and foreign banks or other financial institutions for
the  purpose  of increasing  their net  investment income.  These loans  must be
secured continuously by cash or equivalent collateral, or by a letter of  credit
at  least  equal to  the  market value  of  the securities  loaned  plus accrued
interest or income. There may be a  risk of delay in recovery of the  securities
or  even loss of rights in the  collateral should the borrower of the securities
fail  financially.  Each   Portfolio  will  not   enter  into  securities   loan
transactions  exceeding in  the aggregate,  33 1/3% of  the market  value of its
total assets.  For  more  detailed  information  about  securities  lending  see
"Investment Objectives and Policies" in the Statement of Additional Information.
 
    MONEY  MARKET INSTRUMENTS.   Each Portfolio is permitted  to invest in money
market  instruments,  although  each  Portfolio  intends  to  stay  invested  in
securities  satisfying its primary investment objective to the extent practical.
The Portfolios may  make money  market investments pending  other investment  or
settlement  for liquidity,  or in  adverse market  conditions. The  money market
investments permitted  for the  Portfolios include:  obligations of  the  United
States government and its agencies and instrumentalities; obligations of foreign
sovereignties;   other   debt  securities;   commercial  paper   including  bank
obligations; certificates  of  deposit  (including  Eurodollar  certificates  of
deposit);  and repurchase agreements. For  more detailed information about these
money market investments,  see "Description  of Securities and  Ratings" in  the
Statement of Additional Information.
 
    NON-PUBLICLY   TRADED   SECURITIES,   PRIVATE   PLACEMENTS   AND  RESTRICTED
SECURITIES.  The Portfolios may invest in securities that are neither listed  on
a  stock  exchange  nor  traded  over-the-counter,  including  privately  placed
securities. Investing  in  such  unlisted emerging  country  equity  securities,
including  investments  in new  and early  stage companies,  may involve  a high
degree  of  business  and  financial   risk  that  can  result  in   substantial
 
                                       19
<PAGE>
losses.  As  a  result of  the  absence of  a  public trading  market  for these
securities, they may be  less liquid than  publicly traded securities.  Although
these  securities may be resold in privately negotiated transactions, the prices
realized from  these sales  could be  less  than those  originally paid  by  the
Portfolio,  or  less  than  what  may  be  considered  the  fair  value  of such
securities. Further, companies whose securities are not publicly traded may  not
be  subject to the  disclosure and other  investor protection requirements which
might be applicable if their securities were publicly traded. If such securities
are required  to  be  registered  under  the securities  laws  of  one  or  more
jurisdictions  before being  resold, the Portfolio  may be required  to bear the
expenses of registration.
 
    As a general matter, each Portfolio may not invest more than 15% of its  net
assets  in  illiquid  securities, including  securities  for which  there  is no
readily available secondary  market nor  more than 10%  of its  total assets  in
securities  that are  restricted from  sale to  the public  without registration
("Restricted Securities") under  the Securities  Act of 1933  (the "1933  Act").
Nevertheless,  subject  to  the  foregoing  limit  on  illiquid  securities, the
Portfolio may invest up to 25% of its total assets in Restricted Securities that
can be offered and sold to qualified institutional buyers under Rule 144A  under
that  Act ("144A Securities"). The Board of Directors has adopted guidelines and
delegated to the Adviser, subject to the supervision of the Board of  Directors,
the  daily  function  of  determining  and  monitoring  the  liquidity  of  144A
Securities. Rule 144A securities may become illiquid if qualified  institutional
buyers are not interested in acquiring the securities.
 
    REPURCHASE  AGREEMENTS.  Each Portfolio may enter into repurchase agreements
with brokers, dealers or  banks that meet the  credit guidelines established  by
the  Fund's Board of Directors. In a  repurchase agreement, the Portfolio buys a
security from a seller  that has agreed  to repurchase it  at a mutually  agreed
upon  date and price, reflecting the interest rate effective for the term of the
agreement. The term of these agreements  is usually from overnight to one  week,
and  never exceeds  one year.  Repurchase agreements  may be  viewed as  a fully
collateralized loan  of money  by the  Portfolio to  the seller.  The  Portfolio
always  receives securities with a  market value at least  equal to the purchase
price (including accrued interest) as  collateral, and this value is  maintained
during  the term  of the  agreement. If the  seller defaults  and the collateral
value declines, the Portfolio might incur a loss. If bankruptcy proceedings  are
commenced  with  respect to  the seller,  the  Portfolio's realization  upon the
collateral may  be  delayed or  limited.  The aggregate  of  certain  repurchase
agreements  and  certain  other  investments  is  limited  as  set  forth  under
"Investment Limitations."
 
    REVERSE REPURCHASE  AGREEMENTS.   The Emerging  Markets Debt  Portfolio  may
enter  into reverse  repurchase agreements  with brokers,  dealers, domestic and
foreign  banks  or  other  financial  institutions.  In  a  reverse   repurchase
agreement,  the Portfolio  sells a  security and  agrees to  repurchase it  at a
mutually agreed upon date and price, reflecting the interest rate effective  for
the  term of the agreement. It  may also be viewed as  the borrowing of money by
the  Portfolio.  The  Portfolio's  investment  of  the  proceeds  of  a  reverse
repurchase  agreement is the speculative factor known as leverage. The Portfolio
may enter into a reverse repurchase  agreement only if the interest income  from
investment  of  the  proceeds  is  greater  than  the  interest  expense  of the
transaction and the proceeds are invested for  a period no longer than the  term
of  the agreement.  The Portfolio  will maintain  with the  Custodian a separate
account with a segregated portfolio of cash, U.S. Government securities or other
liquid high grade debt obligations in an  amount at least equal to its  purchase
obligations  under these  agreements. If  interest rates  rise during  a reverse
repurchase agreement,  it  may  adversely  affect  the  Portfolio's  ability  to
maintain  a stable net asset value. The aggregate of these agreements is limited
as set forth under "Investment  Limitations." Reverse repurchase agreements  are
considered  to be  borrowings and are  subject to the  percentage limitations on
borrowings set forth in "Investment Limitations."
 
                                       20
<PAGE>
    RUSSIAN SECURITIES TRANSACTIONS.  The Emerging Markets Portfolio may  invest
in  equity  securities  of  Russian companies.  The  registration,  clearing and
settlement of securities transactions in Russia are subject to significant risks
not normally associated with  securities transactions in  the United States  and
other  more  developed  markets. Ownership  of  shares in  Russian  companies is
evidenced by entries in a company's share register (except where shares are held
through depositories  that  meet the  requirements  of  the 1940  Act)  and  the
issuance  of extracts from the register or,  in certain limited cases, by formal
share certificates. However, Russian  share registers are frequently  unreliable
and  the  Portfolio  could  possibly lose  its  registration  through oversight,
negligence or fraud.  Moreover, Russia  lacks a centralized  registry to  record
securities   transactions  and  registrars  located  throughout  Russia  or  the
companies  themselves  maintain  share   registers.  Registrars  are  under   no
obligation  to provide extracts to potential purchasers in a timely manner or at
all and are not necessarily subject to effective state supervision. In addition,
while registrars are liable under law for losses resulting from their errors, it
may be difficult for the Portfolio to enforce any rights it may have against the
registrar  or  issuer  of  the  securities  in  the  event  of  loss  of   share
registration.  Although Russian companies with  more than 1,000 shareholders are
required by law to employ an independent company to maintain share registers, in
practice, such companies have not always followed this law. Because of this lack
of independence of registrars,  management of a Russian  company may be able  to
exert considerable influence over who can purchase and sell the company's shares
by  illegally instructing the registrar to  refuse to record transactions on the
share register.  Furthermore, these  practices may  prevent the  Portfolio  from
investing  in the securities of certain Russian companies deemed suitable by the
Adviser and  could cause  a  delay in  the sale  of  Russian securities  by  the
Portfolio  if the  company deems  a purchaser  unsuitable, which  may expose the
Portfolio to potential loss on its investment.
 
    In light  of  the risks  described  above, the  Board  of Directors  of  the
Portfolio has approved certain procedures concerning the Portfolio's investments
in  Russian  securities.  Among  these  procedures  is  a  requirement  that the
Portfolio will not  invest in the  securities of a  Russian company unless  that
issuer's   registrar  has   entered  into   a  contract   with  the  Portfolio's
sub-custodian containing certain  protective conditions  including, among  other
things,  the  sub-custodian's right  to conduct  regular share  confirmations on
behalf of  the  Portfolio. This  requirement  will  likely have  the  effect  of
precluding  investments in  certain Russian  companies that  the Portfolio would
otherwise make.
 
    SHORT SALES.  The Emerging Markets Debt Portfolio may from time to time sell
securities short without limitation. A short sale is a transaction in which  the
Investment  Fund would  sell securities  it does not  own (but  has borrowed) in
anticipation of  a decline  in the  market  price of  the securities.  When  the
Portfolio  makes a short  sale, the proceeds  it receives from  the sale will be
held on behalf of a broker until the Portfolio replaces the borrowed securities.
To deliver  the securities  to the  buyer, the  Portfolio will  need to  arrange
through  a broker to borrow the securities and, in so doing, the Investment Fund
will become obligated to replace the  securities borrowed at their market  price
at  the time of replacement, whatever that  price may be. The Portfolio may have
to pay a premium to borrow the securities and must pay any dividends or interest
payable on the securities until they are replaced.
 
    The Portfolio's obligation to replace the securities borrowed in  connection
with  a short sale will be secured  by collateral deposited with the broker that
consists of cash, U.S.  government securities or other  liquid, high grade  debt
obligations.  In addition, the Portfolio will place in a segregated account with
its Custodian an amount of cash, U.S. government securities or other liquid high
grade debt obligations equal to the  difference, if any, between (1) the  market
value  of the securities sold at the time they were sold short and (2) any cash,
U.S.
 
                                       21
<PAGE>
government securities or other liquid  high grade debt obligations deposited  as
collateral  with the broker in connection with the short sale (not including the
proceeds of the short sale). Short sales by the Investment Fund involve  certain
risks  and special considerations. Possible losses  from short sales differ from
losses that could be incurred from a purchase of a security, because losses from
short sales may be unlimited, whereas  losses from purchases can equal only  the
total amount invested.
 
    STOCK  OPTION  AND INDEX  FUTURES  CONTRACTS.   Each  Portfolio may  seek to
increase its return or may hedge all  or a portion of its portfolio  investments
through  stock  options  and  stock  index  futures  contracts  with  respect to
securities in  which  the Portfolio  may  invest. There  currently  are  limited
options  and stock index futures markets in emerging countries and the nature of
the strategies adopted by the Adviser  and the extent to which those  strategies
are  used will depend on the development of stock option and stock index futures
contracts by emerging country stock  exchanges. Each Portfolio will only  engage
in  transactions in  stock options and  stock index futures  contracts which are
traded on a recognized securities or futures exchange.
 
    The Emerging  Markets Debt  Portfolio may  write (i.e.,  sell) covered  call
options  on  securities  and loan  participations  and assignments  held  in its
portfolio, which options  give the  purchaser the  right to  buy the  underlying
security,  loan  participation  or assignment  covered  by the  option  from the
Portfolio at the stated  exercise price. A "covered"  call option means that  so
long  as the Portfolio is obligated as the writer of the option, it will own (i)
the underlying security, loan participation or assignment subject to the option,
or (ii)  securities  convertible or  exchangeable  without the  payment  of  any
consideration into the security, loan participation or assignment subject to the
option.  As a matter of operating policy,  the aggregate value of the underlying
securities, loan participations and assignments on which options will be written
at any one  time will not  exceed 5% of  the total assets  of the Portfolio.  In
addition,  as a matter of  operating policy, the Portfolio  may purchase put and
call options on securities, loan participations or assignments.
 
    The Portfolio  will  receive a  premium  from writing  call  options,  which
increases  the Portfolio's return on the underlying security, loan participation
or assignment in the event the option expires unexercised or is closed out at  a
profit.  By writing a call,  the Portfolio will limit  its opportunity to profit
from  an  increase  in  the  market  value  of  the  underlying  security,  loan
participation  or assignment above the exercise price  of the option for as long
as the Portfolio's obligation as writer  of the option continues. Thus, in  some
periods  the  Portfolio will  receive  less total  return  and in  other periods
greater total  return from  writing  covered call  options  than it  would  have
received from its underlying securities, loan participations and assignments had
it  not written call options. The Portfolio pays a premium to purchase an option
and the risk assumed by the Portfolio when it purchases an option is the loss of
this premium. Because  the price of  an option tends  to move with  that of  its
underlying  security, if  the Portfolio is  to make  a profit, the  price of the
underlying security, loan participation or assignment must change and the change
must be sufficient to cover the premiums and commissions paid. A price change in
the security, loan participation  or assignment underlying  the option does  not
assure  a profit because  prices in the  options markets may  not always reflect
such change.
 
    The Emerging Markets Debt Portfolio may purchase and sell indexed  financial
futures  contracts. An indexed futures contract is  an agreement to take or make
delivery of an amount of cash equal  to the difference between the value of  the
index  at the beginning and at the end of the contract period. Successful use of
indexed futures will be  subject to the Adviser's  ability to predict  correctly
movements  in the  direction of  the relevant debt  market. No  assurance can be
given that the Adviser's judgment in this respect will be correct.
 
                                       22
<PAGE>
    The Portfolio may sell indexed  financial futures contracts in  anticipation
of  or during a market decline to attempt to offset the decrease in market value
of securities in its portfolio that  might otherwise result. When the  Portfolio
is  not fully  invested in  emerging country  debt securities  and anticipates a
significant market advance,  it may purchase  indexed futures in  order to  gain
rapid  market exposure that may in part or entirely offset increases in the cost
of securities that it  intends to purchase. In  a substantial majority of  these
transactions,  the Portfolio will  purchase such securities  upon termination of
the futures position but,  under unusual market  conditions, a futures  position
may be terminated without the corresponding purchase of debt securities.
 
    STRUCTURED  SECURITIES.   The Emerging Markets  Debt Portfolio  may invest a
portion of its assets in entities organized and operated solely for the  purpose
of  restructuring the investment characteristics  of sovereign debt obligations.
This type of restructuring involves the deposit with, or purchase by, an entity,
such as a  corporation or trust,  of specified instruments  (such as  commercial
bank  loans or  Brady Bonds)  and the  issuance by  that entity  of one  or more
classes of  securities  ("Structured  Securities") backed  by,  or  representing
interests  in,  the  underlying instruments.  The  cash flow  on  the underlying
instruments may be apportioned among  the newly issued Structured Securities  to
create  securities with  different investment  characteristics, such  as varying
maturities, payment priorities and interest  rate provisions, and the extent  of
the  payments made  with respect  to Structured  Securities is  dependent on the
extent of  the  cash flow  on  the underlying  instruments.  Because  Structured
Securities  of  the  type in  which  the  Portfolio anticipates  it  will invest
typically involve no  credit enhancement,  their credit risk  generally will  be
equivalent  to that of the underlying instruments. The Portfolio is permitted to
invest in  a class  of  Structured Securities  that  is either  subordinated  or
unsubordinated to the right of payment of another class. Subordinated Structured
Securities   typically  have  higher  yields  and  present  greater  risks  than
unsubordinated Structured Securities. Structured  Securities are typically  sold
in  private placement  transactions, and  there currently  is no  active trading
market for Structured Securities.
 
    TEMPORARY INVESTMENTS.  During periods in which the Adviser believes changes
in economic, financial or political  conditions make it advisable, the  Emerging
Markets  Portfolio may reduce  its holdings in equity  and other securities, and
the Emerging Markets Debt Portfolio may reduce its holdings in emerging  country
debt securities, for temporary defensive purposes, and the Portfolios may invest
in certain short-term (less than twelve months to maturity) and medium-term (not
greater  than five  years to  maturity) debt  securities or  may hold  cash. The
short-term and medium-term  debt securities  in which the  Portfolio may  invest
consist  of (a) obligations  of the U.S. or  emerging country governments, their
respective agencies or instrumentalities; (b) bank deposits and bank obligations
(including certificates of deposit, time  deposits and bankers' acceptances)  of
U.S.  or emerging country  banks denominated in any  currency; (c) floating rate
securities  and  other  instruments  denominated  in  any  currency  issued   by
international development agencies; (d) finance company and corporate commercial
paper  and  other short-term  corporate debt  obligations  of United  States and
emerging country corporations meeting the Portfolio's credit quality  standards;
and (e) repurchase agreements with banks and broker-dealers with respect to such
securities.  For temporary defensive  purposes, the Portfolios  intend to invest
only in short-term and medium-term debt securities that the Adviser believes  to
be  of high quality, i.e., subject to relatively low risk of loss of interest or
principal (there  is currently  no rating  system for  debt securities  in  most
emerging countries).
 
    WHEN-ISSUED  AND DELAYED DELIVERY  SECURITIES.  Each  Portfolio may purchase
securities on a  when-issued or  delayed delivery basis.  In such  transactions,
instruments  are bought with payment and delivery  taking place in the future in
order to secure what is considered to  be an advantageous yield or price at  the
time of the
 
                                       23
<PAGE>
transaction.  Each Portfolio will maintain with the Custodian a separate account
with a segregated portfolio of high  grade debt securities or equity  securities
or cash in an amount at least equal to these commitments. The payment obligation
and  the interest  rates that will  be received are  each fixed at  the time the
Portfolio enters into the  commitment and no interest  accrues to the  Portfolio
until  settlement. Thus,  it is possible  that the  market value at  the time of
settlement could be  higher or  lower than the  purchase price  if, among  other
factors, the general level of interest rates has changed. It is a current policy
of  each Portfolio not to enter into when-issued commitments or delayed delivery
securities exceeding,  in  the  aggregate,  15%  of  the  market  value  of  the
Portfolio's total assets less liabilities, other than the obligations created by
these commitments.
 
                             INVESTMENT LIMITATIONS
 
    Each  Portfolio is  a non-diversified  portfolio under  the 1940  Act, which
means that the Portfolio is not limited by the 1940 Act in the proportion of its
assets that may be invested  in the obligations of  a single issuer. Thus,  each
Portfolio  may invest a greater proportion of  its assets in the securities of a
smaller number of issuers and, as a result, will be subject to greater risk with
respect to its portfolio securities.  However, each Portfolio intends to  comply
with  the diversification requirements  imposed by the  Internal Revenue Code of
1986, as  amended, for  qualification  as a  regulated investment  company.  See
"Taxes"  below  and  "Investment  Limitations" in  the  Statement  of Additional
Information.
 
    Each Portfolio  operates  under  certain investment  restrictions  that  are
deemed  fundamental limitations and may be changed only with the approval of the
holders of a  majority of  the Portfolio's outstanding  shares. See  "Investment
Limitations"  in  the Statement  of  Additional Information.  In  addition, each
Portfolio operates  under  certain  non-fundamental  investment  limitations  as
described  below and in the Statement  of Additional Information. Each Portfolio
may not  (i) enter  into repurchase  agreements  with more  than seven  days  to
maturity  if, as a result, more than 15%  of the market value of the Portfolio's
net assets would be invested in such repurchase agreements and other investments
for which market  quotations are not  readily available or  which are  otherwise
illiquid;  (ii) borrow money,  except from banks  for extraordinary or emergency
purposes, and then only  in amounts up  to 10% of the  value of the  Portfolio's
total  assets taken  at cost  at the time  of borrowing;  or purchase securities
while borrowings exceed 5% of its total assets, except the Emerging Markets Debt
Portfolio is not subject to such limits  on borrowing and may borrow from  banks
and  other entities  in amounts  not in excess  of 33  1/3% of  its total assets
(including the  amount borrowed)  less liabilities;  (iii) mortgage,  pledge  or
hypothecate  any assets except in connection  with any such borrowing in amounts
up to 10% of the value of the  Portfolio's net assets at the time of  borrowing;
(iv)  invest in fixed time deposits with a duration of over seven calendar days;
or (v) invest in fixed time deposits  with a duration of from two business  days
to seven calendar days if more than 10% of the Portfolio's total assets would be
invested in these deposits.
 
LOCAL ADMINISTRATOR FOR THE EMERGING MARKETS PORTFOLIO
 
    The  Emerging Markets  Portfolio is required  under Brazilian law  to have a
local administrator in Brazil. Unibanco-Uniao (the "Brazilian Administrator"), a
Brazilian corporation, acts as the Portfolio's Brazilian administrator  pursuant
to  an agreement with  the Portfolio (the  "Brazilian Administration Agreement).
Under  the  Brazilian  Administration  Agreement,  the  Brazilian  Administrator
performs   various  services   for  the   Portfolio,  including   effecting  the
registration of the Portfolio's foreign capital with the Central Bank of  Brazil
effecting   all  foreign  exchange  transactions   related  to  the  Portfolio's
investments in Brazil and obtaining all approvals required for the Portfolio  to
make  remittances of income  and capital gains  and for the  repatriation of the
 
                                       24
<PAGE>
Portfolio's investments  pursuant  to  Brazilian  law.  For  its  services,  the
Brazilian Administrator is paid an annual fee equal to 0.125% of the Portfolio's
average weekly net assets invested in Brazil, paid monthly. The principal office
of  the Brazilian Administrator  is located at Avenida  Eusebio Matoso, 891, Sao
Paulo, S.P, Brazil.  The Brazilian Administration  Agreement is terminable  upon
six  months' notice by either party. The Brazilian Administrator may be replaced
only by an entity authorized to act as a joint manager of a managed portfolio of
bonds and securities under Brazilian law.
 
    The Emerging Markets  Portfolio is required  under Colombian law  to have  a
local administrator in Colombia. CitiTrust S.A. (the "Colombian Administrator"),
a  Colombian  Trust Company,  acts  as the  Portfolio's  Colombian administrator
pursuant to an agreement with  the Portfolio (the "Colombian Agreement").  Under
the  Colombian Agreement, the Colombian  Administrator performs various services
for the  Portfolio,  including effecting  the  registration of  the  Portfolio's
foreign  capital  with  the  Central Bank  of  Colombia,  effecting  all foreign
exchange transactions related  to the  Portfolio's investments  in Colombia  and
obtaining all approvals required for the Portfolio to make remittances of income
and  capital  gains  and for  the  repatriation of  the  Portfolio's investments
pursuant to Colombian law. For its services, the Colombian Administrator is paid
an annual fee of $1000  plus .20% per transaction.  The principal office of  the
Colombian  Administrator is  located at Sociedad  Fiduciaria International S.A.,
8-89, Piso  2,  Santa  Fe  de  Bogota,  Colombia.  The  Colombian  Agreement  is
terminable upon 30 days' notice by either party. The Colombian Administrator may
be  replaced only by an entity authorized to act as a joint manager of a managed
portfolio of bonds and securities under Colombian law.
 
                             MANAGEMENT OF THE FUND
 
    INVESTMENT ADVISER.  Morgan Stanley Asset Management Inc. is the  Investment
Adviser  and Administrator of the  Fund and each of  the Portfolios. The Adviser
provides investment advice  and portfolio  management services,  pursuant to  an
Investment  Advisory Agreement  and, subject  to the  supervision of  the Fund's
Board  of  Directors,  makes  each  of  the  Portfolio's  day-to-day  investment
decisions,  arranges for the  execution of portfolio  transactions and generally
manages each of the Portfolio's investments. The Adviser is entitled to  receive
from  each Portfolio an  annual management fee, payable  quarterly, equal to the
percentage of average daily  net assets set forth  in the table below.  However,
the Adviser has agreed to a reduction in the fees payable to it and to reimburse
the Portfolio, if necessary, if such fees would cause the total annual operating
expenses  of either  Portfolio to exceed  the respective  percentages of average
daily net assets set forth in the table below.
 
<TABLE>
<CAPTION>
                                                  MAXIMUM TOTAL ANNUAL
                                                        OPERATING
                                                   EXPENSES AFTER FEE
                                                         WAIVERS
                                  MANAGEMENT    -------------------------
          PORTFOLIO                   FEE        CLASS A         CLASS B
- ------------------------------    -----------   ---------       ---------
<S>                               <C>           <C>             <C>
Emerging Markets Portfolio             1.25%       1.75%           2.00%
Emerging Markets Debt
 Portfolio                             1.00%       1.75%           2.00%
</TABLE>
 
    The Adviser, with  principal offices  at 1221  Avenue of  the Americas,  New
York,  New  York  10020,  conducts a  worldwide  portfolio  management business,
providing a broad  range of portfolio  management services to  customers in  the
United  States and abroad. At December 31,  1995, the Adviser, together with its
affiliated   asset   management   companies,   managed   investments    totaling
approximately  $57.4 billion, including approximately $41.9 billion under active
management and  $15.5  billion as  Named  Fiduciary or  Fiduciary  Adviser.  See
"Management of the Fund" in the Statement of Additional Information.
 
                                       25
<PAGE>
    PORTFOLIO  MANAGERS.  The following  individuals have primary responsibility
for the Portfolio indicated below.
 
    EMERGING MARKETS  PORTFOLIO --  MADHAV  DHAR.   Madhav  Dhar is  a  Managing
Director  of Morgan Stanley.  He joined the  Adviser in 1984  to focus on global
asset allocation and investment  strategy and now  heads the Adviser's  emerging
markets  group and serves  as the group's principal  Portfolio Manager. Mr. Dhar
also coordinates  the Adviser's  developing country  funds effort  and has  been
involved  in the launching of  the Adviser's country funds.  He is a Director of
the  Morgan  Stanley  Emerging  Markets  Fund,  Inc.  (a  closed-end  investment
company).  He holds a B.S. (honors)  from St. Stephens College, Delhi University
(India), and an M.B.A. from Carnegie-Mellon University. Mr. Dhar has had primary
responsibility for managing the Portfolio's assets since inception.
 
    EMERGING MARKETS  DEBT PORTFOLIO  --  PAUL GHAFFARI.    Paul Ghaffari  is  a
Principal  of  Morgan Stanley.  He joined  the Adviser  in June  1993 as  a Vice
President and Portfolio  Manager for  the Morgan Stanley  Emerging Markets  Debt
Fund  (a  closed-end  investment company).  Prior  to joining  the  Adviser, Mr.
Ghaffari was  a Vice  President in  the Fixed  Income Division  of the  Emerging
Markets  Sales and Trading Department  at Morgan Stanley. From  1983 to 1992, he
worked in LDC Sales  and Trading Department  and the Mortgage-Backed  Securities
Department  at J.P. Morgan &  Co. Inc. and worked  in the Treasury Department at
the Morgan Guaranty Trust  Co. He holds a  B.A. in International Relations  from
Pamona  College and an  M.S. in Foreign Service  from Georgetown University. Mr.
Ghaffari has  had primary  responsibility for  managing the  Portfolio's  assets
since inception.
 
    ADMINISTRATOR.    The Adviser  also  provides the  Fund  with administrative
services pursuant to  an Administration Agreement.  The services provided  under
the  Administration Agreement are subject to the supervision of the Officers and
the Board of  Directors of  the Fund  and include  day-to-day administration  of
matters  related  to the  corporate existence  of the  Fund, maintenance  of its
records, preparation of reports, supervision of the Fund's arrangements with its
custodian,  and  assistance  in  the  preparation  of  the  Fund's  registration
statements  under  federal and  state  laws. The  Administration  Agreement also
provides that  the Administrator,  through  its agents,  will provide  the  Fund
dividend  disbursing and  transfer agent  services. For  its services  under the
Administration Agreement, the Fund  pays the Adviser a  monthly fee which on  an
annual basis equals 0.15% of the average daily net assets of each Portfolio.
 
    Under  an agreement between  the Adviser and The  Chase Manhattan Bank, N.A.
("Chase"), Chase  provides certain  administrative services  to the  Fund. In  a
merger  completed on September 1, 1995, Chase succeeded to all of the rights and
obligations under the  U.S. Trust Administration  Agreement between the  Adviser
and  United States Trust Company  of New York ("U.S.  Trust"), pursuant to which
U.S. Trust had agreed  to provide certain administrative  services to the  Fund.
Pursuant to a delegation clause in the U.S. Trust Administration Agreement, U.S.
Trust  delegated  its  administration  responsibilities  to  Chase  Global Funds
Services Company  ("CGFSC"), formerly  known as  Mutual Funds  Service  Company,
which  after the merger with Chase is a subsidiary of Chase and will continue to
provide certain administrative services to the Fund. The Adviser supervises  and
monitors  administrative services provided by CGFSC. The services provided under
the Administration Agreement  and the  U.S. Trust  Administration Agreement  are
also subject to the supervision of the Board of Directors of the Fund. The Board
of  Directors of the Fund has approved the provision of services described above
pursuant to  the  Administration Agreement  and  the U.S.  Trust  Administration
Agreement as being in the best interest of the
 
                                       26
<PAGE>
Fund.  CGFSC's  business address  is  73 Tremont  Street,  Boston, Massachusetts
02108-3913. For additional information regarding the Administration Agreement or
the U.S. Trust  Administration Agreement, see  "Management of the  Fund" in  the
Statement of Additional Information.
 
    DIRECTORS  AND OFFICERS.  Pursuant to  the Fund's Articles of Incorporation,
the Board of Directors  decides upon matters of  general policy and reviews  the
actions  of the Fund's  Adviser, Administrator and  Distributor. The Officers of
the Fund conduct and supervise its daily business operations.
 
    DISTRIBUTOR.   Morgan Stanley  serves as  the exclusive  Distributor of  the
shares  of  the Fund.  Under its  Distribution Agreement  with the  Fund, Morgan
Stanley sells  shares  of each  Portfolio  upon the  terms  and at  the  current
offering  price described in this Prospectus. Morgan Stanley is not obligated to
sell any certain number of shares of any Portfolio.
 
    The Portfolios currently offer  only the classes of  shares offered by  this
Prospectus.  The Portfolio may in the future offer one or more classes of shares
with features, distribution expenses or  other expenses that are different  from
those of the classes currently offered.
 
    The  Fund has  adopted a Plan  of Distribution  with respect to  the Class B
shares for each  Portfolio pursuant to  Rule 12b-1  under the 1940  Act (each  a
"Plan").  Under  each Plan,  the  Distributor is  entitled  to receive  from the
Portfolios a distribution  fee, which is  accrued daily and  paid quarterly,  of
0.25%  of the Class B  shares' average daily net  assets on an annualized basis.
The Distributor  expects  to  reallocate  most of  its  fee  to  its  investment
representatives.  The Distributor may, in its discretion, voluntarily waive from
time to  time all  or  any portion  of  its distribution  fee  and each  of  the
Distributor  and the Adviser is free to  make additional payments out of its own
assets to promote the  sale of Fund shares,  including payments that  compensate
financial institutions for distribution services or shareholder services.
 
    Each Plan is designed to compensate the Distributor for its services, not to
reimburse  the Distributor for its expenses,  and the Distributor may retain any
portion of the fee that it does not expend in fulfillment of its obligations  to
the Fund.
 
    PAYMENTS  TO  FINANCIAL INSTITUTIONS.   The  Adviser  or its  affiliates may
compensate certain financial institutions for the continued investment of  their
customers'  assets in the  Emerging Markets Portfolio pursuant  to the advice of
such financial institutions. These payments will be made directly by the Adviser
or its affiliates from their assets, and will not be made from the assets of the
Fund or  by  the  assessment  of  a  sales  charge  on  shares.  Such  financial
institutions may also perform certain shareholder or recordkeeping services that
would  otherwise be performed  by CGFSC. The  Adviser may elect  to enter into a
contract to pay the financial institutions for such services.
 
    EXPENSES.  Each Portfolio is responsible  for payment of certain other  fees
and  expenses (including  organizational costs,  legal fees,  accountant's fees,
custodial fees, and printing and mailing costs) specified in the  Administration
and Distribution Agreements.
 
                               PURCHASE OF SHARES
 
    Class A and Class B shares of each Portfolio may be purchased, without sales
commission,  at the net asset  value per share next  determined after receipt of
the purchase order by the Portfolio. See "Valuation of Shares."
 
                                       27
<PAGE>
MINIMUM INVESTMENT AND ACCOUNT SIZES; CONVERSION FROM CLASS A TO CLASS B SHARES
 
    For an account for either  Portfolio opened on or  after January 2, 1996  (a
"New  Account"), the  minimum initial  investment and  minimum account  size are
$500,000 for Class A  shares and $100,000 for  Class B shares. Managed  Accounts
may  purchase  Class  A shares  without  being  subject to  any  minimum initial
investment or  minimum  account  size  requirements  for  a  Portfolio  account.
Employees  of the  Adviser and  of its  affiliates may  purchase Class  A Shares
subject to conditions, including a lower minimum initial investment, established
by Officers of the Fund.
 
    If the  value  of a  New  Account, containing  Class  A shares  falls  below
$500,000   (but   remains  at   or  above   $100,000)  because   of  shareholder
redemption(s), the Fund will  notify the shareholder, and  if the account  value
remains  below  $500,000 (but  remains at  or above  $100,000) for  a continuous
60-day period, the Class A shares in such account will convert to Class B shares
and will be subject to the distribution fee and other features applicable to the
Class B shares. The Fund,  however, will not convert Class  A shares to Class  B
shares  based solely upon changes in the  market that reduce the net asset value
of shares. Under current  tax law, conversions between  share classes are not  a
taxable event to the shareholder.
 
    Shares  in a Portfolio account opened prior  to January 2, 1996 (a "Pre-1996
Account") were  designated  Class A  shares  on January  2,  1996. Shares  in  a
Pre-1996  Account  with  a  value  of  $100,000 or  more  on  March  1,  1996 (a
"Grandfathered Class A Account") remained  Class A shares regardless of  account
size  thereafter. Except for shares  in a Managed Account,  shares in a Pre-1996
Account with a value of  less than $100,000 on  March 1, 1996 (a  "Grandfathered
Class  B Account") converted to  Class B shares on  March 1, 1996. Grandfathered
Class A Accounts and Managed Accounts are not subject to conversion from Class A
shares to Class B shares.
 
    Investors may also invest in the  Fund by purchasing shares through a  trust
department, broker, dealer, agent, financial planner, financial services firm or
investment  adviser.  An  investor  may  be  charged  an  additional  service or
transaction fee by that institution. The minimum investment levels may be waived
at the discretion  of the  Adviser for (i)  certain employees  and customers  of
Morgan  Stanley  or  its  affiliates  and  certain  trust  departments, brokers,
dealers, agents,  financial  planers,  financial services  firms  or  investment
advisers  that  have  entered  into  an agreement  with  Morgan  Stanley  or its
affiliates; and (ii) retirement and deferred compensation plans and trusts, used
to fund such  plans, including,  but not limited  to, those  defined in  Section
401(a),  403(b) or  457 of the  Internal Revenue  Code of 1986,  as amended, and
"rabbi trusts".  The  Fund  reserves  the  right  to  modify  or  terminate  the
conversion  features of  the shares  as stated above  at any  time upon 60-days'
notice to shareholders.
 
MINIMUM ACCOUNT SIZES AND INVOLUNTARY REDEMPTION OF SHARES
 
    If the value of  a New Account falls  below $100,000 because of  shareholder
redemption(s),  the Fund will  notify the shareholder, and  if the account value
remains below  $100,000 for  a  continuous 60-day  period,  the shares  in  such
account  are subject to redemption  by the Fund and,  if redeemed, the net asset
value of  such  shares will  be  promptly paid  to  the shareholder.  The  Fund,
however,  will not redeem  shares based solely  upon changes in  the market that
reduce the net asset value of shares.
 
                                       28
<PAGE>
    Grandfathered Class A Accounts, Grandfathered  Class B Accounts and  Managed
Accounts are not subject to involuntary redemption.
 
    The  Fund  reserves  the  right  to  modify  or  terminate  the  involuntary
redemption features of  the shares  as stated above  at any  time upon  60-days'
notice to shareholders.
 
CONVERSION FROM CLASS B TO CLASS A SHARES
 
    If the value of Class B shares in a Portfolio account increases, whether due
to  shareholder share  purchases or  market activity,  to $500,000  or more, the
Class B shares  will convert  to Class  A shares.  Under current  tax law,  such
conversion  is not a taxable event to  the shareholder. Class A shares converted
from Class B shares  are subject to the  same minimum account size  requirements
that  are applicable to New Accounts containing Class A shares, as stated above.
The Fund reserves the  right to modify or  terminate this conversion feature  at
any time upon 60-days' notice to shareholders.
 
INITIAL PURCHASES DIRECTLY FROM THE FUND
 
    The  Fund's determination of an investor's eligibility to purchase shares of
a given class  will take precedence  over the investor's  selection of a  class.
Assuming  the investor is eligible for the  class, the Fund will select the most
favorable class for the investor, if the investor has not done so.
 
1) BY CHECK.   An account may  be opened  by completing and  signing an  Account
   Registration  Form, and mailing  it, together with  a check ($500,000 minimum
   for Class A shares of each Portfolio and $100,000 for Class B shares of  each
   Portfolio,  with certain exceptions  for Morgan Stanley  employees and select
   customers) payable to "Morgan Stanley Institutional Fund, Inc. --  [portfolio
   name]", to:
 
      Morgan Stanley Institutional Fund, Inc.
      P.O. Box 2798
      Boston, Massachusetts 02208-2798
 
     Payment will  be accepted only  in U.S. dollars,  unless prior approval for
  payment by  other currencies  is given  by the  Fund. The  Portfolio(s) to  be
  purchased should be designated on the Account Registration Form. For purchases
  by  check,  the Fund  is  ordinarily credited  with  Federal Funds  within one
  business day. Thus your purchase of shares by check is ordinarily credited  to
  your  account  at the  net asset  value per  share of  each of  the Portfolios
  determined on the next business day after receipt.
 
2) BY FEDERAL  FUNDS WIRE.   Purchases  may be  made by  having your  bank  wire
   Federal  Funds to the Fund's bank account.  In order to ensure prompt receipt
   of your Federal Funds Wire, it is important that you follow these steps:
 
A.  Telephone  the Fund  (toll free: 1-800-548-7786)  and provide  us with  your
    name,  address,  telephone  number, Social  Security  or  Tax Identification
    Number, the  portfolio(s) selected,  the class  selected, the  amount  being
    wired,  and by  which bank.  We will  then provide  you with  a Fund account
    number. (Investors with existing accounts should also notify the Fund  prior
    to wiring funds.)
 
                                       29
<PAGE>
B.    Instruct  your  bank to  wire  the  specified amount  to  the  Fund's Wire
    Concentration Bank Account (be  sure to have your  bank include the name  of
    the  portfolio(s)  selected,  the  class  selected  and  the  account number
    assigned to you) as follows:
 
    Chase Manhattan Bank, N.A.
    One Manhattan Plaza
    New York, NY 10081-1000
    ABA#021000021
    DDA# 910-2-733293
    Attn: Morgan Stanley Institutional Fund, Inc.
    Ref: (Portfolio name, your account number, your account name)
 
    Please call the Fund at 1-800-548-7786 prior to wiring funds.
 
C.  Complete and sign the Account  Registration Form and mail it to the  address
    shown thereon.
 
  Purchase  orders for shares of each Portfolio  which are received prior to the
  regular close of the NYSE (currently 4:00 p.m. Eastern Time) will be  executed
  at  the price computed  on the date of  receipt as long  as the Transfer Agent
  receives payment by check or  in Federal Funds prior  to the regular close  of
  the NYSE on such day.
 
  Federal Funds purchase orders will be accepted only on a day on which the Fund
  and Chase (the "Custodian Bank") are open for business. Your bank may charge a
  service fee for wiring Federal funds.
 
3) BY  BANK WIRE.   The  same procedure outlined  under "By  Federal Funds Wire"
   above must be  followed in  purchasing shares  by bank  wire. However,  money
   transferred  by bank wire may or may  not be converted into Federal Funds the
   same day, depending on the time the  money is received and the bank  handling
   the wire. Prior to such conversion, an investor's money will not be invested.
   Your bank may charge a service fee for wiring funds.
 
ADDITIONAL INVESTMENTS
 
    You  may  add to  your account  at any  time (minimum  additional investment
$1,000, except  for  automatic  reinvestment  of  dividends  and  capital  gains
distributions for which there are no minimums) by purchasing shares at net asset
value  by mailing a check to the  Fund (payable to "Morgan Stanley Institutional
Fund Inc. -- [portfolio name]") at the above address or by wiring monies to  the
Custodian  Bank as outlined above.  It is very important  that your account name
and portfolio be specified in the letter  or wire to ensure proper crediting  to
your  account. In order to  ensure that your wire  orders are invested promptly,
you are  requested to  notify  one of  the  Fund's representatives  (toll  free:
1-800-548-7786)  prior to the wire date.  Additional investments will be applied
to purchase additional  shares in  the same  class held  by a  shareholder in  a
Portfolio account.
 
OTHER PURCHASE INFORMATION
 
    The  purchase price of the  Class A and Class B  shares of the Portfolios is
the net asset value next determined after the order is received. See  "Valuation
of  Shares." An order received prior to the  regular close of the New York Stock
Exchange ("NYSE"), which is currently 4:00  p.m. Eastern Time, will be  executed
at the price
 
                                       30
<PAGE>
computed  on the date of  receipt; an order received  after the regular close of
the NYSE will be executed at the price computed on the next day the NYSE is open
as long as  the Transfer Agent  receives payment  by check or  in Federal  Funds
prior to the regular close of the NYSE on such day.
 
    Although  the legal rights of Class A  and Class B shares will be identical,
the different expenses borne  by each class will  result in different net  asset
values  and dividends. The net  asset value of Class  B shares will generally be
lower than the net asset value of Class A shares as a result of the distribution
expense charged to Class B shares. It  is expected, however, that the net  asset
value  per share of the two classes  will tend to converge immediately after the
recording of dividends  which will  differ by  approximately the  amount of  the
distribution expense accrual differential between the classes.
 
    In  the interest  of economy and  convenience, and because  of the operating
procedures of the Fund, certificates representing shares of the Portfolios  will
not  be issued. All shares  purchased are confirmed to  you and credited to your
account on the Fund's books  maintained by the Adviser  or its agents. You  will
have  the  same  rights  and  ownership  with  respect  to  such  shares  as  if
certificates had been issued.
 
    To ensure that checks are collected by the Fund, withdrawals of  investments
made  by check are  not presently permitted  until payment for  the purchase has
been received,  which may  take up  to eight  business days  after the  date  of
purchase.  As a  condition of this  offering, if  a purchase is  canceled due to
nonpayment or because your check does not clear, you will be responsible for any
loss the Fund or its  agents incur. If you are  already a shareholder, the  Fund
may  redeem shares from your account(s) to  reimburse the Fund or its agents for
any loss. In addition,  you may be prohibited  or restricted from making  future
purchases in the Fund.
 
    Investors  may  also invest  in the  Fund by  purchasing shares  through the
Distributor.
 
EXCESSIVE TRADING
 
    Frequent  trades  involving  either   substantial  portfolio  assets  or   a
substantial  portion of your  account or accounts controlled  by you can disrupt
management of a portfolio and raise its expenses. Consequently, in the  interest
of  all the stockholders of each  Portfolio and the Portfolio's performance, the
Fund may in its discretion bar  a stockholder that engages in excessive  trading
of  shares of any class  of a portfolio from further  purchases of shares of the
Fund for an indefinite period. The  Fund considers excessive trading to be  more
than  one purchase and sale involving shares of the same class of a portfolio of
the Fund  within  any  120-day  period. As  an  example,  exchanging  shares  of
portfolios of the Fund as follows amounts to excessive trading: exchanging Class
A shares of Portfolio A for Class A shares of Portfolio B, then exchanging Class
A  shares of Portfolio B for Class A  shares of Portfolio C and again exchanging
Class A shares of Portfolio C for Class A shares of Portfolio B within a 120-day
period. Two  types  of transactions  are  exempt from  these  excessive  trading
restrictions:  (1) trades exclusively  between money market  portfolios; and (2)
trades done  in  connection  with  an asset  allocation  service,  such  as  TFM
Accounts, managed or advised by MSAM and/or any of its affiliates.
 
                              REDEMPTION OF SHARES
 
    You  may  withdraw all  or  any portion  of the  amount  in your  account by
redeeming shares at any time. Please note  that purchases made by check are  not
permitted to be redeemed until payment of the purchase has been collected, which
may  take up to eight business days after purchase. The Fund will redeem Class A
shares or Class  B shares of  each Portfolio  at the next  determined net  asset
value of shares of the applicable class. On days
 
                                       31
<PAGE>
that  both the NYSE and the Custodian Bank  are open for business, the net asset
value per share of each of the Portfolios is determined at the regular close  of
trading of the NYSE (currently 4:00 p.m. Eastern Time). Shares of the Portfolios
may  be redeemed  by mail or  telephone. No  charge is made  for redemption. Any
redemption proceeds may be more or less  than the purchase price of your  shares
depending on, among other factors, the market value of the investment securities
held by the Portfolio.
 
BY MAIL
 
    Each  Portfolio will redeem its  Class A or Class B  shares at the net asset
value determined on the date the request is received, if the request is received
in "good order" before  the regular close  of the NYSE.  Your request should  be
addressed  to Morgan  Stanley Institutional Fund,  Inc., P.O.  Box 2798, Boston,
Massachusetts 02208-2798, except that deliveries by overnight courier should  be
addressed  to Morgan  Stanley Institutional Fund,  Inc., c/o  Chase Global Funds
Services Company, 73 Tremont Street, Boston, Massachusetts 02108-3913.
 
    "Good order"  means that  the  request to  redeem  shares must  include  the
following documentation:
 
         (a)  A letter of instruction or a stock assignment specifying the class
    and number  of  shares  or dollar  amount  to  be redeemed,  signed  by  all
    registered  owners  of the  shares  in the  exact  names in  which  they are
    registered;
 
        (b)  Any  required   signature  guarantees   (see  "Further   Redemption
    Information" below); and
 
         (c)  Other  supporting legal  documents, if  required,  in the  case of
    estates, trusts,  guardianships, custodianships,  corporations, pension  and
    profit sharing plans and other organizations.
 
    Shareholders who are uncertain of requirements for redemption should consult
with a Morgan Stanley Institutional Fund representative.
 
BY TELEPHONE
 
    Provided  you have previously elected the Telephone Redemption Option on the
Account Registration  Form, you  can  request a  redemption  of your  shares  by
calling  the Fund  and requesting  the redemption proceeds  be mailed  to you or
wired to your bank.  Please contact one of  Morgan Stanley Institutional  Fund's
representatives  for further details. In times of drastic market conditions, the
telephone redemption option  may be  difficult to implement.  If you  experience
difficulty in making a telephone redemption, your request may be made by mail or
overnight courier and will be implemented at the net asset value next determined
after  it is received. Redemption requests sent to the Fund through express mail
must be sent to Morgan Stanley Institutional Fund, Inc., c/o Chase Global  Funds
Services  Company, 73 Tremont Street, Boston,  Massachusetts 02108. The Fund and
the  Fund's  transfer  agent  (the  "Transfer  Agent")  will  employ  reasonable
procedures  to  confirm  that  the instructions  communicated  by  telephone are
genuine. These  procedures include  requiring the  investor to  provide  certain
personal  identification information at the time  an account is opened and prior
to effecting each transaction requested by telephone. In addition, all telephone
transaction requests will be recorded and  investors may be required to  provide
additional  telecopied  written  instructions  regarding  transaction  requests.
Neither the  Fund nor  the Transfer  Agent  will be  responsible for  any  loss,
liability, cost or expense for following instructions received by telephone that
either of them reasonably believes to be genuine.
 
                                       32
<PAGE>
    To  change the commercial  bank or account  designated to receive redemption
proceeds, a written  request must  be sent  to the  Fund at  the address  above.
Requests  to change the bank  or account must be  signed by each shareholder and
each signature must be guaranteed.
 
FURTHER REDEMPTION INFORMATION
 
    Normally the  Fund will  make payment  for all  shares redeemed  within  one
business  day of receipt  of the request, but  in no event  will payment be made
more than  seven days  after receipt  of  a redemption  request in  good  order.
However,  payments to investors  redeeming shares which  were purchased by check
will not be made until  payment for the purchase  has been collected, which  may
take up to eight days after the date of purchase. The Fund may suspend the right
of  redemption or postpone the date upon which redemptions are effected at times
when the NYSE is closed, or  under any emergency circumstances as determined  by
the Securities and Exchange Commission (the "Commission").
 
    If  the Board of  Directors determines that  it would be  detrimental to the
best interests of  the remaining  shareholders of  a Portfolio  to make  payment
wholly  or partly in cash, the Fund may  pay the redemption proceeds in whole or
in part by a distribution in-kind of securities held by the Portfolio in lieu of
cash   in    conformity   with    applicable    rules   of    the    Commission.
Distributions-in-kind  will be made in  readily marketable securities. Investors
may incur brokerage charges on the  sale of portfolio securities so received  in
payment of redemptions.
 
    To  protect  your account,  the Fund  and its  agents from  fraud, signature
guarantees are required for  certain redemptions to verify  the identity of  the
person  who has  authorized a redemption  from your account.  Please contact the
Fund for further  information. See "Redemption  of Shares" in  the Statement  of
Additional Information.
 
                              SHAREHOLDER SERVICES
 
EXCHANGE FEATURES
 
    You  may exchange shares that you own  in either Portfolio for shares of any
other available  portfolio of  the  Fund (other  than the  International  Equity
Portfolio,  which is  closed to  new investors). In  exchanging for  shares of a
portfolio with more  than one  class, the  class of  shares you  receive in  the
exchange  will be determined in the same  manner as any other purchase of shares
and will not  be based  on the  class of  shares surrendered  for the  exchange.
Consequently,  the same minimum initial investment  and minimum account size for
determining the  class  of shares  received  in  the exchange  will  apply.  See
"Purchase  of Shares."  Shares of  the portfolios  may be  exchanged by  mail or
telephone. The privilege to exchange shares  by telephone is automatic and  made
available  without shareholder election. Before you make an exchange, you should
read the prospectus of the portfolio(s) in which you seek to invest. Because  an
exchange  transaction  is treated  as a  redemption followed  by a  purchase, an
exchange would be considered  a taxable event for  shareholders subject to  tax.
The  exchange privilege  is only available  with respect to  portfolios that are
registered for  sale  in  a  shareholder's  state  of  residence.  The  exchange
privilege  may be modified or  terminated by the Fund  at any time upon 60-days'
notice to shareholders.
 
BY MAIL
 
    In order to  exchange shares  by mail, you  should include  in the  exchange
request  the name, class of shares and account number of your current portfolio,
the names of the portfolio(s) and class(es)  of shares into which you intend  to
exchange  shares, and the signatures of all registered account holders. Send the
exchange request  to Morgan  Stanley Institutional  Fund, Inc.,  P.O. Box  2798,
Boston, Massachusetts 02208-2798.
 
                                       33
<PAGE>
BY TELEPHONE
 
    When  exchanging shares by  telephone, have ready the  name, class of shares
and account number of  your current portfolio, the  name(s) of the  portfolio(s)
and  class(es) of shares into  which you intend to  exchange shares, your Social
Security number  or Tax  I.D. number,  and your  account address.  Requests  for
telephone  exchanges received prior to 4:00 p.m. (Eastern Time) are processed at
the close of business that same day based on the net asset value of the class of
each of  the portfolios  involved in  the exchange  of shares  at the  close  of
business.  Requests received  after 4:00 p.m.  (Eastern Time)  are processed the
next business  day based  on the  net asset  value determined  at the  close  of
business  on such day.  For additional information  regarding responsibility for
the authenticity of  telephoned instructions,  see "Redemption of  Shares --  By
Telephone" above.
 
TRANSFER OF REGISTRATION
 
    You  may transfer  the registration  of any of  your Fund  shares to another
person by writing  to Morgan  Stanley Institutional  Fund Inc.,  P.O. Box  2798,
Boston,  Massachusetts 02208-2798.  As in the  case of  redemptions, the written
request must  be  received  in good  order  before  any transfer  can  be  made.
Transferring  the  registration of  shares may  affect  the eligibility  of your
account for  a  given  class  of  each Portfolio's  shares  and  may  result  in
involuntary  conversion or redemption  of your shares.  See "Purchase of Shares"
above.
 
                              VALUATION OF SHARES
 
    The net asset  value per share  of a class  of shares of  the Portfolios  is
determined by dividing the total market value of the Portfolio's investments and
other  assets attributable to  such class, less  any liabilities attributable to
such class, by  the total  number of  outstanding shares  of such  class of  the
Portfolio.  Net  asset value  is  calculated separately  for  each class  of the
Portfolio. Net asset value per  share is determined as  of the regular close  of
the  NYSE on each day  that the NYSE is open  for business. Price information on
listed securities is  taken from the  exchange where the  security is  primarily
traded.  Securities  listed  on  a U.S.  securities  exchange  for  which market
quotations are available are valued at the last quoted sale price on the day the
valuation is made. Securities listed on  a foreign exchange are valued at  their
closing  price.  Unlisted securities  and listed  securities  not traded  on the
valuation date for which market quotations are not readily available are  valued
at  a price within a  range not exceeding the current  asked price nor less than
the current bid price. The current bid and asked prices are determined based  on
the bid and asked prices quoted on such valuation date by reputable brokers.
 
    Bonds and other fixed income securities are valued according to the broadest
and  most representative market,  which will ordinarily  be the over-the-counter
market. Net asset value includes interest  on fixed income securities, which  is
accrued  daily.  In addition,  bonds and  other fixed  income securities  may be
valued on the basis of prices provided by a pricing service when such prices are
believed to  reflect  the fair  market  value  of such  securities.  The  prices
provided  by a pricing service are determined without regard to bid or last sale
prices, but take into  account institutional size trading  in similar groups  of
securities  and any developments related  to the specific securities. Securities
not priced in this manner are valued  at the most recently quoted bid price,  or
when securities exchange valuations are used, at the latest quoted sale price on
the  day of valuation. If there is no  such reported sale, the latest quoted bid
price will be used. Securities purchased with remaining maturities of 60 days or
less are valued at amortized cost, if it approximates market value. In the event
that amortized  cost  does  not  approximate  market  value,  market  prices  as
determined above will be used.
 
                                       34
<PAGE>
    The value of other assets and securities for which no quotations are readily
available  (including  restricted  and unlisted  foreign  securities)  and those
securities for which it is inappropriate to determined prices in accordance with
the above-stated procedures, are  determined in good faith  at fair value  using
methods  determined by the  Board of Directors. For  purposes of calculating net
asset value per share, all assets and liabilities initially expressed in foreign
currencies will be translated into U.S. dollars at the mean of the bid price and
asked price of such currencies against the U.S. dollar last quoted by any  major
bank.
 
    Although  the legal rights of Class A  and Class B shares will be identical,
the different expenses borne  by each class will  result in different net  asset
values  and dividends for the class.  Dividends will differ by approximately the
amount of the distributions expense accrual differential among the classes.  The
net  asset value of  Class B shares will  generally be lower  than the net asset
value of the Class A shares as  a result of the distribution expense charged  to
Class B shares.
 
                            PERFORMANCE INFORMATION
 
    The  Fund may from time to time advertise the total return for each class of
the Portfolios.  THESE FIGURES  ARE BASED  ON HISTORICAL  EARNINGS AND  ARE  NOT
INTENDED  TO  INDICATE  FUTURE PERFORMANCE.  The  "total return"  shows  what an
investment in a class of the Portfolio would have earned over a specified period
of time (such as one,  five or ten years),  assuming that all distributions  and
dividends by the Portfolio were reinvested in the same class on the reinvestment
dates  during the period. Total return does not take into account any federal or
state income taxes that  may be payable on  dividends and distributions or  upon
redemption.  The Fund  may also  include comparative  performance information in
advertising or  marketing the  Portfolio's shares,  including data  from  Lipper
Analytical  Services, Inc.,  other industry  publications, business periodicals,
rating services and market indices.
 
    The performance figures  for Class  B shares  will generally  be lower  than
those  for Class  A shares because  of the  distribution fee charged  to Class B
shares.
 
                   DIVIDENDS AND CAPITAL GAINS DISTRIBUTIONS
 
    All income dividends and capital gains  distributions for a class of  shares
will automatically be reinvested in additional shares of such class at net asset
value,  except that,  upon written  notice to  the Fund  or by  checking off the
appropriate box in the Distribution  Option Section on the Account  Registration
Form,  a shareholder  may elect  to receive  income dividends  and capital gains
distributions in cash.
 
    Each Portfolio expects to distribute substantially all of its net investment
income in the form of annual dividends. Net realized gains of each Portfolio, if
any, after reduction  for any tax  loss carryforwards will  also be  distributed
annually.  Confirmations of the purchase of shares of each Portfolio through the
automatic reinvestment of income dividends and capital gains distributions  will
be  provided, pursuant  to Rule 10b-10(b)  under The Securities  Exchange Act of
1934, as amended, on the next  monthly client statement following such  purchase
of shares. Consequently, confirmations of such purchases will not be provided at
the  time of completion of such purchases as might otherwise be required by Rule
10b-10.
 
    Undistributed net  investment income  is included  in each  Portfolio's  net
assets  for the purpose of calculating net  asset value per share. Therefore, on
the "ex-dividend" date,  the net  asset value  per share  excludes the  dividend
(I.E.,  is reduced  by the  per share  amount of  the dividend).  Dividends paid
shortly after the purchase of shares by an investor, although in effect a return
of capital, are taxable to shareholders subject to income tax.
 
                                       35
<PAGE>
    Because of  the  distribution  fee  and  any  other  expenses  that  may  be
attributable  to the  Class B  shares, the  net income  attributable to  and the
dividends payable  on  Class  B  shares  will  be  lower  than  the  net  income
attributable  to and the dividends  payable on Class A  shares. As a result, the
net asset value per share of the classes of each Portfolio will differ at times.
Expenses of each  Portfolio allocated to  a particular class  of shares  thereof
will be borne on a pro rata basis by each outstanding share of that class.
 
                                     TAXES
 
    The following summary of certain federal income tax consequences is based on
current tax laws and regulations, which may be changed by legislative, judicial,
or administrative action.
 
    No  attempt has been made to present  a detailed explanation of the federal,
state, or  local  income tax  treatment  of  a Portfolio  or  its  shareholders.
Accordingly,  shareholders  are urged  to consult  their tax  advisors regarding
specific questions as to federal, state and local income taxes.
 
    Each Portfolio  is treated  as  a separate  entity  for federal  income  tax
purposes  and is not  combined with the Fund's  other portfolios. Each Portfolio
intends to qualify for the  special tax treatment afforded regulated  investment
companies  under Subchapter M of  the Internal Revenue Code  of 1986, as amended
(the "Code"), so that the  Portfolio will be relieved  of federal income tax  on
that  part of its net investment income and net capital gain that is distributed
to shareholders.
 
    Each Portfolio distributes  substantially all of  its net investment  income
(including,  for  this purpose,  net short-term  capital gain)  to shareholders.
Dividends from a Portfolio's net  investment income are taxable to  shareholders
as  ordinary  income, whether  received in  cash or  in additional  shares. Such
dividends  paid   by  a   Portfolio   generally  will   qualify  for   the   70%
dividends-received  deduction  for corporate  shareholders. Each  Portfolio will
report annually to its shareholders the amount of dividend income qualifying for
such treatment.
 
    Distributions of net capital gain (the excess of net long-term capital  gain
over  net  short-term capital  loss) are  taxable  to shareholders  as long-term
capital gain, regardless of how long  shareholders have held their shares.  Each
Portfolio  sends  reports annually  to shareholders  of  the federal  income tax
status of all distributions made during the preceding year.
 
    Each  Portfolio  intends   to  make  sufficient   distributions  or   deemed
distributions  of its ordinary income and capital gain net income (the excess of
short-term and long-term  capital gains  over short-term  and long-term  capital
losses), including any available capital loss carryforwards, prior to the end of
each calendar year to avoid liability for federal excise tax.
 
    Dividends  and  other  distributions  declared by  a  Portfolio  in October,
November or December of any year and payable to shareholders of record on a date
in such month will be deemed to have been paid by the Portfolio and received  by
the  shareholders on December 31  of that year if  the distributions are paid by
the Portfolio at any time during the following January.
 
    The sale, exchange  or redemption of  shares may result  in taxable gain  or
loss to the selling, exchanging or redeeming shareholder, depending upon whether
the  fair market value  of the redemption  proceeds exceeds or  is less than the
Shareholder's adjusted  basis in  the  sold, exchanged  or redeemed  shares.  If
capital  gain distributions have been made with  respect to shares that are sold
at a loss after being held for six months or less, then the loss is treated as a
long-term capital loss to the extent of the capital gain distributions.
 
                                       36
<PAGE>
    The conversion of Class A shares to  Class B shares should not be a  taxable
event to the shareholder.
 
    Shareholders  are urged  to consult with  their tax  advisors concerning the
application of state and local income taxes to investments in a Portfolio, which
may differ from the federal income tax consequences described above.
 
    Investment income  received  by  a Portfolio  from  sources  within  foreign
countries  may be subject to foreign income taxes withheld at the source. To the
extent that a  Portfolio is liable  for foreign income  taxes so withheld,  each
Portfolio  intends to operate so as to meet the requirements of the Code to pass
through to the shareholders credit for foreign income taxes paid. Although  each
Portfolio  intends to  meet Code  requirements to  pass through  credit for such
taxes, there can be no assurance that each Portfolio will be able to do so.
 
    THE  TAX  DISCUSSION  SET  FORTH  ABOVE  IS  INCLUDED  HEREIN  FOR   GENERAL
INFORMATION  ONLY. PROSPECTIVE INVESTORS  SHOULD CONSULT THEIR  OWN TAX ADVISERS
WITH RESPECT TO THE TAX CONSEQUENCES TO THEM OF AN INVESTMENT IN THE PORTFOLIO.
 
                             PORTFOLIO TRANSACTIONS
 
    The Investment  Advisory  Agreement authorizes  the  Adviser to  select  the
brokers  or  dealers that  will execute  the purchases  and sales  of investment
securities for the Portfolios and directs the Adviser to use its best efforts to
obtain the best available price and most favorable execution with respect to all
transactions for the  Portfolios. The  Fund has  authorized the  Adviser to  pay
higher commissions in recognition of brokerage services which, in the opinion of
the Adviser, are necessary for the achievement of better execution, provided the
Adviser believes this to be in the best interest of the Fund.
 
    Since shares of the Portfolios are not marketed through intermediary brokers
or  dealers, it is  not the Fund's  practice to allocate  brokerage or principal
business on the basis of sales of  shares which may be made through such  firms.
However,  the Adviser may  place portfolio orders  with qualified broker-dealers
who recommend the  Fund's portfolios or  who act  as agents in  the purchase  of
shares of the Fund's portfolios for their clients.
 
    In  purchasing and selling  securities for the Portfolios,  it is the Fund's
policy to seek to obtain quality execution at the most favorable prices, through
responsible  broker-dealers.  In   selecting  broker-dealers   to  execute   the
securities  transactions for the Portfolios, consideration will be given to such
factors as the price of the security,  the rate of the commission, the size  and
difficulty  of  the  order,  the  reliability,  integrity,  financial condition,
general execution and operational capabilities of competing broker-dealers,  and
the  brokerage  and  research services  which  they  provide to  the  Fund. Some
securities considered for investment by  the Portfolios may also be  appropriate
for  other clients  served by  the Adviser.  If purchase  or sale  of securities
consistent with the  investment policies  of the Portfolio  and one  or more  of
these  other clients served  by the Adviser  is considered at  or about the same
time, transactions in such securities will be allocated among the Portfolios and
such other  clients in  a manner  deemed  fair and  reasonable by  the  Adviser.
Although  there is  no specified formula  for allocating  such transactions, the
various allocation  methods  used  by  the Adviser,  and  the  results  of  such
allocations, are subject to periodic review by the Fund's Board of Directors.
 
    Subject to the overriding objective of obtaining the best possible execution
of  orders,  the  Adviser may  allocate  a  portion of  the  Portfolio brokerage
transactions   to   Morgan    Stanley   or   broker    affiliates   of    Morgan
 
                                       37
<PAGE>
Stanley.  In order for Morgan Stanley or  its affiliates to effect any portfolio
transactions for the Fund, the commissions, fees or other remuneration  received
by Morgan Stanley or such affiliates 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
a securities exchange during a comparable period of time. Furthermore, the Board
of Directors of the Fund,  including a majority of  those Directors who are  not
"interested  persons," as  defined in  the Investment  Company Act  of 1940 (the
"1940 Act") have  adopted procedures  which are reasonably  designed to  provide
that  any commissions, fees or other remuneration paid to Morgan Stanley or such
affiliates are consistent with the foregoing standard.
 
    Portfolio securities will not  be purchased from or  through, or sold to  or
through,  the Adviser or Morgan Stanley  or any "affiliated persons," as defined
in the 1940 Act, of Morgan Stanley when such entities are acting as  principals,
except to the extent permitted by law.
 
    Although  neither  Portfolio will  invest  for short-term  trading purposes,
investment securities may be sold from time to time without regard to the length
of time they have  been held. The Emerging  Markets Portfolio anticipates  that,
under  normal circumstances, its annual portfolio  turnover rate will not exceed
50%.  The  Emerging  Markets  Debt  Portfolio  anticipates  that,  under  normal
circumstances,  its annual  portfolio turnover rate  will not  exceed 100%. High
portfolio turnover involves correspondingly greater transaction costs which will
be borne  directly by  the  respective Portfolio.  In addition,  high  portfolio
turnover  may  result  in more  capital  gains  which would  be  taxable  to the
shareholders of the  respective Portfolio.  The tables set  forth in  "Financial
Highlights" present the Portfolio's historical turnover rates.
 
                              GENERAL INFORMATION
 
DESCRIPTION OF COMMON STOCK
 
    The  Fund was  organized as  a Maryland  corporation on  June 16,  1988. The
Articles of Incorporation, as amended and restated, permit the Fund to issue  up
to  34 billion shares of common stock,  with $.001 par value per share. Pursuant
to the Fund's Articles of Incorporation, the Board of Directors may increase the
number of shares the  Fund is authorized  to issue without  the approval of  the
shareholders  of the  Fund. Subject  to the  notice period  to shareholders with
respect to shares held by the shareholders, the Board of Directors has the power
to designate one or more classes of  shares of common stock and to classify  and
reclassify  any  unissued shares  with respect  to such  classes. The  shares of
common stock of each  portfolio are currently classified  into two classes,  the
Class  A shares and the Class B  shares, except for the International Small Cap,
Money Market and  Municipal Money Market  Portfolios, which only  offer Class  A
shares.
 
    The   shares  of   the  Portfolios,  when   issued,  will   be  fully  paid,
nonassessable, fully transferable and  redeemable at the  option of the  holder.
The  shares have no preference as to conversion, exchange, dividends, retirement
or other features and have no  pre-emptive rights. The shares of each  Portfolio
have non-cumulative voting rights, which means that the holders of more than 50%
of  the  shares voting  for  the election  of Directors  can  elect 100%  of the
Directors if they choose to do so.  Persons or organizations owning 25% or  more
of  the outstanding shares of a Portfolio  may be presumed to "control" (as that
term is defined in the 1940 Act) that Portfolio. Under Maryland law, the Fund is
not required to hold an annual meeting of its shareholders unless required to do
so under the 1940 Act.
 
                                       38
<PAGE>
REPORTS TO SHAREHOLDERS
 
    The Fund will send to its  shareholders annual and semi-annual reports;  the
financial  statements  appearing in  annual reports  are audited  by independent
accountants. Monthly unaudited portfolio  data is also  available from the  Fund
upon request.
 
    In addition, the Adviser, or its agent, as Transfer Agent, will send to each
shareholder having an account directly with the Fund a monthly statement showing
transactions in the account, the total number of shares owned, and any dividends
or distributions paid.
 
CUSTODIAN
 
    As  of September 1,  1995, domestic securities  and cash are  held by Chase,
which replaced U.S.  Trust as  the Fund's domestic  custodian. Chase  is not  an
affiliate  of  the Adviser  or the  Distributor.  Morgan Stanley  Trust Company,
Brooklyn, New York ("MSTC"),  an affiliate of the  Adviser and the  Distributor,
acts  as the Fund's custodian for foreign  assets held outside the United States
and employs subcustodians  approved by  the Board of  Directors of  the Fund  in
accordance  with regulations of  the Securities and  Exchange Commission for the
purpose of providing  custodial services  for such  assets. MSTC  may also  hold
certain  domestic assets for  the Fund. For more  information on the custodians,
see "General Information -- Custody Arrangements" in the Statement of Additional
Information.
 
DIVIDEND DISBURSING AND TRANSFER AGENT
 
    Chase  Global   Funds  Services   Company,   73  Tremont   Street,   Boston,
Massachusetts 02108-3913, acts as Dividend Disbursing and Transfer Agent for the
Fund.
 
INDEPENDENT ACCOUNTANTS
 
    Price  Waterhouse LLP  serves as  independent accountants  for the  Fund and
audits its annual financial statements.
 
LITIGATION
 
    The Fund is not involved in any litigation.
 
                                       39
<PAGE>
                 (This page has been left blank intentionally.)
<PAGE>
   MORGAN STANLEY INSTITUTIONAL FUND, INC.
          EMERGING MARKETS AND EMERGING MARKETS DEBT PORTFOLIOS
           P.O. BOX 2798, BOSTON, MA 02208-2798
 
                           ACCOUNT REGISTRATION FORM
 
<TABLE>
<C>   <S>                                       <C>
                                                If you need assistance in filling out
                                                this form for the Morgan Stanley
      ACCOUNT INFORMATION                       Institutional Fund, please contact your
      Fill in where applicable                  Morgan Stanley representative or call us
                                                toll free 1-(800)-548-7786. Please print
                                                all items except signature, and mail to
                                                the Fund at the address above.
</TABLE>
 
<TABLE>
<C>   <S>                                       <C>
  A)  REGISTRATION
</TABLE>
 
                            1.
<TABLE>
<C>   <S>                                       <C>
      1. INDIVIDUAL
</TABLE>
 
                                                              First
Name                      Initial                          Last Name
<TABLE>
<C>   <S>                                       <C>
      2. JOINT TENANTS
</TABLE>
 
<TABLE>
<C>   <S>                                       <C>
        (RIGHTS OF SURVIVORSHIP
</TABLE>
 
                            2.
<TABLE>
<C>   <S>                                       <C>
        PRESUMED UNLESS
</TABLE>
 
                                                              First
Name                      Initial                          Last Name
<TABLE>
<C>   <S>                                       <C>
        TENANCY IN COMMON
</TABLE>
 
<TABLE>
<C>   <S>                                       <C>
        IS INDICATED)
</TABLE>
 
                                                              First
Name                      Initial                          Last Name
 
<TABLE>
<C>   <S>                                       <C>
 
                            3.
 
      3. CORPORATIONS,
        TRUSTS AND OTHERS
        Please call the Fund for additional
      documents that may be required to set up
      account and to authorize transactions.
</TABLE>
 
<TABLE>
<S>                    <C>               <C>                        <C>               <C>
Type of Registration:  / / INCORPORATED  / / UNINCORPORATED         / / PARTNERSHIP   / / UNIFORM GIFT/TRANSFER TO MINOR
                                         ASSOCIATION                                    (ONLY ONE CUSTODIAN AND MINOR PERMITTED)
</TABLE>
 
                            / / TRUST __________  / / OTHER (Specify) __________
 
<TABLE>
<C>   <S>                                       <C>
                                    Street or P.O. Box
 
  B)  MAILING ADDRESS
      Please fill in completely, including
      telephone number(s).
</TABLE>
 
                            City                                           State
                                                                             Zip
                                                                              --
                                           Home Telephone
No.                                                   Business Telephone No.
                                                         --       -- --       --
                            / / United States Citizen  / / Resident Alien  / /
Non-Resident Alien: Indicate Country of Residence ______________________________
 
<TABLE>
<C>   <S>                                       <C>                                       <C>
  C)  TAXPAYER                                  PART 1. Enter your Taxpayer               IMPORTANT TAX INFORMATION
      IDENTIFICATION                            Identification Number. For most           You  (as a payee) are required by law to
      NUMBER                                    individual taxpayers, this is your        provide us (as payer) with your  correct
      If the account is in more than one name,  Social Security Number.                   Taxpayer Identification Number. Accounts
      CIRCLE THE                                TAXPAYER IDENTIFICATION NUMBER            that   have   a  missing   or  incorrect
                                                                                          Taxpayer Identification  Number will  be
                                                                                          subject  to backup withholding  at a 31%
                                                                                          rate on
</TABLE>
 
                          --
 
<TABLE>
<C>   <S>                                       <C>                                       <C>
      NAME OF THE PERSON WHOSE TAXPAYER         -- -- -- -- -- -- -- -- -- -- -- --       dividends,   distributions   and   other
      IDENTIFICATION NUMBER IS PROVIDED IN      OR                                        payments.  If you  have not  provided us
      SECTION A) ABOVE. If no name is circled,  SOCIAL SECURITY NUMBER                    with your correct taxpayer
      the number                                                                          identification  number,   you   may   be
                                                                                          subject  to a $50 penalty imposed by the
                                                                                          Internal Revenue Service.
                                                                                          Backup withholding is not an  additional
                                                                                          tax;   the  tax   liability  of  persons
                                                                                          subject to  backup withholding  will  be
                                                                                          reduced  by the amount  of tax withheld.
                                                                                          If withholding
</TABLE>
 
                           --        --
 
<TABLE>
<C>   <S>                                       <C>                                       <C>
      will be considered to be that of the      -- -- -- -- -- -- -- -- -- -- -- --       results in  an overpayment  of taxes,  a
      last name listed. For Custodian account   PART 2. BACKUP WITHHOLDING                refund may be obtained.
      of a minor (Uniform Gift/Transfer to      / / Check this box if you are NOT         You may be notified that you are subject
      Minor Act), give the Social Security      subject to Backup Withholding under the   to   backup  withholding  under  Section
      Number of the minor.                      provisions of Section 3406(a)(1)(C) of    3406(a)(1)(C) of  the  Internal  Revenue
                                                the Internal Revenue Code.                Code   because  you  have  underreported
                                                                                          interest  or  dividends   or  you   were
                                                                                          required  to but failed to file a return
                                                                                          which would have  included a  reportable
                                                                                          interest  or  dividend  payment.  IF YOU
                                                                                          HAVE NOT BEEN SO NOTIFIED, CHECK THE BOX
                                                                                          IN PART 2 AT LEFT.
</TABLE>
 
<TABLE>
<C>   <S>                                       <C>                             <C>                   <C>
  D)  PORTFOLIO AND                             For Purchase of the following   / / Class A Shares $  / / Class B Shares $
      CLASS SELECTION                           Portfolio(s):                   / / Class A Shares $  / / Class B Shares $
      (Class A shares minimum $500,000 and      Emerging Markets Portfolio
      Class B shares minimum $100,000). Please  Emerging Markets Debt
      indicate Portfolio, class and amount.     Portfolio
                                                                                Total Initial Investment $
</TABLE>
 
                                    Payment by:
 
<TABLE>
<C>   <S>                                       <C>
                                    / / Check (MAKE CHECK PAYABLE TO MORGAN
STANLEY INSTITUTIONAL FUND, INC.--PORTFOLIO NAME)
  E)  METHOD OF
      INVESTMENT
      Please indicate manner of payment.
</TABLE>
 
<TABLE>
<S>                                                           <C>
/ / Exchange $ From                                            -- - - - - - - - - - -- - -
                                           Name of Portfolio           Account No.
/ / Account previously established by:  / / Phone
exchange  / / Wire on                                          -- - - - - - - - - - -- - -
                                                              Account No.            (Check
                                                               (Previously assigned by the
                                                                      Fund)   Digit)
                                                              Date
</TABLE>
 
<PAGE>
 
<TABLE>
<S>                                                           <C>                             <C>
  F)  DISTRIBUTION                              Income dividends and capital gains distributions (if any)
      OPTION                                    will be reinvested in additional shares unless either box
                                                below is checked.
                                                / / Income dividends to be paid in cash, capital gains
                                                distributions (if any) in shares.
                                                / / Income dividends and capital gains distributions (if
                                                any) to be paid in cash.
</TABLE>
<TABLE>
<C>   <S>                             <C>
  G)  TELEPHONE                       / / I/we hereby authorize the Fund and
      REDEMPTION                      its agents to honor any telephone
      Please select at time of        requests to wire redemption proceeds to
      initial application if you      the commercial bank indicated at right
      wish to redeem shares by        and/or mail redemption proceeds to the
      telephone. A SIGNATURE          name and address in which my/our fund
      GUARANTEE IS REQUIRED IF BANK   account is registered if such requests
      ACCOUNT IS NOT REGISTERED       are believed to be authentic.
      IDENTICALLY TO YOUR FUND        The Fund and the Fund's Transfer Agent
      ACCOUNT.                        will employ reasonable procedures to
      TELEPHONE REQUESTS FOR          confirm that instructions communicated
      REDEMPTIONS WILL NOT BE         by telephone are genuine. These
      HONORED UNLESS THE BOX IS       procedures include requiring the
      CHECKED.                        investor to provide certain personal
                                      identification information at the time
                                      an account is opened and prior to
                                      effecting each transaction requested by
                                      telephone. In addition, all telephone
                                      transaction requests will be recorded
                                      and investors may be required to provide
                                      additional telecopied written
                                      instructions of transaction requests.
                                      Neither the Fund nor the Transfer Agent
                                      will be responsible for any loss,
                                      liability, cost or expense for following
                                      instructions received by telephone that
                                      it reasonably believes to be genuine.
 
<CAPTION>
  G)
      Name of COMMERCIAL Bank (Not Savings Bank)
      Bank Account No.
                                                   Bank ABA No.
      Name(s) in which your BANK Account is Established
      Bank's Street Address
      City                           State                           Zip
</TABLE>
 
<TABLE>
<C>   <S>                                       <C>
  H)  INTERESTED PARTY
      OPTION                                    Name
      In addition to the account statement
      sent to my/our registered address, I/we
      hereby authorize the fund to mail         Address
      duplicate statements to the name and
      address provided at right.                City        State        Zip Code
</TABLE>
 
<TABLE>
<C>   <S>                                       <C>
  I)  DEALER
      INFORMATION
                                                Representative
                                                Name                  Representative
                                                No.                     Branch
                                                No.
 
</TABLE>
<TABLE>
<C>        <S>                    <C>
       J)  SIGNATURE OF
           ALL HOLDERS
           AND TAXPAYER
           CERTIFICATION
 
</TABLE>
 
<TABLE>
<S>                                  <C>
The undersigned certify(ies)  that I/we  have full  authority and  legal
capacity  to purchase and redeem shares of the Fund and affirm that I/we
have received a current Prospectus  of the Morgan Stanley  Institutional
Fund,  Inc. and agree to  be bound by its  terms. UNDER THE PENALTIES OF
PERJURY, I/WE CERTIFY THAT THE INFORMATION PROVIDED IN SECTION C)  ABOVE
IS TRUE, CORRECT AND COMPLETE.
 
THE  INTERNAL  REVENUE  SERVICE DOES  NOT  REQUIRE YOUR  CONSENT  TO ANY
PROVISION OF THIS  DOCUMENT OTHER  THAN THE  CERTIFICATIONS REQUIRED  TO
AVOID BACKUP WITHHOLDING.
 
(X)                                  (X)
Signature                                           Date Signature                                           Date
                                     Sign Here ,
</TABLE>
<PAGE>
- -------------------------------------------
- -------------------------------------------
- -------------------------------------------
- -------------------------------------------
 
  NO  DEALER, SALES  REPRESENTATIVE OR ANY  OTHER PERSON HAS  BEEN AUTHORIZED TO
GIVE ANY INFORMATION OR TO MAKE ANY REPRESENTATIONS, OTHER THAN THOSE  CONTAINED
IN THIS PROSPECTUS, IN CONNECTION WITH THE OFFER MADE BY THIS PROSPECTUS AND, IF
GIVEN OR MADE, SUCH OTHER INFORMATION OR REPRESENTATIONS MUST NOT BE RELIED UPON
AS  HAVING BEEN AUTHORIZED BY THE FUND  OR THE DISTRIBUTOR. THIS PROSPECTUS DOES
NOT CONSTITUTE AN OFFER BY THE FUND OR THE DISTRIBUTOR TO SELL OR A SOLICITATION
OF AN OFFER TO BUY ANY OF  THE SECURITIES OFFERED HEREBY IN ANY JURISDICTION  TO
ANY  PERSON TO WHOM  IT IS UNLAWFUL TO  MAKE SUCH OFFER  OR SOLICITATION IN SUCH
JURISDICTION.
 
                           --------------------------
 
                               TABLE OF CONTENTS
 
<TABLE>
<S>                                                 <C>
                                                    PAGE
                                                    ----
Fund Expenses.....................................    2
Financial Highlights..............................    4
Prospectus Summary................................    7
Investment Objectives and Policies................   11
Additional Investment Information.................   15
Investment Limitations............................   24
Management of the Fund............................   25
Purchase of Shares................................   27
Redemption of Shares..............................   31
Shareholder Services..............................   33
Valuation of Shares...............................   34
Performance Information...........................   35
Dividends and Capital Gains Distributions.........   35
Taxes.............................................   36
Portfolio Transactions............................   37
General Information...............................   38
Account Registration Form
</TABLE>
 
                           EMERGING MARKETS PORTFOLIO
                        EMERGING MARKETS DEBT PORTFOLIO
 
                               PORTFOLIOS OF THE
                                 MORGAN STANLEY
                            INSTITUTIONAL FUND, INC.
 
                                  Common Stock
                               ($.001 PAR VALUE)
 
                                 -------------
                                   PROSPECTUS
                                 -------------
 
                               Investment Adviser
                                 Morgan Stanley
                             Asset Management Inc.
 
                                  Distributor
                              Morgan Stanley & Co.
                                  Incorporated
 
- ---------------------------------
- ---------------------------------
- ---------------------------------
- ---------------------------------
<PAGE>
- --------------------------------------------------------------------------------
                              P R O S P E C T U S
     ----------------------------------------------------------------------
 
                           U.S. REAL ESTATE PORTFOLIO
 
                                PORTFOLIO OF THE
                    MORGAN STANLEY INSTITUTIONAL FUND, INC.
 
                P.O. BOX 2798, BOSTON, MASSACHUSETTS 02208-2798
                      FOR INFORMATION CALL 1-800-548-7786
                                ----------------
 
    Morgan  Stanley Institutional Fund, Inc. (the "Fund") is a no-load, open-end
management investment company, or mutual fund, which offers redeemable shares in
a   series   of   diversified   and   non-diversified   investment    portfolios
("portfolios").   The  Fund   currently  consists   of  twenty-eight  portfolios
representing a  broad range  of  investment choices.  The  Fund is  designed  to
provide clients with attractive alternatives for meeting their investment needs.
This  prospectus (the  "Prospectus") pertains  to the  Class A  and the  Class B
shares of the U.S. Real Estate Portfolio (the "Portfolio"). On January 2,  1996,
the  Portfolio began offering two classes of  shares: the Class A shares and the
Class B  shares,  except  for  the Money  Market,  Municipal  Money  Market  and
International  Small Cap Portfolios which only  offer Class A shares. All shares
of the Portfolio owned prior to January 2, 1996 were redesignated Class A shares
on January 2,  1996. The Class  A and Class  B shares currently  offered by  the
Portfolio  have  different minimum  investment  requirements and  fund expenses.
Shares of  the  portfolios are  offered  with no  sales  charge or  exchange  or
redemption fee (with the exception of the International Small Cap Portfolio).
 
    INVESTORS  SHOULD NOTE THAT THE PORTFOLIO MAY  INVEST UP TO 10% OF ITS TOTAL
ASSETS IN RESTRICTED SECURITIES OTHER THAN RULE 144A SECURITIES AND NO MORE THAN
15% OF ITS TOTAL ASSETS IN RESTRICTED SECURITIES THAT ARE RULE 144A  SECURITIES.
SEE  "ADDITIONAL  INVESTMENT  INFORMATION  --  NON-PUBLICLY  TRADED  SECURITIES,
PRIVATE  PLACEMENTS  AND  RESTRICTED  SECURITIES."  INVESTMENTS  IN   RESTRICTED
SECURITIES  IN EXCESS OF  5% OF A  PORTFOLIO'S TOTAL ASSETS  MAY BE CONSIDERED A
SPECULATIVE ACTIVITY, MAY INVOLVE GREATER RISK AND MAY INCREASE THE  PORTFOLIO'S
EXPENSES.
 
    The  Fund is designed  to meet the investment  needs of discerning investors
who place a premium on quality  and personal service. With Morgan Stanley  Asset
Management   Inc.  as   Adviser  and   Administrator  (the   "Adviser"  and  the
"Administrator"), and with Morgan Stanley & Co. Incorporated ("Morgan  Stanley")
as Distributor, the Fund makes available to institutional investors and high net
worth  individual  investors  a  series of  portfolios  which  benefit  from the
investment expertise and commitment to excellence associated with Morgan Stanley
and its affiliates.
 
    This Prospectus is designed to set forth concisely the information about the
Fund that a prospective investor should  know before investing and it should  be
retained  for future reference. The Fund  offers additional portfolios which are
described in other prospectuses and  under "Prospectus Summary" below. The  Fund
currently  offers the following portfolios:  (i) GLOBAL AND INTERNATIONAL EQUITY
- -- Active Country Allocation, Asian  Equity, Emerging Markets, European  Equity,
Global  Equity, Gold, International  Equity, International Magnum, International
Small Cap, Japanese Equity  and Latin American Portfolios;  (ii) U.S. EQUITY  --
Emerging  Growth, Equity  Growth, Aggressive  Equity, MicroCap,  Small Cap Value
Equity, Value Equity  and U.S. Real  Estate Portfolios; (iii)  EQUITY AND  FIXED
INCOME  -- Balanced Portfolio; (iv) FIXED INCOME -- Emerging Markets Debt, Fixed
Income,  Global  Fixed  Income,  High  Yield,  Mortgage-Backed  Securities   and
Municipal  Bond Portfolios; and  (v) MONEY MARKET --  Money Market and Municipal
Money Market Portfolios. Additional information about the Fund is contained in a
"Statement of Additional Information" dated  May 1, 1996, which is  incorporated
herein   by  reference.  The   Statement  of  Additional   Information  and  the
prospectuses pertaining to the other portfolios  of the Fund are available  upon
request  and without charge  by writing or  calling the Fund  at the address and
telephone number set forth above.
 
 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.
 
                  THE DATE OF THIS PROSPECTUS IS MAY 1, 1996.
                     SUPPLEMENTED THROUGH DECEMBER 30, 1996
<PAGE>
                                 FUND EXPENSES
 
    The  following table illustrates the expenses and fees that a shareholder of
the Portfolio will incur:
 
<TABLE>
<CAPTION>
SHAREHOLDER TRANSACTION EXPENSES
- --------------------------------------------------
<S>                                                 <C>
Maximum Sales Load Imposed on Purchases
  Class A.........................................     None
  Class B.........................................     None
Maximum Sales Load Imposed on Reinvested Dividends
  Class A.........................................     None
  Class B.........................................     None
Deferred Sales Load
  Class A.........................................     None
  Class B.........................................     None
Redemption Fees
  Class A.........................................     None
  Class B.........................................     None
Exchange Fees
  Class A.........................................     None
  Class B.........................................     None
</TABLE>
 
<TABLE>
<CAPTION>
ANNUAL FUND OPERATING EXPENSES
- --------------------------------------------------
 (AS A PERCENTAGE OF AVERAGE NET ASSETS)
<S>                                                 <C>
Management Fee (Net of Fee Waiver)*
  Class A.........................................    0.47%
  Class B.........................................    0.47%
12b-1 Fees
  Class A.........................................     None
  Class B.........................................    0.25%
Other Expenses
  Class A.........................................    0.53%
  Class B.........................................    0.53%
                                                    ---------
Total Operating Expenses (Net of Fee Waivers)*
  Class A.........................................    1.00%
  Class B.........................................    1.25%
                                                    ---------
                                                    ---------
</TABLE>
 
- ------------------------
*The Adviser has  agreed to waive  its management fees  and/or to reimburse  the
 Portfolio,  if necessary, if such fees would cause the Portfolio's total annual
 operating expenses, as a percentage of average daily net assets, to exceed  the
 percentages set forth in the table above. Absent the fee waiver, the management
 fee  would be  0.80%. Absent the  fee waiver and/or  expense reimbursement, the
 Portfolio's total operating expenses  would be 1.33% of  the average daily  net
 assets  of the Class A shares and 1.58%  of the average daily net assets of the
 Class B shares. As a result of this reduction, the Management Fee stated  above
 is  lower than the contractual  fee stated under "Management  of the Fund." The
 Adviser reserves the right to terminate  any of its fee waivers and/or  expense
 reimbursements  at any time in its  sole discretion. For further information on
 Fund expenses, see "Management of the Fund."
 
                                       2
<PAGE>
    The purpose of the  table above is to  assist the investor in  understanding
the  various expenses that  an investor in  the Portfolio will  bear directly or
indirectly. The Class  A expenses  and fees for  the Portfolio  based on  actual
figures  for the period ended  December 31, 1995. The  Class B expenses and fees
for the Portfolio are  based on estimates, assuming  that the average daily  net
assets  of  the Class  B shares  of  the Portfolio  will be  $50,000,000. "Other
Expenses" include  Board  of  Directors'  fees  and  expenses,  amortization  of
organizational  costs, filing fees, professional  fees and costs for shareholder
reports. Due to  the continuous nature  of Rule  12b-1 fees, long  term Class  B
shareholders  may pay  more than the  equivalent of the  maximum front-end sales
charges otherwise  permitted by  the  Rules of  Fair  Practice of  the  National
Association of Securities Dealers, Inc. ("NASD").
 
    The  following  example illustrates  the expenses  that you  would pay  on a
$1,000 investment assuming (1) a 5% annual rate of return and (2) redemption  at
the  end of each time period. As noted in the table above, the Portfolio charges
no redemption fees of any kind. The example is based on total operating expenses
of the Portfolio after fee waivers.
 
<TABLE>
<CAPTION>
                                                                       1 YEAR       3 YEARS      5 YEARS     10 YEARS
                                                                     -----------  -----------  -----------  -----------
<S>                                                                  <C>          <C>          <C>          <C>
U.S. Real Estate Portfolio
  Class A..........................................................   $      10    $      32    $      55    $     122
  Class B..........................................................   $      13    $      40    $      69    $     151
</TABLE>
 
    THIS EXAMPLE SHOULD  NOT BE CONSIDERED  A REPRESENTATION OF  PAST OR  FUTURE
EXPENSES  OR  PERFORMANCE. ACTUAL  EXPENSES MAY  BE GREATER  OR LESS  THAN THOSE
SHOWN.
 
    The Fund intends  to comply  with all  state laws  that restrict  investment
company  expenses. Currently, the  most restrictive state  law requires that the
aggregate annual expenses  of an  investment company  shall not  exceed two  and
one-half  percent (2 1/2%) of  the first $30 million  of average net assets, two
percent (2%) of the next $70 million of average net assets, and one and one-half
percent (1 1/2%) of the remaining net assets of such investment company.
 
    The Adviser has agreed to a reduction  in the amounts payable to it, and  to
reimburse  the Portfolio,  if necessary, if  in any  fiscal year the  sum of the
Portfolio's expenses exceeds the limit set by applicable state law.
 
                                       3
<PAGE>
                              FINANCIAL HIGHLIGHTS
 
    The following table provides financial highlights for the Class A shares  of
the Portfolio for the period presented. The audited financial highlights for the
Class  A shares for  the period ended December  31, 1995 are  part of the Fund's
financial statements which appear in the Fund's December 31, 1995 Annual  Report
to  Shareholders and  which is  included in  the Fund's  Statement of Additional
Information. The  Portfolio's  financial  highlights for  each  of  the  periods
presented  have been audited by Price  Waterhouse, LLP, whose unqualified report
thereon is also included in the Statement of Additional Information.  Additional
performance information for the Class A shares is included in the Annual Report.
The Annual Report and the financial statements therein, along with the Statement
of Additional Information, are available at no cost from the Fund at the address
and  telephone  number noted  on the  cover page  of this  Prospectus. Financial
highlights are not  available for the  new Class  B shares since  they were  not
offered  as of December  31, 1995. The  following information should  be read in
conjunction with the financial statements and notes thereto.
 
                                       4
<PAGE>
                           U.S. REAL ESTATE PORTFOLIO
 
<TABLE>
<CAPTION>
                                      PERIOD FROM
                                     FEBRUARY 24,
                                       1995* TO
                                     DECEMBER 31,
                                         1995
                                     -------------
<S>                                  <C>
NET ASSET VALUE, BEGINNING OF
 PERIOD............................  $   10.00
                                     -------------
INCOME FROM INVESTMENT OPERATIONS
  Net Investment Income (1)........       0.26
  Net Realized and Unrealized Gain
   on Investments..................       1.84
                                     -------------
  Total from Investment
   Operations......................       2.10
                                     -------------
DISTRIBUTIONS
  Net Investment Income............      (0.24)
  Net Realized Gain................      (0.44)
                                     -------------
    Total Distribution.............      (0.68)
                                     -------------
NET ASSET VALUE, END OF PERIOD.....  $   11.42
                                     -------------
                                     -------------
TOTAL RETURN.......................      21.07%
                                     -------------
                                     -------------
RATIOS AND SUPPLEMENTAL DATA:
  Net Assets, End of Period
   (Thousands).....................  $  69,509
  Ratio of Expenses to Average Net
   Assets (1)(2)...................       1.00%**
  Ratio of Net Investment Income to
   Average Net Assets (1)(2).......       4.04%**
  Portfolio Turnover Rate..........        158%
</TABLE>
 
- ------------------------------
 
<TABLE>
<S> <C>                                                 <C>
(1) Effect of voluntary expense limitation during the period:
    Per share benefit to net investment income........  $  0.02
    Ratios before expense limitation:
    Expenses to Average Net Assets....................     1.33%**
    Net Investment Income to Average Net Assets.......     3.71%**
</TABLE>
 
(2) Under the terms of an Investment Advisory Agreement, the Adviser is entitled
    to receive a management  fee calculated at  an annual rate  of 0.80% of  the
    average daily net assets of the Portfolio. The Adviser has agreed to waive a
    portion of this fee and/or reimburse expenses of the Portfolio to the extent
    that  the  total operating  expenses of  the Portfolio  exceed 1.00%  of the
    average daily net  assets of the  Class A  shares and 1.25%  of the  average
    daily  net assets of  the Class B  shares. In the  period ended December 31,
    1995,  the  Adviser  waived  management  fees  and/or  reimbursed   expenses
    totalling $129,000, for the Portfolio.
 
 * Commencement of Operations.
 
** Annualized.
 
                                       5
<PAGE>
                               PROSPECTUS SUMMARY
 
THE FUND
 
    The   Fund  consists  of  twenty-eight  portfolios,  offering  institutional
investors and high net  worth individual investors a  broad range of  investment
choices coupled with the advantages of a no-load mutual fund with Morgan Stanley
and  its affiliates providing customized  services as Adviser, Administrator and
Distributor. Each portfolio offers Class A shares and, except the  International
Small Cap, Money Market and Municipal Money Market Portfolios, also offers Class
B  shares. Each portfolio has its own investment objective and policies designed
to meet  specific  goals. The  investment  objective  of the  U.S.  Real  Estate
Portfolio is as follows:
 
    -The  U.S.  REAL ESTATE  PORTFOLIO  seeks to  provide  above-average current
     income and long-term capital appreciation by investing primarily in  equity
     securities  of companies in  the U.S. real  estate industry, including real
     estate investment trusts.
 
    The other portfolios of the Fund  are described in other prospectuses  which
may be obtained from the Fund at the address and phone number noted on the cover
page  of this  Prospectus. The objectives  of these other  portfolios are listed
below:
 
    GLOBAL AND INTERNATIONAL EQUITY:
 
    -The  ACTIVE   COUNTRY   ALLOCATION  PORTFOLIO   seeks   long-term   capital
     appreciation  by investing in accordance with country weightings determined
     by the  Adviser in  equity securities  of non-U.S.  issuers which,  in  the
     aggregate, replicate broad country indices.
 
    -The   ASIAN  EQUITY  PORTFOLIO  seeks  long-term  capital  appreciation  by
     investing primarily in equity securities of Asian issuers.
 
    -The CHINA GROWTH PORTFOLIO seeks to provide long-term capital  appreciation
     by  investing primarily in the equity securities of issuers in The People's
     Republic of China, Hong Kong and Taiwan.
 
    -The EMERGING  MARKETS PORTFOLIO  seeks  long-term capital  appreciation  by
     investing primarily in equity securities of emerging country issuers.
 
    -The  EUROPEAN  EQUITY  PORTFOLIO seeks  long-term  capital  appreciation by
     investing primarily in equity securities of European issuers.
 
    -The  GLOBAL  EQUITY  PORTFOLIO  seeks  long-term  capital  appreciation  by
     investing  primarily in equity securities  of issuers throughout the world,
     including U.S. issuers.
 
    -The GOLD  PORTFOLIO  seeks  long-term  capital  appreciation  by  investing
     primarily  in equity securities of foreign  and domestic issuers engaged in
     gold-related activities.
 
    -The INTERNATIONAL EQUITY PORTFOLIO seeks long-term capital appreciation  by
     investing primarily in equity securities of non-U.S. issuers.
 
    -The  INTERNATIONAL MAGNUM PORTFOLIO seeks long-term capital appreciation by
     investing primarily in equity securities of non-U.S. issuers in  accordance
     with EAFE country (as defined in "Investment Objective and Policies" below)
     weightings determined by the Adviser.
 
    -The  INTERNATIONAL SMALL CAP PORTFOLIO seeks long-term capital appreciation
     by investing primarily in equity securities of non-U.S. issuers with equity
     market capitalizations of less than $1 billion.
 
    -The JAPANESE  EQUITY  PORTFOLIO  seeks long-term  capital  appreciation  by
     investing primarily in equity securities of Japanese issuers.
 
                                       6
<PAGE>
    -The  LATIN  AMERICAN  PORTFOLIO  seeks  long-term  capital  appreciation by
     investing primarily in equity securities of Latin American issuers and debt
     securities  issued  or   guaranteed  by  Latin   American  governments   or
     governmental entities.
 
    U.S. EQUITY:
 
    -The  AGGRESSIVE EQUITY  PORTFOLIO seeks  capital appreciation  by investing
     primarily in corporate equity and equity-linked securities.
 
    -The  EQUITY  GROWTH  PORTFOLIO  seeks  long-term  capital  appreciation  by
     investing  primarily  in growth-oriented  equity  securities of  medium and
     large capitalization companies.
 
    -The EMERGING  GROWTH  PORTFOLIO  seeks long-term  capital  appreciation  by
     investing  primarily  in  growth-oriented equity  securities  of  small- to
     medium-sized corporations.
 
    -The MICROCAP PORTFOLIO  seeks long-term capital  appreciation by  investing
     primarily in growth-oriented equity securities of small corporations.
 
    -The  SMALL CAP VALUE EQUITY PORTFOLIO  seeks high long-term total return by
     investing in  undervalued  equity  securities  of  small-  to  medium-sized
     companies.
 
    -The  VALUE EQUITY PORTFOLIO seeks high  total return by investing in equity
     securities which the  Adviser believes  to be undervalued  relative to  the
     stock market in general at the time of purchase.
 
    EQUITY AND FIXED INCOME:
 
    -The  BALANCED PORTFOLIO seeks high total return while preserving capital by
     investing in  a  combination of  undervalued  equity securities  and  fixed
     income securities.
 
    FIXED INCOME:
 
    -The  EMERGING MARKETS DEBT  PORTFOLIO seeks high  total return by investing
     primarily  in  debt  securities   of  government,  government-related   and
     corporate issuers located in emerging countries.
 
    -The  FIXED INCOME PORTFOLIO seeks to produce a high total return consistent
     with the preservation of capital by investing in a diversified portfolio of
     fixed income securities.
 
    -The GLOBAL FIXED INCOME PORTFOLIO seeks to produce an attractive real  rate
     of  return while preserving capital by investing in fixed income securities
     of issuers throughout the world, including United States issuers.
 
    -The HIGH YIELD PORTFOLIO seeks to  maximize total return by investing in  a
     diversified  portfolio of high  yield fixed income  securities that offer a
     yield above  that  generally available  on  debt securities  in  the  three
     highest rating categories of the recognized rating services.
 
    -The  MORTGAGE-BACKED SECURITIES PORTFOLIO seeks to  produce as high a level
     of current income  as is  consistent with  the preservation  of capital  by
     investing  primarily  in  a  variety  of  investment-grade  mortgage-backed
     securities.
 
    -The MUNICIPAL  BOND PORTFOLIO  seeks to  produce a  high level  of  current
     income   consistent  with  preservation  of  principal  through  investment
     primarily in municipal obligations,  the interest on  which is exempt  from
     federal income tax.
 
                                       7
<PAGE>
    MONEY MARKET:
 
    -The  MONEY MARKET PORTFOLIO  seeks to maximize  current income and preserve
     capital while maintaining  high levels  of liquidity  through investing  in
     high quality money market instruments with remaining maturities of one year
     or less.
 
    -The  MUNICIPAL MONEY MARKET PORTFOLIO  seeks to maximize current tax-exempt
     income and  preserve capital  while maintaining  high levels  of  liquidity
     through  investing in high quality  money market instruments with remaining
     maturities of one year or less which are exempt from federal income tax.
 
INVESTMENT MANAGEMENT
 
    Morgan Stanley Asset Management  Inc., a wholly  owned subsidiary of  Morgan
Stanley  Group Inc.,  which at December  31, 1995, together  with its affiliated
asset management  companies, had  approximately $57.4  billion in  assets  under
management  as  an  investment  manager  or  as  a  fiduciary  adviser,  acts as
investment adviser to the  Fund and each of  its portfolios. See "Management  of
the Fund -- Investment Adviser" and "Management of the Fund -- Administrator."
 
HOW TO INVEST
 
    Class  A shares of  the Portfolio are  offered directly to  investors at net
asset value with no  sales commission or  12b-1 charges. Class  B shares of  the
Portfolio  are offered at net  asset value with no  sales commission, but with a
12b-1 fee, which  is accrued daily  and paid  quarterly, equal to  0.25% of  the
Class B shares' average daily net assets on an annualized basis. Share purchases
may  be  made  by  sending  investments directly  to  the  Fund  or  through the
Distributor. Shares  in a  Portfolio account  opened prior  to January  2,  1996
(each,  a "Pre-1996 Account") were designated Class A shares on January 2, 1996.
For a Portfolio account opened  on or after January  2, 1996 (a "New  Account"),
the  minimum initial investment is $500,000 for  Class A shares and $100,000 for
Class B shares. Certain exceptions to the foregoing minimums apply to (1) shares
in a Pre-1996  Account with  a value of  $100,000 or  more on March  1, 1996  (a
"Grandfathered  Class  A  Account");  (2)  Portfolio  accounts  held  by certain
employees of the  Adviser and  of its affiliates;  and (3)  certain advisory  or
asset  allocation accounts, such as Total  Funds Management accounts, managed by
Morgan Stanley or  its affiliates, including  the Adviser ("Managed  Accounts").
The Adviser reserves the right in its sole discretion to determine which of such
advisory or asset allocation accounts shall be Managed Accounts. For information
regarding   Managed  Accounts   please  contact  your   Morgan  Stanley  account
representative or the Fund at the telephone number provided on the cover of this
Prospectus. Shares in a Pre-1996 Account with  a value of less than $100,000  on
March 1, 1996 (a "Grandfathered Class B Account") converted to Class B shares on
March  1, 1996. The minimum investment levels may be waived at the discretion of
the Adviser for  (i) certain employees  and customers of  Morgan Stanley or  its
affiliates  and certain  trust departments, brokers,  dealers, agents, financial
planners, financial services  firms, or  investment advisers  that have  entered
into an agreement with Morgan Stanley or its affiliates; and (ii) retirement and
deferred  compensation plans and trusts used  to fund such plans, including, but
not limited to, those defined in Section  401(a), 403(b) or 457 of the  Internal
Revenue Code of 1986, as amended, and "rabbi trusts". See "Purchase of Shares --
Minimum  Investment  and  Account Sizes;  Conversion  from  Class A  to  Class B
Shares."
 
                                       8
<PAGE>
    The minimum subsequent investment for a Portfolio account is $1,000  (except
for  automatic  reinvestment of  dividends and  capital gains  distributions for
which there  is no  minimum). Such  subsequent investments  will be  applied  to
purchase  additional  shares  in the  same  class  held by  a  shareholder  in a
Portfolio account. See "Purchase of Shares -- Additional Investments."
 
HOW TO REDEEM
 
    Class A shares or  Class B shares  of the Portfolio may  be redeemed at  any
time, without cost, at the net asset value per share of shares of the applicable
class  next determined after  receipt of the  redemption request. The redemption
price may be more or less than the purchase price. Certain redemptions may cause
involuntary redemption or automatic conversion. Class  A or Class B shares  held
in   New  Accounts  are   subject  to  involuntary   redemption  if  shareholder
redemption(s) of such  shares reduces  the value of  such account  to less  than
$100,000 for any continuous 60-day period. Involuntary redemption does not apply
to  Managed Accounts, Grandfathered  Class A Accounts  and Grandfathered Class B
Accounts, regardless of  the value of  such accounts.  Class A shares  in a  New
Account  will convert  to Class  B shares  if shareholder  redemption(s) of such
shares reduces  the  value  of  such  account to  less  than  $500,000  for  any
continuous  60-day period. Class B shares in a New Account will convert to Class
A shares  if  shareholder purchases  of  additional  Class B  shares  or  market
activity cause the value of the Class B shares in the New Account to increase to
$500,000  or  more.  See  "Purchase  of  Shares  --  Minimum  Account  Sizes and
Involuntary Redemption of Shares" and "Redemption of Shares."
 
RISK FACTORS
 
    The  investment  policies  of  the   Portfolio  entail  certain  risks   and
considerations  of  which an  investor should  be  aware. Because  the Portfolio
invests primarily in the securities of companies principally engaged in the real
estate industry, its investments may be subject to the risks associated with the
direct ownership  of real  estate. The  Portfolio's share  price and  investment
return fluctuate, and a shareholder's investment when redeemed may be worth more
or  less than his original cost. Because  it is expected that the Portfolio will
invest a substantial  portion of  its assets  in real  estate investment  trusts
("REITs"),  the Portfolio may  also be subject to  certain risks associated with
the direct  investments of  REITs. Because  the Portfolio  is a  non-diversified
portfolio,  the Portfolio will invest a greater  proportion of its assets in the
securities of a smaller number of issuers and, as a result, will be subject to a
greater risk with respect to its portfolio securities. See "Investment Objective
and Policies -- Risk Factors."
 
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<PAGE>
                       INVESTMENT OBJECTIVE AND POLICIES
 
    The investment objective of the Portfolio is described below, together  with
the  policies the  Fund employs  in its efforts  to achieve  this objective. The
Portfolio's investment  objective  is a  fundamental  policy which  may  not  be
changed without the approval of a majority of the Portfolio's outstanding voting
securities. There is no assurance that the Portfolio will attain its objectives.
The  investment policies described below are not fundamental policies and may be
changed without shareholder approval.
 
    The investment  objective  of the  Portfolio  is to  provide  above  average
current  income  and long-term  capital appreciation  by investing  primarily in
equity securities of companies in the U.S. real estate industry, including  real
estate  investment trusts  ("REITs"). Equity  securities include  common stocks,
shares or units of beneficial  interest of REITs, limited partnership  interests
in  master limited partnerships,  rights or warrants  to purchase common stocks,
securities convertible into common stocks, and preferred stock.
 
    Under normal circumstances,  at least  65% of the  Portfolio's total  assets
will  be invested in income producing equity securities of companies principally
engaged in  the U.S.  real  estate industry.  For  purposes of  the  Portfolio's
investment  policies,  a company  is "principally  engaged"  in the  real estate
industry if (i)  it derives at  least 50% of  its revenues or  profits from  the
ownership,   construction,  management,   financing  or   sale  of  residential,
commercial or industrial real  estate or (ii)  it has at least  50% of the  fair
market  value of  its assets invested  in residential,  commercial or industrial
real estate. Companies  in the real  estate industry may  include among  others:
REITs, master limited partnerships that invest in interests in real estate, real
estate operating companies, and companies with substantial real estate holdings,
such  as  hotel companies,  residential  builders and  land-rich  companies. The
Portfolio seeks  to invest  in equity  securities of  companies that  provide  a
dividend   yield  that  exceeds  the  composite  dividend  yield  of  securities
comprising the Standard & Poor's Stock Price Index ("S&P 500").
 
    A substantial portion of  the Portfolio's total assets  will be invested  in
securities  of REITs.  REITs pool investors'  funds for  investment primarily in
income producing real estate or real  estate related loans or interests. A  REIT
is  not taxed  on income  distributed to its  shareholders or  unitholders if it
complies with regulatory requirements  relating to its organization,  ownership,
assets  and income, and with a regulatory  requirement that it distribute to its
shareholders or unitholders at least 95% of its taxable income for each  taxable
year.  Generally, REITs  can be  classified as  Equity REITs,  Mortgage REITs or
Hybrid REITs. Equity REITs invest the majority of their assets directly in  real
property  and derive  their income primarily  from rents and  capital gains from
appreciation  realized  through  property   sales.  Equity  REITs  are   further
categorized  according to  the types of  real estate securities  they own, e.g.,
apartment properties, retail shopping centers, office and industrial properties,
hotels, health-care facilities, manufactured  housing and mixed-property  types.
Mortgage  REITs invest the majority of their assets in real estate mortgages and
derive their income primarily from  interest payments. Hybrid REITs combine  the
characteristics  of both  Equity and Mortgage  REITs. The  Portfolio will invest
primarily in Equity REITs. A shareholder in the Portfolio should realize that by
investing in REITs indirectly through the  Portfolio, he will bear not only  his
proportionate  share of the expenses of  the Portfolio, but also indirectly, the
management expenses of underlying REITs.
 
    Under normal circumstances, the Portfolio may invest up to 35% of its  total
assets  in  debt securities  issued or  guaranteed by  real estate  companies or
secured by real estate assets and rated, at time of purchase, in one of the four
highest  rating  categories  by  a  nationally  recognized  statistical   rating
organization ("NRSRO") or
 
                                       10
<PAGE>
determined  by the Adviser to be of  comparable quality at the time of purchase,
high quality money market instruments, such as notes, certificates of deposit or
bankers' acceptances issued by domestic  or foreign insures, or high-grade  debt
securities, consisting of corporate debt securities and United States Government
securities.  Securities  rated  in  the  lowest  category  of  investment  grade
securities have  speculative characteristics.  Investment grade  securities  are
securities  that are rated  in one of  the four highest  rating categories by an
NRSRO.
 
    Any remaining assets  not invested  as described  above may  be invested  in
certain securities or obligations, including derivative securities, as set forth
in  "Additional Investment Information" below.  The Portfolio may concentrate in
the U.S. real estate  industry, but may  not invest more than  25% of its  total
assets  in securities of companies in any one other industry (for these purposes
the U.S. Government and its agencies and instrumentalities are not considered an
industry).
 
RISK FACTORS
 
    The  investment  policies  of  the   Portfolio  entail  certain  risks   and
considerations  of  which an  investor should  be  aware. Because  the Portfolio
invests primarily in the securities of companies principally engaged in the real
estate industry, its investments may be subject to the risks associated with the
direct ownership of  real estate. These  risks include: the  cyclical nature  of
real  estate values,  risks related  to general  and local  economic conditions,
overbuilding  and  increased  competition,  increases  in  property  taxes   and
operating  expenses, demographic trends and variations in rental income, changes
in zoning laws, casualty or condemnation losses, environmental risks, regulatory
limitations on  rents,  changes in  neighborhood  values, related  party  risks,
changes  in the appeal of properties to tenants, increases in interest rates and
other real estate  capital market influences.  Generally, increases in  interest
rates  will increase the costs of  obtaining financing, which could directly and
indirectly decrease the  value of the  Portfolio's investments. The  Portfolio's
share price and investment return fluctuate, and a shareholder's investment when
redeemed may be worth more or less than his original cost.
 
    Because  it is expected that the Portfolio will invest a substantial portion
of its assets  in REITs, the  Portfolio will  also be subject  to certain  risks
associated  with  the direct  investments  of REITs.  REITs  may be  affected by
changes in the value of their underlying properties and by defaults by borrowers
or tenants.  Mortgage  REITs  may be  affected  by  the quality  of  the  credit
extended.  Furthermore, REITs  are dependent  on specialized  management skills.
Some REITs may have limited diversification and may be subject to risks inherent
in investments in a limited number  of properties, in a narrow geographic  area,
or  in  a single  property  type. REITs  depend  generally on  their  ability to
generate cash flow to make distributions to shareholders or unitholders, and may
be subject to defaults by borrowers  and to self-liquidations. In addition,  the
performance  of a REIT  may be affected  by its failure  to qualify for tax-free
pass-through of income under the Internal Revenue Code of 1986, as amended  (the
"Code"),  or  its  failure to  maintain  exemption from  registration  under the
Investment Company  Act  of  1940,  as amended  (the  "1940  Act").  Changes  in
prevailing  interest rates may inversely affect the value of the debt securities
in which the Portfolio will invest. Changes in the value of portfolio securities
will not necessarily affect cash income  derived from these securities but  will
affect a Portfolio's net asset value.
 
    Because  the Portfolio is a non-diversified  portfolio, the Portfolio is not
limited by the 1940 Act in the proportion of its assets that may be invested  in
the  obligations of a  single issuer. Thus,  the Portfolio may  invest a greater
proportion of its assets in the securities  of a smaller number of issuers  and,
as  a result, will  be subject to a  greater risk with  respect to its portfolio
securities.  Any  economic,  political,  or  regulatory  developments  affecting
 
                                       11
<PAGE>
the  value of the securities the Portfolio  holds could have a greater impact on
the total  value of  the Portfolio's  holdings than  would be  the case  if  the
Portfolio's  securities  were  diversified among  more  issuers.  The Portfolio,
however, intends to comply with the diversification requirements imposed by  the
Code  for  qualification  as a  regulated  investment company.  See  "Taxes" and
"Investment Limitations."
 
                       ADDITIONAL INVESTMENT INFORMATION
 
    LOANS OF PORTFOLIO SECURITIES.  The  Portfolio may lend their securities  to
brokers, dealers, domestic and foreign banks or other financial institutions for
the purpose of increasing its net investment income. These loans must be secured
continuously by cash or equivalent collateral, or by a letter of credit at least
equal  to the  market value  of the securities  loaned plus  accrued interest or
income. There may be a risk of delay in recovery of the securities or even  loss
of  rights  in  the  collateral  should  the  borrower  of  the  securities fail
financially. A  Portfolio  will  not enter  into  securities  loan  transactions
exceeding,  in the aggregate, 33  1/3% of the market  value of its total assets.
For  more  detailed  information  about  securities  lending,  see   "Investment
Objectives and Policies" in the Statement of Additional Information.
 
    MONEY  MARKET INSTRUMENTS.   The Portfolio  is permitted to  invest in money
market  instruments,  although  the  Portfolio  intends  to  stay  invested   in
securities  satisfying its primary investment objective to the extent practical.
The Portfolio  may make  money market  investments pending  other investment  or
settlement  for liquidity,  or in  adverse market  conditions. The  money market
investments permitted for the Portfolio include obligations of the United States
Government and  its  agencies  and  instrumentalities,  other  debt  securities,
commercial  paper  including  bank  obligations,  certificates  of  deposit, and
repurchase agreements. For  more detailed information  about these money  market
investments,  see "Description  of Securities and  Ratings" in  the Statement of
Additional Information.
 
    NON-PUBLICLY  TRADED   SECURITIES,   PRIVATE   PLACEMENTS   AND   RESTRICTED
SECURITIES.  The Portfolio may invest in securities that are neither listed on a
stock   exchange  nor   traded  over-the-counter,   including  privately  placed
securities. Such  unlisted equity  securities  may involve  a higher  degree  of
business  and financial risk that can result  in substantial losses. As a result
of the absence of a public trading market for these securities, they may be less
liquid than publicly traded securities. Although these securities may be  resold
in privately negotiated transactions, the prices realized from these sales could
be  less than those  originally paid by the  Portfolio or less  than what may be
considered the  fair  value of  such  securities. Furthermore,  companies  whose
securities  are not  publicly traded  may not be  subject to  the disclosure and
other investor  protection  requirements  which might  be  applicable  if  their
securities  were  publicly  traded.  If  such  securities  are  required  to  be
registered under the securities laws of  one or more jurisdictions before  being
resold,  the Portfolio may be required to bear the expenses of registration. The
Portfolio may not invest more than 15% of its net assets in illiquid securities,
including securities for which there  is not readily available secondary  market
nor  more than 10%  of its total  assets in securities  that are restricted from
sale to  the public  without registration  ("Restricted Securities")  under  the
Securities  Act of 1933,  as amended (the "1933  Act"). Nevertheless, subject to
the foregoing limit on illiquid securities,  the Portfolio may invest up to  15%
of  its total assets  in Restricted Securities  that can be  offered and sold to
qualified  institutional  buyers   under  Rule  144A   under  that  Act   ("144A
Securities"). The Board of Directors has adopted guidelines and delegated to the
Adviser,  subject  to  the supervision  of  the  Board of  Directors,  the daily
function of determining and  monitoring the liquidity  of 144A Securities.  144A
Securities  may  become  illiquid  if  qualified  institutional  buyers  are not
interested in acquiring the securities.
 
                                       12
<PAGE>
    REPURCHASE AGREEMENTS.  The Portfolio  may enter into repurchase  agreements
with  brokers, dealers or  banks that meet the  credit guidelines established by
the Fund's Board of Directors. In  a repurchase agreement, the Portfolio buys  a
security  from a seller  that has agreed  to repurchase it  at a mutually agreed
upon date and price, reflecting the interest rate effective for the term of  the
agreement.  The term of these agreements is  usually from overnight to one week,
and never  exceeds one  year. Repurchase  agreements may  be viewed  as a  fully
collateralized  loan  of money  by the  Portfolio to  the seller.  The Portfolio
always receives securities, with a market  value at least equal to the  purchase
price  (including accrued interest)  as collateral and  this value is maintained
during the term  of the  agreement. If the  seller defaults  and the  collateral
value  declines, the Portfolio might incur a loss. If bankruptcy proceedings are
commenced with  respect to  the  seller, the  Portfolio's realization  upon  the
collateral  may  be  delayed or  limited.  The aggregate  of  certain repurchase
agreements  and  certain  other  investments  is  limited  as  set  forth  under
"Investment Limitations."
 
    STOCK  OPTIONS, FUTURES  CONTRACTS AND  OPTIONS IN  FUTURES CONTRACTS.   The
Portfolio may write (i.e., sell)  covered call options on portfolio  securities.
The  Portfolio may write covered put options on portfolio securities. By selling
a covered call option, the Portfolio  would become obligated during the term  of
the  option to  deliver the securities  underlying the option  should the option
holder choose to exercise  the option before the  option's termination date.  In
return  for  the  call it  has  written,  the Portfolio  will  receive  from the
purchaser (or option holder) a premium which is the price of the option, less  a
commission  charged by a broker. The  Portfolio will keep the premium regardless
of whether  the  option is  exercised.  By selling  a  covered put  option,  the
Portfolio  incurs an obligation  to buy the security  underlying the option from
the purchaser of the put at the  option's exercise price at any time during  the
option  period,  at the  purchaser's election  (certain  options written  by the
Portfolio will be exercisable by the purchaser only on a specific date). A  call
option  is "covered" if the Portfolio owns the security underlying the option it
has written or has  an absolute or  immediate right to  acquire the security  by
holding  a call  option on  such security, or  maintains a  sufficient amount of
cash, cash equivalents or liquid securities to purchase the underlying security.
Generally, a put option is "covered" if the Fund maintains cash, U.S. Government
securities or other high grade debt  obligations equal to the exercise price  of
the  option, or if the  Fund holds a put option  on the same underlying security
with a similar or higher exercise price.
 
    When the Portfolio writes  covered call options, it  augments its income  by
the premiums received and is thereby hedged to the extent of that amount against
a  decline in the price of the underlying securities. The premiums received will
offset a  portion  of  the potential  loss  incurred  by the  Portfolio  if  the
securities  underlying the  options are  ultimately sold  by the  Portfolio at a
loss. However, during the  option period, the Portfolio  has, in return for  the
premium  on the option, given up  the opportunity for capital appreciation above
the exercise price should the market price of the underlying security  increase,
but  has retained the risk  of loss should the  price of the underlying security
decline.
 
    The Portfolio  will  write put  options  to  receive the  premiums  paid  by
purchasers  (when the  Adviser wishes  to purchase  the security  underlying the
option at  a price  lower  than its  current market  price,  in which  case  the
Portfolio  will write the covered put at  an exercise price reflecting the lower
purchase price sought) and to close out a long put option position.
 
    The Portfolio may also purchase put  options on its portfolio securities  or
call  options. When the Portfolio purchases a  call option it acquires the right
to buy a designated security at  a designated price (the "exercise price"),  and
when  the  Portfolio purchases  a put  option it  acquires the  right to  sell a
designated security at the exercise price, in each case on or before a specified
date   (the   "termination   date"),   which   is   usually   not   more    than
 
                                       13
<PAGE>
nine  months from the date the option is issued. The Portfolio may purchase call
options to close out a covered call  position or to protect against an  increase
in the price of a security it anticipates purchasing. The Portfolio may purchase
put  options on  securities which  it holds in  its portfolio  to protect itself
against decline in the  value of the  security. If the  value of the  underlying
security were to fall below the exercise price of the put purchased in an amount
greater  than the  premium paid  for the  option, the  Portfolio would  incur no
additional loss.  The Portfolio  may  also purchase  put  options to  close  out
written  put  positions in  a  manner similar  to  call option  closing purchase
transactions. There are no other limits  on the Portfolio's ability to  purchase
call and put options.
 
    The  Portfolio  may  enter into  futures  contracts and  options  on futures
contracts to  remain  fully  invested  and  to  reduce  transaction  costs.  The
Portfolio   may  also  enter  into  futures  transactions  as  a  hedge  against
fluctuations in the price of a security it holds or intends to acquire, but  not
for  speculation or for achieving leverage. The Portfolio may enter into futures
contracts and options on futures contracts provided that not more than 5% of the
Portfolio's total assets at the time of entering into the contract or option  is
required  as deposit to secure obligations under such contracts and options, and
provided that not more than 20% of the Portfolio's total assets in the aggregate
is invested in futures contracts and options on futures contracts.
 
    The Portfolio  may  purchase and  write  call  and put  options  on  futures
contracts that are traded on any international exchange, traded over-the-counter
or  which are synthetic options  or futures or equity  swaps, and may enter into
closing transactions  with respect  to  such options  to terminate  an  existing
position.  An option  on a  futures contract gives  the purchaser  the right (in
return for the premium paid) to assume a position in a futures contract (a  long
position if the option is a call and a short position if the option is a put) at
a  specified  exercise price  at any  time during  the term  of the  option. The
Portfolio will purchase  and write  options on futures  contracts for  identical
purposes  to  those set  forth  above for  the  purchase of  a  futures contract
(purchase of a call option or  sale of a put option)  and the sale of a  futures
contract  (purchase of a put option or sale of a call option), or to close out a
long or short position in future contracts.
 
    Options, futures and options on futures are derivative securities, in  which
the  Portfolio  may invest  for hedging  purposes,  as well  as to  remain fully
invested and to reduce transaction costs. Investing for the latter two  purposes
may  be considered  speculative. The  primary risks  associated with  the use of
options, futures and options  on futures are  (i) imperfect correlation  between
the change in market value of the stocks held by the Portfolio and the prices of
futures  and options relating to the stocks  purchased or sold by the Portfolio;
and (ii) possible lack of a liquid  secondary market for an option or a  futures
contract  and the  resulting inability to  close a futures  position which could
have an adverse impact on  the Portfolio's ability to  hedge. In the opinion  of
the  Board of Directors, the risk that the Portfolio will be unable to close out
a futures position or options contract  will be minimized by only entering  into
futures contracts or options transactions for which there appears to be a liquid
secondary market.
 
    TEMPORARY  INVESTMENTS.  For temporary  defensive purposes, when the Adviser
determines that market conditions warrant, the  Portfolio may invest up to  100%
of  its assets  in money market  instruments consisting of  securities issued or
guaranteed by the United States  Government, its agencies or  instrumentalities,
repurchase  agreements, certificates of deposit  and bankers' acceptances issued
by banks or savings  and loan associations  having net assets  of at least  $500
million  as of the end  of their most recent  fiscal year, high-grade commercial
paper rated, at time of purchase, in the top two categories by a national rating
agency or determined to be of
 
                                       14
<PAGE>
comparable quality by the Adviser  at the time of  purchase and other long-  and
short-term  debt instruments which  are rated A  or higher by  Standard & Poor's
Corporation ("S&P") or Moody's Investors  Service, Inc. ("Moody's") at the  time
of purchase, and may hold a portion of its assets in cash.
 
    WHEN-ISSUED  AND DELAYED  DELIVERY SECURITIES.   The  Portfolio may purchase
securities on a  when-issued or  delayed delivery basis.  In such  transactions,
instruments  are bought with payment and delivery  taking place in the future in
order to secure what is considered to  be an advantageous yield or price at  the
time  of the transaction. Delivery of and  payment for these securities may take
as long as a month or more after  the date of the purchase commitment, but  will
take  place  no more  than 120  days after  the trade  date. The  Portfolio will
maintain with the Custodian  a separate account with  a segregated portfolio  of
high-grade  debt  securities  or cash  in  an  amount at  least  equal  to these
commitments. The payment obligation and the interest rates that will be received
are each fixed  at the  time the  Portfolio enters  into the  commitment and  no
interest  accrues to the  Portfolio until settlement. Thus,  it is possible that
the market value at  the time of  settlement could be higher  or lower than  the
purchase  price if  the general  level of  interest rates  has changed.  It is a
current policy  of  the Portfolio  not  to enter  into  when-issued  commitments
exceeding,  in the aggregate, 15%  of the market value  of the Portfolio's total
assets less liabilities other than the obligations created by these commitments.
 
                             INVESTMENT LIMITATIONS
 
    As a non-diversified investment company, the Portfolio is not limited by the
1940 Act in  the proportion  of its  total assets that  may be  invested in  the
obligations  of  a  single issuer.  Thus,  the  Portfolio may  invest  a greater
proportion of its total assets in the securities of a smaller number of  issuers
and,  as a result, will be subject to greater risk with respect to its portfolio
securities. However, the  Portfolio intends to  comply with the  diversification
requirements  imposed  by the  Internal Revenue  Code of  1986, as  amended, for
qualification a regulated  investment company. See  "Investment Limitations"  in
the Statement of Additional Information.
 
    The Portfolio operates under certain investment restrictions that are deemed
fundamental limitations and may be changed only with the approval of the holders
of   a  majority  of   the  Portfolio's  outstanding   shares.  See  "Investment
Limitations" in  the  Statement  of Additional  Information.  In  addition,  the
Portfolio  operates  under  certain non-fundamental  investment  limitations, as
described below and in  the Statement of  Additional Information. The  Portfolio
may  not: (i)  enter into  repurchase agreements  with more  than seven  days to
maturity if, as a result, more than  15% of the market value of the  Portfolio's
net assets would be invested in such repurchase agreements and other investments
for  which market  quotations are not  readily available or  which are otherwise
illiquid;  (ii)  invest  more  than  10%  of  its  total  assets  in  Restricted
Securities,  except that the Portfolio may invest  up to 15% of its total assets
in Restricted Securities that are 144A Securities, subject to the limitation  on
illiquid  securities described above; (iii) borrow  money, except from banks for
extraordinary or emergency purposes, and then only  in amounts up to 10% of  the
value  of the Portfolio's total assets, taken  at cost at the time of borrowing;
or purchase securities  while borrowings  exceed 5%  of its  total assets;  (iv)
mortgage,  pledge or hypothecate  any assets except in  connection with any such
borrowing in amounts up to 10% of  the value of the Portfolio's total assets  at
the time of borrowing; (v) invest in fixed time deposits with a duration of over
seven  calendar days; or (vi) invest in  fixed timed deposits with a duration of
from two  business  days  to  seven  calendar days  if  more  than  10%  of  the
Portfolio's total assets would be invested in these deposits.
 
                                       15
<PAGE>
                             MANAGEMENT OF THE FUND
 
    INVESTMENT  ADVISER.  Morgan Stanley Asset Management Inc. is the Investment
Adviser and Administrator of  the Fund and each  of its portfolios. The  Adviser
provides  investment  advice and  portfolio management  services pursuant  to an
Investment Advisory  Agreement and,  subject to  the supervision  of the  Fund's
Board  of  Directors,  makes the  Portfolio's  day-to-day  investment decisions,
arranges for the execution of  portfolio transactions and generally manages  the
Portfolio's  investments. The Adviser is entitled  to receive from the Portfolio
an annual management fee, payable quarterly, equal to the percentage of  average
daily  net assets set forth in the  table below. However, the Adviser has agreed
to a reduction  in the fees  payable to it  and to reimburse  the Portfolio,  if
necessary,  if such fees would cause the  total annual operating expenses of the
Portfolio to exceed the  respective percentage of average  daily net assets  set
forth below.
 
<TABLE>
<CAPTION>
                                                  MAXIMUM TOTAL ANNUAL
                                                        OPERATING
                                  MANAGEMENT       EXPENSES AFTER FEE
                                      FEE                WAIVERS
                                  -----------   -------------------------
          PORTFOLIO                              CLASS A         CLASS B
- ------------------------------                  ---------       ---------
<S>                               <C>           <C>             <C>
U.S. Real Estate Portfolio             0.80%       1.00%           1.25%
</TABLE>
 
    The  fee payable by the Portfolio is  higher than the management fee paid by
most investment companies,  but the Adviser  believes the fee  is comparable  to
those of investment companies with similar investment objectives.
 
    The  Adviser, with  principal offices  at 1221  Avenue of  the Americas, New
York, New  York  10020,  conducts a  worldwide  portfolio  management  business,
providing  a broad  range of portfolio  management services to  customers in the
United States and abroad. At December  31, 1995, the Adviser, together with  its
affiliated    asset   management   companies,   managed   investments   totaling
approximately $57.4 billion, including approximately $41.9 billion under  active
management  and  $15.5  billion as  Named  Fiduciary or  Fiduciary  Adviser. See
"Management of the Fund" in the Statement of Additional Information.
 
    PORTFOLIO MANAGER. -- RUSSELL C. PLATT.  Mr. Platt joined Morgan Stanley  in
1982  and  currently is  a  Principal of  the  Firm. Russell  Platt  has primary
responsibility for managing the real  estate securities investment business  for
Morgan  Stanley  Asset  Management  ("MSAM")  and  serves  as  a  member  of the
Investment  Committee  of  The  Morgan  Stanley  Real  Estate  Fund   ("MSREF").
Previously,  Mr. Platt served as  a Director of MSREF,  where he was involved in
capital raising, acquisitions, oversight of investments and investor  relations.
MSREF is a privately held limited partnership engaged in the acquisition of real
estate  assets, portfolios and real estate operating companies with gross assets
of approximately $3.5 billion as of December 1994. From 1991 to 1993, Mr.  Platt
was   head  of  Morgan  Stanley's   Transaction  Development  Group,  which  was
responsible for identifying and structuring real estate investment opportunities
for the Firm and its clients  worldwide. As part of these responsibilities,  Mr.
Platt directed Morgan Stanley Realty's activities in Latin America and served as
U.S. liaison for Morgan Stanley Realty's Japanese real estate clients. From 1990
to  1991, Mr. Platt was based in Morgan Stanley Realty's London Office, where he
was responsible  for European  transaction development.  Prior to  this, he  had
extensive  transaction  responsibilities  involving  portfolio,  retail, office,
hotel and  apartment sales  and financings.  Mr. Platt  graduated from  Williams
College  in 1982 with a  B.A. in Economics and  received his M.B.A. from Harvard
Business School in 1986. Mr. Platt is a  member of the Board of Trustees of  The
National Multi
 
                                       16
<PAGE>
Housing  Council and The Wharton  Real Estate Center, and  a member of The Urban
Land Institute (International Council), the National Association of Real  Estate
Investment Trusts and the Pension Real Estate Association.
 
    THEODORE  R. BIGMAN.   Mr. Bigman joined Morgan  Stanley Asset Management in
1995 as a  Vice President. Together  with Russell Platt,  he is responsible  for
MSAM's real estate securities research. Prior to joining MSAM, he was a Director
at  CS First Boston, where  he worked for eight years  in the Real Estate Group.
Since 1992,  Mr. Bigman  established and  managed the  REIT effort  at CS  First
Boston,  including  primary responsibility  for $2.5  billion of  initial public
offering by real estate investment trusts. Previously, Mr. Bigman had  extensive
real estate experience in a wide variety of transactions involving the financing
and  sale of both individual assets and portfolios of real estate assets as well
as the  acquisition  and sale  of  several  real estate  companies.  Mr.  Bigman
graduated from Brandeis University in 1983 with a B.A. in Economics and received
his  M.B.A. from  Harvard University  in 1987.  He is  a member  of the National
Association of  Real  Estate  Investment Trusts  and  International  Council  of
Shopping Centers.
 
    ADMINISTRATOR.    The Adviser  also  provides the  Fund  with administrative
services pursuant to  an Administration Agreement.  The services provided  under
the  Administration Agreement are subject to the supervision of the Officers and
the Board of  Directors of  the Fund  and include  day-to-day administration  of
matters  related  to the  corporate existence  of the  Fund, maintenance  of its
records, preparation of reports, supervision of the Fund's arrangements with its
custodian,  and  assistance  in  the  preparation  of  the  Fund's  registration
statements  under  Federal and  State  laws. The  Administration  Agreement also
provides that the Administrator,  through its agents, will  provide to the  Fund
dividend  disbursing and  transfer agent  services. For  its services  under the
Administration Agreement, the Fund  pays the Adviser a  monthly fee which on  an
annual basis equals 0.15% of the average daily net assets of the Portfolio.
 
    Under  an agreement between  the Adviser and The  Chase Manhattan Bank, N.A.
("Chase"), Chase  provides certain  administrative services  to the  Fund. In  a
merger  completed on September 1, 1995, Chase succeeded to all of the rights and
obligations under the  U.S. Trust Administration  Agreement between the  Adviser
and  the United  States Trust  Company of New  York ("U.S.  Trust"), pursuant to
which U.S. Trust had  agreed to provide certain  administrative services to  the
Fund.  Pursuant  to  a  delegation  clause  in  the  U.S.  Trust  Administration
Agreement, U.S.  Trust delegated  its administrative  responsibilities to  Chase
Global  Funds Services Company ("CGFSC"), formerly known as Mutual Funds Service
Company, which after the  merger with Chase  is a subsidiary  of Chase and  will
continue  to provide  certain administrative services  to the  Fund. The Adviser
supervises and  monitors such  administrative services  provided by  CGFSC.  The
services  provided  under  the  Administration  Agreement  and  the  U.S.  Trust
Administration Agreement are  also subject to  the supervision of  the Board  of
Directors  of the  Fund. The  Board of  Directors of  the Fund  has approved the
provision of services described above  pursuant to the Administration  Agreement
and  the U.S. Trust Administration Agreement, as  being in the best interests of
the Fund. CGFSC's business address  is 73 Tremont Street, Boston,  Massachusetts
02108-3913. For additional information regarding the Administration Agreement or
the  U.S. Trust  Administration Agreement, see  "Management of the  Fund" in the
Statement of Additional Information.
 
    DIRECTORS AND OFFICERS.  Pursuant  to the Fund's Articles of  Incorporation,
the  Board of Directors decides  upon matters of general  policy and reviews the
actions of the Fund's  Adviser, Administrator and  Distributor. The Officers  of
the Fund conduct and supervise its daily business operations.
 
                                       17
<PAGE>
    DISTRIBUTOR.   Morgan  Stanley serves  as the  exclusive Distributor  of the
shares of  the Fund.  Under its  Distribution Agreement  with the  Fund,  Morgan
Stanley sells shares of the Portfolio upon the terms and at the current offering
price  described in this Prospectus. Morgan Stanley is not obligated to sell any
certain number of shares of the Portfolio.
 
    The Portfolio currently offers  only the classes of  shares offered by  this
Prospectus.  The Portfolio may in the future offer one or more classes of shares
with features, distribution expenses or  other expenses that are different  from
those of the classes currently offered.
 
    The  Fund has  adopted a Plan  of Distribution  with respect to  the Class B
shares pursuant to Rule 12b-1 under the  1940 Act (the "Plan"). Under the  Plan,
the  Distributor is entitled  to receive from the  Portfolio a distribution fee,
which is accrued  daily and  paid quarterly,  of 0.25%  of the  Class B  shares'
average  daily net  assets on  an annualized  basis. The  Distributor expects to
reallocate most of its  fee to its  investment representatives. The  Distributor
may,  in its discretion, voluntarily waive from  time to time all or any portion
of its distribution fee and each of  the Distributor and the Adviser is free  to
make  additional payments  out of  its own  assets to  promote the  sale of Fund
shares,  including   payments  that   compensate  financial   institutions   for
distribution services or shareholder services.
 
    The  Plan is designed to compensate the Distributor for its services, not to
reimburse the Distributor for its expenses,  and the Distributor may retain  any
portion  of the fee that it does not expend in fulfillment of its obligations to
the Fund.
 
    EXPENSES.  The Portfolio  is responsible for payment  of certain other  fees
and  expenses  (including legal  fees,  accountants' fees,  custodial  fees, and
printing and mailing  costs) specified  in the  Administration and  Distribution
Agreements.
 
                               PURCHASE OF SHARES
 
    Class  A and Class B shares of the Portfolio may be purchased, without sales
commission, at the net  asset value per share  next determined after receipt  of
the purchase order by the Portfolio. See "Valuation of Shares."
 
MINIMUM INVESTMENT AND ACCOUNT SIZES; CONVERSION FROM CLASS A TO CLASS B SHARES
 
    For  an account for the Portfolio opened on or after January 2, 1996 (a "New
Account"), the minimum initial investment and minimum account size are  $500,000
for  Class  A shares  and  $100,000 for  Class  B shares.  Managed  Accounts may
purchase Class A shares without being subject to any minimum initial  investment
or  minimum account size requirements for  a Portfolio account. Employees of the
Adviser and of its affiliates may purchase Class A Shares subject to conditions,
including a lower  minimum initial  investment, established by  Officers of  the
Fund.
 
    If  the  value of  a  New Account,  containing  Class A  shares  falls below
$500,000  (but   remains  at   or  above   $100,000)  because   of   shareholder
redemption(s),  the Fund will  notify the shareholder, and  if the account value
remains below  $500,000 (but  remains at  or above  $100,000) for  a  continuous
60-day period, the Class A shares in such account will convert to Class B shares
and will be subject to the distribution fee and other features applicable to the
Class  B shares. The Fund,  however, will not convert Class  A shares to Class B
shares based solely upon changes in the  market that reduce the net asset  value
of  shares. Under current tax  law, conversions between share  classes are not a
taxable event to the shareholder.
 
                                       18
<PAGE>
    Shares in a Portfolio account opened  prior to January 2, 1996 (a  "Pre-1996
Account")  were  designated Class  A  shares on  January  2, 1996.  Shares  in a
Pre-1996 Account  with  a  value  of  $100,000 or  more  on  March  1,  1996  (a
"Grandfathered  Class A  Account") remain Class  A shares  regardless of account
size thereafter. Except for  shares in a Managed  Account, shares in a  Pre-1996
Account  with a value of  less than $100,000 on  March 1, 1996 (a "Grandfathered
Class B account")  convert to  Class B shares  on March  1, 1996.  Grandfathered
Class A Accounts and Managed Accounts are not subject to conversion from Class A
shares to Class B shares.
 
    Investors  may also invest in the Fund  by purchasing shares through a trust
department, broker, dealer, agent, financial planner, financial services firm or
investment adviser.  An  investor  may  be  charged  an  additional  service  or
transaction fee by that institution. The minimum investment levels may be waived
at  the discretion  of the  Adviser for (i)  certain employees  and customers of
Morgan Stanley  or  its  affiliates  and  certain  trust  departments,  brokers,
dealers,  agents, financial  planners, financial  services firms,  or investment
advisers that  have  entered  into  an agreement  with  Morgan  Stanley  or  its
affiliates;  and (ii) retirement and deferred compensation plans and trusts used
to fund such  plans, including,  but not limited  to, those  defined in  Section
401(a),  403(b) or  457 of the  Internal Revenue  Code of 1986,  as amended, and
"rabbi trusts".  The  Fund  reserves  the  right  to  modify  or  terminate  the
conversion  features of  the shares  as stated above  at any  time upon 60-days'
notice to shareholders.
 
MINIMUM ACCOUNT SIZES AND INVOLUNTARY REDEMPTION OF SHARES
 
    If the value of  a New Account falls  below $100,000 because of  shareholder
redemption(s),  the Fund will  notify the shareholder, and  if the account value
remains below  $100,000 for  a  continuous 60-day  period,  the shares  in  such
account  are subject to redemption  by the Fund and,  if redeemed, the net asset
value of  such  shares will  be  promptly paid  to  the shareholder.  The  Fund,
however,  will not redeem  shares based solely  upon changes in  the market that
reduce the net asset value of shares.
 
    Grandfathered Class A Accounts, Grandfathered  Class B Accounts and  Managed
Accounts are not subject to involuntary redemption.
 
    The  Fund  reserves  the  right  to  modify  or  terminate  the  involuntary
redemption features of  the shares  as stated above  at any  time upon  60-days'
notice to shareholders.
 
CONVERSION FROM CLASS B TO CLASS A SHARES
 
    If the value of Class B shares in a Portfolio account increases, whether due
to  shareholder share  purchases or  market activity,  to $500,000  or more, the
Class B shares  will convert  to Class  A shares.  Under current  tax law,  such
conversion  is not a taxable event to  the shareholder. Class A shares converted
from Class B shares  are subject to the  same minimum account size  requirements
that  are applicable to New Accounts containing Class A shares, as stated above.
The Fund reserves the  right to modify or  terminate this conversion feature  at
any time upon 60-days' notice to shareholders.
 
                                       19
<PAGE>
INITIAL PURCHASES DIRECTLY FROM THE FUND
 
    The  Fund's determination of an investor's eligibility to purchase shares of
a given class  will take precedence  over the investor's  selection of a  class.
Assuming  the investor is eligible for the  class, the Fund will select the most
favorable class for the investor, if the investor has not done so.
 
1) BY CHECK.   An account may  be opened  by completing and  signing an  Account
   Registration Form and mailing it, together with a check ($500,000 minimum for
   Class  A  shares of  the Portfolio  and $100,000  for Class  B shares  of the
   Portfolio, with certain  exceptions for Morgan  Stanley employees and  select
   customers)  payable to "Morgan Stanley Institutional  Fund, Inc. -- U.S. Real
   Estate Portfolio", to:
 
      Morgan Stanley Institutional Fund, Inc.
      P.O. Box 2798
      Boston, Massachusetts 02208-2798
 
    Payment will  be accepted only  in U.S. dollars,  unless prior approval  for
  payment  by other currencies is given by  the Fund. The class(es) of shares of
  the Portfolio to be purchased should be designated on the Account Registration
  Form. For purchases  by check, the  Fund is ordinarily  credited with  Federal
  Funds  within one  business day.  Thus, your  purchase of  shares by  check is
  ordinarily credited to your account  at the net asset  value per share of  the
  Portfolio determined on the next business day after receipt.
 
2) BY  FEDERAL  FUNDS WIRE.   Purchases  may be  made by  having your  bank wire
   Federal Funds to the Fund's bank  account. In order to ensure prompt  receipt
   of your Federal Funds Wire, it is important that you follow these steps:
 
A.   Telephone  the Fund  (toll free: 1-800-548-7786)  and provide  us with your
    name, address,  telephone  number,  Social Security  or  Tax  Identification
    Number,  the  portfolio(s) selected,  the class  selected, the  amount being
    wired, and by  which bank.  We will  then provide  you with  a Fund  account
    number.  (Investors with existing accounts should also notify the Fund prior
    to wiring funds.)
 
B.   Instruct  your  bank to  wire  the  specified amount  to  the  Fund's  Wire
    Concentration  Bank Account (be sure  to have your bank  include the name of
    the portfolio(s)  selected,  the  class selected,  and  the  account  number
    assigned to you) as follows:
 
    Chase Manhattan Bank, N.A.
    One Manhattan Plaza
    New York, NY 10081-1000
    ABA #021000021
    DDA #910-2-733293
    Attn: Morgan Stanley Institutional Fund, Inc.
    Ref: (Portfolio name, your account number, your account name)
 
    Please call the Fund at 1-800-548-7786 prior to wiring funds.
 
C.   Complete and sign the Account Registration  Form and mail it to the address
    shown thereon.
 
                                       20
<PAGE>
  Purchase orders for shares  of the Portfolio which  are received prior to  the
  regular  close of the NYSE (currently 4:00 p.m. Eastern Time) will be executed
  at the price computed  on the date  of receipt as long  as the Transfer  Agent
  receives  payment by check or  in Federal Funds prior  to the regular close of
  the NYSE on such day.
 
  Federal Funds purchase orders will be accepted only on a day on which the Fund
  and Chase (the "Custodian Bank") are open for business. Your bank may charge a
  service fee for wiring Federal Funds.
 
3) BY BANK WIRE.   The  same procedure outlined  under "By  Federal Funds  Wire"
   above  must be  followed in  purchasing shares  by bank  wire. However, money
   transferred by bank wire may or may  not be converted into Federal Funds  the
   same  day, depending on the time the  money is received and the bank handling
   the wire. Prior to such conversion, an investor's money will not be invested.
   Your bank may charge a service fee for wiring funds.
 
ADDITIONAL INVESTMENTS
 
    You may  add to  your account  at any  time (minimum  additional  investment
$1,000  except  for  automatic  reinvestment  of  dividends  and  capital  gains
distributions for which there are no minimums) by purchasing shares at net asset
value by mailing a check to  the Fund (payable to "Morgan Stanley  Institutional
Fund,  Inc. --  U.S. Real Estate  Portfolio" at  the above address  or by wiring
monies to the Custodian Bank as outlined  above. It is very important that  your
account  name, the  portfolio name  and the class  selected be  specified in the
letter or wire to assure  proper crediting to your  account. In order to  insure
that  your wire orders are invested promptly, you are requested to notify one of
the Fund's representatives (toll free:  1-800-548-7786) prior to the wire  date.
Additional investments will be applied to purchase additional shares in the same
class held by a shareholder in a Portfolio account.
 
OTHER PURCHASE INFORMATION
 
    The purchase price of the Class A and Class B shares of the Portfolio is the
net  asset value next determined after the  order is received. See "Valuation of
Shares." An order received  prior to the  close of the  New York Stock  Exchange
("NYSE"),  which is currently  4:00 p.m. Eastern  Time, will be  executed at the
price computed on the date of receipt; an order received after the close of  the
NYSE  will be executed at the price computed on the next day the NYSE is open as
long as the Transfer Agent receives payment  by check or in Federal Funds  prior
to the regular close of the NYSE on such day.
 
    Although  the legal rights of Class A  and Class B shares will be identical,
the different expenses borne  by each class will  result in different net  asset
values  and dividends. The net  asset value of Class  B shares will generally be
lower than the net asset value of Class A shares as a result of the distribution
expense charged to Class B shares. It  is expected, however, that the net  asset
value  per share of the two classes  will tend to converge immediately after the
recording of dividends  which will  differ by  approximately the  amount of  the
distribution expense accrual differential between the classes.
 
    In  the interest  of economy and  convenience, and because  of the operating
procedures of the Fund, certificates  representing shares of the Portfolio  will
not  be issued. All shares  purchased are confirmed to  you and credited to your
account on the Fund's books  maintained by the Adviser  or its agents. You  will
have  the  same  rights  and  ownership  with  respect  to  such  shares  as  if
certificates had been issued.
 
                                       21
<PAGE>
    To ensure that checks are collected by the Fund, withdrawals of  investments
made  by check are  not presently permitted  until payment for  the purchase has
been received,  which may  take up  to eight  business days  after the  date  of
purchase.  As a condition  of this offering,  if a purchase  is cancelled due to
nonpayment or because your check does not clear, you will be responsible for any
loss the Fund or its  agents incur. If you are  already a shareholder, the  Fund
may  redeem shares from your account(s) to  reimburse the Fund or its agents for
any loss. In addition,  you may be prohibited  or restricted from making  future
investments in the Fund.
 
    Investors  may  also invest  in the  Fund by  purchasing shares  through the
Distributor.  See  "Purchase   of  Shares"  in   the  Statement  of   Additional
Information.
 
EXCESSIVE TRADING
 
    Frequent   trades  involving  either  substantial   portfolio  assets  or  a
substantial portion of your  account or accounts controlled  by you can  disrupt
management  of a portfolio and raise its expenses. Consequently, in the interest
of all the stockholders  of the Portfolio and  the Portfolio's performance,  the
Fund  may in its discretion bar a  stockholder that engages in excessive trading
of shares of any class  of a portfolio from further  purchases of shares of  the
Fund  for an indefinite period. The Fund  considers excessive trading to be more
than one purchase and sale involving shares of the same class of a portfolio  of
the  Fund  within  any  120-day  period. As  an  example,  exchanging  shares of
portfolios of the Fund as follows amounts to excessive trading: exchanging Class
A shares of Portfolio A for Class A shares of Portfolio B, then exchanging Class
A shares of Portfolio B for Class  A shares of Portfolio C and again  exchanging
Class A shares of Portfolio C for Class A shares of Portfolio B within a 120-day
period.  Two  types  of transactions  are  exempt from  these  excessive trading
restrictions: (1) trades  exclusively between money  market portfolios; and  (2)
trades  done  in  connection  with  an asset  allocation  service,  such  as TFM
Accounts, managed or advised by MSAM and/or any of its affiliates.
 
                              REDEMPTION OF SHARES
 
    You may  withdraw all  or  any portion  of the  amount  in your  account  by
redeeming  shares at any time. Please note  that purchases made by check are not
permitted to be redeemed until payment of the purchase price has been collected,
which may take up to  eight business days after  purchase. The Fund will  redeem
Class  A shares or  Class B shares of  the Portfolio at  the next determined net
asset value of shares of  the applicable class. On days  that both the NYSE  and
the  Custodian Bank are open for business, the  net asset value per share of the
Portfolio is determined at the close of trading of the NYSE (currently 4:00 p.m.
Eastern time). Shares of the Portfolio may be redeemed by mail or telephone.  No
charge  is made  for redemption.  Any redemption  may be  more or  less than the
purchase price of  your shares  depending on,  among other  factors, the  market
value of the investment securities held by the Portfolio.
 
BY MAIL
 
    The  Portfolio will redeem its  Class A shares or Class  B shares at the net
asset value determined on the  date the request is  received, if the request  is
received  in "good  order" before  the regular close  of the  NYSE. Your request
should be addressed to Morgan Stanley  Institutional Fund, Inc., P.O. Box  2798,
Boston,  Massachusetts 02208-2798,  except that deliveries  by overnight courier
should be addressed to Morgan Stanley Institutional Fund, Inc., c/o Chase Global
Funds Services Company, 73 Tremont Street, Boston, Massachusetts 02108-3913.
 
                                       22
<PAGE>
    "Good order"  means that  the  request to  redeem  shares must  include  the
following documentation:
 
        (a)  A letter of instruction or a stock assignment specifying the number
    of  shares or dollar amount to be  redeemed, signed by all registered owners
    of the shares in the exact names in which they are registered;
 
        (b)  Any  required   signature  guarantees   (see  "Further   Redemption
    Information" below); and
 
        (c)    Other supporting  legal documents,  if required,  in the  case of
    estates, trusts,  guardianships, custodianships,  corporations, pension  and
    profit sharing plans and other organizations.
 
    Shareholders who are uncertain of requirements for redemption should consult
with a Morgan Stanley Institutional Fund representative.
 
BY TELEPHONE
 
    Provided  you have previously elected the Telephone Redemption Option on the
Account Registration  Form, you  can  request a  redemption  of your  shares  by
calling  the Fund  and requesting  the redemption proceeds  be mailed  to you or
wired to your bank.  Please contact one of  Morgan Stanley Institutional  Fund's
representatives  for further details. In times of drastic market conditions, the
telephone redemption option  may be  difficult to implement.  If you  experience
difficulty in making a telephone redemption, your request may be made by mail or
overnight courier and will be implemented at the net asset value next determined
after  it is received. Redemption requests sent to the Fund through express mail
must be mailed  to the  address of the  Dividend Disbursing  and Transfer  Agent
listed  under "General Information". The Fund and the Fund's transfer agent (the
"Transfer  Agent")  will  employ  reasonable  procedures  to  confirm  that  the
instructions  communicated by  telephone are  genuine. These  procedures include
requiring the investor to provide certain personal identification information at
the time an account is opened and prior to effecting each transaction  requested
by  telephone. In addition, all telephone  transaction requests will be recorded
and  investors  may  be  required  to  provide  additional  telecopied   written
instructions  regarding transaction requests. Neither  the Fund nor the Transfer
Agent will be responsible for any loss, liability, cost or expense for following
instructions received by telephone that either of them reasonably believes to be
genuine.
 
    To change the commercial  bank or account  designated to receive  redemption
proceeds,  a written  request must  be sent  to the  Fund at  the address above.
Requests to change the bank  or account must be  signed by each shareholder  and
each signature must be guaranteed.
 
FURTHER REDEMPTION INFORMATION
 
    Normally  the  Fund will  make payment  for all  shares redeemed  within one
business day of receipt  of the request,  but in no event  will payment be  made
more  than  seven days  after receipt  of  a redemption  request in  good order.
However, payments to investors  redeeming shares which  were purchased by  check
will  not be made until  payment for the purchase  has been collected, which may
take up to eight days after the date of purchase. The Fund may suspend the right
of redemption or postpone the date upon which redemptions are effected at  times
when  the NYSE is closed, or under  any emergency circumstances as determined by
the Securities and Exchange Commission (the "Commission").
 
    If the Board  of Directors determines  that it would  be detrimental to  the
best  interests of the  remaining shareholders of the  Portfolio to make payment
wholly or partly in cash, the Fund  may pay the redemption proceeds in whole  or
in part by a distribution in-kind of securities held by the Portfolio in lieu of
cash in
 
                                       23
<PAGE>
conformity  with applicable rules of  the Commission. Distributions-in-kind will
be made in readily marketable securities. Investors may incur brokerage  charges
on the sale of portfolio securities so received in payment of redemptions.
 
    To  protect  your account,  the Fund  and its  agents from  fraud, signature
guarantees are required for  certain redemptions to verify  the identity of  the
person  who has  authorized a redemption  from your account.  Please contact the
Fund for further  information. See "Redemption  of Shares" in  the Statement  of
Additional Information.
 
                              SHAREHOLDER SERVICES
 
EXCHANGE FEATURES
 
    You  may exchange  shares that you  own in  the Portfolio for  shares of any
other available  portfolio of  the  Fund (other  than the  International  Equity
Portfolio,  which is  closed to  new investors). In  exchanging for  shares of a
portfolio with more  than one  class, the  class of  shares you  receive in  the
exchange  will be determined in the same  manner as any other purchase of shares
and will not  be based  on the  class of  shares surrendered  for the  exchange.
Consequently,  the same minimum initial investment  and minimum account size for
determining the  class  of shares  received  in  the exchange  will  apply.  See
"Purchase  of Shares."  Shares of  the portfolios  may be  exchanged by  mail or
telephone. The privilege to exchange shares  by telephone is automatic and  made
available  without shareholder election. Before you make an exchange, you should
read the prospectus of the portfolio(s) in which you seek to invest. Because  an
exchange  transaction  is treated  as a  redemption followed  by a  purchase, an
exchange would be considered  a taxable event for  shareholders subject to  tax.
The  exchange privilege  is only available  with respect to  portfolios that are
registered for  sale  in  a  shareholder's  state  of  residence.  The  exchange
privilege  may be modified or  terminated by the Fund  at any time upon 60-days'
notice to shareholders.
 
BY MAIL
 
    In order to  exchange shares  by mail, you  should include  in the  exchange
request  the name, class of shares and account number of your current portfolio,
the names of the portfolio(s) and class(es)  of shares into which you intend  to
exchange  shares, and the signatures of all registered account holders. Send the
exchange request to Morgan  Stanley Institutional Fund,  P.O. Box 2798,  Boston,
Massachusetts 02208-2798.
 
BY TELEPHONE
 
    When  exchanging shares by  telephone, have ready the  name, class of shares
and account number of the current  Portfolio, the names of the portfolio(s)  and
class(es)  of  shares into  which  you intend  to  exchange shares,  your Social
Security number  or Tax  I.D. number,  and your  account address.  Requests  for
telephone  exchanges received prior to 4:00 p.m. (Eastern time) are processed at
the close of business that same day based on the net asset value of the class of
the Portfolios involved in the exchange of the shares at the close of  business.
Requests received after 4:00 p.m. (Eastern time) are processed the next business
day  based on the  net asset value determined  at the close  of business on such
day. For additional information regarding responsibility for the authenticity of
telephoned instructions, see "Redemption of Shares -- By Telephone" above.
 
TRANSFER OF REGISTRATION
 
    You may transfer  the registration  of any of  your Fund  shares to  another
person  by writing  to Morgan Stanley  Institutional Fund, Inc.,  P.O. Box 2798,
Boston,  Massachusetts  02208-2798.   As  in  the   case  of  redemptions,   the
 
                                       24
<PAGE>
written  request must be received in good order before any transfer can be made.
Transferring the  registration of  shares  may affect  the eligibility  of  your
account  for  a  given  class  of  the  Portfolio's  shares  and  may  result in
involuntary conversion or redemption  of your shares.  See "Purchase of  Shares"
above.
 
                              VALUATION OF SHARES
 
    The  net asset  value per  share of a  class of  shares of  the Portfolio is
determined by dividing the total market value of the Portfolio's investments and
other assets attributable to  such class, less  any liabilities attributable  to
such  class, by  the total  number of  outstanding shares  of such  class of the
Portfolio. Net  asset value  is  calculated separately  for  each class  of  the
Portfolio.  Net asset value per share is determined  as of the close of the NYSE
on each day  that the NYSE  is open  for business. Price  information on  listed
securities  is taken from  the exchange where the  security is primarily traded.
Securities listed on a U.S. securities exchange for which market quotations  are
available  are valued at the last quoted sale  price on the day the valuation is
made. Securities listed on a foreign exchange are valued at their closing price.
Unlisted securities and listed securities not  traded on the valuation date  for
which  market quotations are not readily available are valued at a price that is
considered to best  represent fair value  within a  range not in  excess of  the
current  asked price nor  less than the  current bid price.  The current bid and
asked prices are determined  based on the  bid and asked  prices quoted on  such
valuation date by reputable brokers.
 
    Bonds and other fixed income securities are valued according to the broadest
and  most representative market,  which will ordinarily  be the over-the-counter
market. Net asset value includes interest  on fixed income securities, which  is
accrued  daily.  In addition,  bonds and  other fixed  income securities  may be
valued on the basis of prices provided by a pricing service when such prices are
believed to  reflect  the fair  market  value  of such  securities.  The  prices
provided  by a pricing service are determined without regard to bid or last sale
prices, but take into  account institutional-size trading  in similar groups  of
securities  and any developments related  to the specific securities. Securities
not priced in this manner are valued at the most recently quoted sale price,  or
when  securities exchange valuations are used, at the latest quoted bid price on
the day of valuation. If there is  no such reported sale, the latest quoted  bid
price will be used. Securities purchased with remaining maturities of 60 days or
less are valued at amortized cost, if it approximates market value. In the event
that  amortized  cost  does  not  approximate  market  value,  market  prices as
determined above will be used.
 
    The value of other assets and securities for which no quotations are readily
available (including  restricted  and  unlisted foreign  securities)  and  those
securities  for which it is inappropriate to determine prices in accordance with
the above-stated procedures  are determined in  good faith at  fair value  using
methods  determined by the  Board of Directors. For  purposes of calculating net
asset value per share, all assets and liabilities initially expressed in foreign
currencies will  be  translated into  U.S.  dollars at  the  bid price  of  such
currencies against the U.S. dollar last quoted by any major bank.
 
    Although  the legal rights of Class A  and Class B shares will be identical,
the different expenses borne  by each class will  result in different net  asset
values  and dividends for the class.  Dividends will differ by approximately the
amount of the distribution expense  accrual differential among the classes.  The
net  asset value of  Class B shares will  generally be lower  than the net asset
value of the Class A shares as  a result of the distribution expense charged  to
Class B shares.
 
                                       25
<PAGE>
                            PERFORMANCE INFORMATION
 
    The  Fund may from time to time advertise total return for each class of the
Portfolio. THESE FIGURES ARE BASED ON  HISTORICAL EARNINGS AND ARE NOT  INTENDED
TO INDICATE FUTURE PERFORMANCE. The "total return" shows what an investment in a
class  of the Portfolio would have earned  over a specified period of time (such
as one, five or ten years), assuming that all distributions and dividends by the
Portfolio were reinvested in the same class on the reinvestment dates during the
period. Total return  does not  take into account  any federal  or state  income
taxes that may be payable on dividends and distributions or upon redemption. The
Fund  may  also include  comparative performance  information in  advertising or
marketing  the  Portfolio's  shares,  including  data  from  Lipper   Analytical
Services,  Inc.,  other  industry  publications,  business  periodicals,  rating
services and market indices.
 
    The performance figures  for Class  B shares  will generally  be lower  than
those  for Class  A shares because  of the  distribution fee charged  to Class B
shares.
 
                   DIVIDENDS AND CAPITAL GAINS DISTRIBUTIONS
 
    All income dividends and capital gains  distributions for a class of  shares
will be automatically reinvested in additional shares of such class at net asset
value,  except that,  upon written  notice to  the Fund  or by  checking off the
appropriate box in the Distribution  Option Section on the Account  Registration
Form,  a shareholder  may elect  to receive  income dividends  and capital gains
distributions in cash.
 
    The Portfolio expects to distribute substantially all of its net  investment
income  in the form of quarterly dividends  beginning with a distribution at the
end of the first calendar quarter of 1996. Net realized gains for the Portfolio,
if any, after reduction for any tax loss carryforwards will also be  distributed
annually.  Confirmations of the purchase of  shares of the Portfolio through the
automatic reinvestment of income dividends and capital gains distributions  will
be  provided, pursuant  to Rule 10b-10(b)  under the Securities  Exchange Act of
1934, as amended, on the next  monthly client statement following such  purchase
of shares. Consequently, confirmations of such purchases will not be provided at
the time of completion of such purchases, as might otherwise be required by Rule
10b-10.
 
    Undistributed  net  investment income  is  included in  the  Portfolio's net
assets for the purpose of calculating  net asset value per share. Therefore,  on
the  "ex-dividend" date,  the net  asset value  per share  excludes the dividend
(i.e., is  reduced by  the per  share amount  of the  dividend). Dividends  paid
shortly after the purchase of shares by an investor, although in effect a return
of capital, are taxable to shareholders subject to income tax.
 
    Because  of  the  distribution  fee  and  any  other  expenses  that  may be
attributable to  the Class  B shares,  the net  income attributable  to and  the
dividends  payable  on  Class  B  shares  will  be  lower  than  the  net income
attributable to and the dividends  payable on Class A  shares. As a result,  the
net  asset value per share of the classes of the Portfolio will differ at times.
Expenses of the Portfolio allocated to a particular class of shares thereof will
be borne on a pro rata basis by each outstanding share of that class.
 
                                     TAXES
 
    The following summary of certain federal income tax consequences is based on
current tax laws and regulations, which may be changed by legislative, judicial,
or administrative action.
 
                                       26
<PAGE>
    No attempt has been made to  present a detailed explanation of the  federal,
state,  or  local income  tax treatment  of the  Portfolio or  its shareholders.
Accordingly, shareholders  are urged  to consult  their tax  advisers  regarding
specific questions as to federal, state and local income taxes.
 
    The  Portfolio  is  treated as  a  separate  entity for  federal  income tax
purposes and  is  not combined  with  the Fund's  other  portfolios. It  is  the
Portfolio's intent to continue to qualify for the special tax treatment afforded
regulated  investment  companies under  Subchapter M  of the  Code, so  that the
Portfolio will continue to be relieved of federal income tax on that part of its
net investment income and net capital gain that is distributed to shareholders.
 
    The Portfolio distributes  substantially all  of its  net investment  income
(including, for this purpose, the excess of net short-term capital gain over net
long-term  capital  loss) to  shareholders. Dividends  from the  Portfolio's net
investment income  are  taxable  to shareholders  as  ordinary  income,  whether
received  in cash or in additional shares. The Portfolio will report annually to
its shareholders  the amount  of dividend  income qualifying  for the  corporate
dividend received deduction.
 
    Distributions  of net capital gain (the excess of net long-term capital gain
over net  short-term capital  loss)  are taxable  to shareholders  as  long-term
capital  gain, regardless of  how long shareholders have  held their shares. The
Portfolio sends reports annually to its  shareholders of the federal income  tax
status of all distributions made during the preceding year.
 
    The   Portfolio  intends   to  make   sufficient  distributions   or  deemed
distributions of its ordinary income and capital gain net income (the excess  of
short-term  and long-term  capital gains  over short-term  and long-term capital
losses) prior to the end  of each calendar year  to avoid liability for  federal
excise tax.
 
    Dividends  and  other distributions  declared by  the Portfolio  in October,
November or December of any year and payable to shareholders of record on a date
in such month will be deemed to have been paid by the Portfolio and received  by
the  shareholders on December 31  of that year if  the distributions are paid by
the Portfolio at any time during the following January.
 
    The sale, redemption  or exchange of  shares may result  in taxable gain  or
loss to the selling, exchanging or redeeming shareholder, depending upon whether
the fair market value of the sale, exchange or redemption proceeds exceeds or is
less  than the shareholder's  adjusted basis in the  redeemed, exchanged or sold
shares. Any such  taxable gain or  loss generally will  be treated as  long-term
capital  gain or loss  if the shares have  been held for more  than one year and
otherwise generally  will be  treated as  short-term capital  gain or  loss.  If
capital  gain distributions have been made with  respect to shares that are sold
at a loss after  being held for six  months or less, however,  then the loss  is
treated  as  a  long-term  capital  loss  to  the  extent  of  the  capital gain
distributions.
 
    The conversion of Class A shares to  Class B shares should not be a  taxable
event to the shareholder.
 
    Investment  income  received by  the Portfolio  from sources  within foreign
countries may be subject to foreign income taxes withheld at the source. To  the
extent  that the Portfolio is  liable for foreign income  taxes so withheld, the
Portfolio intends to operate so as to meet the requirements of the Code to  pass
through  to the shareholders credit for  foreign income taxes paid. Although the
Portfolio intends to  meet Code  requirements to  pass through  credit for  such
taxes, there can be no assurance that the Portfolio will be able to do so.
 
                                       27
<PAGE>
    Shareholders  are urged  to consult with  their tax  advisers concerning the
application of state  and local income  taxes to investments  in the  Portfolio,
which may differ from the federal income tax consequences described above.
 
    THE   TAX  DISCUSSION  SET  FORTH  ABOVE  IS  INCLUDED  HEREIN  FOR  GENERAL
INFORMATION ONLY. PROSPECTIVE  INVESTORS SHOULD CONSULT  THEIR OWN TAX  ADVISERS
WITH RESPECT TO THE TAX CONSEQUENCES TO THEM OF AN INVESTMENT IN A PORTFOLIO.
 
                             PORTFOLIO TRANSACTIONS
 
    The  Investment  Advisory Agreement  authorizes  the Adviser  to  select the
brokers or  dealers that  will execute  the purchases  and sales  of  investment
securities  for the Portfolio and directs the Adviser to use its best efforts to
obtain the best available price and most favorable execution with respect to all
transactions for  the Portfolio.  The Fund  has authorized  the Adviser  to  pay
higher commissions in recognition of brokerage services which, in the opinion of
the Adviser, are necessary for the achievement of better execution, provided the
Adviser believes this to be in the best interest of the Fund.
 
    Since  shares of the Portfolio are not marketed through intermediary brokers
or dealers, it  is not the  Fund's practice to  allocate brokerage or  principal
business  on the basis of sales of shares  which may be made through such firms.
However, the Adviser  may place portfolio  orders with qualified  broker-dealers
who  recommend the Portfolio or  who act as agents in  the purchase of shares of
the Fund's portfolios for their clients.
 
    In purchasing and  selling securities for  the Portfolio, it  is the  Fund's
policy  to seek to obtain quality execution at the most favorable prices through
responsible  broker-dealers.  In   selecting  broker-dealers   to  execute   the
securities  transactions for the Portfolio, consideration  will be given to such
factors as the price of the security,  the rate of the commission, the size  and
difficulty  of  the  order,  the  reliability,  integrity,  financial condition,
general execution and operational capabilities of competing broker-dealers,  and
the  brokerage  and  research services  which  they  provide to  the  Fund. Some
securities considered for investment  by the Portfolio  may also be  appropriate
for  other clients served by the Adviser.  If the purchase or sale of securities
consistent with the  investment policies  of the Portfolio  and one  or more  of
these  other clients served  by the Adviser  is considered at  or about the same
time, transactions in such securities will be allocated among the Portfolio  and
such  other  clients in  a manner  deemed  fair and  reasonable by  the Adviser.
Although there is  no specified  formula for allocating  such transactions,  the
various  allocation  methods  used  by  the Adviser,  and  the  results  of such
allocations, are subject to periodic review by the Fund's Board of Directors.
 
    Subject to the overriding objective of obtaining the best possible execution
of orders,  the Adviser  may allocate  a portion  of the  Portfolio's  brokerage
transactions  to Morgan Stanley or broker affiliates of Morgan Stanley. In order
for Morgan Stanley or  its affiliates to effect  any portfolio transactions  for
the Fund, the commissions, fees or other remuneration received by Morgan Stanley
or such affiliates 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   a
securities  exchange during a comparable period  of time. Furthermore, the Board
of   Directors    of    the    Fund,   including    a    majority    of    those
 
                                       28
<PAGE>
Directors  who are not  "interested persons," as  defined in the  1940 Act, have
adopted  procedures  which   are  reasonably  designed   to  provide  that   any
commissions,  fees  or  other  remuneration  paid  to  Morgan  Stanley  or  such
affiliates are consistent with the foregoing standard.
 
    Portfolio securities will not  be purchased from or  through, or sold to  or
through,  the Adviser or Morgan Stanley  or any "affiliated persons," as defined
in the 1940 Act of Morgan Stanley  when such entities are acting as  principals,
except to the extent permitted by law.
 
    Although  the  Portfolio will  not invest  for short-term  trading purposes,
investment securities may be sold from time to time without regard to the length
of time they have been held. It is anticipated that under normal  circumstances,
the annual portfolio turnover rate will not exceed 100%. High portfolio turnover
involves  correspondingly greater transaction costs which will be borne directly
by the respective Portfolio. In addition, high portfolio turnover may result  in
more capital gains which would be taxable to the shareholders of the Portfolio.
 
                              GENERAL INFORMATION
 
DESCRIPTION OF COMMON STOCK
 
    The  Fund was  organized as  a Maryland  corporation on  June 16,  1988. The
Articles of Incorporation, as amended and restated, permit the Fund to issue  up
to  34 billion shares of common stock,  with $.001 par value per share. Pursuant
to the Fund's Articles of Incorporation, the Board of Directors may increase the
number of shares the  Fund is authorized  to issue without  the approval of  the
shareholders  of the  Fund. Subject  to the  notice period  to shareholders with
respect to shares held by the shareholders, the Board of Directors has the power
to designate one or more classes of  shares of common stock and to classify  and
reclassify  any  unissued shares  with respect  to such  classes. The  shares of
common stock of each  portfolio are currently classified  into two classes,  the
Class  A shares and the Class B  shares, except for the International Small Cap,
Money Market and  Municipal Money Market  Portfolios, which only  offer Class  A
shares.
 
    The shares of the Portfolio, when issued, will be fully paid, nonassessable,
fully  transferable and redeemable at the option  of the holder. The shares have
no preference  as  to  conversion,  exchange,  dividends,  retirement  or  other
features  and  have no  pre-emptive  rights. The  shares  of the  Portfolio have
non-cumulative voting rights, which means that  the holders of more than 50%  of
the  shares voting for the election of Directors can elect 100% of the Directors
if they choose  to do so.  Persons or organizations  owning 25% or  more of  the
outstanding  shares of the Portfolio may be presumed to "control" (as defined in
the 1940 Act) the  Portfolio. Under Maryland  law, the Fund  is not required  to
hold  an annual meeting of  its shareholders unless required  to do so under the
1940 Act.
 
REPORTS TO SHAREHOLDERS
 
    The Fund will send to its  shareholders annual and semi-annual reports;  the
financial  statements  appearing in  annual reports  are audited  by independent
accountants. Monthly unaudited portfolio  data is also  available from the  Fund
upon request.
 
    In addition, the Adviser, or its agent, as Transfer Agent, will send to each
shareholder having an account directly with the Fund a monthly statement showing
transactions in the account, the total number of shares owned, and any dividends
or distributions paid.
 
                                       29
<PAGE>
CUSTODIAN
 
    As  of September 1,  1995, domestic securities  and cash are  held by Chase,
which replaced U.S.  Trust as  the Fund's domestic  custodian. Chase  is not  an
affiliate  of  the Adviser  or the  Distributor.  Morgan Stanley  Trust Company,
Brooklyn, New York ("MSTC"),  an affiliate of the  Adviser and the  Distributor,
acts  as the Fund's custodian for foreign  assets held outside the United States
and employs subcustodians  approved by  the Board of  Directors of  the Fund  in
accordance  with regulations of  the Securities and  Exchange Commission for the
purpose of providing  custodial services  for such  assets. MSTC  may also  hold
certain  domestic assets for  the Fund. For more  information on the custodians,
see "General Information -- Custody Arrangements" in the Statement of Additional
Information.
 
DIVIDEND DISBURSING AND TRANSFER AGENT
 
    Chase  Global   Funds  Services   Company,   73  Tremont   Street,   Boston,
Massachusetts 02108-3913, acts as Dividend Disbursing and Transfer Agent for the
Fund.
 
INDEPENDENT ACCOUNTANTS
 
    Price  Waterhouse LLP  serves as  independent accountants  for the  Fund and
audits the annual financial statements of each portfolio.
 
LITIGATION
 
    The Fund is not involved in any litigation.
 
                                       30
<PAGE>
   MORGAN STANLEY INSTITUTIONAL FUND, INC.
          U.S. REAL ESTATE PORTFOLIO
           P.O. BOX 2798, BOSTON, MA 02208-2798
 
                           ACCOUNT REGISTRATION FORM
 
<TABLE>
<C>   <S>                                       <C>
                                                If you need assistance in filling out this form for the
      ACCOUNT INFORMATION                       Morgan Stanley Institutional Fund, please contact your
      Fill in where applicable                  Morgan Stanley representative or call us toll free
                                                1-(800)-548-7786. Please print all items except signature,
                                                and mail to the Fund at the address above.
 
  A)  REGISTRATION
      1. INDIVIDUAL
      2. JOINT TENANTS
         (RIGHTS OF SURVIVORSHIP PRESUMED
      UNLESS
         TENANCY IN COMMON
         IS INDICATED)
</TABLE>
 
1.
                               First
Name                          Initial                               Last Name
 
2.
                               First
Name                          Initial                               Last Name
 
                               First
Name                          Initial                               Last Name
 
<TABLE>
<C>   <S>                                       <C>
      3. CORPORATIONS,
         TRUSTS AND OTHERS
         Please call the Fund for additional
      documents that may be required to set up
      account and to authorize transactions.
</TABLE>
 
3.
 
<TABLE>
<S>                     <C>                 <C>                   <C>               <C>
Type of Registration:   / / INCORPORATED    / / UNINCORPORATED    / / PARTNERSHIP   / / UNIFORM GIFT/TRANSFER TO MINOR
                                            ASSOCIATION                               (ONLY ONE CUSTODIAN AND MINOR PERMITTED)
</TABLE>
 
/ / TRUST ________________________  / / OTHER (Specify) ________________________
 
<TABLE>
<C>   <S>                                       <C>
  B)  MAILING ADDRESS
      Please fill in completely, including
      telephone number(s).
</TABLE>
 
Street or P.O. Box
City                                                                       State
                                                                             Zip
                                                                              --
Home Telephone No.                                                   Business
Telephone No.                     --            --              --            --
/ / United States Citizen  / / Resident Alien  / / Non-Resident Alien: Indicate
Country of Residence ___________________________________________________________
 
<TABLE>
<C>   <S>                                       <C>                                       <C>
  C)  TAXPAYER                                  Enter  your Taxpayer Identification Number. For most individual taxpayers, this is
      IDENTIFICATION                            your Social Security Number.
      NUMBER
      1. INDIVIDUAL
      2. JOINT TENANTS
         (RIGHTS OF SURVIVORSHIP PRESUMED
      UNLESS
         TENANCY IN COMMON
         IS INDICATED)
      For Custodian account
      of a minor (Uniform
      Gifts/Transfers to Minor
      Acts), give the Social
      Security Number of
      the minor
                                                                                          OR
                                                1.         TAXPAYER IDENTIFICATION        SOCIAL SECURITY NUMBER
                                                NUMBER ("TIN")                            ("SSN")
                                                                                          OR
                                                2.                                                          TIN SSN
</TABLE>
<PAGE>
<TABLE>
<C>   <S>                                       <C>                                       <C>
                                                                                          OR
                                                TIN                                       SSN
 
                                                IMPORTANT TAX INFORMATION
                                                You  (as a payee) are required  by law to provide us  (as payer) with your correct
                                                TIN(s) or SSN(s). Accounts that have a missing or incorrect TIN(s) or SSN(s)  will
                                                be  subject to backup  withholding at a  31% rate on  dividends, distributions and
                                                other payments. If you have  not provided us with  your correct TIN(s) or  SSN(s),
                                                you  may be  subject to  a $50  penalty imposed  by the  Internal Revenue Service.
                                                Backup withholding is not an additional tax; the tax liability of persons  subject
                                                to  backup  withholding  will  be  reduced  by  the  amount  of  tax  withheld. If
                                                withholding results  in  an  overpayment  of taxes,  a  refund  may  be  obtained.
                                                You  may be  notified that  you are  subject to  backup withholding  under Section
                                                3406(a)(1)(C) of the Internal Revenue Code because you have underreported interest
                                                or dividends or you  were required to,  but failed to, file  a return which  would
                                                have included a reportable interest or dividend payment.
</TABLE>
 
<PAGE>
 
<TABLE>
<C>   <S>                                       <C>                             <C>                   <C>
  D)  PORTFOLIO AND                             For Purchase of the following   / / Class A Shares $  / / Class B Shares $
      CLASS SECTION                             Portfolio:
      (Class A shares minimum $500,000 for      U.S. Real Estate Portfolio
      each Portfolio and Class B shares
      minimum $100,000 for the Global Equity,
      International Equity, Asian Equity,
      European Equity, Japanese Equity and
      Latin American Equity Portfolios).
      Please indicate Portfolio, class and
      amount.
                                                                                Total Initial Investment $
</TABLE>
 
<TABLE>
<C>   <S>                                       <C>
  E)  METHOD OF
      INVESTMENT
      Please indicate portfolio, manner of
      payment.
</TABLE>
 
Payment by:
 
/ / Check (MAKE CHECK PAYABLE TO MORGAN STANLEY INSTITUTIONAL FUND,
INC.--PORTFOLIO NAME)
 
<TABLE>
<S>                                                                                 <C>
/ / Exchange $ From                                                                           -- - - - - - - - - - -- - -
                                                      Name of Portfolio                               Account No.
/ / Account previously established by:  / / Phone exchange  / / Wire on                       -- - - - - - - - - - -- - -
                                                                                            Account No.               (Check
                                                                                      (Previously assigned by the Fund)     Digit)
                                                                            Date
</TABLE>
 
<TABLE>
<C>   <S>                                       <C>
  F)  DISTRIBUTION                              Income dividends and capital gains distributions (if any) to
      OPTION                                    be reinvested in additional shares unless either box below
                                                is checked.
                                                / / Income dividends to be paid in cash, capital gains
                                                distributions (if any) in shares.
                                                / / Income dividends and capital gains distributions (if
                                                any) to be paid in cash.
</TABLE>
<TABLE>
<C>   <S>                             <C>
  G)  TELEPHONE                       / / I/we hereby authorize the Fund and
      REDEMPTION                      its agents to honor any telephone
      AND EXCHANGE                    requests to wire redemption proceeds to
      OPTION                          the commercial bank indicated at right
      Please select at time of        and/or mail redemption proceeds to the
      initial application if you      name and address in which my/our fund
      wish to redeem or exchange      account is registered if such requests
      shares by telephone. A          are believed to be authentic.
      SIGNATURE GUARANTEE IS          The Fund and the Fund's Transfer Agent
      REQUIRED IF BANK ACCOUNT IS     will employ reasonable procedures to
      NOT REGISTERED IDENTICALLY TO   confirm that instructions communicated
      YOUR FUND ACCOUNT.              by telephone are genuine. These
      TELEPHONE REQUESTS FOR          procedures include requiring the
      REDEMPTIONS OR EXCHANGE WILL    investor to provide certain personal
      NOT BE HONORED UNLESS THE BOX   identification information at the time
      IS CHECKED.                     an account is opened and prior to
                                      effecting each transaction requested by
                                      telephone. In addition, all telephone
                                      transaction requests will be recorded
                                      and investors may be required to provide
                                      additional telecopied written
                                      instructions of transaction requests.
                                      Neither the Fund nor the Transfer Agent
                                      will be responsible for any loss,
                                      liability, cost or expense for following
                                      instructions received by telephone that
                                      it reasonably believes to be genuine.
 
<CAPTION>
  G)
      Name of COMMERCIAL Bank (Not Savings Bank)
      Bank Account No.
                                                   Bank ABA No.
      Name(s) in which your BANK Account is Established
      Bank's Street Address
      City                           State                           Zip
</TABLE>
 
<TABLE>
<C>   <S>                        <C>
  H)  INTERESTED PARTY
      OPTION                                                                                      Name
      In addition to the
      account statement sent to
      my/our registered                                                                          Address
      address, I/we hereby
      authorize the fund to      City         State         Zip Code
      mail duplicate statements
      to the name and address
      provided at right.
</TABLE>
 
<TABLE>
<C>   <S>                                       <C>
  I)  DEALER
      INFORMATION
                                                Representative Name                        Representative
                                                No.                            Branch
                                                No.
</TABLE>
 
<PAGE>
 
<TABLE>
<C>   <S>                                       <C>
  J)  SIGNATURE OF
      ALL HOLDERS
      AND TAXPAYER
      CERTIFICATION
      Sign Here ,
</TABLE>
 
<TABLE>
<S>                                                           <C>
The undersigned certify that I/we have full authority and legal capacity to purchase and redeem shares of the Fund and
affirm that I/we have received a current Prospectus of the Morgan Stanley Institutional Fund, Inc. and agree to be bound
by its terms.
  BY  SIGNING THIS APPLICATION, I/WE HEREBY CERTIFY UNDER PENALTIES OF PERJURY THAT THE INFORMATION ON THIS APPLICATION IS
COMPLETE AND CORRECT AND THAT AS REQUIRED BY FEDERAL LAW (PLEASE CHECK APPLICABLE BOXES BELOW):
/ / U.S. CITIZEN(S)/TAXPAYER(S):
       / / I/WE CERTIFY THAT (1) THE NUMBER(S) SHOWN ABOVE ON  THIS FORM IS/ARE THE CORRECT SSN(S) OR TIN(S) AND (2)  I/WE
           ARE  NOT SUBJECT TO ANY BACKUP WITHHOLDING EITHER BECAUSE (A) I/WE ARE EXEMPT FROM BACKUP WITHHOLDING; (B) I/WE
           HAVE NOT BEEN NOTIFIED BY THE INTERNAL REVENUE SERVICE ("IRS") THAT I/WE ARE SUBJECT TO BACKUP WITHHOLDING AS A
           RESULT OF A FAILURE TO REPORT ALL INTEREST OR DIVIDENDS; OR (C) THE IRS HAS NOTIFIED ME/US THAT I AM/WE ARE  NO
           LONGER SUBJECT TO BACKUP WITHHOLDING.
       /  / IF NO TIN(S) OR SSN(S) HAS/HAVE BEEN PROVIDED ABOVE, I/WE  HAVE APPLIED, OR INTEND TO APPLY, TO THE IRS OR THE
           SOCIAL SECURITY ADMINISTRATION FOR A TIN OR A SSN AND I/WE UNDERSTAND THAT IF I/WE DO NOT PROVIDE EITHER NUMBER
           TO CHASE GLOBAL FUNDS SERVICES COMPANY ("CGFSC") WITHIN 60 DAYS OF THE DATE OF THIS APPLICATION OR IF I/WE FAIL
           TO FURNISH MY/OUR CORRECT SSN(S) OR TIN(S),  I/WE MAY BE SUBJECT TO A  PENALTY AND A 31% BACKUP WITHHOLDING  ON
           DISTRIBUTIONS  AND REDEMPTION PROCEEDS.  (PLEASE PROVIDE EITHER NUMBER  ON IRS FORM W-9).  YOU MAY REQUEST SUCH
           FORM BY CALLING CGFSC AT 800-282-4404.
/ / NON-U.S. CITIZEN(S)/TAXPAYER(S):
  INDICATE COUNTRY OF RESIDENCE FOR TAX PURPOSES:
  UNDER PENALTIES OF  PERJURY, I/WE CERTIFY  THAT I/WE  ARE NOT U.S.  CITIZENS OR  RESIDENTS AND I/WE  ARE EXEMPT  FOREIGN
PERSONS AS DEFINED BY THE INTERNAL REVENUE SERVICE.
THE INTERNAL REVENUE SERVICE DOES NOT REQUIRE YOUR CONSENT TO ANY PROVISION OF THIS DOCUMENT OTHER THAN THE CERTIFICATIONS
REQUIRED TO AVOID BACKUP WITHHOLDING.
 
(X)                                                           (X)
Signature                                                     Date Signature (if joint account, both must sign)   Date
</TABLE>
<PAGE>
- -------------------------------------------
- -------------------------------------------
- -------------------------------------------
- -------------------------------------------
 
  NO  DEALER, SALES  REPRESENTATIVE OR ANY  OTHER PERSON HAS  BEEN AUTHORIZED TO
GIVE ANY INFORMATION OR TO MAKE ANY REPRESENTATIONS, OTHER THAN THOSE  CONTAINED
IN THIS PROSPECTUS, IN CONNECTION WITH THE OFFER MADE BY THIS PROSPECTUS AND, IF
GIVEN OR MADE, SUCH OTHER INFORMATION OR REPRESENTATIONS MUST NOT BE RELIED UPON
AS  HAVING BEEN AUTHORIZED BY THE FUND  OR THE DISTRIBUTOR. THIS PROSPECTUS DOES
NOT CONSTITUTE AN OFFER BY THE FUND OR THE DISTRIBUTOR TO SELL OR A SOLICITATION
OF AN OFFER TO BUY ANY OF  THE SECURITIES OFFERED HEREBY IN ANY JURISDICTION  TO
ANY  PERSON TO WHOM  IT IS UNLAWFUL TO  MAKE SUCH OFFER  OR SOLICITATION IN SUCH
JURISDICTION.
 
                           --------------------------
 
                               TABLE OF CONTENTS
 
<TABLE>
<S>                                                 <C>
                                                    PAGE
                                                    ----
Fund Expenses.....................................    2
Financial Highlights..............................    4
Prospectus Summary................................    6
Investment Objective and Policies.................   10
Additional Investment Information.................   12
Investment Limitations............................   15
Management of the Fund............................   16
Purchase of Shares................................   18
Redemption of Shares..............................   22
Shareholder Services..............................   24
Valuation of Shares...............................   25
Performance Information...........................   26
Dividends and Capital Gains Distributions.........   26
Taxes.............................................   26
Portfolio Transactions............................   28
General Information...............................   29
Account Registration Form
</TABLE>
 
                           U.S. REAL ESTATE PORTFOLIO
 
                                PORTFOLIO OF THE
                                 MORGAN STANLEY
                            INSTITUTIONAL FUND, INC.
 
                                  Common Stock
                               ($.001 PAR VALUE)
 
                                 -------------
                                   PROSPECTUS
                                 -------------
 
                               Investment Adviser
                                 Morgan Stanley
                             Asset Management Inc.
 
                                  Distributor
                              Morgan Stanley & Co.
                                  Incorporated
 
                                 MORGAN STANLEY
                            INSTITUTIONAL FUND, INC.
 
                      P.O. BOX 2798, BOSTON, MA 02208-2798
 
- ---------------------------------------
- ---------------------------------------
- ---------------------------------------
- ---------------------------------------
<PAGE>
- --------------------------------------------------------------------------------
                              P R O S P E C T U S
     ----------------------------------------------------------------------
 
                      ACTIVE COUNTRY ALLOCATION PORTFOLIO
 
                               A PORTFOLIO OF THE
                    MORGAN STANLEY INSTITUTIONAL FUND, INC.
 
                P.O. BOX 2798, BOSTON, MASSACHUSETTS 02208-2798
                      FOR INFORMATION CALL 1-800-548-7786
                                ----------------
 
    Morgan  Stanley Institutional Fund, Inc. (the "Fund") is a no-load, open-end
management investment company, or mutual fund, which offers redeemable shares in
a   series   of   diversified   and   non-diversified   investment    portfolios
("portfolios").   The  Fund   currently  consists   of  twenty-eight  portfolios
representing a  broad range  of  investment choices.  The  Fund is  designed  to
provide clients with attractive alternatives for meeting their investment needs.
This  prospectus (the  "Prospectus") pertains  to the  Class A  and the  Class B
shares of the Active Country Allocation Portfolio (the "Portfolio"). On  January
2,  1996, the Portfolio began offering two classes of shares, the Class A shares
and the Class B shares, except for the Money Market, Municipal Money Market  and
International  Small Cap Portfolios which only  offer Class A shares. All shares
of the Portfolio owned prior to January 2, 1996 were redesignated Class A shares
on January 2,  1996. The Class  A and Class  B shares currently  offered by  the
Portfolio  have  different minimum  investment  requirements and  fund expenses.
Shares of  the  portfolios are  offered  with no  sales  charge or  exchange  or
redemption fee (with the exception of the International Small Cap Portfolio).
 
    The ACTIVE COUNTRY ALLOCATION PORTFOLIO seeks long-term capital appreciation
by  investing in accordance with country weightings determined by the Adviser in
equity securities of non-U.S. issuers  which, in the aggregate, replicate  broad
country indices.
 
    The  Fund is designed  to meet the investment  needs of discerning investors
who place a premium on quality  and personal service. With Morgan Stanley  Asset
Management   Inc.  as   Adviser  and   Administrator  (the   "Adviser"  and  the
"Administrator"), and with Morgan Stanley & Co. Incorporated ("Morgan  Stanley")
as  Distributor, the  Fund makes available  to institutional and  high net worth
individual investors a series  of portfolios which  benefit from the  investment
expertise  and commitment to  excellence associated with  Morgan Stanley and its
affiliates.
 
    This Prospectus is designed to set forth concisely the information about the
Fund that a prospective investor should  know before investing and it should  be
retained  for future reference. The Fund  offers additional portfolios which are
described in other prospectuses and  under "Prospectus Summary" below. The  Fund
currently  offers the following portfolios:  (i) GLOBAL AND INTERNATIONAL EQUITY
- -- Active Country Allocation, Asian  Equity, Emerging Markets, European  Equity,
Global  Equity, Gold, International  Equity, International Magnum, International
Small Cap, Japanese Equity  and Latin American Portfolios;  (ii) U.S. EQUITY  --
Aggressive  Equity, Emerging  Growth, Equity  Growth, MicroCap,  Small Cap Value
Equity, U.S. Real  Estate and Value  Equity Portfolios; (iii)  EQUITY AND  FIXED
INCOME  -- Balanced Portfolio; (iv) FIXED INCOME -- Emerging Markets Debt, Fixed
Income,  Global  Fixed  Income,  High  Yield,  Mortgage-Backed  Securities   and
Municipal  Bond Portfolios; and  (v) MONEY MARKET --  Money Market and Municipal
Money Market Portfolios. Additional information about the Fund is contained in a
"Statement of Additional Information," dated May 1, 1996, which is  incorporated
herein   by  reference.  The   Statement  of  Additional   Information  and  the
prospectuses pertaining to the other portfolios  of the Fund are available  upon
request  and without charge  by writing or  calling the Fund  at the address and
telephone number set forth above.
 
 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.
 
                  THE DATE OF THIS PROSPECTUS IS MAY 1, 1996.
                    SUPPLEMENTED THROUGH DECEMBER 30, 1996.
<PAGE>
                                 FUND EXPENSES
 
    The  following table illustrates the expenses and fees that a shareholder of
the Active Country Allocation Portfolio will incur:
 
<TABLE>
<CAPTION>
SHAREHOLDER TRANSACTION EXPENSES
- ------------------------------------------------------------------------------------------
<S>                                                                                         <C>
Maximum Sales Load Imposed on Purchases
  Class A.................................................................................        None
  Class B.................................................................................        None
Maximum Sales Load Imposed on Reinvested Dividends
  Class A.................................................................................        None
  Class B.................................................................................        None
Deferred Sales Load
  Class A.................................................................................        None
  Class B.................................................................................        None
Redemption Fees
  Class A.................................................................................        None
  Class B.................................................................................        None
Exchange Fees
  Class A.................................................................................        None
  Class B.................................................................................        None
</TABLE>
 
<TABLE>
<CAPTION>
ANNUAL FUND OPERATING EXPENSES
- ------------------------------------------------------------------------------------------
<S>                                                                                         <C>
 (AS A PERCENTAGE OF AVERAGE NET ASSETS)
Management Fee (Net of Fee Waiver)*
  Class A.................................................................................       0.27%
  Class B.................................................................................       0.27%
12b-1 Fees
  Class A.................................................................................        None
  Class B.................................................................................       0.25%
Other Expenses
  Class A.................................................................................       0.53%
  Class B.................................................................................       0.53%
                                                                                            -----------
Total Operating Expenses (Net of Fee Waivers)*
  Class A.................................................................................       0.80%
  Class B.................................................................................       1.05%
                                                                                            -----------
                                                                                            -----------
</TABLE>
 
- ------------------------
*The Adviser has  agreed to waive  its management fees  and/or to reimburse  the
 Portfolio,  if necessary, if such fees would cause the Portfolio's total annual
 operating expenses, as a percentage of average daily net assets, to exceed  the
 percentages set forth in the table above. Absent the fee waiver, the management
 fee  would be  0.65%. Absent the  fee waiver and/or  expense reimbursement, the
 Portfolio's total operating expenses  would be 1.18% of  the average daily  net
 assets  of the Class A shares and 1.43%  of the average daily net assets of the
 Class B shares. As a result of this reduction, the Management Fee stated  above
 is  lower than the contractual  fee stated under "Management  of the Fund." The
 Adviser reserves the right to terminate  any of its fee waivers and/or  expense
 reimbursements  at any time in its  sole discretion. For further information on
 Fund expenses, see "Management of the Fund."
 
                                       2
<PAGE>
    The purpose of the  table above is to  assist the investor in  understanding
the  various expenses that  an investor in  the Portfolio will  bear directly or
indirectly. The Class A expenses and fees for the Portfolio are based on  actual
figures  for the fiscal year  ended December 31, 1995.  The Class B expenses and
fees for the Portfolio are based  on estimates, assuming that the average  daily
net  assets of the Class  B shares of the  Portfolio will be $50,000,000. "Other
Expenses" include  Board  of  Directors'  fees  and  expenses,  amortization  of
organizational  costs, filing fees, professional  fees and costs for shareholder
reports. Due to  the continuous nature  of Rule  12b-1 fees, long  term Class  B
shareholders  may pay  more than the  equivalent of the  maximum front-end sales
charges otherwise  permitted by  the  Rules of  Fair  Practice of  the  National
Association of Securities Dealers, Inc. ("NASD").
 
    The  following  example illustrates  the expenses  that you  would pay  on a
$1,000 investment assuming (1) a 5% annual rate of return and (2) redemption  at
the  end of each time period.  As noted in the table  above, the Fund charges no
redemption fees  of  any kind.  The  following example  is  based on  the  total
operating expenses of the Portfolio after fee waivers.
 
<TABLE>
<CAPTION>
                                                                       1 YEAR       3 YEARS      5 YEARS     10 YEARS
                                                                     -----------  -----------  -----------  -----------
<S>                                                                  <C>          <C>          <C>          <C>
Active Country Allocation Portfolio
  Class A..........................................................   $       8    $      26    $      44    $      99
  Class B..........................................................          11           33           58          128
</TABLE>
 
    THIS  EXAMPLE SHOULD  NOT BE CONSIDERED  A REPRESENTATION OF  PAST OR FUTURE
EXPENSES OR  PERFORMANCE. ACTUAL  EXPENSES MAY  BE GREATER  OR LESS  THAN  THOSE
SHOWN.
 
    The  Fund intends  to comply  with all  state laws  that restrict investment
company expenses. Currently, the  most restrictive state  law requires that  the
aggregate  annual expenses  of an  investment company  shall not  exceed two and
one-half percent (2 1/2%) of  the first $30 million  of average net assets,  two
percent (2%) of the next $70 million of average net assets, and one and one-half
percent (1 1/2%) of the remaining net assets of such investment company.
 
    The  Adviser has agreed to a reduction in  the amounts payable to it, and to
reimburse the Portfolio,  if necessary, if  in any  fiscal year the  sum of  the
Portfolio's expenses exceeds the limit set by applicable state law.
 
                                       3
<PAGE>
                              FINANCIAL HIGHLIGHTS
 
    The  following table provides financial highlights for the Class A shares of
the  Portfolio  for  each  of  the  periods  presented.  The  audited  financial
highlights  for the Class A  shares for the fiscal  year ended December 31, 1995
are part of the Fund's financial statements which appear in the Fund's  December
31,  1995 Annual  Report to  Shareholders and which  are included  in the Fund's
Statement of Additional  Information. The Portfolio's  financial highlights  for
each  of the periods presented have been  audited by Price Waterhouse LLP, whose
unqualified report  thereon is  also  included in  the Statement  of  Additional
Information.  Additional  performance  information  for the  Class  A  shares is
included in the Annual  Report. The Annual Report  and the financial  statements
therein, along with the Statement of Additional Information, are available at no
cost  from the Fund at the address and  telephone number noted on the cover page
of this Prospectus. Financial highlights are  not available for the new Class  B
shares  since  they were  not offered  as  of December  31, 1995.  Subsequent to
October 31, 1992 (the Fund's prior fiscal year end), the Fund changed its fiscal
year end to December 31. The following information should be read in conjunction
with the financial statements and notes thereto.
 
                                       4
<PAGE>
                      ACTIVE COUNTRY ALLOCATION PORTFOLIO
 
<TABLE>
<CAPTION>
                                      JANUARY 17,
                                         1992*        TWO MONTHS
                                      TO OCTOBER         ENDED
                                          31,        DECEMBER 31,              YEARS ENDED DECEMBER 31,
                                         1992            1992            1993            1994            1995
                                     -------------   -------------   -------------   -------------   -------------
<S>                                  <C>             <C>             <C>             <C>             <C>
NET ASSET VALUE, BEGINNING OF
 PERIOD............................  $   10.00       $    9.37       $        9.59   $       12.21   $       11.65
                                     -------------   -------------   -------------   -------------   -------------
INCOME FROM INVESTMENT OPERATIONS
  Net Investment Income (1)........       0.11            0.02                0.13            0.19            0.17
  Net Realized and Unrealized Gain/
   (Loss) on Investments...........      (0.74)           0.20                2.75           (0.25)           1.00
                                     -------------   -------------   -------------   -------------   -------------
  Total from Investment
   Operations......................      (0.63)           0.22                2.88           (0.06)           1.17
                                     -------------   -------------   -------------   -------------   -------------
DISTRIBUTIONS
  Net Investment Income............         --              --               (0.09)          (0.14)          (0.25)
  In Excess of Net Investment
   Income..........................         --              --               (0.08)             --           (0.10)
  Net Realized Gain................         --              --                  --           (0.36)          (0.84)
  In Excess of Net Realized Gain...         --              --               (0.09)             --              --
                                     -------------   -------------   -------------   -------------   -------------
  Total Distributions..............         --              --               (0.26)          (0.50)          (1.19)
                                     -------------   -------------   -------------   -------------   -------------
NET ASSET VALUE, END OF PERIOD.....  $    9.37       $    9.59       $       12.21   $       11.65   $       11.63
                                     -------------   -------------   -------------   -------------   -------------
                                     -------------   -------------   -------------   -------------   -------------
TOTAL RETURN.......................      (6.30)%          2.35%              30.72%          (0.52)%         10.57%
                                     -------------   -------------   -------------   -------------   -------------
                                     -------------   -------------   -------------   -------------   -------------
RATIOS AND SUPPLEMENTAL DATA:
Net Assets, End of Period
 (Thousands).......................  $  47,534       $  50,234       $     150,854   $     182,977   $     170,663
Ratio of Expenses to Average Net
 Assets (1)(2).....................       0.88%**         0.80%**             0.80%           0.80%           0.80%
Ratio of Net Investment Income to
 Average Net Assets (1)(2).........       2.32%**         1.22%**             1.29%           1.43%           1.26%
Portfolio Turnover Rate............         62%              2%               % 53            % 51            % 72
- ------------------------------
(1) Effect of voluntary expense
    limitation during the period:
     Per share benefit to net
      investment income............  $    0.03       $    0.01       $        0.05   $        0.03   $        0.05
     Ratios before expense
      limitation:
     Expenses to Average Net
      Assets.......................       1.58%**         1.70%**             1.33%           1.00%           1.18%
     Net Investment Income to
      Average Net Assets...........       1.62%**         0.32%**             0.76%           1.23%           0.88%
</TABLE>
 
(2) Under the terms of an Investment Advisory Agreement, the Adviser is entitled
    to receive a management  fee calculated at  an annual rate  of 0.65% of  the
    average daily net assets of the Portfolio. The Adviser has agreed to waive a
    portion of this fee and/or reimburse expenses of the Portfolio to the extent
    that  the  total operating  expenses of  the Portfolio  exceed 0.80%  of the
    average daily net  assets of the  Class A  shares and 1.05%  of the  average
    daily  net assets  of the Class  B shares.  In the period  ended October 31,
    1992, the two months ended December  31, 1992, and the years ended  December
    31,  1993,  1994  and  1995,  the  Adviser  waived  management  fees  and/or
    reimbursed expenses  totalling  $164,000, $72,000,  $552,000,  $367,000  and
    $618,000, respectively, for the Portfolio.
 
 * Commencement of Operations.
 
** Annualized.
 
                                       5
<PAGE>
                               PROSPECTUS SUMMARY
 
THE FUND
 
    The   Fund  consists  of  twenty-eight  portfolios,  offering  institutional
investors and high net  worth individual investors a  broad range of  investment
choices coupled with the advantages of a no-load mutual fund with Morgan Stanley
and  its affiliates providing customized  services as Adviser, Administrator and
Distributor. Each portfolio offers Class A shares and, except the  International
Small Cap, Money Market and Municipal Money Market Portfolios, also offers Class
B  shares. Each portfolio has its own investment objective and policies designed
to meet its specific goals. This Prospectus pertains to the Class A and Class  B
shares of the Active Country Allocation Portfolio.
 
    -The   ACTIVE   COUNTRY   ALLOCATION  PORTFOLIO   seeks   long-term  capital
     appreciation by investing in accordance with country weightings  determined
     by  the  Adviser in  equity securities  of non-U.S.  issuers which,  in the
     aggregate, replicate broad country indices.
 
    The other portfolios of the Fund  are described in other prospectuses  which
may be obtained from the Fund at the address and phone number noted on the cover
page  of this  Prospectus. The objectives  of these other  portfolios are listed
below:
 
    GLOBAL AND INTERNATIONAL EQUITY:
 
    -The  ASIAN  EQUITY  PORTFOLIO  seeks  long-term  capital  appreciation   by
     investing primarily in the equity securities of Asian issuers.
 
    -The  CHINA GROWTH PORTFOLIO seeks to provide long-term capital appreciation
     by investing primarily in the equity securities of issuers in The  People's
     Republic of China, Hong Kong and Taiwan.
 
    -The  EMERGING  MARKETS PORTFOLIO  seeks  long-term capital  appreciation by
     investing primarily in equity securities of emerging country issuers.
 
    -The EUROPEAN  EQUITY  PORTFOLIO  seeks long-term  capital  appreciation  by
     investing primarily in the equity securities of European issuers.
 
    -The  GLOBAL  EQUITY  PORTFOLIO  seeks  long-term  capital  appreciation  by
     investing primarily  in the  equity securities  of issuers  throughout  the
     world, including United States issuers.
 
    -The  GOLD  PORTFOLIO  seeks  long-term  capital  appreciation  by investing
     primarily in equity securities of  foreign and domestic issuers engaged  in
     gold-related activities.
 
    -The  INTERNATIONAL EQUITY PORTFOLIO seeks long-term capital appreciation by
     investing primarily in the equity securities of non-United States issuers.
 
    -The INTERNATIONAL MAGNUM PORTFOLIO seeks long-term capital appreciation  by
     investing  primarily in equity securities of non-U.S. issuers in accordance
     with EAFE  country  (as defined  in  "Investment Objectives  and  Policies"
     below) weightings determined by the Adviser.
 
    -The  INTERNATIONAL SMALL CAP PORTFOLIO seeks long-term capital appreciation
     by investing  primarily  in  the equity  securities  of  non-United  States
     issuers with equity market capitalizations of less than $1 billion.
 
    -The  JAPANESE  EQUITY  PORTFOLIO seeks  long-term  capital  appreciation by
     investing primarily in equity securities of Japanese issuers.
 
    -The LATIN  AMERICAN  PORTFOLIO  seeks  long-term  capital  appreciation  by
     investing primarily in equity securities of Latin American issuers and debt
     securities   issued  or   guaranteed  by  Latin   American  governments  or
     governmental entities.
 
                                       6
<PAGE>
    US EQUITY:
    -The AGGRESSIVE  EQUITY PORTFOLIO  seeks capital  appreciation by  investing
     primarily in corporate equity and equity-linked securities.
 
    -The  EMERGING  GROWTH  PORTFOLIO seeks  long-term  capital  appreciation by
     investing primarily  in  growth-oriented  equity securities  of  small-  to
     medium-sized corporations.
 
    -The  EQUITY  GROWTH  PORTFOLIO  seeks  long-term  capital  appreciation  by
     investing  in  growth-oriented  equity  securities  of  medium  and   large
     capitalization companies.
 
    -The  MICROCAP PORTFOLIO  seeks long-term capital  appreciation by investing
     primarily in growth-oriented equity securities of small corporations.
 
    -The SMALL CAP VALUE EQUITY PORTFOLIO  seeks high long-term total return  by
     investing  in  undervalued  equity  securities  of  small-  to medium-sized
     companies.
 
    -The U.S.  REAL ESTATE  PORTFOLIO  seeks to  provide above  average  current
     income  and long-term capital appreciation by investing primarily in equity
     securities of companies in  the U.S. real  estate industry, including  real
     estate investment trusts.
 
    -The  VALUE EQUITY PORTFOLIO seeks high  total return by investing in equity
     securities which the  Adviser believes  to be undervalued  relative to  the
     stock market in general at the time of purchase.
 
    EQUITY AND FIXED INCOME:
    -The  BALANCED PORTFOLIO seeks high total return while preserving capital by
     investing in  a  combination of  undervalued  equity securities  and  fixed
     income securities.
 
    FIXED INCOME:
    -The  EMERGING MARKETS DEBT  PORTFOLIO seeks high  total return by investing
     primarily  in  debt  securities   of  government,  government-related   and
     corporate issuers located in emerging countries.
 
    -The  FIXED INCOME PORTFOLIO seeks to produce a high total return consistent
     with the preservation of capital by investing in a diversified portfolio of
     fixed income securities.
 
    -The GLOBAL FIXED INCOME PORTFOLIO seeks to produce an attractive real  rate
     of  return while preserving capital by investing in fixed income securities
     of issuers throughout the world, including United States issuers.
 
    -The HIGH YIELD PORTFOLIO seeks to  maximize total return by investing in  a
     diversified  portfolio of high  yield fixed income  securities that offer a
     yield above  that  generally available  on  debt securities  in  the  three
     highest rating categories of the recognized rating services.
 
    -The  MORTGAGE-BACKED SECURITIES PORTFOLIO seeks to  produce as high a level
     of current income  as is  consistent with  the preservation  of capital  by
     investing  primarily  in  a  variety  of  investment-grade  mortgage-backed
     securities.
 
    -The MUNICIPAL  BOND PORTFOLIO  seeks to  produce a  high level  of  current
     income  consistent with  the preservation  of principal  through investment
     primarily in municipal obligations,  the interest on  which is exempt  from
     federal income tax.
 
    MONEY MARKET:
    -The  MONEY MARKET PORTFOLIO  seeks to maximize  current income and preserve
     capital while maintaining  high levels  of liquidity  through investing  in
     high quality money market instruments with remaining maturities of one year
     or less.
 
                                       7
<PAGE>
    -The  MUNICIPAL MONEY MARKET PORTFOLIO  seeks to maximize current tax-exempt
     income and  preserve capital  while maintaining  high levels  of  liquidity
     through  investing in high-quality money  market instruments with remaining
     maturities of one year or less which are exempt from federal income tax.
 
INVESTMENT MANAGEMENT
 
    Morgan Stanley Asset Management  Inc., a wholly  owned subsidiary of  Morgan
Stanley  Group  Inc.,  which,  together  with  its  affiliated  asset management
companies, at December 31, 1995 had approximately $57.4 billion in assets  under
management  as  an  investment  manager  or  as  a  fiduciary  adviser,  acts as
investment adviser to the  Fund and each of  its portfolios. See "Management  of
the Fund -- Investment Adviser" and "Management of the Fund -- Administrator."
 
HOW TO INVEST
 
    Class  A shares of  the Portfolio are  offered directly to  investors at net
asset value with no  sales commission or  12b-1 charges. Class  B shares of  the
Portfolio  are offered at net  asset value with no  sales commission, but with a
12b-1 fee, which  is accrued daily  and paid  quarterly, equal to  0.25% of  the
Class B shares' average daily net assets on an annualized basis. Share purchases
may  be  made  by  sending  investments directly  to  the  Fund  or  through the
Distributor. Shares  in a  Portfolio account  opened prior  to January  2,  1996
(each,  a "Pre-1996 Account") were designated Class A shares on January 2, 1996.
For a Portfolio account opened  on or after January  2, 1996 (a "New  Account"),
the  minimum initial investment is $500,000 for  Class A shares and $100,000 for
Class B shares. Certain exceptions to the foregoing minimums apply to (1) shares
in a Pre-1996  Account with  a value of  $100,000 or  more on March  1, 1996  (a
"Grandfathered  Class  A  Account");  (2)  Portfolio  accounts  held  by certain
employees of the Adviser and its  affiliates; and (3) certain advisory or  asset
allocation  accounts, such as Total Funds Management accounts, managed by Morgan
Stanley or  its  affiliates, including  the  Adviser ("Managed  Accounts").  The
Adviser  reserves the right  in its sole  discretion to determine  which of such
advisory or asset allocation accounts shall be Managed Accounts. For information
regarding  Managed  Accounts,  please   contact  your  Morgan  Stanley   account
representative or the Fund at the telephone number provided on the cover of this
Prospectus.  Shares in a Pre-1996 Account with  a value of less than $100,000 on
March 1, 1996 (a "Grandfathered Class B Account") converted to Class B shares on
March 1, 1996. The minimum investment levels may be waived at the discretion  of
the  Adviser for (i)  certain employees and  customers of Morgan  Stanley or its
affiliates and certain  trust departments, brokers,  dealers, agents,  financial
planners,  financial services  firms, or  investment advisers  that have entered
into an agreement with Morgan Stanley or its affiliates; and (ii) retirement and
deferred compensation plans and trusts used  to fund such plans, including,  but
not  limited to, those defined in Section  401(a), 403(b) or 457 of the Internal
Revenue Code of 1986, as amended, and "rabbi trusts." See "Purchase of Shares --
Minimum Investment  and  Account Sizes;  Conversion  from  Class A  to  Class  B
Shares."
 
    The  minimum subsequent investment for a Portfolio account is $1,000 (except
for automatic  reinvestment of  dividends and  capital gains  distributions  for
which  there  is no  minimum). Such  subsequent investments  will be  applied to
purchase additional  shares  in  the same  class  held  by a  shareholder  in  a
Portfolio account. See "Purchase of Shares -- Additional Investments."
 
                                       8
<PAGE>
HOW TO REDEEM
 
    Class  A shares or  Class B shares of  the Portfolio may  be redeemed at any
time, without cost, at the net asset value per share of shares of the applicable
class next determined after  receipt of the  redemption request. The  redemption
price may be more or less than the purchase price. Certain redemptions may cause
involuntary  redemption or automatic conversion. Class  A or Class B shares held
in  New  Accounts   are  subject  to   involuntary  redemption  if   shareholder
redemption(s)  of such  shares reduces  the value of  such account  to less than
$100,000 for a continuous 60-day  period. Involuntary redemption does not  apply
to  Managed Accounts, Grandfathered  Class A Accounts  and Grandfathered Class B
Accounts, regardless of  the value of  such accounts.  Class A shares  in a  New
Account  will convert  to Class  B shares  if shareholder  redemption(s) of such
shares reduces the value of such account to less than $500,000 for a  continuous
60-day  period. Class B  shares in a  New Account will  automatically convert to
Class A shares if shareholder purchases  of additional Class B shares or  market
activity cause the value of the Class B shares in the New Account to increase to
$500,000  or  more.  See  "Purchase  of  Shares  --  Minimum  Account  Sizes and
Involuntary Redemption of Shares" and "Redemption of Shares."
 
RISK FACTORS
 
    The  investment  policies  of  the   Portfolio  entail  certain  risks   and
considerations  of which an investor should  be aware. The Portfolio will invest
in securities of foreign issuers, including issuers in emerging countries, which
are subject to certain risks not typically associated with domestic  securities,
including  (1) restrictions on foreign investment and on repatriation of capital
invested in  foreign  countries, (2)  currency  fluctuations, (3)  the  cost  of
converting  foreign currency into  U.S. dollars, (4)  potential price volatility
and lesser liquidity of shares traded  on foreign country securities markets  or
lack  of a secondary  trading market for  such securities and  (5) political and
economic risks, including the risk of nationalization or expropriation of assets
and the risk  of war.  In addition,  accounting, auditing,  financial and  other
reporting  standards in foreign  countries are not  equivalent to U.S. standards
and therefore, disclosure of  certain material information may  not be made  and
less  information may be  available to investors  investing in foreign countries
than in the United States. There is also generally less governmental  regulation
of  the  securities  industry  in  foreign  countries  than  the  United States.
Moreover, it may be more difficult to  obtain a judgment in a court outside  the
United   States.  See  "Investment  Objective   and  Policies"  and  "Additional
Investment Information." In  addition, the  Portfolio may  invest in  repurchase
agreements,  lend its portfolio securities, purchase securities on a when-issued
basis and  invest  in  forward  foreign currency  exchange  contracts  to  hedge
currency   risk  associated  with  investment  in  non-U.S.  dollar  denominated
securities. Each of  these investment strategies  involves specific risks  which
are   described  under  "Investment  Objective  and  Policies"  and  "Additional
Investment Information" herein and under "Investment Objectives and Policies" in
the Statement of Additional Information.
 
                                       9
<PAGE>
                       INVESTMENT OBJECTIVE AND POLICIES
 
    The investment  objective  of the  Active  Country Allocation  Portfolio  is
described  below, together with the policies the  Fund employs in its efforts to
achieve this  objective. The  Active Country  Allocation Portfolio's  investment
objective  is a fundamental policy which may not be changed without the approval
of a majority  of the  Portfolio's outstanding  voting securities.  There is  no
assurance  that  the Fund  will attain  its  objective. The  investment policies
described below  are  not  fundamental  policies  and  may  be  changed  without
shareholder approval.
 
    The  investment objective of  the Active Country  Allocation Portfolio is to
provide long-term capital appreciation by  investing in accordance with  country
weightings  determined by the  Adviser in equity  securities of non-U.S. issuers
which, in the aggregate, replicate broad country indices. The Adviser utilizes a
top-down approach in  selecting investments  for the  Portfolio that  emphasizes
country  selection and  weighting rather  than individual  stock selection. This
approach reflects  the  Adviser's philosophy  that  a diversified  selection  of
securities  representing  exposure to  world  markets, based  upon  the economic
outlook and current valuation  levels for each country,  is an effective way  to
maximize  the  return  and  minimize  the  risk  associated  with  international
investment.
 
    The Adviser determines country allocations  for the Portfolio on an  ongoing
basis  within policy ranges dictated by each country's market capitalization and
liquidity. The Portfolio will invest in the industrialized countries  throughout
the  world that comprise the Morgan  Stanley Capital International EAFE (Europe,
Australia and the Far  East) Index. The Portfolio  will also invest in  emerging
country  equity securities.  With respect to  the Portfolio,  the term "emerging
country" applies  to  any country  which,  in the  opinion  of the  Adviser,  is
generally   considered  to  be   an  emerging  or   developing  country  by  the
international  financial  community,  including   the  International  Bank   for
Reconstruction  and Development (more commonly known  as the World Bank) and the
International Finance Corporation. There are currently over 130 countries which,
in the  opinion of  the Adviser,  are  generally considered  to be  emerging  or
developing  countries by the international financial community, approximately 40
of which currently have stock  markets. These countries generally include  every
nation  in the  world except  the United  States, Canada,  Japan, Australia, New
Zealand and most nations located in Western Europe. Currently, investing in many
emerging countries is not feasible or may involve unacceptable political  risks.
The  Portfolio will focus its investments  on those emerging market countries in
which it believes the economies are developing strongly and in which the markets
are becoming more sophisticated.  With respect to the  portion of the  Portfolio
that  is invested in emerging country equity securities, the Portfolio initially
intends to invest primarily in some or all of the following countries:
 
<TABLE>
<S>              <C>
Argentina        Portugal
Brazil           Philippines
India            South Africa
Indonesia        South Korea
Malaysia         Thailand
Mexico           Turkey
</TABLE>
 
As markets  in other  countries develop,  the Portfolio  expects to  expand  and
further diversify the emerging countries in which it invests. The Portfolio does
not  intend to  invest in any  security in a  country where the  currency is not
freely convertible  to  U.S. dollars,  unless  the Portfolio  has  obtained  the
necessary governmental
 
                                       10
<PAGE>
licensing to convert such currency or other appropriately licensed or sanctioned
contractual guarantee to protect such investment against loss of that currency's
external  value, or the Portfolio  has a reasonable expectation  at the time the
investment is  made  that such  governmental  licensing or  other  appropriately
licensed or sanctioned guarantee would be obtained or that the currency in which
the  security is quoted would be freely  convertible at the time of any proposed
sale of the security by the Portfolio.
 
    An emerging country security is one issued by a company that, in the opinion
of the  Adviser, has  one or  more  of the  following characteristics:  (i)  its
principal  securities trading market is in an emerging country, (ii) alone or on
a consolidated basis it derives  50% or more of  its annual revenue from  either
goods produced, sales made or services performed in emerging countries; or (iii)
it  is organized under the  laws of, and has a  principal office in, an emerging
country. The  Adviser will  base determinations  as to  eligibility on  publicly
available  information  and  inquiries  made  to  the  companies.  (See "Foreign
Investment Risk  Factors and  Special Considerations"  for a  discussion of  the
nature of information publicly available for non-U.S. companies.)
 
    By  analyzing a variety of macroeconomic  and political factors, the Adviser
develops  fundamental  projections  on  interest  rates,  currencies,  corporate
profits and economic growth for each country. These country projections are used
then  to determine what  the Adviser believes to  be a fair  value for the stock
market of each  country. Discrepancies between  actual value and  fair value  as
determined  by the Adviser provide an expected return for each stock market. The
expected return is  adjusted by  currency return expectations  derived from  the
Adviser's  purchasing-power parity exchange rate model  to arrive at an expected
total return in  U.S. dollars.  The final  country allocation  decision is  then
arrived  at by considering the expected total return in light of various country
specific considerations such as market  size, volatility, liquidity and  country
risk.
 
    Within  a particular country,  investments are made  through the purchase of
equity securities which, in aggregate, replicate a broad market index, which  in
most  cases will be the Morgan Stanley Capital International index for the given
country. The Adviser  may overweight  or underweight  an industry  segment of  a
particular  index if it  concludes this would be  advantageous to the Portfolio.
With respect to the  Portfolio, equity securities  include common and  preferred
stock,  convertible  securities,  and  rights and  warrants  to  purchase common
stocks. Indexation  of the  Portfolio's stock  selection reduces  stock-specific
risk  through  diversification and  minimizes  transaction costs,  which  can be
substantial in foreign markets.
 
    Common stocks purchased for the Portfolio normally will be listed on a major
stock exchange in  the subject  country. The Portfolio  will not  invest in  the
stocks  of U.S. issuers. For a description of special considerations and certain
risks associated with investments in foreign issuers, see "Additional Investment
Information." The  Portfolio  may  temporarily reduce  its  equity  holdings  in
response  to adverse  market conditions and  invest in  domestic, Eurodollar and
foreign  short-term  money  market  instruments  for  defensive  purposes.   See
"Investment Objective and Policies" in the Statement of Additional Information.
 
    Any remaining assets of the Portfolio not invested as described above may be
invested  in  certain  securities or  obligations  as set  forth  in "Additional
Investment Information" below.
 
                                       11
<PAGE>
                       ADDITIONAL INVESTMENT INFORMATION
 
    FOREIGN INVESTMENT.   Investment in  obligations of foreign  issuers and  in
foreign  branches of domestic banks involves somewhat different investment risks
than those affecting obligations of U.S. issuers. There may be limited  publicly
available  information with respect to foreign  issuers, and foreign issuers are
not generally subject  to uniform accounting,  auditing and financial  standards
and requirements comparable to those applicable to domestic companies. There may
also  be  less  government  supervision  and  regulation  of  foreign securities
exchanges, brokers and listed companies than in the U.S. Many foreign securities
markets have substantially less volume than U.S. national securities  exchanges,
and  securities of some foreign  issuers are less liquid  and more volatile than
securities  of  comparable  U.S.   issuers.  Brokerage  commissions  and   other
transaction  costs on foreign securities exchanges  are generally higher than in
the U.S.  Dividends and  interest paid  by  foreign issuers  may be  subject  to
withholding  and  other foreign  taxes,  which may  decrease  the net  return on
foreign investments as compared to dividends and interest paid to the Portfolios
by domestic companies.  See "Taxes". Additional  risks include future  political
and  economic developments,  the possibility  that a  foreign jurisdiction might
impose or change  withholding taxes on  income payable with  respect to  foreign
securities,  possible seizure,  nationalization or expropriation  of the foreign
issuer or foreign deposits,  and the possible  adoption of foreign  governmental
restrictions such as exchange controls.
 
    Such investments in securities of foreign issuers are frequently denominated
in  foreign currencies, and since the  Portfolio may temporarily hold uninvested
reserves in bank deposits  in foreign currencies, the  value of the  Portfolio's
assets  as measured in U.S. dollars may  be affected favorably or unfavorably by
changes in currency rates and in exchange control regulations, and the Portfolio
may incur costs in connection with conversions between various currencies.
 
    FORWARD FOREIGN CURRENCY EXCHANGE CONTRACTS.   The Portfolio may enter  into
forward  foreign currency exchange  contracts, that provide  for the purchase or
sale of an amount of a specified foreign currency at a future date. Purposes for
which such  contracts may  be used  include protecting  against a  decline in  a
foreign  currency against the U.S. dollar  between the trade date and settlement
date when  the Portfolio  purchases or  sells securities,  locking in  the  U.S.
dollar  value  of dividends  declared on  securities held  by the  Portfolio and
generally protecting the U.S. dollar value  of securities held by the  Portfolio
against  exchange  rate  fluctuation.  Such  contracts may  also  be  used  as a
protective measure against the effects of fluctuating rates of currency exchange
and exchange control regulations. While such forward contracts may limit  losses
to  the Portfolio as a result of exchange rate fluctuation, they will also limit
any gains that may otherwise have been realized. See "Investment Objectives  and
Policies  -- Forward Foreign Currency Contracts"  in the Statement of Additional
Information.
 
    LOANS OF PORTFOLIO  SECURITIES.  The  Portfolio may lend  its securities  to
brokers, dealers, domestic and foreign banks or other financial institutions for
the purpose of increasing its net investment income. These loans must be secured
continuously  by cash or equivalent collateral or by a letter of credit at least
equal to the  market value  of the securities  loaned plus  accrued interest  or
income.  There may be risks of delay in  recovery of the securities or even loss
of rights  in  the  collateral  should  the  borrower  of  the  securities  fail
financially.  The  Portfolio will  not enter  into securities  loan transactions
exceeding, in the  aggregate, 33  1/3% of the  market value  of the  Portfolio's
total  assets.  For  more  detailed information  about  securities  lending, see
"Investment Objectives and Policies" in the Statement of Additional Information.
 
                                       12
<PAGE>
    MONEY MARKET INSTRUMENTS.   The Portfolio  is permitted to  invest in  money
market   instruments,  although  the  Portfolio  intends  to  stay  invested  in
securities satisfying its primary investment objective to the extent  practical.
The  Portfolio may  make money  market investments  pending other  investment or
settlement for  liquidity, or  in adverse  market conditions.  The money  market
investments permitted for the Portfolio include obligations of the United States
Government  and  its  agencies  and  instrumentalities;  obligations  of foreign
sovereignties;  other   debt  securities;   commercial  paper   including   bank
obligations;  certificates  of  deposit  (including  Eurodollar  certificates of
deposit); and repurchase agreements. For  more detailed information about  these
money  market investments,  see "Description of  Securities and  Ratings" in the
Statement of Additional Information.
 
    OPTIONS AND FUTURES.   The  Portfolio may  write (i.e.,  sell) covered  call
options  and covered put  options on portfolio securities.  By selling a covered
call option, the Portfolio would become obligated during the term of the  option
to  deliver the securities underlying the option should the option holder choose
to exercise the option before the  option's termination date. In return for  the
call  it has written, the  Portfolio will receive from  the purchaser (or option
holder) a premium which is the price of the option, less a commission charged by
a broker. The Portfolio will keep  the premium regardless of whether the  option
is  exercised.  By  selling  a  covered  put  option,  the  Portfolio  incurs an
obligation to buy the security underlying  the option from the purchaser of  the
put  at the option's exercise price at any time during the option period, at the
purchaser's  election  (certain  options  written  by  the  Portfolio  will   be
exercisable  by  the  purchaser only  on  a  specific date).  A  call  option is
"covered" if  the Portfolio  owns  the security  underlying  the option  it  has
written or has an absolute or immediate right to acquire the security by holding
a  call option on such security, or  maintains a sufficient amount of cash, cash
equivalents or liquid securities to purchase the underlying security. Generally,
a put option is "covered" if the Fund maintains cash, U.S. Government securities
or other high grade debt obligations equal to the exercise price of the  option,
or if the Fund holds a put option on the same underlying security with a similar
or higher exercise price.
 
    When  the Portfolio writes  covered call options, it  augments its income by
the premiums received and is thereby hedged to the extent of that amount against
a decline in the price of the underlying securities. The premiums received  will
offset  a  portion  of the  potential  loss  incurred by  the  Portfolio  if the
securities underlying the  options are  ultimately sold  by the  Portfolio at  a
loss.  However, during the option  period, the Portfolio has,  in return for the
premium on the option, given up  the opportunity for capital appreciation  above
the  exercise price should the market price of the underlying security increase,
but has retained the risk  of loss should the  price of the underlying  security
decline.
 
    The Portfolio will write covered put options to receive the premiums paid by
purchasers  (when the  Adviser wishes  to purchase  the security  underlying the
option at  a price  lower  than its  current market  price,  in which  case  the
Portfolio  will write the covered put at  an exercise price reflecting the lower
purchase price sought) and to close out a long put option position.
 
    The Portfolio  may  also purchase  put  or  call options  on  its  portfolio
securities.  When the Portfolio purchases a call option it acquires the right to
buy a designated security at a designated price (the "exercise price"), and when
the Portfolio purchases a put option it acquires the right to sell a  designated
security  at the exercise price, in each case on or before a specified date (the
"termination date"), which is  usually not more than  nine months from the  date
the  option is issued.  The Portfolio may  purchase call options  to close out a
covered call  position or  to protect  against an  increase in  the price  of  a
security   it   anticipates   purchasing.  The   Portfolio   may   purchase  put
 
                                       13
<PAGE>
options on securities which it holds in its portfolio to protect itself  against
a  decline in the value of the security. If the value of the underlying security
were to fall below the exercise price of the put purchased in an amount  greater
than  the premium paid for  the option, the Portfolio  would incur no additional
loss. The  Portfolio may  also purchase  put options  to close  out written  put
positions  in a  manner similar  to call  option closing  purchase transactions.
There are no other limits  on the Portfolio's ability  to purchase call and  put
options.
 
    The  Portfolio  may  enter into  futures  contracts and  options  on futures
contracts as a hedge against fluctuations in the price of a security it holds or
intends to  acquire, but  not for  speculation or  for achieving  leverage.  The
Portfolio  may also enter into futures transactions to remain fully invested and
to reduce transaction costs. The Portfolio may enter into futures contracts  and
options  on futures contracts provided that not  more than 5% of the Portfolio's
total assets at the time of entering into the contract or option is required  as
deposit to secure obligations under all such contracts and options, and provided
that  not more  than 20%  of the  Portfolio's total  assets in  the aggregate is
invested in options, futures contracts and options on futures contracts.
 
    The Portfolio  may  purchase and  write  call  and put  options  on  futures
contracts that are traded on any international exchange, traded over the counter
or  which  are synthetic  options or  futures  or equity  swaps, and  enter into
closing transactions  with respect  to  such options  to terminate  an  existing
position.  An option  on a  futures contract gives  the purchaser  the right (in
return for the premium  paid) to assume  a position in  the futures contract  (a
long  position if the option is  a call and a short  position if the option is a
put) at a specified exercise  price at any time during  the term of the  option.
The Portfolio will purchase and write options on futures contracts for identical
purposes  to  those set  forth  above for  the  purchase of  a  futures contract
(purchase of a call option or  sale of a put option)  and the sale of a  futures
contract  (purchase of a put option or sale of a call option), or to close out a
long or short position in futures contracts.
 
    The primary risks  associated with the  use of futures  and options are  (i)
imperfect  correlation between the change in market  value of the stocks held by
the Portfolio  and the  prices of  futures and  options relating  to the  stocks
purchased or sold by the Portfolio; and (ii) possible lack of a liquid secondary
market  for a futures  contract and the  resulting inability to  close a futures
position which could have an adverse impact on the Portfolio's ability to hedge.
In the opinion of the  Board of Directors, the risk  that the Portfolio will  be
unable  to close out a futures position or options contract will be minimized by
only entering into  futures contracts  or options transactions  for which  there
appears to be a liquid secondary market.
 
    REPURCHASE  AGREEMENTS.  The Portfolio  may enter into repurchase agreements
with brokers, dealers or  banks that meet the  credit guidelines adopted by  the
Fund's  Directors. In a repurchase agreement, the Portfolio buys a security from
a seller that has  agreed to repurchase  it at a mutually  agreed upon date  and
price, reflecting the interest rate effective for the term of the agreement. The
term of these agreements is usually from overnight to one week and never exceeds
one  year. Repurchase agreements may be viewed as a fully collateralized loan of
money by the Portfolio to the  seller. The Portfolio always receives  securities
with  a market  value at  least equal to  the purchase  price (including accrued
interest) as collateral  and this  value is maintained  during the  term of  the
agreement.  If  the  seller  defaults and  the  collateral  value  declines, the
Portfolio might  incur a  loss.  If bankruptcy  proceedings are  commenced  with
respect  to the seller,  the Portfolio's realization upon  the collateral may be
delayed or limited. The aggregate  of certain repurchase agreements and  certain
other investments is limited as set forth under "Investment Limitations."
 
                                       14
<PAGE>
    WHEN-ISSUED  AND DELAYED  DELIVERY SECURITIES.   The  Portfolio may purchase
securities on a  when-issued or  delayed delivery basis.  In such  transactions,
instruments  are bought with payment and delivery  taking place in the future in
order to secure what is considered to  be an advantageous yield or price at  the
time  of the transaction. Delivery of and  payment for these securities may take
as long as a month  or more after the date  of the purchase commitment but  will
take  place  no more  than 120  days after  the trade  date. The  Portfolio will
maintain with the Custodian  a separate account with  a segregated portfolio  of
high-grade  debt  securities  or cash  in  an  amount at  least  equal  to these
commitments. The payment obligation and the interest rates that will be received
are each fixed  at the  time the  Portfolio enters  into the  commitment and  no
interest  accrues to the  Portfolio until settlement. Thus,  it is possible that
the market value at  the time of  settlement could be higher  or lower than  the
purchase  price if  the general  level of  interest rates  has changed.  It is a
current policy  of  the Portfolio  not  to enter  into  when-issued  commitments
exceeding,  in the aggregate, 15%  of the market value  of the Portfolio's total
assets less liabilities other than the obligations created by these commitments.
 
                             INVESTMENT LIMITATIONS
 
    As a  diversified  investment  company,  the Portfolio  is  subject  to  the
following  limitations: (a) as to 75% of its total assets, the Portfolio may not
invest more than 5%  of its total  assets in the securities  of any one  issuer,
except  obligations  of  the  United  States  Government  and  its  agencies and
instrumentalities, and  (b) the  Portfolio may  not  own more  than 10%  of  the
outstanding voting securities of any one issuer.
 
    The  Portfolio also operates under  certain investment restrictions that are
deemed fundamental limitations and may be changed only with the approval of  the
holders  of a  majority of the  Portfolio's outstanding  shares. See "Investment
Limitations" in  the  Statement  of Additional  Information.  In  addition,  the
Portfolio  operates  under  certain  non-fundamental  investment  limitations as
described below and in  the Statement of  Additional Information. The  Portfolio
may  not  (i) enter  into repurchase  agreements  with more  than seven  days to
maturity if, as a result, more than  10% of the market value of the  Portfolio's
net assets would be invested in such repurchase agreements and other investments
for  which market  quotations are not  readily available or  which are otherwise
illiquid; (ii) borrow money,  except from banks  for extraordinary or  emergency
purposes,  and then only  in amounts up to  10% of the  value of the Portfolio's
total assets, taken  at cost at  the time of  borrowing; or purchase  securities
while  borrowings  exceed 5%  of  its total  assets;  (iii) mortgage,  pledge or
hypothecate any assets except in connection  with any such borrowing in  amounts
up  to 10% of the value of the  Portfolio's net assets at the time of borrowing;
(iv) invest in fixed time deposits with a duration of over seven calendar  days;
or  (v) invest in fixed time deposits with  a duration of from two business days
to seven calendar days if more than 10% of the Portfolio's total assets would be
invested in these deposits.
 
                             MANAGEMENT OF THE FUND
 
    INVESTMENT ADVISER.  Morgan Stanley Asset Management Inc. is the  Investment
Adviser  and Administrator of the  Fund and each of  its Portfolios. The Adviser
provides investment advice  and portfolio  management services,  pursuant to  an
Investment  Advisory Agreement  and, subject  to the  supervision of  the Fund's
Board  of  Directors,  makes  each  of  the  Portfolio's  day-to-day  investment
decisions,  arranges for the  execution of portfolio  transactions and generally
manages each of the Portfolio's investments. The Adviser is entitled to  receive
from  the Active Country Allocation Portfolio  an annual management fee, payable
quarterly, equal to 0.65% of the average daily net assets of the Portfolio.
 
                                       15
<PAGE>
    The fees of  the Portfolio,  which involves  international investments,  are
higher  than  those of  most  investment companies  but  comparable to  those of
investment companies  with  similar objectives.  The  Adviser has  agreed  to  a
reduction  in  the  fees  payable  to it  and  to  reimburse  the  Portfolio, if
necessary, if  such fees  would cause  total annual  operating expenses  of  the
Portfolio  to exceed 0.80% of the average daily net assets of the Class A shares
of the Portfolio and 1.05% of the average daily net assets of the Class B shares
of the Portfolio.
 
    The Adviser, with  principal offices  at 1221  Avenue of  the Americas,  New
York,  New  York  10020,  conducts a  worldwide  portfolio  management business,
providing a broad  range of portfolio  management services to  customers in  the
United  States and abroad. At December 31,  1995, the Adviser, together with its
affiliated   asset   management   companies,   managed   investments    totaling
approximately  $57.4 billion, including approximately $41.9 billion under active
management and  $15.5  billion as  Named  Fiduciary or  Fiduciary  Adviser.  See
"Management of the Fund" in the Statement of Additional Information.
 
    PORTFOLIO  MANAGERS.  BARTON  M. BIGGS, MADHAV DHAR,  FRANCINE J. BOVICH AND
ANN D. THIVIERGE. Barton Biggs has been  Chairman and a director of the  Adviser
since  1980 and a Managing  Director of Morgan Stanley since  1975. He is also a
director of Morgan  Stanley Group  Inc. and a  director and  officer of  several
registered  investment  companies  to  which  the  Adviser  and  certain  of its
affiliates provide investment  advisory services.  Mr. Biggs holds  a B.A.  from
Yale  University  and an  M.B.A.  from New  York  University. Madhav  Dhar  is a
Managing Director of Morgan Stanley. He joined  the Adviser in 1984 to focus  on
global  asset allocation  and investment  strategy and  now heads  the Adviser's
emerging markets group and  serves as the  group's principal portfolio  manager.
Mr.  Dhar also coordinates the Adviser's developing country funds effort and has
been involved  in  the launching  of  the Adviser's  country  funds. He  is  the
portfolio manager of the Fund's Emerging Markets Portfolio, the Emerging Markets
and  Global Equity Allocation  Funds of the  Morgan Stanley Fund,  Inc., and the
Morgan Stanley  Emerging Markets  Fund, Inc.  (a closed-end  investment  company
listed  on the  New York  Stock Exchange). Mr.  Dhar is  also a  director of the
Morgan Stanley Emerging  Markets Fund, Inc.  He holds a  B.S. (honors) from  St.
Stephens  College, Delhi University (India),  and an M.B.A. from Carnegie-Mellon
University. Francine Bovich joined  the Adviser as a  Principal in 1993. She  is
responsible  for product development, portfolio  management and communication of
the Adviser's  asset  allocation  strategy to  institutional  investor  clients.
Previously,  Ms. Bovich was a Principal and Executive Vice President of Westwood
Management Corp. ("Westwood"), a  registered investment adviser. Before  joining
Westwood,  she was a  Managing Director of  Citicorp Investment Management, Inc.
(now  Chancellor  Capital  Management),  where  she  was  responsible  for   the
Institutional  Investment  Management  group. Ms.  Bovich  began  her investment
career with  Banker's  Trust  Company.  She  holds  a  B.A.  in  Economics  from
Connecticut  College  and an  M.B.A. in  Finance from  New York  University. Ann
Thivierge is a Principal of the Adviser. She is a member of the Adviser's  asset
allocation  committee,  primarily representing  the  Total Fund  Management team
since its inception in 1991. Prior to joining the Adviser in 1986, she spent two
years at Edgewood  Management Company,  a privately  held investment  management
firm.  Ms. Thivierge holds a B.A.  in International Relations from James Madison
College, Michigan  State University,  and an  M.B.A. in  Finance from  New  York
University.
 
    ADMINISTRATOR.    The Adviser  also  provides the  Fund  with administrative
services pursuant to  an Administration Agreement.  The services provided  under
the  Administration Agreement are subject to the supervision of the Officers and
the Board of  Directors of  the Fund  and include  day-to-day administration  of
matters  related  to the  corporate existence  of the  Fund, maintenance  of its
records, preparation of reports, supervision of the Fund's arrangements with its
custodian  and  assistance  in  the  preparation  of  the  Fund's   registration
statements under
 
                                       16
<PAGE>
Federal  and State  laws. The  Administration Agreement  also provides  that the
Administrator, through its agents, will provide the Fund dividend disbursing and
transfer agent services.  For its services  under the Administration  Agreement,
the Fund pays the Adviser a monthly fee which on an annual basis equals 0.15% of
the average daily net assets of the Portfolio.
 
    Under  an agreement between  the Adviser and The  Chase Manhattan Bank, N.A.
("Chase"), Chase  provides certain  administrative services  to the  Fund. In  a
merger  completed on September 1, 1995, Chase succeeded to all of the rights and
obligations under the  U.S. Trust Administration  Agreement between the  Adviser
and  the United  States Trust  Company of New  York ("U.S.  Trust"), pursuant to
which U.S. Trust had  agreed to provide certain  administrative services to  the
Fund.  Pursuant  to  a  delegation  clause  in  the  U.S.  Trust  Administration
Agreement, U.S.  Trust delegated  its administration  responsibilities to  Chase
Global  Funds Services Company ("CGFSC"), formerly known as Mutual Funds Service
Company, which after the  merger with Chase  is a subsidiary  of Chase and  will
continue  to provide  certain administrative services  to the  Fund. The Adviser
supervises and  monitors such  administrative services  provided by  CGFSC.  The
services  provided  under  the  Administration  Agreement  and  the  U.S.  Trust
Administration Agreement are  also subject to  the supervision of  the Board  of
Directors  of the  Fund. The  Board of  Directors of  the Fund  has approved the
provision of services described above  pursuant to the Administration  Agreement
and  the U.S. Trust Administration  Agreement as being in  the best interests of
the Fund. CGFSC's business address  is 73 Tremont Street, Boston,  Massachusetts
02108-3913. For additional information regarding the Administration Agreement or
the  U.S. Trust  Administration Agreement, see  "Management of the  Fund" in the
Statement of Additional Information.
 
    LOCAL ADMINISTRATOR  FOR THE  PORTFOLIO.   The Portfolio  is required  under
Brazilian  law  to have  a local  administrator  in Brazil.  Unibanco-Uniao (the
"Brazilian Administrator"),  a Brazilian  corporation, acts  as the  Portfolio's
Brazilian  administrator  pursuant  to  an  agreement  with  the  Portfolio (the
"Brazilian  Administration  Agreement").  Under  the  Brazilian   Administration
Agreement,  the  Brazilian  Administrator  performs  various  services  for  the
Portfolio, including  effecting  the  registration of  the  Portfolio's  foreign
capital  with  the  Central  Bank  of  Brazil,  effecting  all  foreign exchange
transactions related to the Portfolio's investments in Brazil and obtaining  all
approvals  required for the Portfolio to  make remittances of income and capital
gains and  for  the repatriation  of  the Portfolio's  investments  pursuant  to
Brazilian  law. For its services, the  Brazilian Administrator is paid an annual
fee equal to  0.125% of the  Portfolio's average weekly  net assets invested  in
Brazil,  paid monthly.  The principal office  of the  Brazilian Administrator is
located at Avenida Eusebio Matoso, 891,  Sao Paulo, S.P., Brazil. The  Brazilian
Administration  Agreement is terminable upon six months' notice by either party.
The Brazilian Administrator may be replaced only by an entity authorized to  act
as  a  joint  manager of  a  managed  portfolio of  bonds  and  securities under
Brazilian law.
 
    DIRECTORS AND OFFICERS.  Pursuant  to the Fund's Articles of  Incorporation,
the  Board of Directors  decides upon matters  of general policy  and review the
actions of the Fund's  Adviser, Administrator and  Distributor. The Officers  of
the Fund conduct and supervise its daily business operations.
 
    DISTRIBUTOR.   Morgan  Stanley serves  as the  exclusive Distributor  of the
shares of  the Fund.  Under its  Distribution Agreement  with the  Fund,  Morgan
Stanley  sells shares  of the Fund  upon the  terms and at  the current offering
price described in this Prospectus. Morgan Stanley is not obligated to sell  any
certain number of shares of the Fund.
 
                                       17
<PAGE>
    The  Portfolio currently offers  only the classes of  shares offered by this
Prospectus. The Portfolio may in the future offer one or more classes of  shares
with  features, distribution expenses or other  expenses that are different from
those of the classes currently offered.
 
    The Fund has  adopted a Plan  of Distribution  with respect to  the Class  B
shares  pursuant to Rule 12b-1 under the  1940 Act (the "Plan"). Under the Plan,
the Distributor is entitled  to receive from the  Portfolio a distribution  fee,
which  is accrued  daily and  paid quarterly,  of 0.25%  of the  Class B shares'
average daily net  assets on  an annualized  basis. The  Distributor expects  to
reallocate  most of its  fee to its  investment representatives. The Distributor
may, in its discretion, voluntarily waive from  time to time all or any  portion
of  its distribution fee and each of the  Distributor and the Adviser is free to
make additional payments  out of  its own  assets to  promote the  sale of  Fund
shares,   including   payments  that   compensate  financial   institutions  for
distribution services or shareholder services.
 
    The Plan is designed to compensate the Distributor for its services, not  to
reimburse  the Distributor for its expenses,  and the Distributor may retain any
portion of the fee that it does not expend in fulfillment of its obligations  to
the Fund.
 
    EXPENSES.   The Portfolio  is responsible for payment  of certain other fees
and expenses  (including  legal  fees, accountants'  fees,  custodial  fees  and
printing  and mailing  costs) specified  in the  Administration and Distribution
Agreements.
 
                               PURCHASE OF SHARES
 
    Class A and Class B shares of the Portfolio may be purchased, without  sales
commission,  at the net asset  value per share next  determined after receipt of
the purchase order by the Portfolio. See "Valuation of Shares."
 
MINIMUM INVESTMENT AND ACCOUNT SIZES; CONVERSION FROM CLASS A TO CLASS B SHARES
 
    For an account for the Portfolio opened on or after January 2, 1996 (a  "New
Account"),  the minimum initial investment and minimum account size are $500,000
for Class  A  shares and  $100,000  for Class  B  shares. Managed  Accounts  may
purchase Class A shares without being subject to such minimum initial investment
or  minimum account size requirements for  a Portfolio account. Employees of the
Adviser and of its affiliates may purchase Class A Shares subject to conditions,
including a lower minimum investment, established by Officers of the Fund.
 
    If the  value  of a  New  Account, containing  Class  A shares  falls  below
$500,000   (but   remains  at   or  above   $100,000)  because   of  shareholder
redemption(s), the Fund will  notify the shareholder, and  if the account  value
remains  below  $500,000 (but  remains at  or above  $100,000) for  a continuous
60-day period, the Class A shares in such account will convert to Class B shares
and will be subject to the distribution fee and other features applicable to the
Class B shares. The Fund,  however, will not convert Class  A shares to Class  B
shares  based solely upon changes in the  market that reduce the net asset value
of shares. Under current  tax law, conversions between  share classes are not  a
taxable event to the shareholder.
 
    Shares  in a Portfolio account opened prior  to January 2, 1996 (a "Pre-1996
Account") were  designated  Class A  shares  on January  2,  1996. Shares  in  a
Pre-1996  Account  with  a  value  of  $100,000 or  more  on  March  1,  1996 (a
"Grandfathered Class A Account") remained  Class A shares regardless of  account
size thereafter. Except
 
                                       18
<PAGE>
for  shares in a Managed  Account, shares in a Pre-1996  Account with a value of
less than  $100,000  on  March  1, 1996  (a  "Grandfathered  Class  B  Account")
converted to Class B shares on March 1, 1996. Grandfathered Class A Accounts and
Managed  Accounts are not subject  to conversion from Class  A shares to Class B
shares.
 
    Investors may also invest in the  Fund by purchasing shares through a  trust
department, broker, dealer, agent, financial planner, financial services firm or
investment  adviser.  An  investor  may  be  charged  an  additional  service or
transaction fee by that institution. The minimum investment levels may be waived
at the discretion  of the  Adviser for (i)  certain employees  and customers  of
Morgan  Stanley  or  its  affiliates  and  certain  trust  departments, brokers,
dealers, agents,  financial planners,  financial services  firms, or  investment
advisers  that  have  entered  into  an agreement  with  Morgan  Stanley  or its
affiliates; and (ii) retirement and deferred compensation plans and trusts  used
to  fund such  plans, including,  but not limited  to, those  defined in Section
401(a), 403(b) or  457 of the  Internal Revenue  Code of 1986,  as amended,  and
"rabbi trusts." Broker-dealers who make purchases for their customers may charge
a fee for such services.
 
    The  Fund reserves the right to  modify or terminate the conversion features
of the shares as stated above at any time upon 60-days' notice to shareholders.
 
MINIMUM ACCOUNT SIZES AND INVOLUNTARY REDEMPTION OF SHARES
 
    If the value of  a New Account falls  below $100,000 because of  shareholder
redemption(s),  the Fund will  notify the shareholder, and  if the account value
remains below  $100,000 for  a  continuous 60-day  period,  the shares  in  such
account  are subject to redemption  by the Fund and,  if redeemed, the net asset
value of  such  shares will  be  promptly paid  to  the shareholder.  The  Fund,
however,  will not redeem  shares based solely  upon changes in  the market that
reduce the net asset value of shares.
 
    Grandfathered Class A Accounts, Grandfathered  Class B Accounts and  Managed
Accounts are not subject to involuntary redemption.
 
    The  Fund  reserves  the  right  to  modify  or  terminate  the  involuntary
redemption features of  the shares  as stated above  at any  time upon  60-days'
notice to shareholders.
 
CONVERSION FROM CLASS B TO CLASS A SHARES
 
    If the value of Class B shares in a Portfolio account increases, whether due
to  shareholder share  purchases or  market activity,  to $500,000  or more, the
Class B shares  will convert  to Class  A Shares.  Under current  tax law,  such
conversion  is not a taxable event to  the shareholder. Class A shares converted
from Class B shares  are subject to the  same minimum account size  requirements
that  are applicable to New Accounts containing Class A shares, as stated above.
The Fund reserves the  right to modify or  terminate this conversion feature  at
any time upon 60-days' notice to shareholders.
 
INITIAL PURCHASES DIRECTLY FROM THE FUND
 
    The  Fund's determination of an investor's eligibility to purchase shares of
a given class  will take precedence  over the investor's  selection of a  class.
Assuming  the investor is eligible for the  class, the Fund will select the most
favorable class for the investor, if the investor has not done so.
 
                                       19
<PAGE>
INITIAL INVESTMENTS
 
1) BY CHECK.   An account may  be opened  by completing and  signing an  Account
   Registration Form and mailing it, together with a check ($500,000 minimum for
   Class  A  shares of  the Portfolio  and $100,000  for Class  B shares  of the
   Portfolio, with certain  exceptions for Morgan  Stanley employees and  select
   customers)  payable  to "Morgan  Stanley Institutional  Fund, Inc.  -- Active
   Country Allocation Portfolio", to:
 
      Morgan Stanley Institutional Fund, Inc.
      P.O. Box 2798
      Boston, Massachusetts 02208-2798
 
    Payment will  be accepted only  in U.S. dollars,  unless prior approval  for
  payment  by other currencies is given by  the Fund. The Class(es) of shares of
  the Portfolio to be purchased should be designated on the Account Registration
  Form. For purchases  by check, the  Fund is ordinarily  credited with  Federal
  Funds  within  one business  day. Thus  your  purchase of  shares by  check is
  ordinarily credited to your account  at the net asset  value per share of  the
  Portfolio determined on the next business day after receipt.
 
2) BY  FEDERAL  FUNDS WIRE.   Purchases  may be  made by  having your  bank wire
   Federal Funds to the Fund's bank  account. In order to ensure prompt  receipt
   of your Federal Funds Wire, it is important that you follow these steps:
 
A.   Telephone  the Fund  (toll free: 1-800-548-7786)  and provide  us with your
    name, address,  telephone  number,  Social Security  or  Tax  Identification
    Number,  the  portfolio(s) selected,  the class  selected, the  amount being
    wired, and by  which bank.  We will  then provide  you with  a Fund  account
    number.  (Investors with existing accounts should also notify the Fund prior
    to wiring funds.)
 
B.   Instruct  your  bank to  wire  the  specified amount  to  the  Fund's  Wire
    Concentration  Bank Account (be sure  to have your bank  include the name of
    the portfolio(s)  selected,  the  class  selected  and  the  account  number
    assigned to you) as follows:
 
    Chase Manhattan Bank, N.A.
    One Manhattan Plaza
    New York, NY 10081-1000
    ABA #021000021
    DDA #910-2-733293
    Attn: Morgan Stanley Institutional Fund, Inc.
    Ref: (Portfolio name, your account number, your account name)
 
    Please call the Fund at 1-800-548-7786 prior to wiring funds.
 
C.   Complete and sign the Account Registration  Form and mail it to the address
    shown thereon.
 
  Purchase orders for shares  of the Portfolio which  are received prior to  the
  regular  close of the NYSE (currently 4:00 p.m. Eastern Time) will be executed
  at the price computed  on the date  of receipt as long  as the Transfer  Agent
  receives  payment by check or  in Federal Funds prior  to the regular close of
  the NYSE on such day.
 
                                       20
<PAGE>
  Federal Funds purchase orders will be accepted only on a day on which the Fund
  and Chase (the "Custodian Bank") are open for business. Your bank may charge a
  service fee for wiring Federal Funds.
 
3) BY BANK WIRE.   The  same procedure outlined  under "By  Federal Funds  Wire"
   above  must be  followed in  purchasing shares  by bank  wire. However, money
   transferred by bank wire may or may  not be converted into Federal Funds  the
   same  day, depending on the time the  money is received and the bank handling
   the wire. Prior to such conversion, an investor's money will not be  invested
   and, therefore, will not be earning dividends. Your bank may charge a service
   fee for wiring funds.
 
ADDITIONAL INVESTMENTS
 
    You  may  add to  your account  at any  time (minimum  additional investment
$1,000, except  for  automatic  reinvestment  of  dividends  and  capital  gains
distributions for which there are no minimums) by purchasing shares at net asset
value  by mailing a check to the  Fund (payable to "Morgan Stanley Institutional
Fund, Inc. -- Active Country Allocation  Portfolio") at the above address or  by
wiring monies to the Custodian Bank as outlined above. It is very important that
your account name, the portfolio name and the class selected be specified in the
letter  or wire to assure  proper crediting to your  account. In order to ensure
that your wire orders are invested promptly, you are requested to notify one  of
the  Fund's representatives (toll-free  1-800-548-7786) prior to  the wire date.
Additional investments will be applied to purchase additional shares in the same
class held by a shareholder in a Portfolio account.
 
OTHER PURCHASE INFORMATION
 
    The purchase price of the Class A and Class B shares of the Portfolio is the
net asset value next determined after  the order is received. See "Valuation  of
Shares."  An order received  prior to the  close of the  New York Stock Exchange
("NYSE"), which is  currently 4:00 p.m.  Eastern Time, will  be executed at  the
price  computed on the date of receipt; an order received after the close of the
NYSE will be executed at the price computed on the next day the NYSE is open  as
long  as the Transfer Agent receives payment  by check or in Federal Funds prior
to the regular close of the NYSE on such day.
 
    Although the legal rights of Class A  and Class B shares will be  identical,
the  different expenses borne by  each class will result  in different net asset
values and dividends. The net  asset value of Class  B shares will generally  be
lower than the net asset value of Class A shares as a result of the distribution
expense  charged to Class B shares. It  is expected, however, that the net asset
value per share of the two classes  will tend to converge immediately after  the
recording  of dividends  which will  differ by  approximately the  amount of the
distribution expense accrual differential between the classes.
 
    In the interest  of economy and  convenience, and because  of the  operating
procedures  of the Fund, certificates representing  shares of the Portfolio will
not be issued. All shares  purchased are confirmed to  you and credited to  your
account  on the Fund's books  maintained by the Adviser  or its agents. You will
have  the  same  rights  and  ownership  with  respect  to  such  shares  as  if
certificates had been issued.
 
    To  ensure that checks are collected by the Fund, withdrawals of investments
made by check  are not presently  permitted until payment  for the purchase  has
been  received,  which may  take up  to eight  business days  after the  date of
purchase. As a condition  of this offering,  if a purchase  is cancelled due  to
nonpayment or
 
                                       21
<PAGE>
because your check does not clear, you will be responsible for any loss the Fund
or  its agents  incur. If  you are  already a  shareholder, the  Fund may redeem
shares from your account(s) to reimburse the Fund or its agents for any loss. In
addition, you may be prohibited or restricted from making future investments  in
the Fund.
 
    Investors  may  also invest  in the  Fund by  purchasing shares  through the
Distributor.
 
EXCESSIVE TRADING
 
    Frequent  trades  involving  either   substantial  portfolio  assets  or   a
substantial  portion of your  account or accounts controlled  by you can disrupt
management of a portfolio and raise its expenses. Consequently, in the  interest
of  all the stockholders  of the Portfolio and  the Portfolio's performance, the
Fund may in its discretion bar  a stockholder that engages in excessive  trading
of  shares of any class  of a portfolio from further  purchases of shares of the
Fund for an indefinite period. The  Fund considers excessive trading to be  more
than  one purchase and sale involving shares of the same class of a portfolio of
the Fund  within  any  120-day  period. As  an  example,  exchanging  shares  of
portfolios of the Fund as follows amounts to excessive trading: exchanging Class
A shares of Portfolio A for Class A shares of Portfolio B, then exchanging Class
A  shares of Portfolio B for Class A  shares of Portfolio C and again exchanging
Class A shares of Portfolio C for Class A shares of Portfolio B within a 120-day
period. Two  types  of transactions  are  exempt from  these  excessive  trading
restrictions:  (1) trades exclusively  between money market  portfolios; and (2)
trades done  in  connection  with  an asset  allocation  service,  such  as  TFM
Accounts, managed or advised by MSAM and/or any of its affiliates.
 
                              REDEMPTION OF SHARES
 
    You  may  withdraw all  or  any portion  of the  amount  in your  account by
redeeming shares at any time. Please note  that purchases made by check are  not
permitted to be redeemed until payment of the purchase has been collected, which
may  take up to eight business days after purchase. The Fund will redeem Class A
shares or Class B shares of the Portfolio at the next determined net asset value
of shares of the applicable class. On days that both the NYSE and the  Custodian
Bank  are open for business,  the net asset value per  share of the Portfolio is
determined at the  close of  trading of the  NYSE (currently  4:00 p.m.  Eastern
Time).  Shares of the Portfolio may be  redeemed by mail or telephone. No charge
is made for redemption.  Any redemption proceeds  may be more  or less than  the
purchase  price of  your shares  depending on,  among other  factors, the market
value of the investment securities held by the Portfolio.
 
BY MAIL
 
    The Portfolio will redeem its  Class A shares or Class  B shares at the  net
asset  value determined on the  date the request is  received, if the request is
received in "good  order" before  the regular close  of the  NYSE. Your  request
should  be addressed to Morgan Stanley  Institutional Fund, Inc., P.O. Box 2798,
Boston, Massachusetts 02208-2798,  except that deliveries  by overnight  courier
should be addressed to Morgan Stanley Institutional Fund, Inc., c/o Chase Global
Funds Services Company, 73 Tremont Street, Boston, Massachusetts 02108-3913.
 
    "Good  order"  means that  the  request to  redeem  shares must  include the
following documentation:
 
        (a)  A letter of instruction or a stock assignment specifying the  class
    and  number  of  shares or  dollar  amount  to be  redeemed,  signed  by all
    registered owners  of  the shares  in  the exact  names  in which  they  are
    registered;
 
        (b)   Any  required   signature  guarantees   (see  "Further  Redemption
    Information" below); and
 
                                       22
<PAGE>
        (c)   Other supporting  legal documents,  if required,  in the  case  of
    estates,  trusts, guardianships,  custodianships, corporations,  pension and
    profit-sharing plans and other organizations.
 
    Shareholders who are uncertain of requirements for redemption should consult
with a Morgan Stanley Institutional Fund representative.
 
BY TELEPHONE
 
    Provided you have previously elected the Telephone Redemption Option on  the
Account  Registration  Form, you  can  request a  redemption  of your  shares by
calling the Fund  and requesting  the redemption proceeds  be mailed  to you  or
wired  to your bank.  Please contact one of  Morgan Stanley Institutional Fund's
representatives for further details. In times of drastic market conditions,  the
telephone  redemption option  may be difficult  to implement.  If you experience
difficulty in making a telephone redemption, your request may be made by mail or
overnight courier and will be implemented at the net asset value next determined
after it is received. Redemption requests sent to the Fund through express  mail
must  be mailed  to the  address of the  Dividend Disbursing  and Transfer Agent
listed under "General Information." The Fund and the Fund's transfer agent  (the
"Transfer  Agent")  will  employ  reasonable  procedures  to  confirm  that  the
instructions communicated  by telephone  are genuine.  These procedures  include
requiring the investor to provide certain personal identification information at
the  time an account is opened and prior to effecting each transaction requested
by telephone. In addition, all  telephone transaction requests will be  recorded
and   investors  may  be  required  to  provide  additional  telecopied  written
instructions regarding transaction requests. Neither  the Fund nor the  Transfer
Agent will be responsible for any loss, liability, cost or expense for following
instructions received by telephone that either of them reasonably believes to be
genuine.
 
    To  change the commercial  bank or account  designated to receive redemption
proceeds, a written  request must  be sent  to the  Fund at  the address  above.
Requests  to change the bank  or account must be  signed by each shareholder and
each signature must be guaranteed.
 
FURTHER REDEMPTION INFORMATION
 
    Normally the  Fund will  make payment  for all  shares redeemed  within  one
business  day of receipt  of the request, but  in no event  will payment be made
more than  seven days  after receipt  of  a redemption  request in  good  order.
However,  payments to investors  redeeming shares which  were purchased by check
will not be made until  payment for the purchase  has been collected, which  may
take up to eight days after the date of purchase. The Fund may suspend the right
of  redemption or postpone the date upon which redemptions are effected at times
when the NYSE is closed, or  under any emergency circumstances as determined  by
the Securities and Exchange Commission (the "Commission").
 
    If  the Board of  Directors determines that  it would be  detrimental to the
best interests of the  remaining shareholders of the  Portfolio to make  payment
wholly  or partly in cash, the Fund may  pay the redemption proceeds in whole or
in part by a distribution in-kind of securities held by the Portfolio in lieu of
cash   in    conformity   with    applicable    rules   of    the    Commission.
Distributions-in-Kind  will be made in  readily marketable securities. Investors
may incur brokerage charges on the  sale of portfolio securities so received  in
payment of redemptions.
 
                                       23
<PAGE>
    To  protect  your account,  the Fund  and its  agents from  fraud, signature
guarantees are required for  certain redemptions to verify  the identity of  the
person  who has  authorized a redemption  from your account.  Please contact the
Fund for further  information. See "Redemption  of Shares" in  the Statement  of
Additional Information.
 
                              SHAREHOLDER SERVICES
 
EXCHANGE FEATURES
 
    You  may exchange  shares that you  own in  the Portfolio for  shares of any
other available  portfolio of  the  Fund (other  than the  International  Equity
Portfolio,  which is  closed to  new investors). In  exchanging for  shares of a
portfolio with more  than one  class, the  class of  shares you  receive in  the
exchange  will be determined in the same  manner as any other purchase of shares
and will not  be based  on the  class of  shares surrendered  for the  exchange.
Consequently,  the same minimum initial investment  and minimum account size for
determining the  class  of shares  received  in  the exchange  will  apply.  See
"Purchase  of Shares."  Shares of  the portfolios  may be  exchanged by  mail or
telephone. The privilege to exchange shares  by telephone is automatic and  made
available  without shareholder election. Before you make an exchange, you should
read the prospectus of the portfolio(s) in which you seek to invest. Because  an
exchange  transaction  is treated  as a  redemption followed  by a  purchase, an
exchange would be considered  a taxable event for  shareholders subject to  tax.
The  exchange privilege  is only available  with respect to  portfolios that are
registered for  sale  in  a  shareholder's  state  of  residence.  The  exchange
privilege  may be modified or  terminated by the Fund  at any time upon 60-days'
notice to shareholders.
 
BY MAIL
 
    In order to  exchange shares  by mail, you  should include  in the  exchange
request  the  name and  account  number of  the  Portfolio, the  name(s)  of the
portfolio(s) and class(es) of shares into  which you intend to exchange  shares,
and  the signatures of all registered account holders. Send the exchange request
to  Morgan  Stanley  Institutional  Fund,  Inc.,  P.O.  Box  2798,  Boston,   MA
02208-2798.
 
BY TELEPHONE
 
    When  exchanging shares by  telephone, have ready the  name, class of shares
and account number of the current  portfolio, the names of the portfolio(s)  and
class(es)  of  shares into  which  you intend  to  exchange shares,  your Social
Security number  or Tax  I.D. number,  and your  account address.  Requests  for
telephone  exchanges received prior to 4:00 p.m. (Eastern Time) are processed at
the close of business that same day based on the net asset value of the class of
the portfolios involved  in the  exchange of shares  at the  close of  business.
Requests  received after 4:00 p.m. are processed  the next business day based on
the net  asset value  determined  at the  close of  business  on such  day.  For
additional   information  regarding  responsibility   for  the  authenticity  of
telephoned instructions, see "Redemption of Shares -- By Telephone" above.
 
TRANSFER OF REGISTRATION
 
    You may transfer  the registration  of any of  your Fund  shares to  another
person  by writing  to Morgan Stanley  Institutional Fund, Inc.,  P.O. Box 2798,
Boston, Massachusetts 02208-2798.  As in  the case of  redemptions, the  written
request  must  be  received in  good  order  before any  transfer  can  be made.
Transferring the  registration of  shares  may affect  the eligibility  of  your
account  for  a  given  class  of  the  Portfolio's  shares  and  may  result in
involuntary conversion or redemption  of your shares.  See "Purchase of  Shares"
above.
 
                                       24
<PAGE>
                              VALUATION OF SHARES
 
    The  net asset  value per  share of a  class of  shares of  the Portfolio is
determined by dividing the total market value of the Portfolio's investments and
other assets attributable to  such class, less  any liabilities attributable  to
such  class, by  the total  number of  outstanding shares  of such  class of the
Portfolio. Net  asset value  is  calculated separately  for  each class  of  the
Portfolio.  Net asset value per share is determined  as of the close of the NYSE
on each day  that the NYSE  is open  for business. Price  information on  listed
securities  is taken from  the exchange where the  security is primarily traded.
Securities listed on a U.S. securities exchange for which market quotations  are
available  are valued at the last quoted sale  price on the day the valuation is
made. Securities listed on a foreign exchange are valued at their closing price.
Unlisted securities and listed securities not  traded on the valuation date  for
which  market quotations  are readily  available are valued  at a  price that is
considered to best represent fair value within a range not exceeding the current
asked price nor  less than  the current  bid price.  The current  bid and  asked
prices are determined based on the bid and asked prices quoted on such valuation
date by reputable brokers.
 
    Bonds and other fixed income securities are valued according to the broadest
and  most representative market,  which will ordinarily  be the over-the-counter
market. Net asset value includes interest  on fixed income securities, which  is
accrued  daily.  In addition,  bonds and  other fixed  income securities  may be
valued on the basis of prices provided by a pricing service when such prices are
believed to  reflect  the fair  market  value  of such  securities.  The  prices
provided  by a pricing service are determined without regard to bid or last sale
prices, but take into  account institutional size trading  in similar groups  of
securities  and any developments related  to the specific securities. Securities
not priced in this manner are valued  at the most recently quoted bid price,  or
when securities exchange valuations are used, at the latest quoted sale price on
the  day of valuation. If there is no  such reported sale, the latest quoted bid
price will be used. Securities purchased with remaining maturities of 60 days or
less are valued at amortized cost, if it approximates market value. In the event
that amortized  cost  does  not  approximate  market  value,  market  prices  as
determined above will be used.
 
    The value of other assets and securities for which no quotations are readily
available  (including  restricted  and unlisted  foreign  securities)  and those
securities for which it is inappropriate to determine prices in accordance  with
the  above-stated procedure  are determined  in good  faith at  fair value using
methods determined by the  Board of Directors. For  purposes of calculating  net
asset value per share, all assets and liabilities initially expressed in foreign
currencies will be translated into U.S. dollars at the mean of the bid price and
asked  price of such currencies against the U.S. dollar last quoted by any major
bank.
 
    Although the legal rights of Class A  and Class B shares will be  identical,
the  different expenses borne by  each class will result  in different net asset
values and dividends for the class.  Dividends will differ by approximately  the
amount  of the distribution expense accrual  differential among the classes. The
net asset value of  Class B shares  will generally be lower  than the net  asset
value  of the Class A shares as a  result of the distribution expense charged to
Class B shares.
 
                            PERFORMANCE INFORMATION
 
    The Fund may from time to time advertise total return for each class of  the
Portfolio.  THESE FIGURES ARE BASED ON  HISTORICAL EARNINGS AND ARE NOT INTENDED
TO INDICATE FUTURE PERFORMANCE. The "total return" shows what an investment in a
class of the Portfolio would have earned  over a specified period of time  (such
as one, five or ten
 
                                       25
<PAGE>
years),  assuming that  all distributions  and dividends  by the  Portfolio were
reinvested in the same class on the reinvestment dates during the period.  Total
return  does not take into account any federal or state income taxes that may be
payable on  dividends and  distributions or  on redemption.  The Fund  may  also
include  comparative  performance information  in  advertising or  marketing the
Portfolio's shares. Such  performance information may  include data from  Lipper
Analytical  Services, Inc.,  other industry  publications, business periodicals,
rating services and market indices.
 
    The performance figures  for Class  B shares  will generally  be lower  than
those  for Class  A shares because  of the  distribution fee charged  to Class B
shares.
 
                   DIVIDENDS AND CAPITAL GAINS DISTRIBUTIONS
 
    All income dividends and capital gains  distributions for a class of  shares
will automatically be reinvested in additional shares of such class at net asset
value,  except that,  upon written  notice to  the Fund  or by  checking off the
appropriate box in the Distribution  Option Section on the Account  Registration
Form,  a shareholder  may elect  to receive  income dividends  and capital gains
distributions in cash. The Portfolio expects to distribute substantially all  of
its  net investment income in the form  of annual dividends. Net realized gains,
if any, after reduction  for any available tax  loss carryforwards will also  be
distributed  annually. Confirmations of the purchase  of shares of the Portfolio
through the  automatic  reinvestment  of  income  dividends  and  capital  gains
distributions  will be  provided, pursuant to  Rule 10b-10  under the Securities
Exchange Act of 1934, as amended, on the next monthly client statement following
such purchase of shares. Consequently, confirmations of such purchases will  not
be  provided at the time  of completion of such  purchases as might otherwise be
required by Rule 10b-10.
 
    Undistributed net  investment  income is  included  in the  Portfolio's  net
assets  for the purpose of calculating net  asset value per share. Therefore, on
the "ex-dividend" date,  the net  asset value  per share  excludes the  dividend
(i.e.,  is reduced  by the  per share  amount of  the dividend).  Dividends paid
shortly after the purchase of shares by an investor, although in effect a return
of capital, are taxable to shareholders subject to income tax.
 
    Because of  the  distribution  fee  and  any  other  expenses  that  may  be
attributable  to the  Class B  shares, the  net income  attributable to  and the
dividends payable  on  Class  B  shares  will  be  lower  than  the  net  income
attributable  to and the dividends  payable on Class A  shares. As a result, the
net asset value per share of the classes of the Portfolio will differ at  times.
Expenses of the Portfolio allocated to a particular class of shares thereof will
be borne on a pro rata basis by each outstanding share of that class.
 
                                     TAXES
 
    The following summary of certain federal income tax consequences is based on
current tax laws and regulations, which may be changed by legislative, judicial,
or administrative action.
 
    No  attempt has been made to present  a detailed explanation of the federal,
state, or  local income  tax treatment  of the  Portfolio or  its  shareholders.
Accordingly,  shareholders  are urged  to consult  their tax  advisors regarding
specific questions as to federal, state and local income taxes.
 
    The Portfolio  is  treated as  a  separate  entity for  federal  income  tax
purposes  and is  not combined with  the Fund's other  portfolios. The Portfolio
intends  to  qualify   for  the   special  tax   treatment  afforded   regulated
 
                                       26
<PAGE>
investment companies under Subchapter M of the Internal Revenue Code of 1986, as
amended  (the "Code"), so that the Portfolio  will be relieved of federal income
tax on that  part of  its net  investment income and  net capital  gain that  is
distributed to shareholders.
 
    The  Portfolio distributes  substantially all  of its  net investment income
(including, for  this purpose,  net short-term  capital gain)  to  shareholders.
Dividends from the Portfolio's net investment income are taxable to shareholders
as ordinary income, whether received in cash or reinvested in additional shares.
Such  dividends paid  by the  Portfolio will generally  not qualify  for the 70%
dividends-received deduction  for  corporate shareholders.  The  Portfolio  will
report annually to its shareholders the amount of dividend income qualifying for
such treatment.
 
    Distributions  of net  capital gains (i.e.,  net long-term  capital gains in
excess of  net  short-term  capital  losses)  are  taxable  to  shareholders  as
long-term  capital gains,  regardless of how  long the shareholder  has held the
Portfolio's shares. The Portfolio sends reports annually to shareholders of  the
federal income tax status of all distributions made during the preceding year.
 
    The   Portfolio  intends   to  make   sufficient  distributions   or  deemed
distributions of its ordinary income and capital gain net income (the excess  of
short-term  and long-term  capital gains  over short-term  and long-term capital
losses), including any available capital loss carryforwards, prior to the end of
each calendar year to avoid liability for federal excise tax.
 
    Dividends and  other distributions  declared by  the Portfolio  in  October,
November or December of any year and payable to shareholders of record on a date
in  such month will be deemed to have been paid by the Portfolio and received by
the shareholders on December 31  of that year if  the distributions are paid  by
the Portfolio at any time during the following January.
 
    The  sale, exchange or  redemption of shares  may result in  taxable gain or
loss to the selling, exchanging or redeeming shareholder, depending upon whether
the fair market value  of the redemption  proceeds exceeds or  is less than  the
shareholder's  adjusted  basis in  the redeemed,  exchanged  or sold  shares. If
capital gain distributions have been made  with respect to shares that are  sold
at a loss after being held for six months or less, then the loss is treated as a
long-term capital loss to the extent of the capital gain distributions.
 
    The  conversion of Class A shares to Class  B shares should not be a taxable
event to the shareholder.
 
    Shareholders are urged  to consult  with their tax  advisers concerning  the
application  of state  and local income  taxes to investments  in the Portfolio,
which may differ from the federal income tax consequences described above.
 
    Investment income  received by  the Portfolio  from sources  within  foreign
countries  may be subject to foreign income taxes withheld at the source. To the
extent that the Portfolio  is liable for foreign  income taxes so withheld,  the
Portfolio  intends to operate so as to meet the requirements of the Code to pass
through to the shareholders credit for  foreign income taxes paid. Although  the
Portfolio  intends to  meet Code  requirements to  pass through  credit for such
taxes, there can be no assurance that the Portfolio will be able to do so.
 
                                       27
<PAGE>
    THE  TAX  DISCUSSION  SET  FORTH  ABOVE  IS  INCLUDED  HEREIN  FOR   GENERAL
INFORMATION  ONLY. PROSPECTIVE INVESTORS  SHOULD CONSULT THEIR  OWN TAX ADVISERS
WITH RESPECT TO THE TAX CONSEQUENCES TO THEM OF AN INVESTMENT IN THE PORTFOLIO.
 
                             PORTFOLIO TRANSACTIONS
 
    The Investment  Advisory  Agreement authorizes  the  Adviser to  select  the
brokers  or  dealers that  will execute  the purchases  and sales  of investment
securities for the Portfolio and directs the Adviser to use its best efforts  to
obtain the best available price and most favorable execution with respect to all
transactions  for  the Portfolio.  The Fund  has authorized  the Adviser  to pay
higher commissions in recognition of brokerage services which, in the opinion of
the Adviser, are necessary for the achievement of better execution, provided the
Adviser believes this to be in the best interest of the Fund.
 
    Since shares of the Portfolio are not marketed through intermediary  brokers
or  dealers, it is  not the Fund's  practice to allocate  brokerage or principal
business on the basis of sales of  shares which may be made through such  firms.
However,  the Adviser may  place portfolio orders  with qualified broker-dealers
who recommend the  Fund's portfolios or  who act  as agents in  the purchase  of
shares of the Fund's portfolios for their clients.
 
    In  purchasing and  selling securities for  the Portfolio, it  is the Fund's
policy to seek to obtain quality execution at the most favorable prices, through
responsible  broker-dealers.  In   selecting  broker-dealers   to  execute   the
securities  transactions for the Portfolio, consideration  will be given to such
factors as the price of the security,  the rate of the commission, the size  and
difficulty  of  the  order,  the  reliability,  integrity,  financial condition,
general execution and operational capabilities of competing broker-dealers,  and
the  brokerage  and  research services  which  they  provide to  the  Fund. Some
securities considered for investment  by the Portfolio  may also be  appropriate
for  other clients  served by  the Adviser.  If purchase  or sale  of securities
consistent with the  investment policies  of the Portfolio  and one  or more  of
these  other clients served  by the Adviser  is considered at  or about the same
time, transactions in such securities will be allocated among the Portfolio  and
clients in a manner deemed fair and reasonable by the Adviser. Although there is
no  specified formula for  allocating such transactions,  the various allocation
methods used by the Adviser, and the results of such allocations, are subject to
periodic review by the Fund's Board of Directors.
 
    Subject to the overriding objective of obtaining the best possible execution
of orders, the  Adviser may  allocate a  portion of  each portfolio's  brokerage
transactions  to Morgan Stanley or broker affiliates of Morgan Stanley. In order
for Morgan Stanley or  its affiliates to effect  any portfolio transactions  for
the Fund, the commissions, fees or other remuneration received by Morgan Stanley
or such affiliates 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   a
securities  exchange during a comparable period  of time. Furthermore, the Board
of Directors of  the Fund, including  a majority  of the Directors  who are  not
"interested  persons," have adopted procedures  which are reasonably designed to
provide that any commissions, fees or other remuneration paid to Morgan  Stanley
or such affiliates are consistent with the foregoing standard.
 
                                       28
<PAGE>
    Portfolio  securities will not be purchased from,  or through, or sold to or
through, the Adviser or Morgan Stanley  or any "affiliated persons," as  defined
in  the Investment Company Act  of 1940, as amended  (the "1940 Act"), of Morgan
Stanley when  such entities  are  acting as  principals,  except to  the  extent
permitted by law.
 
    Although  the  Portfolio will  not invest  for short-term  trading purposes,
investment securities may be sold from time to time without regard to the length
of time they have been held. It is anticipated that the annual turnover rate  of
the Portfolio will not exceed 100% in normal circumstances.
 
                              GENERAL INFORMATION
 
DESCRIPTION OF COMMON STOCK
 
    The  Fund was  organized as  a Maryland  corporation on  June 16,  1988. The
Articles of Incorporation, as amended and restated, permit the Fund to issue  up
to  34 billion shares of common stock,  with $.001 par value per share. Pursuant
to the Fund's Articles of Incorporation, the Board of Directors may increase the
number of shares the  Fund is authorized  to issue without  the approval of  the
shareholders  of the  Fund. Subject  to the  notice period  to shareholders with
respect to shares held by shareholders, the Board of Directors has the power  to
designate  one or  more classes of  shares of  common stock and  to classify and
reclassify any  unissued shares  with respect  to such  classes. The  shares  of
common  stock of each  portfolio are currently classified  into two classes, the
Class A shares and the Class B  shares, except for the International Small  Cap,
Money  Market and  Municipal Money Market  Portfolios, which only  offer Class A
shares.
 
    The shares of the Portfolio, when issued, will be fully paid, nonassessable,
fully transferable and redeemable at the  option of the holder. The shares  have
no  preference  as  to  conversion,  exchange,  dividends,  retirement  or other
features and  have  no preemptive  rights.  The  shares of  the  Portfolio  have
non-cumulative  voting rights, which means that the  holders of more than 50% of
the shares voting for the election of Directors can elect 100% of the  Directors
if  they choose  to do so.  Persons or organizations  owning 25% or  more of the
outstanding shares of a portfolio may be presumed to "control" (as that term  is
defined  in the 1940  Act) that Portfolio.  Under Maryland law,  the Fund is not
required to hold an annual meeting of its shareholders unless required to do  so
under the 1940 Act.
 
REPORTS TO SHAREHOLDERS
 
    The  Fund will send to its  shareholders annual and semi-annual reports; the
financial statements  appearing in  annual reports  are audited  by  independent
accountants.  Monthly unaudited portfolio  data is also  available from the Fund
upon request.
 
    In addition, the Adviser or its agent, as Transfer Agent, will send to  each
shareholder having an account directly with the Fund a monthly statement showing
transactions in the account, the total number of shares owned, and any dividends
or distributions paid.
 
CUSTODIAN
 
    As  of September 1,  1995, domestic securities  and cash are  held by Chase,
which replaced U.S.  Trust as  the Fund's domestic  custodian. Chase  is not  an
affiliate  of  the Adviser  or the  Distributor.  Morgan Stanley  Trust Company,
Brooklyn, New York ("MSTC"),  an affiliate of the  Adviser and the  Distributor,
acts  as the Fund's custodian for foreign  assets held outside the United States
and employs subcustodians  approved by  the Board of  Directors of  the Fund  in
accordance  with regulations of  the Securities and  Exchange Commission for the
 
                                       29
<PAGE>
purpose of providing  custodial services  for such  assets. MSTC  may also  hold
certain  domestic assets for  the Fund. For more  information on the custodians,
see "General Information -- Custody Arrangements" in the Statement of Additional
Information.
 
DIVIDEND DISBURSING AND TRANSFER AGENT
 
    Chase  Global   Funds  Services   Company,   73  Tremont   Street,   Boston,
Massachusetts 02108-3913, acts as Dividend Disbursing and Transfer Agent for the
Fund.
 
INDEPENDENT ACCOUNTANTS
 
    Price  Waterhouse LLP  serves as  independent accountants  for the  Fund and
audits its annual financial statements.
 
LITIGATION
 
    The Fund is not involved in any litigation.
 
                                       30
<PAGE>
<PAGE>
   MORGAN STANLEY INSTITUTIONAL FUND, INC.
          ACTIVE COUNTRY ALLOCATION PORTFOLIO
           P.O. BOX 2798, BOSTON, MA 02208-2798
 
                           ACCOUNT REGISTRATION FORM
 
<TABLE>
<C>   <S>                                                           <C>
                                                                    If you need assistance in filling out this form for the
      ACCOUNT INFORMATION                                           Morgan Stanley Institutional Fund, please contact your
      Fill in where applicable                                      Morgan Stanley representative or call us toll free
                                                                    1-(800)-548-7786. Please print all items except signature,
                                                                    and mail to the Fund at the address above.
 
  A)  REGISTRATION
      1. INDIVIDUAL
      2. JOINT TENANTS
         (RIGHTS OF SURVIVORSHIP PRESUMED UNLESS
         TENANCY IN COMMON
         IS INDICATED)
</TABLE>
 
1.
                  First Name                  Initial                  Last Name
 
2.
                  First Name                  Initial                  Last Name
 
                  First Name                  Initial                  Last Name
 
<TABLE>
<C>   <S>                                       <C>
      3. CORPORATIONS,
         TRUSTS AND OTHERS
         Please call the Fund for additional
      documents that may be required to set up
      account and to authorize transactions.
</TABLE>
 
3.
 
<TABLE>
<S>                     <C>                 <C>                   <C>               <C>
Type of Registration:   / / INCORPORATED    / / UNINCORPORATED    / / PARTNERSHIP   / / UNIFORM GIFT/TRANSFER TO MINOR
                                            ASSOCIATION                               (ONLY ONE CUSTODIAN AND MINOR PERMITTED)
</TABLE>
 
/ / TRUST ________________________  / / OTHER (Specify) ________________________
 
<TABLE>
<C>   <S>                                       <C>
  B)  MAILING ADDRESS
      Please fill in completely, including
      telephone number(s).
</TABLE>
 
Street or P.O. Box
City                                                                       State
                                                                             Zip
                                                                              --
Home Telephone No.                                                   Business
Telephone No.                     --            --              --            --
/ / United States Citizen  / / Resident Alien  / / Non-Resident Alien: Indicate
Country of Residence ___________________________________________________________
 
<TABLE>
<C>   <S>                                                           <C>                             <C>
  C)  TAXPAYER                                                      Enter your Taxpayer Identification Number. For most individual
      IDENTIFICATION                                                taxpayers, this is your Social Security Number.
      NUMBER
      1. INDIVIDUAL
      2. JOINT TENANTS
         (RIGHTS OF SURVIVORSHIP PRESUMED UNLESS
         TENANCY IN COMMON
         IS INDICATED)
      For Custodian account
      of a minor (Uniform
      Gifts/Transfers to Minor
      Acts), give the Social
      Security Number of
      the minor
                                                                                                    OR
                                                                    1.         TAXPAYER             SOCIAL SECURITY NUMBER
                                                                    IDENTIFICATION NUMBER           ("SSN")
                                                                    ("TIN")
                                                                                                    OR
                                                                    2.         TIN                  SSN
                                                                                                    OR
                                                                    TIN                             SSN
</TABLE>
<PAGE>
 
<TABLE>
<C>   <S>                                                           <C>                             <C>
                                                                    IMPORTANT TAX INFORMATION
                                                                    You  (as a payee) are required by law to provide us (as payer)
                                                                    with your  correct  TIN(s) or  SSN(s).  Accounts that  have  a
                                                                    missing  or  incorrect TIN(s)  or  SSN(s) will  be  subject to
                                                                    backup withholding at a  31% rate on dividends,  distributions
                                                                    and  other payments.  If you  have not  provided us  with your
                                                                    correct TIN(s) or SSN(s), you may be subject to a $50  penalty
                                                                    imposed by the Internal Revenue Service.
                                                                    Backup withholding is not an additional tax; the tax liability
                                                                    of  persons subject to  backup withholding will  be reduced by
                                                                    the amount  of  tax withheld.  If  withholding results  in  an
                                                                    overpayment    of   taxes,   a   refund   may   be   obtained.
                                                                    You may be notified that you are subject to backup withholding
                                                                    under Section  3406(a)(1)(C)  of  the  Internal  Revenue  Code
                                                                    because  you have  underreported interest or  dividends or you
                                                                    were required to,  but failed  to, file a  return which  would
                                                                    have included a reportable interest or dividend payment.
</TABLE>
 
<PAGE>
 
<TABLE>
<C>   <S>                        <C>                             <C>                   <C>
  D)  PORTFOLIO AND              For Purchase of the following
      CLASS SECTION              Portfolio(s):                   / / Class A Shares $  / / Class B Shares $
      (Class A shares minimum    Active Country Allocation
      $500,000 for each          Portfolio
      Portfolio and Class B
      shares minimum $100,000
      for the Global Equity,
      International Equity,
      Asian Equity, European
      Equity, Japanese Equity
      and Latin American Equity
      Portfolios). Please
      indicate Portfolio, class
      and amount.
                                                                 Total Initial Investment $
</TABLE>
 
<TABLE>
<C>   <S>                        <C>
  E)  METHOD OF
      INVESTMENT
      Please indicate
      portfolio, manner of
      payment.
</TABLE>
 
Payment by:
 
/ / Check (MAKE CHECK PAYABLE TO MORGAN STANLEY INSTITUTIONAL FUND,
INC.--PORTFOLIO NAME)
 
<TABLE>
<S>                                                                                 <C>
/ / Exchange $ From                                                                           -- - - - - - - - - - -- - -
                                                      Name of Portfolio                               Account No.
/ / Account previously established by:  / / Phone exchange  / / Wire on                       -- - - - - - - - - - -- - -
                                                                                            Account No.               (Check
                                                                                      (Previously assigned by the Fund)     Digit)
                                                                            Date
</TABLE>
 
<TABLE>
<C>   <S>                        <C>
  F)  DISTRIBUTION               Income dividends and capital gains distributions (if any) to
      OPTION                     be reinvested in additional shares unless either box below
                                 is checked.
                                 / / Income dividends to be paid in cash, capital gains
                                 distributions (if any) in shares.
                                 / / Income dividends and capital gains distributions (if
                                 any) to be paid in cash.
</TABLE>
 
<TABLE>
<C>   <S>                             <C>                                       <C>
  G)  TELEPHONE                       / / I/we hereby authorize the Fund and
      REDEMPTION                      its agents to honor any telephone         Name of COMMERCIAL Bank (Not Savings
      AND EXCHANGE                    requests to wire redemption proceeds to   Bank)
      OPTION                          the commercial bank indicated at right    Bank Account No.
      Please select at time of        and/or mail redemption proceeds to the
      initial application if you      name and address in which my/our fund
      wish to redeem or exchange      account is registered if such requests                                        Bank
      shares by telephone. A          are believed to be authentic.                                                  ABA
      SIGNATURE GUARANTEE IS          The Fund and the Fund's Transfer Agent                                         No.
      REQUIRED IF BANK ACCOUNT IS     will employ reasonable procedures to
      NOT REGISTERED IDENTICALLY TO   confirm that instructions communicated    Name(s) in which your BANK Account is
      YOUR FUND ACCOUNT.              by telephone are genuine. These           Established
      TELEPHONE REQUESTS FOR          procedures include requiring the
      REDEMPTIONS OR EXCHANGE WILL    investor to provide certain personal      Bank's Street
      NOT BE HONORED UNLESS THE BOX   identification information at the time    Address
      IS CHECKED.                     an account is opened and prior to
                                      effecting each transaction requested by   City                   State                   Zip
                                      telephone. In addition, all telephone
                                      transaction requests will be recorded
                                      and investors may be required to provide
                                      additional telecopied written
                                      instructions of transaction requests.
                                      Neither the Fund nor the Transfer Agent
                                      will be responsible for any loss,
                                      liability, cost or expense for following
                                      instructions received by telephone that
                                      it reasonably believes to be genuine.
</TABLE>
 
<TABLE>
<C>   <S>                        <C>
  H)  INTERESTED PARTY
      OPTION                                                                                      Name
      In addition to the
      account statement sent to
      my/our registered                                                                          Address
      address, I/we hereby
      authorize the fund to      City         State         Zip Code
      mail duplicate statements
      to the name and address
      provided at right.
</TABLE>
 
<TABLE>
<C>   <S>                        <C>
  I)  DEALER
      INFORMATION
                                 Representative Name                        Representative
                                 No.                            Branch
                                 No.
</TABLE>
 
<TABLE>
<C>   <S>                        <C>
  J)  SIGNATURE OF
      ALL HOLDERS
      AND TAXPAYER
      CERTIFICATION
      Sign Here ,
</TABLE>
 
<TABLE>
<S>                                  <C>
The undersigned certify that I/we have full authority and legal capacity
to purchase and redeem shares of the Fund and affirm that I/we have
received a current Prospectus of the Morgan Stanley Institutional Fund,
Inc. and agree to be bound by its terms.
  BY  SIGNING THIS APPLICATION,  I/WE HEREBY CERTIFY  UNDER PENALTIES OF
PERJURY THAT THE INFORMATION ON THIS APPLICATION IS COMPLETE AND CORRECT
AND THAT  AS REQUIRED  BY  FEDERAL LAW  (PLEASE CHECK  APPLICABLE  BOXES
BELOW):
/ / U.S. CITIZEN(S)/TAXPAYER(S):
       /  / I/WE CERTIFY THAT (1) THE NUMBER(S) SHOWN ABOVE ON THIS FORM
           IS/ARE THE  CORRECT SSN(S)  OR TIN(S)  AND (2)  I/WE ARE  NOT
           SUBJECT TO ANY BACKUP WITHHOLDING EITHER BECAUSE (A) I/WE ARE
           EXEMPT  FROM  BACKUP  WITHHOLDING;  (B)  I/WE  HAVE  NOT BEEN
           NOTIFIED BY THE  INTERNAL REVENUE SERVICE  ("IRS") THAT  I/WE
           ARE SUBJECT TO BACKUP WITHHOLDING AS A RESULT OF A FAILURE TO
           REPORT ALL INTEREST OR DIVIDENDS; OR (C) THE IRS HAS NOTIFIED
           ME/US   THAT  I  AM/WE  ARE   NO  LONGER  SUBJECT  TO  BACKUP
           WITHHOLDING.
       / / IF  NO TIN(S) OR  SSN(S) HAS/HAVE BEEN  PROVIDED ABOVE,  I/WE
           HAVE  APPLIED, OR INTEND  TO APPLY, TO THE  IRS OR THE SOCIAL
           SECURITY  ADMINISTRATION  FOR  A  TIN  OR  A  SSN  AND   I/WE
           UNDERSTAND THAT IF I/WE DO NOT PROVIDE EITHER NUMBER TO CHASE
           GLOBAL FUNDS SERVICES COMPANY ("CGFSC") WITHIN 60 DAYS OF THE
           DATE  OF THIS APPLICATION  OR IF I/WE  FAIL TO FURNISH MY/OUR
           CORRECT SSN(S) OR TIN(S),  I/WE MAY BE  SUBJECT TO A  PENALTY
           AND  A 31% BACKUP WITHHOLDING ON DISTRIBUTIONS AND REDEMPTION
           PROCEEDS. (PLEASE PROVIDE EITHER NUMBER ON IRS FORM W-9). YOU
           MAY REQUEST SUCH FORM BY CALLING CGFSC AT 800-282-4404.
/ / NON-U.S. CITIZEN(S)/TAXPAYER(S):
  INDICATE COUNTRY OF RESIDENCE FOR TAX PURPOSES:
  UNDER PENALTIES  OF  PERJURY, I/WE  CERTIFY  THAT I/WE  ARE  NOT  U.S.
CITIZENS  OR RESIDENTS AND I/WE ARE EXEMPT FOREIGN PERSONS AS DEFINED BY
THE INTERNAL REVENUE SERVICE.
THE INTERNAL  REVENUE  SERVICE DOES  NOT  REQUIRE YOUR  CONSENT  TO  ANY
PROVISION  OF THIS  DOCUMENT OTHER  THAN THE  CERTIFICATIONS REQUIRED TO
AVOID BACKUP WITHHOLDING.
 
                                     (X)
(X)                                  Signature (if joint account, both
Signature                                                                     Date must sign)         Date
</TABLE>
 
<PAGE>
<PAGE>
- -------------------------------------------
- -------------------------------------------
- -------------------------------------------
- -------------------------------------------
 
  NO  DEALER, SALES  REPRESENTATIVE OR ANY  OTHER PERSON HAS  BEEN AUTHORIZED TO
GIVE ANY INFORMATION OR TO MAKE ANY REPRESENTATIONS, OTHER THAN THOSE  CONTAINED
IN THIS PROSPECTUS, IN CONNECTION WITH THE OFFER MADE BY THIS PROSPECTUS AND, IF
GIVEN OR MADE, SUCH OTHER INFORMATION OR REPRESENTATIONS MUST NOT BE RELIED UPON
AS  HAVING BEEN AUTHORIZED BY THE FUND  OR THE DISTRIBUTOR. THIS PROSPECTUS DOES
NOT CONSTITUTE AN OFFER BY THE FUND OR THE DISTRIBUTOR TO SELL OR A SOLICITATION
OF AN OFFER TO BUY ANY OF  THE SECURITIES OFFERED HEREBY IN ANY JURISDICTION  TO
ANY  PERSON TO WHOM  IT IS UNLAWFUL TO  MAKE SUCH OFFER  OR SOLICITATION IN SUCH
JURISDICTION.
 
                           --------------------------
 
                               TABLE OF CONTENTS
 
<TABLE>
<S>                                                 <C>
                                                    PAGE
                                                    ----
Fund Expenses.....................................    2
Financial Highlights..............................    4
Prospectus Summary................................    6
Investment Objective and Policies.................   10
Additional Investment Information.................   12
Investment Limitations............................   15
Management of the Fund............................   15
Purchase of Shares................................   18
Redemption of Shares..............................   22
Shareholder Services..............................   24
Valuation of Shares...............................   25
Performance Information...........................   26
Dividends and Capital Gains Distributions.........   26
Taxes.............................................   27
Portfolio Transactions............................   28
General Information...............................   29
Account Registration Form
</TABLE>
 
                      ACTIVE COUNTRY ALLOCATION PORTFOLIO
 
                               A PORTFOLIO OF THE
 
                                 MORGAN STANLEY
                            INSTITUTIONAL FUND, INC.
 
                                  Common Stock
                               ($.001 PAR VALUE)
 
                                 -------------
                                   PROSPECTUS
                                 -------------
 
                               Investment Adviser
                                 Morgan Stanley
                             Asset Management Inc.
 
                                  Distributor
                              Morgan Stanley & Co.
                                  Incorporated
 
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