<PAGE>
SUPPLEMENT DATED JANUARY 30, 1998
TO STATEMENT OF ADDITIONAL INFORMATION DATED MAY 1, 1997
AS SUPPLEMENTED THROUGH SEPTEMBER 26, 1997
MORGAN STANLEY INSTITUTIONAL FUND, INC. (THE "FUND")
P.O. BOX 2798
BOSTON, MASSACHUSETTS
02208-2798
-------------
The Statement of Additional Information is being further supplemented to
reflect (i) certain changes in the non-fundamental investment limitations of the
High Yield Portfolio; (ii) changes in the biographical information of Andrew
McNally IV, a Director of the Fund; and (iii) the election of Stefanie V. Chang
as a Vice President of the Fund. The Statement of Additional Information is
further supplemented as follows:
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On page 23 of the Statement of Additional Information, non-fundamental
limitation numbers (2), (3), (7), (8) and (9) are hereby deleted and replaced
with the following:
(2) except for the High Yield Portfolio, purchase or retain securities
of an issuer if those Officers and Directors of the Fund or its
investment adviser owning more than 1/2 of 1% of such securities
together own more than 5% of such securities;
(3) pledge, mortgage, or hypothecate any of its assets to an extent
greater than 10% of its total assets at fair market value, except
that the High Yield Portfolio may pledge, mortgage or hypothecate a
maximum of 50% of its assets, not counting assets segregated to
comply with coverage requirements under Section 18(f) of the 1940
Act, and the SEC's rules, regulations, orders, and interpretations
thereunder;
(7) make loans except (i) by purchasing bonds, debentures or similar
obligations (including repurchase agreements, subject to the
limitations as described in the respective Prospectuses) that are
publicly distributed, except that the High Yield Portfolio also may
purchase such securities that are not publicly distributed; (ii) by
lending its portfolio securities to banks, brokers, dealers and other
financial institutions so long as such loans are not consistent with
the 1940 Act or the Rules and Regulations or interpretations of the
Commission thereunder; and (iii) the High Yield Portfolio may lend
securities to institutional investors in addition to entities
described in (ii);
(8) 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, or purchase securities while borrowings
exceed 5% of its total assets, except that (i) the Latin American,
Emerging Markets Debt and Technology Portfolios may borrow in
accordance with Fundamental Restriction No. (5) above; and (ii) the
High Yield Portfolio may borrow up to 33 1/3% of its total assets in
the aggregate, including reverse repurchase agreements; and
(9) except for the High Yield Portfolio, invest in fixed time deposits
with a duration of over seven calendar days or 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.
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<PAGE>
The first paragraph on page 24 is hereby deleted and replaced with the
following:
With respect to fundamental investment limitation number (7), the
Fund will determine industry concentration in accordance with the
classifications of industries based on the Industry Numbers from the
Standard Industrial Classification Manual as prepared by the Office of
Management and Budget, except that (i) with respect to the Money Market,
Municipal Money Market and High Yield Portfolios, (a) financial service
companies will be classified according to the end users of their
services, for example, automobile finance, bank finance and diversified
finance will each be considered a separate industry and (b) asset-backed
securities will be classified according to the underlying assets
securing such securities; and (ii) with respect to the High Yield
Portfolio, utility companies will be classified according to their
services, for example, electric, gas, gas transmission, and telephone
will be treated as separate industries.
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The biographical information of Andrew McNally IV on page 25 is hereby
deleted and replaced with the following:
<TABLE>
<CAPTION>
PRINCIPAL OCCUPATION DURING PAST FIVE
NAME, ADDRESS AND DATE OF BIRTH POSITION WITH FUND YEARS
- ---------------------------------------- -------------------- ----------------------------------------
<S> <C> <C>
Andrew McNally IV Director Director of Allendale Insurance Co.,
8255 North Central Park Avenue Mercury Finance (consumer finance);
Skokie, IL 60076 Zenith Electronics, Hubbell, Inc.
11/11/39 (industrial electronics); Director of
Morgan Stanley Universal Funds, Inc. and
Morgan Stanley Strategic Adviser Fund,
Inc.; Formerly, Chairman and Chief
Executive Officer of Rand McNally &
Company (publishing).
</TABLE>
--------------
The following biographical information for Stefanie V. Chang is inserted
between the biographical information for Joseph P. Stadler and Valerie Y. Lewis
on page 25:
<TABLE>
<CAPTION>
PRINCIPAL OCCUPATION DURING PAST FIVE
NAME, ADDRESS AND DATE OF BIRTH POSITION WITH FUND YEARS
- ---------------------------------------- -------------------- ----------------------------------------
<S> <C> <C>
Stefanie V. Chang* Vice President Vice President of Morgan Stanley & Co.
1221 Avenue of the Americas Incorporated and Morgan Stanley Asset
New York, NY 10020 Management Inc.; Vice President of
11/30/66 various investment companies managed by
Morgan Stanley Asset Management Inc.
Previously practiced law with the New
York law firm of Rogers & Wells.
</TABLE>
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PLEASE RETAIN THIS SUPPLEMENT FOR FUTURE REFERENCE
<PAGE>
SUPPLEMENT DATED JANUARY 30, 1998
TO PROSPECTUS DATED MAY 1, 1997
PREVIOUSLY SUPPLEMENTED ON AUGUST 14, 1997
TECHNOLOGY PORTFOLIO
A PORTFOLIO OF THE
MORGAN STANLEY INSTITUTIONAL FUND, INC. (THE "FUND")
P.O. BOX 2798
BOSTON, MASSACHUSETTS
02208-2798
-------------
The Prospectus is further amended and supplemented to reflect a change in
the portfolio management of the Technology Portfolio. Christopher R. Blair will
no longer serve as Portfolio Manager for the Technology Portfolio. Stephen C.
Sexauer and William T. Corcoran will share primary responsibility for managing
the assets of the Technology Portfolio. Accordingly, the second full paragraph
on page 20 is hereby deleted and replaced with the following:
PORTFOLIO MANAGERS. STEPHEN C. SEXAUER AND WILLIAM T. CORCORAN.
Stephen C. Sexauer is a Principal of Morgan Stanley and the Adviser
and is a member of the Adviser's investment management team. In addition
to portfolio management, his equity research responsibilities include
financials, energy, utilities and technology. Mr. Sexauer joined the
Adviser in July 1989 after three years as Vice President at Salomon
Brothers. Previously, he was with Merrill Lynch Economics and Wharton
Econometrics. Mr. Sexauer received a B.S. in Economics from the
University of Illinois and an M.B.A. in Economics and Statistics from
the University of Chicago. William T. Corcoran joined the Adviser in
1996 as a Securities Analyst in the Emerging Growth Stock and Technology
Groups. Prior to joining the Adviser, he worked at Scotia McLeod, Inc.
for three years in Corporate Finance and Equity Research. Mr. Corcoran
received his B.A. degree from McGill University in 1991 and M.B.A. from
Columbia Business School in 1996. He is a Chartered Financial Analyst.
--------------
PLEASE RETAIN THIS SUPPLEMENT FOR FUTURE REFERENCE
<PAGE>
SUPPLEMENT DATED JANUARY 30, 1998
TO PROSPECTUS DATED MAY 1, 1997
PREVIOUSLY SUPPLEMENTED ON SEPTEMBER 26, 1997
EQUITY GROWTH PORTFOLIO
EMERGING GROWTH PORTFOLIO
AGGRESSIVE EQUITY PORTFOLIO
PORTFOLIOS OF THE
MORGAN STANLEY INSTITUTIONAL FUND, INC. (THE "FUND")
P.O. BOX 2798
BOSTON, MASSACHUSETTS
02208-2798
-------------
The Prospectus is further amended and supplemented to reflect a change in
the portfolio management of the Emerging Growth Portfolio. Christopher R. Blair
will no longer serve as Portfolio Manager for the Emerging Growth Portfolio.
Kurt A. Feuerman will continue to be primarily responsible for managing the
assets of the Emerging Growth Portfolio. Accordingly, the last three paragraphs
on page 23 and the first paragraph on page 24 are hereby deleted and replaced
with the following:
EMERGING GROWTH AND AGGRESSIVE EQUITY PORTFOLIOS -- KURT A.
FEUERMAN. Information about Mr. Feuerman is included under the Equity
Growth Portfolio above.
--------------
PLEASE RETAIN THIS SUPPLEMENT FOR FUTURE REFERENCE
