<PAGE>
SUPPLEMENT DATED SEPTEMBER 25, 1998
TO PROSPECTUS DATED MAY 1, 1998
SMALL CAP VALUE EQUITY PORTFOLIO
VALUE EQUITY PORTFOLIO
GLOBAL FIXED INCOME PORTFOLIO
HIGH YIELD PORTFOLIO
PORTFOLIOS OF THE
MORGAN STANLEY INSTITUTIONAL FUND, INC.
P.O. BOX 2798
BOSTON, MASSACHUSETTS
02208-2798
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The Prospectus is hereby amended and supplemented to reflect a change in the
portfolio management of the Value Equity Portfolio. Philip W. Friedman no longer
serves as Portfolio Manager of the Value Equity Portfolio. Stephen C. Sexauer
now has primary responsibility for managing the Portfolio's assets. Accordingly,
the section "VALUE EQUITY AND BALANCED PORTFOLIOS" on page 29 is hereby deleted
and replaced with the following:
VALUE EQUITY PORTFOLIO -- STEPHEN C. SEXAUER. 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. Mr. Sexauer has had primary responsibility
for managing the Portfolio's assets since January 1992.
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PLEASE RETAIN THIS SUPPLEMENT FOR FUTURE REFERENCE
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SUPPLEMENT DATED SEPTEMBER 25, 1998
TO PROSPECTUS DATED MAY 1, 1998
TECHNOLOGY PORTFOLIO
A PORTFOLIO OF THE
MORGAN STANLEY INSTITUTIONAL FUND, INC.
P.O. BOX 2798
BOSTON, MASSACHUSETTS
02208-2798
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The Prospectus is hereby amended and supplemented to reflect a change in the
portfolio management of the Technology Portfolio. Alexander Umansky now shares
primary responsibility for managing the Portfolio's assets with Stephen C.
Sexauer. Accordingly, the section "PORTFOLIO MANAGERS." on page 20 is hereby
deleted and replaced with the following:
PORTFOLIO MANAGERS. STEPHEN C. SEXAUER AND ALEXANDER UMANSKY. 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. Alexander Umansky joined the
Adviser in 1994 as a Compliance Analyst. In 1996, he became a research
analyst in the Institutional Equity Group. Prior to joining the Adviser, he
was a financial analyst in Morgan Stanley's Global Risk Management
department. He graduated from New York University's Stern School of Business
with a B.S. in Computer Science and Finance. Stephen C. Sexauer and
Alexander Umansky have had primary responsibility for managing the
Portfolio's assets since January 1998 and September 1998, respectively.
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PLEASE RETAIN THIS SUPPLEMENT FOR FUTURE REFERENCE
<PAGE>
SUPPLEMENT DATED SEPTEMBER 25, 1998
TO PROSPECTUS DATED MAY 1, 1998
EQUITY GROWTH PORTFOLIO
EMERGING GROWTH PORTFOLIO
AGGRESSIVE EQUITY PORTFOLIO
PORTFOLIOS OF THE
MORGAN STANLEY INSTITUTIONAL FUND, INC.
P.O. BOX 2798
BOSTON, MASSACHUSETTS
02208-2798
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The Prospectus is hereby amended and supplemented to reflect changes in the
portfolio management of the Equity Growth, Emerging Growth and Aggressive Equity
Portfolios. Kurt A. Feuerman no longer serves as a Portfolio Manager of the
Portfolios. Accordingly, the section "PORTFOLIO MANAGERS." on page 24 is hereby
deleted and replaced with the following:
PORTFOLIO MANAGERS. The following persons have primary responsibility
for managing the Portfolios indicated.
EQUITY GROWTH PORTFOLIO -- PHILIP W. FRIEDMAN, MARGARET K. JOHNSON AND
WILLIAM S. AUSLANDER. Philip W. Friedman is a Managing Director of Morgan
Stanley and the Adviser and is a member of the investment management team of
the Adviser. In addition to portfolio management, his equity research
responsibilities include business equipment and services, capital goods,
consumer durables, multi-industry and transportation. Prior to joining the
Adviser in 1997, he was the North American Director of Equity Research at
Morgan Stanley. From 1990 to 1995, he was a member of Morgan Stanley's
Equity Research team. Mr. Friedman graduated from Rutgers University with a
B.A. (PHI BETA KAPPA AND SUMMA CUM LAUDE) in Economics. He also holds an
M.B.A. from the J.L. Kellogg School of Management at Northwestern
University. Margaret K. Johnson is a Principal of the Adviser and Morgan
Stanley and a Portfolio Manager in the Institutional Equity Group. She
joined the Adviser in 1984. She holds a B.A. degree from Yale College and is
a Chartered Financial Analyst. William S. Auslander is a Vice President of
the Adviser and Morgan Stanley. He joined the Adviser in 1995 as an equity
analyst in the Institutional Equity Group. Prior to joining the Adviser, he
worked at Icahn & Co. for nine years as an equity analyst. He graduated from
the University of Wisconsin at Madison with a B.A. in Economics and received
an M.B.A. from Columbia University. Margaret K. Johnson has shared primary
responsibility for managing the Portfolio's assets since July 1993. Philip
W. Friedman and William S. Auslander have shared primary responsibility for
managing the Portfolio's assets since September 1998.
EMERGING GROWTH PORTFOLIO -- DANIEL R. LASCANO. Daniel R. Lascano is a
Vice President of the Adviser and Morgan Stanley. He joined the Adviser in
1993 as an equity analyst. Prior to joining the Adviser, Mr. Lascano worked
at Morgan Stanley as a research assistant in the Equity Group. Mr. Lascano
<PAGE>
graduated from the University of California at Berkeley with a B.A. in
Economics and Statistics. Daniel R. Lascano has had primary responsibility
for managing the Portfolio's assets since May 1998.
AGGRESSIVE EQUITY PORTFOLIO -- PHILIP W. FRIEDMAN, WILLIAM S. AUSLANDER
AND KENNETH RADER. Information about Messrs. Friedman and Auslander is
included under the Equity Growth Portfolio above. Kenneth Rader is a Vice
President of the Adviser and Morgan Stanley. He joined the Adviser in 1998
and is a portfolio manager in the Institutional Equity Group. Prior to
joining Morgan Stanley, he worked for various hedge funds since 1992,
including BEM Management and Odyssey Partners. He holds a B.S. degree from
the University of Pennsylvania and is a Chartered Financial Analyst. Philip
W. Friedman, William S. Auslander and Kenneth Rader have shared primary
responsibility for managing the Portfolio's assets since September 1998.
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PLEASE RETAIN THIS SUPPLEMENT FOR FUTURE REFERENCE
