<PAGE>
MORGAN GRENFELL INVESTMENT TRUST
Institutional Funds
Supplement dated June 21, 1999 to
Statement of Additional Information
dated March 1, 1999
THIS SUPPLEMENT PROVIDES NEW AND ADDITIONAL INFORMATION BEYOND THAT
CONTAINED IN THE PROSPECTUS AND STATEMENT OF ADDITIONAL INFORMATION ("SAI"). IT
SHOULD BE RETAINED AND READ IN CONJUNCTION WITH SUCH PROSPECTUS AND SAI.
TRUSTEES AND OFFICERS
THE FOLLOWING PARAGRAPH IS HEREBY DELETED FROM THE SECTION TITLED "TRUSTEES
AND OFFICERS" WITHIN THE STATEMENT OF ADDITIONAL INFORMATION.
<TABLE>
<CAPTION>
POSITIONS PRINCIPAL OCCUPATION
NAME AND ADDRESS WITH TRUST DURING PAST FIVE YEARS
- ------------------------------------- ------------------------------------- -------------------------------------
<S> <C> <C>
Patrick W.W. Disney (1)(3)* Senior Vice President and Trustee Director, Morgan Grenfell Investment
20 Finsbury Circus Services Limited ("MGIS") (since
London EC2M 1NB 1988)
ENGLAND
(age 42)
</TABLE>
APPENDIX C
PORTFOLIO MANAGER INFORMATION
THE FOLLOWING PARAGRAPHS ARE HEREBY DELETED FROM THE SECTION TITLED
"APPENDIX C -- PORTFOLIO MANAGER INFORMATION" WITHIN THE STATEMENT OF ADDITIONAL
INFORMATION.
<TABLE>
<CAPTION>
FUNDS PORTFOLIO MANAGERS
- --------------------------------------------------------- ---------------------------------------------------------
<S> <C>
Morgan Grenfell International Select Equity Fund Patrick Disney
Morgan Grenfell Global Equity Fund Patrick Disney
</TABLE>
<TABLE>
<CAPTION>
PORTFOLIO MANAGER EXPERTISE PROFESSIONAL EXPERIENCE
- ------------------------------------- ------------------------------------- -------------------------------------
<S> <C> <C>
Patrick Disney EAFE Markets Managing Director, MGIS (since 1988),
Director, MGIS (1987-1988) EAFE Team
(since 1981).
</TABLE>
PLEASE RETAIN THIS SUPPLEMENT FOR FUTURE REFERENCE.
<PAGE>
MORGAN GRENFELL INVESTMENT TRUST
Supplement dated June 21, 1999 to
Statement of Additional Information
dated March 1, 1999
THIS SUPPLEMENT PROVIDES NEW AND ADDITIONAL INFORMATION BEYOND THAT
CONTAINED IN THE PROSPECTUS AND STATEMENT OF ADDITIONAL INFORMATION ("SAI"). IT
SHOULD BE RETAINED AND READ IN CONJUNCTION WITH SUCH PROSPECTUS AND SAI.
TRUSTEES AND OFFICERS
THE FOLLOWING PARAGRAPH IS HEREBY DELETED FROM THE SECTION TITLED "TRUSTEES
AND OFFICERS" WITHIN THE STATEMENT OF ADDITIONAL INFORMATION.
<TABLE>
<CAPTION>
POSITIONS PRINCIPAL OCCUPATION
NAME AND ADDRESS WITH TRUST DURING PAST FIVE YEARS
- ------------------------------------- ------------------------------------- -------------------------------------
<S> <C> <C>
Patrick W.W. Disney (1)(3)* Senior Vice President and Trustee Director, Morgan Grenfell Investment
20 Finsbury Circus Services Limited ('MGIS') (since
London EC2M 1NB 1988).
ENGLAND
(age 42)
</TABLE>
INVESTMENT ADVISORY AND OTHER SERVICES
PORTFOLIO MANAGEMENT
Robert Guzman has joined the investment team for the Fixed Income Funds as a
portfolio manager. Mr. Guzman has been in the investment advisory business since
1986 and has managed funds with Bankers Trust and the Union Bank of Switzerland.
The following paragraph replaces in its entirety the third paragraph under
"Investment Advisory and Other Services -- Portfolio Management" in the SAI.
The Smaller Companies Fund and Microcap Fund are each managed by a team of
three experienced portfolio managers, Audrey M.T. Jones, John P. Callaghan and
Mary P. Dugan. Ms. Jones has served as a member of the Funds' portfolio
management team since the Funds' inception. Mr. Callaghan joined the Funds'
portfolio management team (and the Adviser) in June 1997 and, prior to such
time, worked as a portfolio manager for Odyssey Partners and Weiss, Peck &
Greer. Ms. Jones has been employed by the Adviser as a portfolio manager since
1986. Ms. Dugan joined the Funds' portfolio management team (and the Adviser) as
a portfolio manager in June 1999 and, prior to such time, worked as a portfolio
manager or analyst at Bankers Trust Company and Fred Alger Asset Management.
David A. Baratta, formerly a portfolio manager and officer of the Funds (and
the Adviser), has resigned.
PLEASE RETAIN THIS SUPPLEMENT FOR FUTURE REFERENCE.
