<PAGE>
SUPPLEMENT TO PROSPECTUS
OF
DEAN WITTER SELECT DIMENSIONS INVESTMENT SERIES
DATED MARCH 2, 1998, REVISED MAY 1, 1998
ON MARCH 24, 1998, MORGAN STANLEY, DEAN WITTER, DISCOVER & CO., THE PARENT
COMPANY OF THE FUND'S INVESTMENT MANAGER AND TRANSFER AGENT, WAS RENAMED MORGAN
STANLEY DEAN WITTER & CO. The current Prospectus reflects the new name.
ON JUNE 22, 1998, DEAN WITTER SELECT DIMENSIONS INVESTMENT SERIES WAS RENAMED
MORGAN STANLEY DEAN WITTER SELECT DIMENSIONS INVESTMENT SERIES. All references
in the current Prospectus to "Dean Witter Select Dimensions Investment Series"
or "the Fund" apply to Morgan Stanley Dean Witter Select Dimensions Investment
Series.
ON JUNE 22, 1998, THE DEAN WITTER FUNDS WERE RENAMED THE "MORGAN STANLEY DEAN
WITTER FUNDS." All references in the current Prospectus to the "Dean Witter
Funds" apply to the Morgan Stanley Dean Witter Funds.
ON JUNE 22, 1998, DEAN WITTER INTERCAPITAL INC., THE FUND'S INVESTMENT MANAGER,
WAS RENAMED MORGAN STANLEY DEAN WITTER ADVISORS INC. All references in the
current Prospectus to "Dean Witter InterCapital Inc.," "InterCapital" or "the
Investment Manager" apply to Morgan Stanley Dean Witter Advisors Inc.
ON MARCH 24, 1998, DEAN WITTER TRUST FSB, THE FUND'S TRANSFER AGENT, WAS RENAMED
MORGAN STANLEY DEAN WITTER TRUST FSB. The current Prospectus reflects the new
name.
ON JUNE 22, 1998, DEAN WITTER DISTRIBUTORS INC., THE DISTRIBUTOR OF THE OTHER
DEAN WITTER FUNDS, WAS RENAMED MORGAN STANLEY DEAN WITTER DISTRIBUTORS INC. All
references in the current Prospectus to "Dean Witter Distributors Inc." or
"Distributors" apply to Morgan Stanley Dean Witter Distributors Inc.
ON JUNE 22, 1998, DEAN WITTER SERVICES COMPANY INC., A SUBSIDIARY OF
INTERCAPITAL THAT PERFORMS CERTAIN ADMINISTRATIVE SERVICES FOR THE FUND, WAS
RENAMED MORGAN STANLEY DEAN WITTER SERVICES COMPANY INC. All references in the
current Prospectus to "Dean Witter Services Company Inc." or "DWSC" apply to
Morgan Stanley Dean Witter Services Company Inc.
June 22, 1998
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