<PAGE>
Filed Pursuant to Rule 497(e)
Registration File No.: 33-63685
SUPPLEMENT TO THE PROSPECTUS OF
TCW/DW MID-CAP EQUITY TRUST
DATED JANUARY 30, 1998
THE FUND AND ITS MANAGEMENT. On February 25, 1999, acting on a proposal in
connection with an overall consolidation of the TCW/DW Family of Funds and the
Morgan Stanley Dean Witter Family of Funds, the Board of Trustees unanimously
recommended that the Fund engage Morgan Stanley Dean Witter Advisors Inc.
("MSDW Advisors"), the parent company of Morgan Stanley Dean Witter Services
Company Inc. ("MSDW Services"), the Fund's current manager, to serve as the
Fund's new investment manager and that a new investment management agreement
between the Fund and MSDW Advisors (the "New Investment Management Agreement")
be submitted to shareholders for approval at a special meeting expected to be
held in June 1999. Under the proposed New Investment Management Agreement, MSDW
Advisors would be responsible for all of the services that are presently being
provided in accordance with the current management agreement between the Fund
and MSDW Services (the "Current Management Agreement") and the current advisory
agreement between the Fund and TCW Funds Management, Inc. ("TCW") (the "Current
Advisory Agreement"), except that the New Investment Management Agreement would
provide that MSDW Advisors could, at its own expense, enter into a sub-advisory
agreement with another money manager.
The advisory fee rates MSDW Advisors would charge the Fund under the New
Investment Management Agreement would be 0.75% of the Fund's net assets not
exceeding $500 million and 0.725% on assets exceeding $500 million. The
combined fee rate in effect under the Fund's Current Management and Advisory
Agreements is 1.00% of the Fund's net assets and therefore the fee rate under
the New Investment Management Agreement would be 0.25% lower with respect to
the portion of daily net assets not exceeding $500 million and would be 0.275%
lower with respect to the portion of daily net assets exceeding $500 million.
At the February 25, 1999 meeting, the Trustees also recommended that a new
sub-advisory agreement (the "New Sub-Advisory Agreement") between MSDW Advisors
and TCW be submitted to shareholders at the same special meeting of
shareholders to be held in June 1999. TCW is a wholly-owned subsidiary of The
TCW Group, Inc. In return for the services that TCW would render under the New
Sub-Advisory Agreement, MSDW Advisors would pay TCW monthly compensation equal
to 40% of the compensation it receives under the New Investment Management
Agreement.
At their February 25, 1999 meeting, the Trustees of the Fund also
nominated for election or re-election, as appropriate, the following eight
nominees to the Fund's Board of Trustees at the June meeting of shareholders:
Michael Bozic, Charles A. Fiumefreddo, Edwin Jacob (Jake) Garn, Wayne E.
Hedien, Dr. Manuel H. Johnson, Michael E. Nugent, Philip J. Purcell and John L.
Schroeder. Messrs. Fiumefreddo, Johnson, Nugent and Schroeder currently serve
as Trustees of the Fund and were previously elected by shareholders. Messrs.
Bozic, Garn, Hedien and Purcell are nominated to replace Messrs. Argue,
DeMartini, Larkin and Stern, who intend to resign as Trustees, and they would
commence service at the time the New Investment Management Agreement takes
effect. Messrs. Bozic, Garn, Hedien and Purcell currently hold directorships or
trusteeships with 84 other investment companies for which MSDW Advisors serves
as investment manager or investment advisor.
Finally, at the February 25, 1999 meeting, the Trustees also voted to
change the name of the Fund upon effectiveness of the proposals from "TCW/DW
Mid-Cap Equity Trust" to "Morgan Stanley Dean Witter Mid-Cap Equity Trust."
February 25, 1999
