PROSPECTUS SUPPLEMENT
(To Prospectus Dated January 28, 1998)
807,746 Shares of Common Stock
($.50 Par Value)
OMNICOM GROUP INC.
---------------------
This document supplements the Prospectus dated January 28, 1998 relating
to 807,746 shares of Common Stock, par value $.50 per share (the "Common Stock")
of the Omnicom Group, Inc., a New York corporation ("Omnicom" or the "Company").
Each share of Common Stock offered hereby was issued upon exchange of an
Exchangeable Share (an "Exchangeable Share") of GPC International Holdings Inc.
("GPC"), a corporation incorporated under the laws of Canada, issued in a
private offering in Canada by GPC and the Company. The shares of Common Stock
offered hereby were initially acquired upon exchange of the Exchangeable Shares
in a private offering in Canada. This Prospectus Supplement is incorporated by
reference into the Prospectus, and all terms used herein shall have the meaning
assigned to them in the Prospectus. On May 22, 1998 the closing price of the
Common Stock as reported on the New York Stock Exchange was $47.625 per share.
The Common Stock is traded under the symbol "OMC."
The Selling Shareholder does not own in excess of 1% of the Common Stock
of the Company and since the Selling Shareholders may sell all, some or none of
the shares of Common Stock offered hereby, no estimate can be made of the
aggregate number of shares of Common Stock that will be owned by the Selling
Shareholder upon completion of the offering to which this Prospectus Supplement
relates. In accordance with the Section of the Prospectus entitled "Selling
Shareholders" (which appears on page 10 of the Prospectus), the following
information is provided with respect to the beneficial owner of the Common
Stock.
Amount of Shares Amount of
Beneficially Owned Shares to be
Name of Selling Shareholder(s) as of March 22, 1998(1) Offered for Sale
- ------------------------------ ----------------------- ----------------
3423611 Canada Inc.(1) 120,358 120,358
(1) The ultimate controlling shareholder is an officer and director of GPC and
a subsidiary of GPC.
Except for the purchase of the shares of Common Stock, their current
holdings of Exchangeable Shares and the information disclosed in the footnote
above, the Selling Shareholder has not had a material relationship with the
Company or any of its affiliates within the past three years.
-----------------------
THESE SECURITIES HAVE NOT BEEN APPROVED OR DISAPPROVED BY THE SECURITIES AND
EXCHANGE COMMISSION OR ANY STATE SECURITY COMMISSION NOR HAS THE SECURITIES AND
EXCHANGE COMMISSION OR ANY STATE SECURITIES COMMISSION PASSED UPON THE ACCURACY
OR ADEQUACY OF THIS PROSPECTUS. ANY REPRESENTATION TO THE CONTRARY IS A CRIMINAL
OFFENSE.
-----------------------
The date of this Prospectus Supplement is May 26, 1998.
