Prospectus Supplement filed under Rule 424(b)(3) Registration No. 333-45569 Prospectus Supplement The Prospectus dated February 4, 1998 relating to the offer for resale of up to $250,000,000 aggregate principal amount of The Interpublic Group of Companies, Inc.'s 1.80% Convertible Subordinated Notes due September 16, 2004 is hereby supplemented to include the following information in the "Selling Security- holders" table in the Prospectus Supplement dated February 25, 1998: Principal Amount of Registered Selling Holders Notes - ---------------------------------------------- ---------------- Key Asset Management, Inc..................... $200,000 - ---------------------------------------------- ---------------- Total of Above................................ $200,000 ================ The "Selling Securityholder" table in the Prospectus, as supplemented, is amended so that the principal amount of registered Notes held by Morgan Stanley Dean Witter is decreased from $2,530,000 to $2,250,000. This Prospectus Supplement is dated December 28, 1998.