Prospectus Supplement filed under Rule 424(b)(3) Registration No. 333-84573 Prospectus Supplement Dated November 5, 1999 The Prospectus dated August 13, 1999 relating to the offer for resale of up to $361,000,000 aggregate principal amount of The Interpublic Group of Companies, Inc.'s 1.87% Convertible Subordinated Notes due 2006, and such shares of common stock as may be issued upon conversion of the notes, is hereby supplemented to include the following information in the "Selling Securityholders" table in the Prospectus Supplement dated August 13, 1999: Principal Amount of Registered Selling Securityholders Notes - ----------------------------------------------------------- ---------------- Credit Suisse First Boston Corporation .................... $500,000 Warburg Dillon Read LLC ................................... 250,000 - ----------------------------------------------------------- -------- Total of Above $750,000 ======== ------------------ The "Selling Securityholders" table in the Prospectus, as supplemented, is amended so that the principal amount of registered notes held by Merrill Lynch, Pierce, Fenner & Smith, Inc. is reduced from $1,085,000 to $300,000.