Prospectus Supplement filed under Rule 424(b)(3) Registration No. 333-84573 Prospectus Supplement Dated August 20, 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 Selling Securityholders of Registered Notes ----------------------- ------------------- AIG/National Union Fire Insurance............................................... 900,000 Alembic Inc. ................................................................... 200,000 Aloha Airlines Non-Pilots Pension Trust......................................... 180,000 Aloha Airlines Pilots Retirement Trust.......................................... 95,000 Arkansas Teachers Retirement System............................................. 3,175,000 Bancroft Convertible Fund, Inc. ................................................ 1,500,000 Bankers Trust Trustee for Chrysler Corp. Emp. #1 Pension Plan dated 4/1/89...... 3,120,000 Baptist Health of South Florida................................................. 215,000 Boilermakers Blacksmith Pension Trust........................................... 1,475,000 Boston Museum of Fine Art....................................................... 165,000 C&H Sugar Company, Inc. ........................................................ 275,000 Chase Manhattan N.A. Trustee for IBM Retirement Plan dated 12/18/45............. 4,177,000 Donaldson, Lufkin & Jenrette Securities Corp. .................................. 1,000,000 Ellsworth Convertible Growth and Income Fund, Inc. ............................. 1,500,000 Engineers Joint Pension Fund.................................................... 445,000 Franklin & Marshall College..................................................... 240,000 Fundamental Investors........................................................... 6,668,000 GLG Global Convertible Fund..................................................... 4,000,000 Hawaiian Airlines Employees Pension Plan--IAM................................... 155,000 Hawaiian Airlines Pension Plan for Salaried Employees........................... 40,000 Hawaiian Airlines Pilots Retirement Plan........................................ 245,000 Island Holdings, Inc. .......................................................... 30,000 Island Insurance Convertible Account............................................ 290,000 Kapiolani Medical Center........................................................ 350,000 Nicholas-Applegate Convertible Fund............................................. 645,000 Nicholas-Applegate High-Quality Convertible..................................... 30,000 Penn Treaty Network America Insurance Company................................... 210,000 Performance GIC InterFund SA75.................................................. 1,000,000 Physicians Life................................................................. 333,000 Pilgrim Convertible Fund........................................................ 3,370,000 PIMCO Convertible Bond Fund..................................................... 850,000 PIMCO Total Return Fund......................................................... 5,000,000 Queens Health Plan.............................................................. 65,000 Reynolds Metal Company.......................................................... 1,000,000 San Diego City Retirement....................................................... 1,250,000 San Diego County Convertible.................................................... 3,290,000 Southern Farm Bureau Life Insurance--FRIC....................................... 1,340,000 Starvest Combined Portfolio..................................................... 1,275,000 Starvest Managed Portfolio...................................................... 230,000 State of Oregon/SAIF Corporation................................................ 9,000,000 State Street Bank Custodian for 6E Pension Trust................................ 1,653,000 Teachers Insurance and Annuity Association of America........................... 7,000,000 The Income Fund of America, Inc. ............................................... 17,000,000 The Midland Life Insurance Company.............................................. 1,185,000 Transamerica Life Insurance and Annuity Co. .................................... 18,000,000 Transamerica Occidental Life Insurance.......................................... 5,000,000 Wake Forest University.......................................................... 1,090,000 Total........................................................................... 110,256,000 ===========