Exhibit 11 THE INTERPUBLIC GROUP OF COMPANIES, INC. AND ITS SUBSIDIARIES SUPPLEMENTAL COMPUTATION OF EARNINGS PER SHARE (unaudited) (Dollars in Thousands Except Per Share Data) Three Months Ended March 31 Basic 1998 1997 Net income $ 35,840 $ 29,431 Weighted average number of common shares outstanding 132,394,115 126,734,506 Earnings per common and common equivalent share $ .27 $ .23 Three Months Ended March 31 Diluted <F1> 1998 1997 Net income $ 35,840 $ 29,431 Add: Dividends paid net of related income tax applicable to restricted stock 123 91 Net income, as adjusted $ 35,963 $ 29,522 Weighted average number of common shares outstanding 132,394,115 126,734,506 Weighted average number of incremental shares in connection with restricted stock and assumed exercise of stock options 5,051,940 3,934,750 Total 137,446,055 130,669,256 Earnings per common and common equivalent share $ .26 $ .23 <F1> The computation of diluted EPS for 1998 excludes the assumed conversion of the 1.80% Convertible Subordinated Notes because they were anti-dilutive. Similarly, the computation of diluted EPS for 1997 excludes the assumed conversion of the 3 3/4% Convertible Subordinated Debentures as they were anti-dilutive.