Exhibit 11A GATX CORPORATION AND SUBSIDIARIES COMPUTATION OF BASIC NET INCOME PER SHARE OF COMMON STOCK In Millions, Except Per Share Amounts Three Months Ended March 31 ------------------ 1998 1997 ------- ------- Average number of shares of common stock outstanding 24.5 20.3 Net income ......................................... $ 37.4 $ 31.2 Deduct - Dividends paid and accrued on preferred stock ........................... -- 3.3 ----- ----- Net income, as adjusted ............................ $ 37.4 $ 27.9 ======= ======= Basic net income per share ......................... $ 1.52 $ 1.37 ======== ======== Note: 1997 amounts have been restated to reflect Financial Accounting Standards Board Statement No. 128 (FAS 128), Earnings Per Share, which was required to be adopted on December 31, 1997.