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                                                                     EXHIBIT 11A


                        GATX CORPORATION AND SUBSIDIARIES

            COMPUTATION OF BASIC NET INCOME PER SHARE OF COMMON STOCK
                     (IN MILLIONS, EXCEPT PER SHARE AMOUNTS)



<TABLE>
<CAPTION>
                                                  THREE MONTHS ENDED        SIX MONTHS ENDED
                                                       JUNE 30                   JUNE 30
                                                  ------------------       -----------------
                                                    2000      1999          2000      1999
                                                  -------   --------       ------   --------
<S>                                               <C>       <C>            <C>      <C>
Average number of shares of common stock
    outstanding                                      47.6     49.5           48.0     49.4

Net income                                         $ 41.5   $ 38.1         $ 82.1   $ 77.3

Deduct - Dividends paid and accrued on preferred
   stock                                             --       --             --       --
                                                   ------   ------         ------   ------

Net income, as adjusted                            $ 41.5   $ 38.1         $ 82.1   $ 77.3
                                                   ======   ======         ======   ======

Basic net income per share                         $  .87   $  .77         $ 1.71   $ 1.56
                                                   ======   ======         ======   ======
</TABLE>



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