<DOCUMENT>
<TYPE>EX-11.(A)
<SEQUENCE>2
<FILENAME>c58495ex11-a.txt
<DESCRIPTION>COMPUTATION OF BASIC NET INCOME PER SHARE
<TEXT>

<PAGE>   1
                                                                     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     NINE MONTHS ENDED
                                                        SEPTEMBER 30           SEPTEMBER 30
                                                     -------------------   ---------------------
                                                       2000       1999       2000        1999
                                                     --------   --------   ---------   ---------
<S>                                                  <C>        <C>        <C>         <C>
Average number of shares of common stock
   outstanding                                           47.5       49.5        47.9        49.4

Net income                                           $   45.1   $   42.2   $   127.2   $   119.5

Deduct - Dividends paid and accrued on preferred
   stock                                                    -          -           -           -
                                                     --------   --------   ---------   ---------
Net income, as adjusted                              $   45.1   $   42.2   $   127.2   $   119.5
                                                     ========   ========   =========   =========
Basic net income per share                           $    .95   $    .85   $    2.65   $    2.42
                                                     ========   ========   =========   =========
</TABLE>




</TEXT>
</DOCUMENT>
