Filed Pursuant to 424(b)(3)
                                                     Registration Nos. 333-86212
                                                                    333-86212-01
PROSPECTUS SUPPLEMENT NO. 11
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                                  $175,000,000

                                GATX Corporation

                     7.5% Convertible Senior Notes due 2007
                     Fully and Unconditionally Guaranteed by
                           GATX Financial Corporation

                                       and

                             Shares of Common Stock
                  issuable upon conversion of the Senior Notes

     This prospectus supplement supplements the prospectus dated June 19, 2002
of GATX Corporation and GATX Financial Corporation, as supplemented by
prospectus supplement no. 1 dated June 26, 2002, prospectus supplement no. 2
dated July 3, 2002, prospectus supplement no. 3 dated July 23, 2002, prospectus
supplement no. 4 dated August 9, 2002, prospectus supplement no. 5 dated August
29, 2002, prospectus supplement no. 6 dated September 12, 2002, prospectus
supplement no. 7 dated September 24, 2002, prospectus supplement no. 8 dated
October 3, 2002, prospectus supplement no. 9 dated October 11, 2002 and
prospectus supplement no. 10 dated October 18, 2002, relating to the sale by
certain holders of our 7.5% convertible senior notes due 2007 and the shares of
our common stock issuable upon conversion of the notes. You should read this
prospectus supplement in conjunction with the prospectus as supplemented to
date. This prospectus supplement is qualified by reference to the prospectus as
so supplemented except to the extent that the information in this prospectus
supplement supersedes the information contained in the prospectus as so
supplemented. Capitalized terms used in this prospectus supplement and not
otherwise defined herein have the meanings specified in the prospectus.

     The table of Selling Holders contained in the prospectus is hereby amended
to add the entity named below as a Selling Holder:

                                   Principal Amount of
                                    Notes Beneficially      Number of Shares
                                        Owned That           of Common Stock
      Name of Selling Holder            May be Sold         That May be Sold
      ----------------------            -----------         ----------------
     American Samoa Government            $24,000                  704


     Investing in the notes and our common stock involves risks. See "Risk
Factors" beginning on page 5 of the prospectus.

     Neither the Securities and Exchange Commission nor any state securities
commission has approved or disapproved of these securities or passed upon the
accuracy or adequacy of this prospectus. Any representation to the contrary is a
criminal offense.

           The date of this prospectus supplement is October 31, 2002