Filed Pursuant to Rule 424(b)(3)
                                                Registration Nos. 333-86212
                                                                  333-86212-01
PROSPECTUS SUPPLEMENT NO. 4
- ---------------------------

                                  $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 and prospectus supplement no. 3 dated July 23, 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
     ----------------------        -----------                 ----------------

     CC Investments, LDC           $1,500,000                      44,001

     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 August 9, 2002