UNITED STATES
SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

PURSUANT TO SECTION 13 OR 15(d) OF THE
SECURITIES EXCHANGE ACT OF 1934

Date of report (Date of earliest event reported): December 7, 2006

GATX Corporation

(Exact name of registrant as specified in its charter)

New York
(State or other jurisdiction of
incorporation) 1-2328
(Commission File
Number) 36-1124040
(IRS Employer
Identification No.)

500 West Monroe Street
Chicago, Illinois 60661-3676
(Address of principal executive offices, including zip code)

(312) 621-6200
Registrant’s telephone number, including area code)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

o Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

o Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

o Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

o Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

Item 1.01 Entry into a Material Definitive Agreement.

     On December 11, 2006, GATX Financial Corporation (“GFC”), a wholly owned subsidiary of GATX Corporation (“GATX”), as Borrower, and GATX, as Guarantor, entered into Amendment No. 1 to the Amended and Restated Five Year Credit Agreement (the “Amendment”) with the lenders named therein and Citicorp USA, Inc., as Administrative Agent. The Amendment added GATX as a guarantor of the obligations of GFC under the Amended and Restated Five Year Credit Agreement, dated as of June 27, 2005, and amended financial covenants contained therein such that those covenants apply to GATX rather than to GFC.

Item 5.02 Departure of Directors or Principal Officers; Election of Directors; Appointment of Principal Officers.

     On December 7, 2006, the Board of Directors of GATX Corporation elected James F. Earl, 49, to the newly created position of executive vice president and chief operating officer. Mr. Earl initially joined GATX’s Capital Rail Group in 1988 as director. From 2001 to 2004, Mr. Earl was responsible for the North American commercial activities of GATX’s rail business, including sales, marketing, fleet management, customer service and locomotive operations. In 2004, Mr. Earl was named executive vice president — rail, managing the entire rail operation at GATX. Mr. Earl received his Bachelor of Science in Business Administration from Washington University in St. Louis in 1979 and his MBA from the University of Pennsylvania’s Wharton School in 1981.

SIGNATURE

     Pursuant to the requirements of the Securities Exchange Act of 1934, the Registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized.

GATX CORPORATION

(Registrant)

/s/ Robert C. Lyons

Robert C. Lyons
Vice-President, Chief Financial Officer
(Duly Authorized Officer)

Date: December 13, 2006