SEC FORM 3

SEC Form 3

FORM 3

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

INITIAL STATEMENT OF BENEFICIAL OWNERSHIP OF SECURITIES

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934
or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person^*

Porzenheim Clifford J

(Last)

(First)

(Middle)

500 W. MONROE ST.

(Street)

CHICAGO

60661

(City)

(State)

(Zip)

2. Date of Event Requiring Statement (Month/Day/Year)
12/07/2006

3. Issuer Name and Ticker or Trading Symbol
GATX CORP [ GMT ]

4. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

	Director	10% Owner
X	Officer (give title below)	Other (specify below)
	VP - Strategic Growth

5. If Amendment, Date of Original Filed (Month/Day/Year)

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Beneficially Owned
1. Title of Security (Instr. 4)	2. Amount of Securities Beneficially Owned (Instr. 4)	3. Ownership Form: Direct (D) or Indirect (I) (Instr. 5)	4. Nature of Indirect Beneficial Ownership (Instr. 5)
Common Stock 401(k)	7,285.914	I	401k
Common Stock	12,659.9356⁽⁹⁾	D

Table II - Derivative Securities Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 4)	2. Date Exercisable and Expiration Date (Month/Day/Year)		3. Title and Amount of Securities Underlying Derivative Security (Instr. 4)		4. Conversion or Exercise Price of Derivative Security	5. Ownership Form: Direct (D) or Indirect (I) (Instr. 5)	6. Nature of Indirect Beneficial Ownership (Instr. 5)
1. Title of Derivative Security (Instr. 4)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares	4. Conversion or Exercise Price of Derivative Security	5. Ownership Form: Direct (D) or Indirect (I) (Instr. 5)	6. Nature of Indirect Beneficial Ownership (Instr. 5)
1998 NQ Stock Option (Right to Buy)	07/24/1999⁽¹⁾	07/24/2008	Common Stock	4,500	$39.7188	D
1999 NQ Stock Option (Right to Buy)	07/23/2000⁽²⁾	07/23/2009	Common Stock	5,000	$39.4688	D
2000 NQ Stock Option (Right to Buy)	03/10/2001⁽³⁾	03/10/2010	Common Stock	8,000	$30.4688	D
2001 NQ Exchange Stock Option (Right to Buy)	01/26/2001	01/26/2011	Common Stock	3,497	$45.0625	D
2001 NQ Stock Option (Right to Buy)	07/27/2002⁽⁴⁾	07/27/2011	Common Stock	7,000	$39.145	D
2002 NQ Stock Option (Right to Buy)	12/31/2003	04/26/2012	Common Stock	4,500	$31.735	D
2003 NQ Stock Option (Right to Buy)	08/01/2004⁽⁵⁾	08/01/2013	Common Stock	14,000	$21.85	D
2004 NQ Stock Option (Right to Buy)	08/06/2005⁽⁶⁾	08/06/2011	Common Stock	5,100	$24.365	D
2005 NQ Stock Option (Right to Buy)	03/25/2006⁽⁷⁾	03/25/2012	Common Stock	4,600	$32.645	D
Stock-Settled Stock Appreciation Right	03/10/2007⁽⁸⁾	03/10/2013	Common Stock	4,000	$38.625	D

Explanation of Responses:

1. 50% of option granted may be exercised commencing 1 year from the date of the grant, an additional 25% commencing 2 years from the date of the grant and the remaining 25% commencing 3 years from the date of the grant.

2. 50% of option granted may be exercised commencing 1 year from the date of the grant, an additional 25% commencing 2 years from the date of the grant and the remaining 25% commencing 3 years from the date of the grant.

3. 50% of option granted may be exercised commencing 1 year from the date of the grant, an additional 25% commencing 2 years from the date of the grant and the remaining 25% commencing 3 years from the date of the grant.

4. 50% of option granted may be exercised commencing 1 year from the date of the grant, an additional 25% commencing 2 years from the date of the grant and the remaining 25% commencing 3 years from the date of the grant.

5. 50% of option granted may be exercised commencing 1 year from the date of the grant, an additional 25% commencing 2 years from the date of the grant and the remaining 25% commencing 3 years from the date of the grant.

6. 50% of option granted may be exercised commencing 1 year from the date of the grant, an additional 25% commencing 2 years from the date of the grant and the remaining 25% commencing 3 years from the date of the grant.

7. 50% of option granted may be exercised commencing 1 year from the date of the grant, an additional 25% commencing 2 years from the date of the grant and the remaining 25% commencing 3 years from the date of the grant.

8. 50% of Stock-Settled Stock Appreciation Right granted may be exercised commencing 1 year from the date of the grant, an additional 25% commencing 2 years from the date of the grant and the remaining 25% commencing 3 years from the date of the grant.

9. 5,000 shares are restricted stock vesting on October 1, 2008.

	Lisa M. Ibarra, by Power of Attorney on behalf of Clifford J. Porzenheim	12/12/2006
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 5 (b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
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