SEC Form 4

FORM 4		UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934 or Section 30(h) of the Investment Company Act of 1940	OMB APPROVAL OMB Number: 3235-0287 Estimated average burden hours per response: 0.5
	Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

1. Name and Address of Reporting Person* Meissner Laurel G. (Last) (First) (Middle) AON CORPORATION - CORPORATE LAW DEPT 200 EAST RANDOLPH STREET, 8TH FLOOR (Street) CHICAGO IL 60601 (City) (State) (Zip)	2. Issuer Name and Ticker or Trading Symbol AON CORP [ AON ]	5. Relationship of Reporting Person(s) to Issuer (Check all applicable) Director 10% Owner X Officer (give title below) Other (specify below) SVP & Global Controller
	3. Date of Earliest Transaction (Month/Day/Year) 02/16/2012
	4. 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 Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	3. Transaction Code (Instr. 8)		4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
			Code	V	Amount	(A) or (D)	Price
Common Stock	02/16/2012		A(1)		15,289	A	(1)	16,400	D
Common Stock	02/16/2012		F(2)		4,862	D	$47.56	11,538	D
Common Stock	02/17/2012		M(3)		899	A	(3)	12,437	D
Common Stock	02/17/2012		F(4)		283	D	$47.62	12,154	D
Common Stock	02/20/2012		M(3)		636	A	(3)	12,790	D
Common Stock	02/20/2012		F(4)		201	D	$47.62	12,589	D

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	4. Transaction Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares
Restricted Stock Unit Award (Right to Receive)	(5)	02/16/2012		A		2,944		02/16/2013(6)	02/16/2015	Common Stock	2,944	$0	2,944	D
Restricted Stock Unit Award (Right to Receive)	(5)	02/17/2012		M			899	02/17/2012	02/17/2012	Common Stock	899	$0	1,797	D
Restricted Stock Unit Award (Right to Receive)	(5)	02/20/2012		M			636	02/20/2012	02/20/2012	Common Stock	636	$0	1,270	D

Explanation of Responses:

1. Represents shares of common stock issued upon the settlement of performance share units originally granted approximately three years ago under the fourth cycle of the Leadership Performance Program ("LPP4") on March 19, 2009. The number of shares issued was determined by the Organization and Compensation Committee of Aon's Board of Directors on February 16, 2012 based upon Aon's performance relative to a cumulative adjusted three year earnings per share target for the period beginning January 1, 2009 and ending December 31, 2011. In accordance with the terms of LPP4, and the achievement of specified growth targets under LPP4, settlement occurred at 124% of the original target value. The terms of LPP4 are more fully described in a Current Report on Form 8-K filed with the SEC on March 25, 2009, and in the plan document filed as Exhibit 10.5 to Aon's Quarterly Report on Form 10-Q for the quarter ended March 31, 2009 filed with the SEC on May 8, 2009.

2. Shares of common stock withheld by the issuer for the payment of withholding taxes in connection with the settlement of a performance share unit award.

3. Shares of common stock acquired upon the vesting of a restricted stock unit award.

4. Shares of common stock withheld by the issuer for the payment of withholding taxes in connection with the vesting of a restricted stock unit award.

5. The restricted stock unit award converts to shares of common stock on a 1-for-1 basis.

6. The restricted stock unit award will vest in accordance with the terms of the Aon Stock Incentive Plan as follows: 33 1/3% of the awards will vest on each of the first through third anniversaries of the date of grant.

Remarks:

Exhibit List: Exhibit 24 - Power of Attorney of Laurel G. Meissner.

	/s/ Matthew M. Rice - Matthew M. Rice pursuant to a power of attorney from Laurel Meissner	02/21/2012
	** Signature of Reporting Person	Date
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