Aon plc — Director's Dealing 2010

Mar 1, 2010

SEC Form 4 — Statement of Changes in Beneficial Ownership

Issuer: AON CORP (AOC)
CIK: 0000315293
Period of Report: 2009-02-27

Reporting Person: McGill Stephen P (Chairman/CEO - ARS)

Non-Derivative Transactions

Date	Security	Code	Shares	Price	A/D	Holdings After	Ownership
2009-02-27	Common Stock	S	45332	$38.90	Disposed	15588	Direct
2010-02-25	Common Stock	A	60648	—	Acquired	86449	Direct
2010-02-25	Common Stock	F	22969	$40.99	Disposed	63480	Direct

Derivative Transactions

Date	Security	Exercise Price	Code	Shares	A/D	Expiration	Underlying	Ownership
2010-02-25	Restricted Stock Unit Award (Right to Receive)	$	A	14089	Acquired	2013-02-25	Common Stock (14089)	Direct

Footnotes

F1: Represents shares of common stock issued upon the settlement of performance share units originally granted approximately three years ago under the second cycle of the Leadership Performance Program ("LPP2") on March 15, 2007. The number of shares issued was determined by the Organization and Compensation Committee of Aon's Board of Directors on February 25, 2010 based upon Aon's performance relative to a cumulative adjusted three year earnings per share target for the period beginning January 1, 2007 and ending December 31, 2009. In accordance with the terms of LPP2, and the achievement of specified growth targets under LPP2, settlement occurred at 200% of the original target value. The terms of LPP2 are more fully described in a Current Report on Form 8-K filed with the SEC on March 21, 2007, and in the plan document filed as Exhibit 10.2 to Aon's Quarterly Report on Form 10-Q for the quarter ended March 31, 2008 filed with the SEC on May 9, 2008.

F2: 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.

F3: The restricted stock unit award converts to shares of common stock on a 1-for-1 basis.

F4: 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.

F5: The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $38.765 to $39.03, inclusive. The reporting person undertakes to provide to Aon Corporation, or the Staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote.

F6: The number of shares shown in Column 5 represents the number of shares owned by the reporting person immediately following the disposition of shares of common stock on February 27, 2009. Following the vesting of additional restricted stock units on various dates in March 2009, May 2009 and February 2010, all of which have been timely reported, the amount of securities beneficially owned by the reporting person immediately in advance of the transactions that occurred on February 25, 2010 was 25801.