Aon plc — Director's Dealing 2011

May 18, 2011

SEC Form 4 — Statement of Changes in Beneficial Ownership

Issuer: AON CORP (AOC)
CIK: 0000315293
Period of Report: 2011-05-17

Reporting Person: Besio Gregory J (EVP/CAO)

Non-Derivative Transactions

Date	Security	Code	Shares	Price	A/D	Holdings After	Ownership
2011-05-17	Common Stock	M	6000	—	Acquired	54794	Direct
2011-05-17	Common Stock	F	2487	$52.37	Disposed	52307	Direct

Derivative Transactions

Date	Security	Exercise Price	Code	Shares	A/D	Expiration	Underlying	Ownership
2011-05-17	Restricted Stock Unit Award (Right to Receive)	$	M	6000	Disposed	2011-05-17	Common Stock (6000)	Direct

Holdings (Non-Derivative)

Security	Shares	Ownership
Common Stock	6597	Indirect

Footnotes

F1: Shares of common stock acquired upon the vesting of a restricted stock unit award.

F2: 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.

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

F4: Includes 151 shares held pursuant to the Aon employee stock purchase plan, and shares acquired pursuant to dividend reinvestment.