Aon (AON)

Plan Benefits

        Because all awards to Aon employees under the Stock Incentive Plan are made at the discretion of the Committee, the benefits and amounts that will hereafter be received or allocated under the Stock Incentive Plan are not determinable at this time. Information regarding awards in 2005 under the Stock Incentive Plan to the named executive officers is provided in the Summary Compensation Table and related footnotes on pages 30-33 and in the Option Grants in 2005 Fiscal Year table on page 34. In 2005, under the Stock Incentive Plan, (i) options for 1,600,000 shares and 236,746 restricted stock units were granted to all current executive officers, including named executive officers, as a group, (ii) stock awards for 5,767 shares were granted to members of the Board who are not executive officers and (iii) options for 4,369,559 shares and 4,450,045 restricted stock units were granted to all other eligible employees as a group. In 2006, non-employee directors will receive equity-based awards as described under "Compensation of the Board of Directors—Outside Director Compensation—2006 Changes." On March 22, 2006, the closing sale price per share of Common Stock as reported on the New York Stock Exchange was $41.90.

        With respect to awards to executive officers, by way of reference, Aon is including the following information about performance-based long-term incentive awards to the named executive officers and other eligible executive officers, as a group. On March 16, 2006, the Committee approved performance-based long-term incentive awards to named executive officers and other eligible executive officers, other than Patrick G. Ryan and Gregory C. Case. On March 17, 2006, upon the recommendation of the Committee, the independent directors of Aon's Board approved performance-based long-term incentive awards to Mr. Ryan and Mr. Case. The awards for executive officers were granted pursuant to Aon's Leadership Performance Program, which the Committee approved and adopted on March 16,

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Aon Corporation 2005

2006, as a sub-plan of the Stock Incentive Plan. The Leadership Performance Program is part of Aon's broad-based stock award strategy that is intended to drive the overall success of Aon while encouraging employee retention. 75% of each Leadership Performance Program award represents performance share units that will be earned and settled in Common Stock based upon Aon's performance relative to a cumulative earnings per share target over the period beginning January 1, 2006 and ending December 31, 2008 (the "Performance Period"). The total performance score can range from a minimum of 0% to a maximum of 150% of target. The Committee has the discretion to adjust Aon's performance results, if necessary, to take into account extraordinary or unusual items occurring during the Performance Period. The performance share units were valued as of the date of grant based upon the fair market value of Common Stock as of such date. Upon completion of the Performance Period, an award will be determined and settled in Common Stock.

        The remaining 25% of each Leadership Performance Program award is an option to purchase shares of Common Stock that will vest ratably over the Performance Period. The options for each eligible executive officer other than Mr. Ryan and Mr. Case were granted effective March 16, 2006, and the options for Mr. Ryan and Mr. Case were granted effective March 17, 2006. The number of stock options was determined by dividing the dollar value of the award apportioned to stock options (i.e., 25% of the total award value) by the fair market value of a share of Common Stock on the grant date and multiplying the resulting number by three. The exercise price of the options equals the fair market value of a share of Common Stock on the date of grant.

        The following table sets forth information with respect to the performance share units and stock options granted on March 16 and 17, 2006, for the named executive officers and all other current executive officers as a group.

(1)

The dollar values given for performance share units assume achievement of the target level of the award and are based on a price of $41.195 for awards granted on March 16, 2006 and $41.365 for awards granted on March 17, 2006, in each case the average of the high and low prices per share of Common Stock on the NYSE on the date of grant of the awards.

(2)

As consideration for his participation in the Leadership Performance Program, Mr. Case waived his entitlement for each year of the Performance Period to an annual option grant valued not less than $1,800,000 that would otherwise be payable pursuant to his employment agreement, dated April 4, 2005.

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Aon Corporation 2005