Aon plc Stock Ownership Guidelines

Purpose:  The purpose of the Stock Ownership Guidelines is to encourage ownership of Aon plc (“Aon”) common stock, to further align the interests of Aon's Chief Executive Officer (the “CEO”), Chief Financial Officer (the “CFO”), members of Aon's Executive Committee and additional members of senior management as designated by the Governance/Nominating Committee from time to time (collectively with the CEO and the CFO, the “Executives”) with the interests of stockholders and to further promote Aon's commitment to sound corporate governance.

Ownership Requirement:  Currently, the CEO is expected to hold an investment position in Aon common stock equal to four times his or her annual base salary and all other Executives are expected to hold an investment position in Aon common stock equal to two times their respective annual base salaries. Effective immediately, the CEO is expected to hold an investment position in Aon common stock equal to six times his or her annual base salary. Effective January 1, 2012, all Executives other than the CEO are expected to hold an investment position in Aon common stock equal to three times their respective annual base salaries.

Measurement:  Compliance with these ownership guidelines will be measured on the first trading day of each calendar year, using each Executive’s base salary then in effect and the closing price of Aon common stock on that day.

Although there is no specific period of time in which the Executives will be required to achieve the appropriate ownership requirement, they are expected to make continuous progress toward their respective ownership requirements consistent with the retention policies set forth in these Stock Ownership Guidelines.

Retention Policies:  Effective immediately, until the CEO has achieved an investment position in Aon common stock equal to six times his or her base salary, the CEO is required to retain an amount equal to one hundred percent (100%) of the net profit shares received upon: (i) the exercise of options to purchase Aon common stock; (ii) the vesting of restricted stock units; and (iii) the vesting of performance share units. Effective immediately through December 31, 2011, until an Executive other than the CEO has achieved an investment position in Aon common stock equal to two times such Executive’s annual base salary, such Executive is required to retain an amount equal to one hundred percent (100%) of the net profit shares received upon: (i) the exercise of options to purchase Aon common stock; (ii) the vesting of restricted stock units; and (iii) the vesting of performance share units. Effective January 1, 2012, until an Executive other than the CEO has achieved an investment position in Aon common stock equal to three times such Executive’s annual base salary, such Executive is required to retain an amount equal to one hundred percent (100%) of the net profit shares received upon: (i) the exercise of options to purchase Aon common stock; (ii) the vesting of restricted stock units; and (iii) the vesting of performance share units. In addition, except as provided in the following sentence, effective immediately through December 31, 2011, once an Executive other than the CEO has achieved an investment position in Aon common stock equal to two times such Executive’s annual base salary, such Executive must, while subject to the Stock Ownership Guidelines, maintain an investment position equal to or greater than two times such Executive’s base salary. In the event of: (i) an increase to an Executive’s base salary; or (ii) a decline in the price of Aon common stock, in each case that results in non-compliance with the Stock Ownership Guidelines, such Executive will be required to retain an amount equal to one hundred percent (100%) of the net profit shares received upon the exercise of options to purchase Aon common stock, the vesting of restricted stock units and the vesting of performance share units until such Executive meets the applicable ownership requirement then in effect. For purposes of the Stock Ownership Guidelines, “net profit shares” are those shares that remain after deducting the exercise price, if applicable in the event of the exercise of options, and withholding taxes

Holdings Considered:  The following holdings will be considered when measuring stock ownership:

• Shares owned outright, including shares owned jointly with a spouse or separately by a spouse and/or children that share the director’s household;
• Shares owned through an Aon-sponsored savings/retirement plan, such as the Aon Savings Plan;
• Shares purchased through the Aon Employee Stock Purchase Plan;
• Shares obtained through the exercise of stock options;
• Shares issued upon the vesting of restricted stock units and performance share units;
• Phantom stock held in the Aon deferred compensation plan; and
• Phantom stock held in the Aon Supplemental Savings Plan.

Those holdings that will not be considered when measuring stock ownership include the following:

• Unvested restricted stock units or performance units; and
• Vested or unvested stock options.

Failure to Meet Ownership Requirement:  Failure by an Executive to meet or to show sustained progress toward meeting the ownership requirement may result in a reduction in future long term incentive grants and/or the requirement to retain all stock obtained through the vesting or exercise of equity grants.

Hardship:  There may be instances in which the Stock Ownership Guidelines would place a severe hardship on an Executive or prevent an Executive from complying with a court order, such as in the case of a divorce settlement. It is expected that such instances will be rare. Under these circumstances, the Executive will work with the Senior Vice President of Human Resources, subject to the approval of the CEO, to develop an alternative stock ownership plan that reflects the intention of the ownership guidelines. In the case of a hardship involving the CEO, approval for an alternative stock ownership plan will be sought from the Chair of the Organization & Compensation Committee.

Effective Date of Policy:  January 1, 2006 (as revised July 18, 2008 and as further revised September 16,2010)