Aon Liquidates Equity Ownership in Endurance Specialty Holdings Ltd; Retains Ownership of Stock Purchase Warrants.

CHICAGO -- Aon Corporation (NYSE:AOC) has sold virtually all of its equity investment in Endurance Specialty Holdings Ltd., a Bermuda-based insurance and reinsurance company. The company sold 9.8 million shares at a net realized price of $32.70 per share resulting in proceeds of $320.5 million. Aon will retain 4.1 million stock purchase warrants.

Patrick G. Ryan, chairman and CEO of Aon Corporation, said, "We are very proud to have participated in the founding of Endurance in December 2001, at a time when the insurance industry needed additional capacity. The additional capacity created by the establishment of Endurance and other insurers during that period has contributed to the present easing of property/casualty insurance premium pricing."

Aon Corporation (www.aon.com) is a leading provider of risk management services, insurance and reinsurance brokerage, human capital and management consulting, and specialty insurance underwriting. The company employs approximately 51,000 professionals in its 600 offices in more than 120 countries. Backed by broad resources, industry knowledge and technical expertise, Aon professionals help a wide range of clients develop effective risk management and workforce productivity solutions.

This press release contains certain statements relating to future results, which are forward-looking statements as that term is defined in the Private Securities Litigation Reform Act of 1995. These forward-looking statements are subject to certain risks and uncertainties that could cause actual results to differ materially from either historical or anticipated results, depending on a variety of factors. Potential factors that could impact results include the general economic conditions in different countries around the world, fluctuations in global equity and fixed income markets, exchange rates, rating agency actions, resolution of pending regulatory investigations and related issues, including those related to compensation arrangements with underwriters, pension funding, ultimate paid claims may be different from actuarial estimates and actuarial estimates may change over time, changes in commercial property and casualty markets and commercial premium rates, the competitive environment, the actual costs of resolution of contingent liabilities and other loss contingencies, and the heightened level of potential errors and omissions liability arising from placements of complex policies and sophisticated reinsurance arrangements in an insurance market in which insurer reserves are under pressure. Further information concerning the Company and its business, including factors that potentially could materially affect the Company's financial results, is contained in the Company's filings with the Securities and Exchange Commission.