Chicago, London - 12 May 2005 - Aon Corporation today announced the appointment of Steve McGill, 47, as chief executive officer of a new Global Large Corporate business unit that addresses the sophisticated risk management needs of the largest global corporations.

McGill was chief executive of Jardine Lloyd Thompson Group plc., an international insurance broker. During a brokerage career spanning more than 25 years, he has worked with a wide range of leading global companies. He is a director of the International Insurance Society and deputy president of the Insurance Institute of London.

Aon President and CEO Greg Case said, “As a leading insurance broker, Steve McGill has built a formidable reputation as someone who delivers distinctive value to large corporations. We are delighted to have him join the senior team to help drive this business forward.”

Dick Verbeek, chairman of the Global Large Corporate business unit, and Dennis Mahoney, chairman, Aon Limited, said in a joint statement, “Steve’s impressive accomplishments in the insurance industry, especially with major corporations, will add significantly to the value that we deliver to our clients.”

McGill added, “I am excited by Aon’s increasing focus on this segment. There are significant opportunities available to us, and by harnessing Aon’s resources, global network and client relationship skills, we can meet the highest expectations of these clients throughout the world.”

This business unit includes professional staff in the key financial centers who will work closely with Aon’s strong country and regional organizations to provide advice, program design and support for complex risk management needs.


About Aon

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 48,000 professionals in its 500 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.