Aon Acquires Horizon Consulting Group, Inc., Property Claim Consultant to Policyholders

CHICAGO – September 19, 2000 – Aon Corporation (NYSE: AOC) announced today that it has acquired Horizon Consulting Group, Inc., a firm specializing in commercial policyholder claim consulting services, involving complex first party property, business interruption and fidelity claims. Terms and conditions of the transaction were not disclosed.

The new entity will be known as Cambridge Horizon Consultants, Inc. (Cambridge Horizon) and will operate as part of Cambridge Integrated Services Group, Inc. (Cambridge), Aon's full-service claims and loss cost management service provider.

Stephen A. Eisenmann, president of Cambridge Integrated, explained that "the acquisition enhances Cambridge's ability to provide innovative, value-added services to clients who require increasingly advanced forms of loss cost management services."

John Morrongiello, who headed Horizon Consulting and will serve as president of Cambridge Horizon, described the company's business: "As an advocate for the policyholder, we provide the insured with a team of experts to evaluate the unforeseen exposures of catastrophic property losses." he explained. "Our resources include adjusters, forensic accountants, risk managers, estimators and engineers".

For questions about services provided by Cambridge Horizon Consultants, John Morrongiello can be reached at (212) 274-9100.

Cambridge Integrated Services Group, a member company of Aon Corporation, has more than 100 offices operating in the United States. Cambridge Integrated Services Group can be found on the Internet at www.cambridgeintegrated.com.

Aon Corporation is a holding company that comprises a family of insurance brokerage, consulting and underwriting subsidiaries. Aon's common stock is listed on the Chicago, Frankfurt, London and New York stock exchanges. Visit www.aon.com for more information.