Chicago-based insurance broker Aon Corp. said Lester B. Knighthas been named the non-executive chairman of the board. He willreplace Patrick G. Ryan, who retires Aug. 1.

An independent director since 1999, Mr. Knight, 50, is a founderand managing partner of RoundTable Healthcare Partners, a healthcare-focused private equity investment firm.

Prior to RoundTable, he was the chairman and chief executiveofficer of Allegiance Corporation. In addition, Mr. Knight servesas a Trustee of Northwestern University and as a director ofEvanston Northwestern Healthcare and Junior Achievement ofChicago.

Andy McKenna, Aon's lead director and chair of the ad hocnominating committee, said in a statement, “Aon's choice of anindependent non-executive chairman is consistent with bestgovernance practices of leading global firms. The Aon family andour shareholders should be confident in Lester's ability to sustainthe independent oversight of their interests.”

Mr. Ryan said, “As I have remarked many times since announcingmy retirement earlier this year, Aon is extremely well-positionedfor growth and success under the leadership of Greg Case and hismanagement team. Our board has never been more excited about thefuture of Aon. Lester is a wonderful choice and will ensurecontinued close collaboration between the board andmanagement.”

“I am gratified to serve Aon's shareholders in a new capacityand want to thank Pat [Ryan], Andy [McKenna] and the board forhonoring me with this opportunity,” said Mr. Knight. “I lookforward to working with the board, Greg [Case] and the managementteam to ensure Aon continues to strengthen and extend its positionof global market leadership.”