CHICAGO - Insurance broker Aon Corp. said Wednesday it has agreed to sell its Auto Insurance Specialist Management Group unit to Mercury General Corp. for $120 million.

In addition, the deal also includes a potential earn out of up to $34.7 million payable over the two years following the transaction closing date, the company said.

Los Angeles-based Mercury General (nyse: MCY - news - people ) offers automobile and homeowners insurance.

The deal, which is expected to close in the first quarter of 2009, includes business transacted under the Auto Insurance Specialists Inc., PoliSeek and Aon (nyse: AOC - news - people ) Recreation insurance brands.

Shares of Aon closed at $39.97 on Tuesday, while Mercury General shares closed at $51.65.

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