Martin Sullivan, a former American International Group chief executive, has been chosen to run a new insurance brokerage business for Willis Group, the third largest insurance broker.

Sullivan was named deputy chairman of Willis Group Holdings PLC and chairman and CEO of Willis Global Solutions, a new business unit of the company targeting large-scale customers of Marsh & McLennan Cos. and Aon Corp.

The new business is positioned to oversee brokerage and risk-management advisory services for Willis’s multinational and global accounts.

“This new unit will distinguish the company as a significant player in the global marketplace positioned to serve the world’s largest clients and challenge entrenched brokers who have a significant share of multinational business,” Willis said in a statement.

Sullivan ran AIG from 2005 to 2008, replacing Maurice “Hank” Greenberg, who stepped down amid a scandal over the company’s accounting. Sullivan joined AIG in England in 1971.