Brian Duperreault is president and chief executive officer of MMC since January 2008. Formerly he was chairman and chief executive officer of ACE Limited from 1994 to 2004, and was chairman until the end of 2007. Before ACE, he was with American International Group (AIG) for more than 20 years, holding numerous positions and eventually becoming executive vice president of AIG Foreign General Insurance and chairman and chief executive of AIG's American International Underwriters (AIU).