Evan Greenberg to succeed Duperreault as Ace's CEO.

After a 10-year tenure, Ace Ltd. Chairman Brian Duperreault will step down as the company's chief executive officer in May, to be succeeded by Evan Greenberg, Ace's current president and the former chief operating officer of American International Group Inc., the company said.

The move marks the third time that Duperreault has turned over operations to Greenberg, the chairman noted in a March 11 conference call, adding that on each of the two previous occasions, Greenberg went on to improve the company.

Greenberg joined Ace in November 2001 to oversee the company's global reinsurance operations, going on to be named chief executive officer of Ace Tempest Re, vice chairman of the Ace group of companies and eventually president of Ace Ltd.

Before joining Ace, Greenberg had spent 25 years with AIG, where he was named president in 1997, and later, co-chief operating officer. Greenberg's father, Maurice R. "Hank" Greenberg, confirmed in early 2000 that the younger Greenberg was being groomed to succeed him as the company's chairman and CEO.

Continuing in his role as chairman, Duperreault said he expects to devote much of his time to external affairs, including lobbying for asbestos and class-action reform in the United States as well as the 50 other countries in which Ace writes business. He said he also would continue to work with Greenberg on broad issues of strategy, which Greenberg said he welcomed.

"Don't expect any significant management changes, and don't expect any of the team stepping down, either because they want to or because I want them to," Greenberg said. "Over the last year, we have put in place a management structure and people to populate that structure that I am confident in, and that I think fits where Ace is at this point in time."