NEW YORK (Bloomberg) ? Shares of Ace Ltd. headed for their biggest gain in more than five months after the Bermuda-based insurer said a review of asbestos-related liabilities showed its most vulnerable unit had set aside enough to pay expected claims.

The stock rose $1.61, or 2.7 percent, to $60.32 at 12:50 p.m. in New York Stock Exchange composite trading. It hasn't increased as much in a single day since June 29.

Reviews by Bermuda-based Ace and an independent actuary found that Brandywine Holdings Corp., a unit the company bought from Cigna Corp. in 1999, wouldn't require additional reserves to pay claims on asbestos and environmental hazards. In 2004, the last time Ace commissioned an independent study, the company added $465 million to reserves.

"This is good news," Evan Greenberg, Ace's chief executive officer, said at a conference hosted by Goldman Sachs Group Inc. in New York yesterday. "The gaming of the system has substantially diminished."

Greenberg said state legislation and recent judicial decisions have started to limit questionable asbestos claims in the US.