of its stock.

The buyback, which will take place over an unspecified time, represents about 2.7 percent of ACE's outstanding stock.

Companies use buybacks to increase earnings per share by reducing shares outstanding.

ACE, which celebrated its 15th anniversary on Thursday, has about $30 billion in assets. Its stock traded at $40, up 18.7 cents, or 0.5 percent, late on Friday on the New York Stock Exchange.