The pace of mergers and acquisitions is gaining speed in 2010 thanks to American International Group Inc.

MetLife Inc.'s $15.5 billion deal Monday to buy AIG's American Life Insurance Co., or Alico, brought the total value of dealmaking globally this year to $500.3 billion. That was up 21 percent from the year-ago period, according to data collected by deal-tracking firm Dealogic.

The transaction is the fifth-largest deal globally so far this year, and the second-largest U.S. transaction announced in 2010.

AIG's sale of Asia-based life insurer, AIA Group, to Britain's Prudential PLC last week for $35.5 billion tops the global 2010 list.

The MetLife-Alico deal is the sixth-largest insurance transaction on record. Prudential's purchase of AIA is No. 1.

AIG still has the No. 2 and No. 3 spots respectively, with its acquisitions of American General Corp. in 2001 and SunAmerica Inc. in 1998.

With deals valued at $61.7 billion so far this year, insurance is the second most targeted sector in 2010, just behind healthcare, which has had $62.7 billion in deals to date, according to Dealogic.

New York-based AIG has been working for the past year and half to sell assets and streamline operations so it can repay its government bailout debt. AIG's bailout package was originally worth up to $182.5 billion.