No question about it -- AIG is BIG. Based in the US but with operations reaching around the globe, American International Group (AIG) is one of the world's largest insurance firms. Its subsidiaries provide general property/casualty insurance, life insurance and retirement services, and financial services to some 90 million commercial, institutional, and individual customers in more than 130 countries around the world. Commercial property/casualty products account for 40% of the group's revenue. Best Buy, HP, and Nortek are among AIG's customers. The company traces its roots to 1919, when Cornelius Vander Starr established American Asiatic Underwriters in Shanghai.