The story is well told in a three-part series in the Los Angeles Times ending today. Part 1: Bold innovators led AIG's stunning rise. Part 2: Complex deals veiled risk for AIG. Part 3: Credit rating downgrade, real estate collapse crippled AIG. Just as a credit rating agency did not consider the possibility of a nationwide decline in housing prices, the geniuses at AIG did not consider the possibility that AIG's credit rating could slip from AAA to AA. When that happened, AIG had to respond to demands for more collateral and could not.