U.S. taxpayers could realize a profit of more than $15.1 billion from the massive government bailout of insurer American International Group, a congressional watchdog said.

According to a report by the Government Accountability Office issued on Monday, the total return depends on the overall health of AIG and a number of other factors relating to Treasury's ownership stake.

The U.S. Treasury acquired shares in AIG as part of a $182 billion bailout of the insurer in 2008, the largest rescue of a single corporation, and has reduced the investment over time.

Treasury sold AIG common stock in May 2011 and this March. Another sale on Monday — that realized $5.8 billion — reduced taxpayer equity interest in AIG to 61 percent.

The AIG portfolio includes a Federal Reserve Bank of New York loan to Maiden Lane III of about $8 billion, which the GAO analysis expects to be repaid in full and net additional returns.

"When all the assistance is considered, the amount the federal government ultimately takes in could exceed the total support extended to AIG by more than $15.1 billion," GAO found.