Moody's Investors Service affirmed American International Group's (AIG) A3 long-term issuer rating and negative outlook, reflecting the rating agency's concerns about the possible end of government support for the insurer.

The Moody's announcement comes in the wake of AIG's announcement of its plan to repay the U.S. Government.

Under the plan, AIG said it would repay its $20 billion direct debt to the Federal Reserve Bank of New York (FRBNY) and the $26 billion in interest the FRBNY has in two special purpose vehicles (SPVs) using its own resources and proceeds from other assets, including an initial public offering of American International Assurance Co. Ltd (AIA) on the Hong King Stock Exchange and proceeds from the $15.5 billion sale of American Life Insurance Co. (ALICO) to MetLife Inc.

Additionally, as part of the plan, $49.1 billion of preferred shares held by the Treasury Department would be converted into about 1.66 billion shares of AIG common stock. The Treasury will then sell the shares to the public over time.

Bruce Ballentine, Moody's lead analyst for AIG, said in a statement, "The proposed repayment plan signals AIG's progress in stabilizing its core insurance operations and exiting noncore businesses. It also points the way toward a sustainable capital structure."

However, Moody's added that the plan "hastens the end of explicit government support for AIG, which has been an important consideration in the company's ratings."

Moody's noted that the government will retain significant ownership of AIG for the near term, but the rating agency said it "believes that the ownership stake and implicit support will decline over the next couple of years. Therefore, the ratings of AIG and its subsidiaries will increasingly depend on their stand-alone credit profiles, raising the risk of downgrades if the credit metrics do not improve as expected."

To attain a stable rating, Moody's said AIG must improve the intrinsic credit profiles of Chartis and SunAmerica Financial Group (SFG). AIG must also exit or de-risk noncore businesses, maintain robust liquidity within its major operations, and develop a standalone capital structure consistent with the company's current ratings.

Moody's said AIG could be downgraded if it fails to "improve certain credit metrics of the core insurance operations, such as profitability, reserve adequacy at Chartis and investment performance at SFG."

Retention of noncore business risks that could strain capital and liquidity, and an inadequate standalone capital structure could also lead to a downgrade, Moody's said.