SAN FRANCISCO -- Standard & Poor's said late Friday it may downgrade the ratings of American International Group Inc. because of significant declines in the insurer's share price and an increase in credit spreads on the company's debt. S&P has an AA-/A-1+ rating on AIG. "We believe that AIG has sufficient capital and liquidity to meet its policy obligations and potential collateral requirements, which are significantly greater than the expected cash losses on the mortgage-related assets," said Rodney Clark, an S&P credit analyst, in a statement. "However, additional market value losses will place some strain on the company's resources."