Insurer may need further lifelines

US taxpayers may not be done bailing out American International Group Inc after the head of the Federal Reserve said a fourth rescue of the insurer was needed to keep the financial system from failing.

"We're not done with AIG by a long shot," said Phillip Phan, professor of management at the Johns Hopkins Carey Business School in Baltimore. "The problem is we still don't know the extent of the risk AIG has."

The rescue, which now leaves taxpayers on the hook for $163 billion at AIG, a government official said, was raised after the New York-based company reported a $61.7 billion fourth-quarter loss on March 2. AIG still has billions of dollars in unrealized losses on assets and faces declining revenue on premiums because of the slump in commercial insurance and the company's struggle to attract new business.