The American International Group is rapidly running through $123 billion in emergency lending provided by the Federal Reserve, raising questions about how a company claiming to be solvent in September could have developed such a big hole by October. Some analysts say at least part of the shortfall must have been there all along, hidden by irregular accounting.

"You don't just suddenly lose $120 billion overnight," said Donn Vickrey of Gradient Analytics, an independent securities research firm in Scottsdale, Ariz.

Mr. Vickrey says he believes AIG must have already accumulated tens of billions of dollars worth of losses by mid-September, when it came close to collapse and received an $85 billion emergency line of credit by the Fed. That loan was later supplemented by a $38 billion lending facility.

But losses on that scale do not show up in the company's financial filings. Instead, AIG replenished its capital by issuing $20 billion in stock and debt in May and reassured investors that it had an ample cushion. It also said that it was making its accounting more precise.

AIG had come under fire for accounting irregularities some years back and had brought in a former accounting expert from the Securities and Exchange Commission. He began to focus on the company's accounting for its credit-default swaps and collided with Joseph Cassano, the head of the company's financial products division, according to a letter read by Mr. Waxman at the recent Congressional hearing.

When the expert tried to revise AIG's method for measuring its swaps, he said that Mr. Cassano told him, "I have deliberately excluded you from the valuation because I was concerned that you would pollute the process."