The committee called Mr. Geithner, former Treasury Secretary Henry M. Paulson Jr. and other officials to explain, once again, the confounding results of an $85 billion rescue loan made to A.I.G. in September 2008. The loan sheltered big banks from any losses, but saddled A.I.G. with a debt so crushing that the Treasury soon had to step in and provide even more rescue money. Mr. Geithner was the president of the Federal Reserve Bank of New York in September 2008, when the first rescue loan to A.I.G. was extended.

After Mr. Geithner’s statement, the questions focused almost immediately on trying to determine why those negotiating on behalf of the taxpayers did not push the banks to make concessions, like returning the collateral to A.I.G. or accepting less than full value for their contracts with the insurer.

At times, the hearing took on a scolding, even berating, tone, that at one point turned personal.