On Aug. 2, 2007, Countrywide’s access to crucial market financing dried up; commercial paper investors would not buy its obligations, the report quoted Angelo R. Mozilo, the company chief executive, as saying. But Eric P. Sieracki, the company’s chief financial officer, said in a statement that day that Countrywide had plenty of liquidity and had experienced “no disruption in financing its ongoing daily operations, including placement of commercial paper.”

This rather interesting take on reality prompted Moody’s to reaffirm the company’s A3 debt rating. Two weeks later, Countrywide drew down all of its $11.5 billion in credit lines, signaling extreme distress to the markets. The stock plunged; a few months later the lender was taken over in distress by Bank of America.

Mr. Sieracki declined to comment, but his lawyer said on Friday that the Aug. 2 statement was accurate at the time Mr. Sieracki made it.

On Page 264, the report lays out Citigroup’s silence about the ticking time bombs it had shoved off its balance sheet but that would soon have to be repatriated, generating enormous losses. A spokeswoman for Citigroup said that it was a different company today, and that it had overhauled its risk management and bolstered its financial strength.

We already know, of course, that our government moved mountains to help the banks during the crisis. But the report adds to our understanding of events by describing how the Treasury Department changed the tax code to benefit banks acquiring weaker institutions. Never mind that the Constitution allows only Congress to write tax rules.

I.R.S. Notice 2008-83 came out of nowhere on Sept. 30, 2008, the report noted on Page 371. It removed existing limits on the use of tax losses that could be taken by a bank when it acquired a troubled institution. The change appeared just as Citigroup was mounting its $1-a-share bid for Wachovia. (The beleaguered bank was headed by Robert K. Steel, a former under secretary of domestic finance at Treasury who had left his post two months earlier. “Secretary Paulson had recused himself from the decision because of his ties to Steel,” the report said, “but other members of Treasury had ‘vigorously advocated’ saving Wachovia.”)

Two days after the tax change, Wells Fargo topped Citi’s proposal by offering $7 a share. The change in the code had made such a deal more economical for Wells because it could reduce its taxable income by $3 billion in the first year after acquiring Wachovia. Previously, Wells could have reduced its income by just $1 billion in Year 1.