Whether the Fed should have tried to save Lehman is still a subject of heated debate. And it is unclear whether the firm could have been rescued at all.

What happened that September was the culmination of circumstances reaching back years — of ordinary people too eager to borrow, of banks too eager to lend and of Wall Street financial engineers reaping multimillion-dollar bonuses. Even so, saving Lehman from complete collapse might have shielded the economy from what turned out to be a crippling blow. And as the subsequent rescue of A.I.G., the insurance giant, demonstrated, a rescue could have included substantial protections for taxpayers.

Back in 2008, the Fed possessed broad authority to lend to banks in trouble. Section 13-3 of the Federal Reserve Act provided that “in unusual and exigent circumstances” the Fed could lend to any institution, as long as the loan was “secured to the satisfaction of the Federal Reserve Bank.” In the eyes of the Fed, that means a firm must be solvent and have adequate collateral to lend against, and making that determination was the responsibility of the New York Fed, the regional Fed bank that had begun to assume responsibility for Lehman. On that September weekend, teams from the New York Fed were told to assess Lehman’s solvency and collateral.

Whether and how much the Fed could lend Lehman depended on those teams’ findings, although the final decision rested with Mr. Geithner, Mr. Bernanke and the Federal Reserve Board.

Image “Let me also say, for the record, strongly: There was no authority, there was no law that would have let us save Lehman Brothers,” said Henry M. Paulson Jr., at the House Committee on Financial Services on Nov. 18, 2008. Credit Alex Wong/Getty Images

A Question of Valuation

In recent interviews, members of the teams said that Lehman had considerable assets that were liquid and easy to value, like United States Treasury securities. The question was Lehman’s illiquid assets — primarily a real estate portfolio that Lehman had recently valued at $50 billion. By Lehman’s account, the firm had a surplus of assets over liabilities of $28.4 billion.

Others had already taken a stab at valuing Lehman’s troubled assets. Kenneth D. Lewis, then the chief executive of Bank of America — who, with the government’s encouragement, was considering a bid for Lehman — asserted that Lehman had a “$66 billion hole” in its balance sheet.

A group of bankers summoned to the Fed by Mr. Paulson, who was hoping they would mount a private rescue, did not accept Lehman’s $50 billion valuation for its real estate and could not decide whether Lehman was solvent. But potential private rescuers had a motive to lowball Lehman’s value. Fed officials involved in the valuation stressed that the Fed could hold distressed assets for much longer than private parties, allowing time for those assets to recover in value. Also, because the Fed sets monetary policy, it exerts enormous influence over the assets’ ultimate value.