The amount of money the central bank parceled out was surprising even to Gary H. Stern, president of the Federal Reserve Bank of Minneapolis from 1985 to 2009, who says he “wasn’t aware of the magnitude.” It dwarfed the Treasury Department’s better-known $700 billion Troubled Asset Relief Program, or TARP. Add up guarantees and lending limits, and the Fed had committed $7.77 trillion as of March 2009 to rescuing the financial system, more than half the value of everything produced in the U.S. that year.

“TARP at least had some strings attached,” says Brad Miller, a North Carolina Democrat on the House Financial Services Committee, referring to the program’s executive-pay ceiling. “With the Fed programs, there was nothing.”…

TARP and the Fed lending programs went “hand in hand,” says Sherrill Shaffer, a banking professor at the University of Wyoming in Laramie and a former chief economist at the New York Fed. While the TARP money helped insulate the central bank from losses, the Fed’s willingness to supply seemingly unlimited financing to the banks assured they wouldn’t collapse, protecting the Treasury’s TARP investments, he says.

“Even though the Treasury was in the headlines, the Fed was really behind the scenes engineering it,” Shaffer says.

Congress, at the urging of Bernanke and Paulson, created TARP in October 2008 after the bankruptcy of Lehman Brothers Holdings Inc. made it difficult for financial institutions to get loans. Bank of America and New York-based Citigroup each received $45 billion from TARP. At the time, both were tapping the Fed. Citigroup hit its peak borrowing of $99.5 billion in January 2009, while Bank of America topped out in February 2009 at $91.4 billion…

Lawmakers knew none of this.