The Federal Reserve, forced by Congress to release details on trillions of dollars' worth of loans made during the financial crisis, disclosed the breadth of its lending to U.S. businesses desperate to raise cash and the surprising degree to which it supported struggling foreign banks in the worst days of 2008 and 2009.

The lending, most of which has been paid back, represents the Fed's most aggressive intervention in the economy ever, and included loans to stalwart industrial companies such as General Electric Co. and Verizon...