The Federal Reserve turned $76.9 billion of its profits over to the U.S. Treasury last year, close to the record amount transferred to government coffers in 2010 amid gains generated in its expanding portfolio of securities.

Preliminary unaudited results released by the central bank Tuesday showed the Fed had net income of $78.9 billion in 2011. In 2010, the Fed booked a record $81.7 billion profit and returned $79.3 billion of it to the Treasury.

Though...