WASHINGTON (MarketWatch) -- The Federal Reserve and its district banks said Tuesday it earned $77.4 billion last year, down from $81.7 billion in 2010 but the second-highest level in the central bank's history. The bumper earnings allowed the Fed to distribute $75.4 billion to the U.S. Treasury, also the second-highest level ever. The earnings was derived primarily from $83.6 billion in interest income on securities acquired through open market operations, from Treasury securities, federal agency and government-sponsored enterprise mortgage-backed securities, and GSE debt securities. The Fed repeated that it doesn't expect to record a loss on any of its emergency loan programs. On its portfolio of assets, unrealized losses totaled $4.3 billion, which the Fed attributed to "instrument-specific credit risk" on commercial and residential mortgage loans; the Fed earned $428 million on the securities it did sell.