The Federal Reserve has ratcheted up its effort to pump massive amounts of capital into the residential mortgage market, purchasing $10.2 billion of mortgage-backed securities from Fannie Mae, Freddie Mac and Ginnie Mae last week as part of its $500 billion agency MBS purchase program that began in December. Freddie got the lion’s share, $6.9 billion, or 68 percent, while Fannie snared only...