I asked Fed Chairman Ben Bernanke during his quarterly press conference this week if the central bank had its own estimate for the implicit subsidy that banks considered too big to fail receive in the form of cheaper borrowing. Senator Elizabeth Warren had confronted him at a recent hearing with a Bloomberg estimate of $83 billion which itself was derived from an IMF study. At the time, he dismissed her concern: “That’s one study Senator, you don’t know if that’s an accurate number.”