The big policy news this week has been the Fed’s decision to buy $1 trillion of long-term bonds, going beyond the normal policy of buying only short-term debt. Good move — but it’s probably worth pointing out that yes, this does expose the Fed, and indirectly the taxpayer, to some risks. And in so doing, it blurs the line between fiscal and monetary policy.
Now, the Fed isn’t taking on any serious default risk — Treasuries are backed by the full faith etc of the US government, and agency debt is de facto backed by the same, although the market doesn’t seem to believe that. Anyway, the Fed is for these purposes a government agency itself, so all this is debt between different parts of USG.
The Fed is, however, creating a new liability: the monetary base it creates to buy these bonds. In effect, it’s printing $1 trillion of money, and using those funds to buy bonds. Is this inflationary? We hope so! The whole reason for quantitative easing is that normal monetary expansion, printing money to buy short-term debt, has no traction thanks to near-zero rates. Gaining some traction — in effect, having some inflationary effect — is what the policy is all about.
~ Paul Krugman, "Fiscal aspects of quantitative easing (wonkish)," New York Times, March 20, 2009