The Fed is making huge "profits," and depositing them with the Treasury.
Now, in order to support the financial sector and stop deflation, the Fed bought up huge quantities of debt, spending down its account at the Treasury.
It is making lots of money on some of that debt, which turns out to have been pretty solid.
On the other hand, lots of that debt is still pretty low in value, because of uncertainty. More than $1.5 trillion of that debt is private, or quasi-private (it's not t-bills!), in the sense that it is made up of mortgage-backed securities or collateralized debt obligations, or else bonds issued directly by the mortgage giants.
Here's the thing: if inflation cranks up, the Fed is going to have to unload a buttload of debt, really fast. The only way to sell that much debt, and take excess cash out of the economy, is to sell at fire sale prices.
So, if there is inflation, the Fed is going to take truly ginormous capital losses on the debt it will have to sell. But this is exactly Bernanke's plan, the one he is so sure will work to prevent inflation. Big Ben's talk at the AEA meetings made much of this policy. But who in the world is going to buy CDOs in this market?
The lagniappe: Lots of the CDOs are based on fixed interest rate mortgages. If there is inflation, the capital value of those gets hammered. All the rest are based on ARMs of some kind. And for those the PAYMENTS skyrocket with nominal interest rates, and defaults go up, and AGAIN the CDOs' capital value takes it right up the ol' gazoch, with a red hot poker.
This is not really a good policy.
(Nod to the Ward Boss)