[quote=CA renter]How much of the $1.25 trillion in MBS on the Federal Reserve balance sheet is marked to market?

http://www.newyorkfed.org/markets/mbs_faq.html

edit: According to the most recent information I could find, it is just below a trillion at the moment, though recent trend changes are up.

http://research.stlouisfed.org/fred2/series/WMBSEC

http://timeline.stlouisfed.org/index.cfm?p=data&rd_id=39%5B/quote%5D

It is, in theory, marked to market, at least to the extent market is below net aggregate cost. There were proposals at one time for Treasury to buy sub-prime debt at face value. I don’t recall if any of those proposals were enacted. (Treasury acts as a matter of law. The Fed has the luxury of acting solely based on policy.) The fed has been buying debt at current market values.