Fed has to pay all the debt of FNMA to totally own FNMA before it can legaly restruct FNMA and liguadate it. There are too too many domestic and foreign investors own a piece of FNMA. Simply liquadate FNMA equals to drop US debt rating to junks level. Still I do not think FNMA common shares worth anything since FNMA would post too much financial risk to the nation if not backed by the Fed. Also, FNMA is the cash cow for Fed at the current setting. If you are willing to take some risk to get rich from FNMA, you should only invest in the prefered since FNMA has to pay back the par as long as it is not bankrupted.