Fannie Mae common shares rose more than 400% in the past three months, and its most widely preferred shares went from less than $2 per share to more than $5 in the past two months.

The stocks, however, are really only worth the trade because the company is under government control and may not operate on its own.

Since both Fannie Mae and Freddie Mac were put in government conservatorship during the housing and mortgage market crashes, they are required to pay all profits to the U.S. Treasury department in the form of dividends. Shareholders get nothing.