In a discussion of the future of Fannie Mae and Freddie Mac the Washington Post noted that the government had committed $125 billion to cover their losses. While the article reports that these losses have been a major political issue, it would have been useful to point out that the losses were, in effect, subsidies to banks.
Fannie Mae and Freddie Mac buy mortgages in the secondary market. If they lose money it means that they paid banks more for these mortgages than they were worth. This overpayment is effectively a subsidy to banks who otherwise would have been left holding the mortgages on their books and likely would have incurred losses when they went bad.