WSJ Editorial: The Price of Fannie Mae

Some perspective on the possible failure:

As opposed to GM or Ford, most Americans have never heard of Fannie Mae and Freddie Mac. Yet the insolvency of either mortgage giant would have far more profound consequences for every American taxpayer than the bankruptcy of those car companies. It's time Americans understood the price they could soon pay for the Beltway's confidence game with these high-risk "government-sponsored enterprises."...

...What Americans need to know is how damaging such a failure would be. This wouldn't merely be a matter of the Federal Reserve guaranteeing $29 billion in dodgy mortgage paper, a la Bear Stearns. Fannie and Freddie are among the largest financial companies in the world. Their liabilities – mortgage-backed securities (MBSs) and other debt – add up to some $5 trillion.

To put that in perspective, consider that total U.S. federal debt is about $9.5 trillion, compared to a total U.S. GDP of $14 trillion. About $5.3 trillion of that debt is held by the public (in the form of Treasury bonds and the like), while $4.2 trillion is intragovernment debt such as Social Security IOUs. This is the liability side of America's federal balance sheet, and its condition influences how much the government can borrow and at what rates.

The liabilities of Fan and Fred are currently not on this U.S. balance sheet. But one danger is a run on the debt of either company, putting pressure on the Treasury and Federal Reserve to publicly guarantee that debt to prevent a systemic financial collapse. In an instant, what has long been an implicit taxpayer guarantee for both companies would be made explicit – committing American taxpayers to honoring as much as $5 trillion in new liabilities. U.S. debt held by the public would more than double, and the national balance sheet would look very ugly...