Daniel Gross warns that the impact of a default would be massive:
A U.S. debt default, or the whiff of one, would be a much more significant financial event [than the Lehman disaster]. As Yalman Onaran of Bloomberg noted, “The $12 trillion of outstanding government debt is 23 times the $517 billion Lehman owed when it filed for bankruptcy on Sept. 15, 2008.” True. But the increase in damage wouldn’t be arithmetic, it would be exponential—Lehman to the 10th power rather than Lehman times ten.
A debt default, even if momentary and partial, wouldn’t be like blowing up a much bigger stick of dynamite. As Warren Buffett suggests, it would be like detonating a nuclear bomb.
Why would a default be so much worse than Lehman Brothers? It has largely to do with who owns U.S. government debt and how much debt those companies and institutions have. Lehman caused a company to fall, a sector to fall, and stocks to fall a bunch. A U.S. government default—or again, even the whiff of one—would cause all that to happen, plus it would bring down a bunch of governments and possibly ignite a revolution and a couple of wars.
The Dish 