Dow Plunge Open Thread

Thar she blows. Is it a long-overdue return to common sense? Those pesky laws of gravity again? Is it all Greece's fault? Is it all Jim Cramer's fault? Is it all Elizabeth Warren's fault? Will we end the day below the non-magical 10,000 figure? Dow 3,600?

Your guess is as good as anybody else's so pipe up in the comments.

Update: DJIA rises through the late afternoon, closes at 10520.32.

CNBC is blaming a trading error at Citigroup, in which somebody entered "billion" instead of "million." (Thank God the government kept Citi from going out of business!)

Nasdaq closes down at 2319.

The waves of panic that greeted this temporary drop, in addition to demonstrating how thoroughly the system is rigged against short sellers and the valuable information they provide, brings back an old question: If the government is willing to spend trillions of dollars to prop up house prices, in the belief that this asset is so central to Americans' personal financial situations, why shouldn't it be spending just as much to make sure the Dow never goes down? If the price of your house—which you still get to live in even if it loses value—is sacrosanct, why isn't the price of your 401(k) plan?