Glitch Undercuts the Dow

The Dow fell over 400 points today. And some IT guy's ass is fired. From Stocks Have Worst Day Since 9/11 Attacks:

The Dow's decline accelerated at a faster than normal pace during the afternoon after a computer glitch kept some trades from being immediately reflected in the index of 30 blue chip stocks. Dow Jones & Co., the media company which manages the flagship index, said the problem occurred after it was discovered computers were not properly calculating trades, prompting a switch to a backup computer.

The result was a massive plunge in the average in the seconds it took Dow Jones to switch to its secondary computers.