Five years ago today the Dow Jones Industrial Average printed an intraday high of 11,908 and closed at a record high 11,723. Since that time, the dot-com bust, 9/11 and corporate malfeasance drove the Dow to a low of 7,286 on October 9th, 2002, a decline of 39% over 33 months. The DJIA closed today at 10,558.
As badly as the Dow has suffered, it's nothing compared to the Nasdaq. It would post a record close on March 10th, 2000 at 5,049 and drop to 1,108 on October 10th, 2002, losing 78% of its value.