Tuesday’s DJIA Plunge: Backup Computers Freaked Out

Dow Jones & Co., the media company that manages the well-known index of 30 blue chip stocks, said it discovered shortly before 2 p.m. that its computers weren't properly handling the day's huge volume in trades at the New York Stock Exchange. It switched to a backup computer, and the result was a massive swoon in the index as the secondary system took over processing shortly before 3 p.m. The Dow plunged about 200 points almost instantly, and was down as much as 546 points - its worst single-session decline in more than five years, and one that sent the blue chips into negative territory for the year.