The Dow Jones Industrial Average dropped 998.5 points during the 2010 Flash Crash on May 6, 2010.
The sudden fall happened during afternoon trading in the United States. Major indexes and individual securities plunged rapidly, and some trades occurred at extremely unusual prices before the market recovered much of the loss.
Investigations linked the event to a combination of market conditions, automated trading, and a large sell order. The crash demonstrated how electronic markets could transmit and amplify pressure at extraordinary speed.
The 998.5-point figure was the Dow’s largest intraday point drop at that time. It is a point measure, not a percentage measure, so it should not be confused with Black Monday’s record percentage decline in 1987.