The official common name of the 2010 crash caused by rapid automated trading in U.S. markets is the Flash Crash.
On May 6, 2010, major U.S. stock indexes plunged and then recovered much of the loss within minutes. The Dow Jones Industrial Average briefly fell nearly 1,000 points, or about 9%, before rebounding. Some individual securities experienced even more extreme temporary price movements.
Investigations by U.S. regulators concluded that a large automated sell order, combined with high-frequency trading and stressed market conditions, helped produce the abrupt decline. The event exposed weaknesses in market structure and prompted measures such as single-stock circuit breakers and revised trading controls. It is different from a conventional bear market because the defining feature was the extraordinary speed of the drop and partial recovery during one trading session.