The May 6, 2010 U.S. market plunge caused by an exceptionally rapid trading breakdown was called the Flash Crash.
On May 6, 2010, major U.S. equity indexes suddenly dropped and then recovered much of the loss within minutes. The Dow Jones Industrial Average briefly fell almost 1,000 points, an unusually large move for such a short period. Many individual securities also traded at extreme prices before normal conditions returned.
Investigations by U.S. regulators concluded that a large automated sell order, combined with high-frequency trading and fragmented market liquidity, helped intensify the move. The event led to changes including market-wide circuit breakers and rules addressing clearly erroneous trades. It was not the same as a conventional recession-driven crash: its defining feature was speed and partial reversal. The nickname therefore describes the event’s rapid mechanics rather than a specific calendar day such as Black Monday.