The 2010 market event in which U.S. stock indexes plunged rapidly and then partly recovered was the Flash Crash.
On May 6, 2010, the Dow Jones Industrial Average dropped almost 1,000 points, or about 9%, within minutes before recovering much of the loss. Many individual securities experienced extraordinary temporary price movements, including trades at implausibly low or high prices.
Investigations concluded that high-frequency trading and a large sell order interacted with existing market stress and fragmented electronic liquidity. The event was not a conventional multi-year bear market; it was a sudden, computer-amplified liquidity shock. The U.S. Securities and Exchange Commission and futures regulators later described mechanisms involving automated trading and introduced safeguards intended to reduce the chance of similar disorder.