The rapid 2010 U.S. stock-market plunge is commonly called the Flash Crash.
On May 6, 2010, major U.S. equity indexes fell sharply in a matter of minutes before recovering much of the loss. The Dow Jones Industrial Average temporarily dropped nearly 1,000 points, its largest intraday point decline at that time. Many individual securities also traded at bizarrely low or high prices before normal conditions returned.
Investigations concluded that automated trading and the interaction of high-frequency trading systems played an important role. A large sell order in E-mini S&P 500 futures helped increase pressure, while algorithms and liquidity withdrawal amplified the move. Later regulatory changes introduced stronger controls, including circuit breakers and volatility protections.
The event is not the same as a traditional multi-month bear market. It was a very fast market-disruption episode, and the name describes its speed rather than a particular economic depression.