What was the U.S. stock-market crash on May 6, 2010 commonly called?

The U.S. stock-market crash on May 6, 2010, was commonly called the Flash Crash.

During the afternoon of May 6, major U.S. equity indexes dropped rapidly and then recovered much of the loss within minutes. The Dow Jones Industrial Average briefly fell nearly 1,000 points, an unusually large move for such a short period. Many individual securities also experienced extreme and temporary price swings.

Investigations concluded that automated trading and the interaction of different types of orders played an important role. A large sell order in the E-mini S&P 500 futures market helped trigger a chain of activity in an already nervous market. The episode showed how quickly electronic markets can transmit stress.

The Flash Crash did not represent a normal full-day collapse. Its defining feature was speed: prices plunged and rebounded in minutes. Regulators later strengthened safeguards, including circuit breakers and rules concerning clearly erroneous trades.