What event on May 6, 2010 caused U.S. stock markets to plunge and rebound within minutes?

The Flash Crash on May 6, 2010 caused U.S. stock markets to plunge and rebound within minutes.

During the episode, the Dow Jones Industrial Average fell about 1,000 points, or roughly 9%, before recovering much of the loss. Some individual securities briefly traded at extremely low prices.

Investigations identified a combination of factors, including market stress, automated trading, high-frequency trading, and a large sell order. The precise interaction among algorithms and fragmented markets made the event difficult to explain as a single simple mistake.

The crash prompted regulatory changes. U.S. exchanges introduced or strengthened circuit breakers and other controls intended to pause trading during unusually rapid price movements. It is distinct from longer crashes such as 1929 or 2008.