Which 2010 U.S. market event caused a rapid, temporary plunge in major stock indexes?

The rapid 2010 U.S. market plunge was called the 2010 Flash Crash.

On May 6, 2010, major U.S. stock indexes dropped suddenly and then recovered much of the loss within minutes. The Dow Jones Industrial Average briefly fell about 1,000 points, or roughly 9%, during the session.

The event exposed the speed and complexity of electronic trading. High-frequency firms, automated orders, market fragmentation, and stressed liquidity interacted in ways that made the decline unusually abrupt. Some individual securities recorded trades at extreme prices before normal trading returned.

Investigations concluded that a large automated sell order helped trigger the conditions, while later analysis examined the roles of other traders and market mechanisms. The crash led regulators and exchanges to introduce safeguards such as circuit breakers and improved coordination.