During the 2010 Flash Crash, approximately how long did the most intense market plunge last?

During the 2010 Flash Crash, the most intense market plunge lasted about 36 minutes.

On 6 May 2010, U.S. stock indexes fell rapidly during the afternoon before recovering much of the loss. The Dow Jones Industrial Average dropped about 1,000 points, or roughly 9%, within minutes, and many individual securities briefly traded at extraordinarily low prices.

The episode’s most dramatic phase ran from about 2:32 p.m. to 3:07 p.m. Eastern Time, a period of approximately 36 minutes. Investigations found that automated high-frequency trading and a large sell order in E-mini S&P 500 futures interacted with deteriorating liquidity, although the event involved several connected market mechanisms.

The Flash Crash is different from a conventional bear market: it was exceptionally fast and much of the decline reversed the same day. Regulators later introduced measures such as circuit breakers and coordinated trading pauses to reduce the risk of similar disorder.