How long did the most intense phase of the 2010 Flash Crash last, according to U.S. regulators?

The most intense phase of the 2010 Flash Crash lasted about 36 minutes, according to investigations of the event.

On May 6, 2010, U.S. markets experienced an extraordinarily rapid fall and partial recovery. The Dow Jones Industrial Average dropped nearly 1,000 points, or about 9%, before regaining much of the loss. The S&P 500 and other major indexes also moved violently, while some individual securities briefly traded at bizarre prices.

Investigators linked the episode to a combination of market stress, automated trading, liquidity withdrawal, and a large sell order. A later U.S. Department of Justice case associated the initiating trades with trader Navinder Singh Sarao, though the event exposed broader structural weaknesses in electronic markets.

The 36-minute figure describes the sharpest disturbance, not the entire trading day. Markets opened normally, became unstable in the afternoon, and recovered much of the fall before the close.