During the 2010 Flash Crash, in which U.S. stock index did the largest points drop occur?

During the 2010 Flash Crash, the largest points drop occurred in the Dow Jones Industrial Average.

On May 6, 2010, the Dow fell about 1,000 points, or nearly 9%, within minutes before recovering much of the loss. The S&P 500 and Nasdaq Composite also experienced abrupt declines. Many individual securities briefly traded at extremely low or high prices, creating a highly unusual market environment.

Investigations by U.S. regulators concluded that a large automated sell order, combined with high-frequency trading and already fragile market conditions, helped produce the rapid plunge. The event led to changes including single-stock circuit breakers and market-wide safeguards. It was not a conventional, weeks-long bear market but a sudden intraday market disruption.