What index briefly fell nearly 1,000 points during the 2010 Flash Crash?

The index that briefly fell nearly 1,000 points during the 2010 Flash Crash was the Dow Jones Industrial Average.

On May 6, 2010, the Dow dropped about 998.5 points from its intraday level, a decline of roughly 9.2%, before recovering much of the loss within minutes. It closed down 347.80 points, so the often-quoted “nearly 1,000 points” figure refers to the dramatic intraday fall rather than the final closing loss.

The Dow is a price-weighted index tracking 30 prominent U.S. companies. Because it is price-weighted, a stock’s dollar price—not simply its company size—affects its influence on the index. That makes the Dow different from the S&P 500, which is weighted by market capitalization, and the Nasdaq Composite, which covers thousands of Nasdaq-listed companies.

The Russell 2000 was not the index generally associated with the nearly 1,000-point plunge. Nor did the S&P 500 or Nasdaq report the event in points on the same scale: their movements are usually discussed as percentages or index points. The Flash Crash affected several markets simultaneously, but the Dow’s enormous point move made it the headline figure.