Which index lost 22.6% on 19 October 1987 during the United States stock-market crash?

The Dow Jones Industrial Average lost 22.6% on 19 October 1987 during the United States stock-market crash.

That percentage represented a fall of 508 points, from 2,246.74 to 1,738.74. Because the Dow was widely followed and its percentage loss exceeded the previous record by a wide margin, the session became the defining statistic of Black Monday.

The S&P 500 also suffered a severe decline, falling 20.47%, while the Nasdaq Composite fell 11.5%. The Dow is therefore the correct index for the often-quoted 22.6% figure, not the broader S&P 500.

The crash prompted market regulators to examine trading safeguards. U.S. exchanges later introduced circuit breakers designed to pause trading after exceptionally large declines.