Which stock index lost 22.6% on October 19, 1987, the crash known as Black Monday?

The Dow Jones Industrial Average lost 22.6% on October 19, 1987, during the crash known as Black Monday.

That one-day percentage decline remains the largest in the Dow’s history. The fall followed sharp losses in markets around the world, including Hong Kong, London, and Australia. Investors were concerned about valuation, trade imbalances, interest rates, and the growing use of computerized trading strategies.

Black Monday is often confused with the 1929 market collapse because both events produced dramatic headlines, but the percentage loss was greater in 1987. The Dow recovered much of the decline relatively quickly, and the crash did not lead to a depression comparable to the 1930s. Regulators later strengthened market safeguards, including circuit breakers designed to pause trading during exceptionally rapid falls.