The Dow Jones Industrial Average fell 22.6% on Black Monday, October 19, 1987.
It was the largest one-day percentage decline in the Dow’s history. The fall followed sharp losses in markets around the world, including Hong Kong, London, and Australia. Investors were alarmed by rising interest rates, worries about economic growth, and large trade imbalances.
Computerized program trading and portfolio insurance may have intensified the selling. These strategies automatically sold futures or stocks as prices fell, adding pressure during a market already experiencing heavy uncertainty. The crash was not caused by a single company failure.
The decline is often confused with the 1929 Wall Street Crash, but the two events occurred under very different financial and regulatory conditions. After 1987, the U.S. Securities and Exchange Commission and exchanges introduced circuit breakers designed to pause trading during extreme moves.