The Dow Jones Industrial Average fell 22.6% on Black Monday in 1987.
The plunge occurred on October 19, 1987, when the Dow lost 508 points, then the largest one-day point decline in its history. Selling spread rapidly across international markets, making the event a global stock-market crash rather than a problem confined to New York.
Several factors were blamed, including high valuations, rising interest rates, trade tensions, and computerized portfolio-insurance strategies that encouraged further selling as prices dropped. Economists still debate the relative importance of these causes, but the scale and speed of the decline are undisputed.
The 1987 crash differed from 1929 in an important way: it was not followed by a comparable decade-long depression. Central banks supplied liquidity, and markets eventually recovered. The episode did lead regulators to introduce circuit breakers, which can temporarily halt trading during unusually severe price movements.