Which U.S. stock-market crash began after the Dow Jones Industrial Average fell 22.6% on one day?

The U.S. stock-market crash associated with a 22.6% one-day Dow decline was Black Monday in 1987.

On October 19, 1987, the Dow Jones Industrial Average fell 508 points, or 22.6%. The percentage loss remains the largest single-day decline in the Dow’s history. Markets in other countries also dropped sharply, making the event an international stock-market crash rather than an isolated U.S. sell-off.

Several factors were cited, including high share valuations, concerns about interest rates and trade deficits, and unusually large use of computerized trading strategies. Portfolio insurance programs automatically sold as prices weakened, which may have accelerated the downward spiral. Regulators later introduced circuit breakers to pause trading during extreme moves.

The name can be confused with the several “Black” days in the 1929 crash. Black Tuesday refers to October 29, 1929, while Black Monday in this question refers specifically to October 19, 1987. The two crashes differed greatly in their economic aftermath.