Which U.S. stock index fell 22.6% on Black Monday, October 19, 1987?

The Dow Jones Industrial Average fell 22.6% on Black Monday, October 19, 1987.

That one-day percentage decline remains the largest in the Dow’s history. The sell-off spread across international markets, with major exchanges in Asia, Europe, and North America recording severe losses during the same global panic.

Several explanations were investigated, including rising interest rates, trade concerns, investor anxiety, and the growing use of computerized portfolio insurance. Program trading could automatically sell futures or shares as prices dropped, potentially adding momentum to an already crowded retreat.

The 1987 crash differed from 1929 because the economy did not enter a comparable decade-long depression. Market reforms followed, including circuit breakers designed to pause trading during exceptionally sharp declines. The S&P 500 also suffered heavily, but the famous 22.6% figure specifically refers to the Dow’s closing decline.