The Dow Jones Industrial Average lost 22.6% on 19 October 1987, the largest one-day percentage fall in its history.
The date became known as Black Monday. Selling occurred across international markets, and the decline followed sharp falls in several overseas exchanges. Investors were concerned about valuation, interest rates, trade tensions and portfolio-insurance strategies that could generate further selling as prices dropped.
Unlike the 1929 crash, the 1987 collapse did not lead to a decade-long depression. The United States economy continued expanding, although the market shock was severe and confidence was badly damaged. The Federal Reserve responded by publicly supporting the financial system and supplying liquidity.
The percentage loss is different from a point loss. Because the Dow’s level was much higher in 1987 than in earlier decades, later crashes could produce larger numerical point declines without matching Black Monday’s percentage record. That distinction is important when comparing market crashes across different eras.