The Dow Jones Industrial Average fell 22.6% on Black Monday, October 19, 1987. It dropped 508 points, from 2,246.74 to 1,738.74, making it the largest one-day percentage decline in the index’s history.
The crash followed a powerful five-year bull market. Concerns about overvalued shares, rising interest rates, trade and budget deficits, and automated portfolio-insurance selling intensified the pressure. Heavy sell orders overwhelmed trading systems and caused widespread delays and halts.
Black Monday was not limited to the United States: markets plunged across Asia, Europe, and North America. The Federal Reserve supplied liquidity to the financial system, helping prevent a deeper banking panic. Trading curbs were later introduced to slow extreme market movements.
A common mix-up is confusing the 22.6% figure with the Dow’s 508-point loss. They describe the same day in different ways; the percentage is the standard answer when the question asks for the drop.