The Dow Jones Industrial Average fell 22.6% on Black Monday in 1987. This percentage remains the largest one-day percentage decline in the Dow's history.
The drop occurred on October 19, 1987, after a period of market weakness and rising investor anxiety. The sell-off was not confined to the United States: major markets around the world also fell sharply. The scale and speed of the decline made it a defining example of how increasingly connected financial markets could transmit panic across borders.
The crash is often compared with the 1929 Wall Street Crash, but the surrounding economic conditions were different. The 1987 event did not lead to a prolonged depression, and markets later recovered. Investigations focused on trading mechanisms, including computerized program trading and portfolio insurance, which could generate additional sell orders as prices declined. U.S. exchanges later adopted trading halts to give participants time to reassess unusually rapid moves.