The largest one-day percentage fall in the Dow during the Black Monday crash occurred in 1987.
On October 19, 1987, the Dow Jones Industrial Average lost 22.6% of its value. The percentage fall exceeded the steepest single-day declines associated with the 1929 crash. Markets in other countries also suffered severe losses, making 1987 a landmark year in the history of global financial integration.
Several conditions preceded the plunge: share valuations had risen strongly, interest-rate concerns affected sentiment, and the United States faced trade and currency tensions. Computerized trading strategies and portfolio-insurance programs could accelerate selling once prices began to drop.
The year is sometimes confused with 1929 because both crashes are linked with famous weekday names and intense panic. Their economic aftermaths differed substantially. The 1987 crash was followed by reforms such as market-wide trading halts, while the economy did not enter a Great Depression-style collapse.