The 1987 market crash remembered for the largest one-day percentage fall in the Dow Jones Industrial Average was Black Monday.
On 19 October 1987, the Dow Jones Industrial Average fell 508 points, or 22.6 percent. The decline occurred amid international market weakness, rising interest rates, concerns about economic growth, and widespread use of computerized trading strategies. Other major markets also dropped sharply, making the event global rather than solely American.
The name Black Monday is sometimes confused with Black Monday dates from other financial crises. The 1987 episode is specifically the worldwide stock-market crash that began in Hong Kong and spread westward through Europe and North America. Unlike the 1929 Wall Street Crash, it did not lead to a depression.
After the crash, regulators introduced or strengthened measures such as trading curbs and circuit breakers. These mechanisms are designed to pause trading during exceptionally rapid price movements and remain part of modern market infrastructure.