The 1987 global stock-market crash is known as Black Monday.
On October 19, 1987, the Dow Jones Industrial Average plunged 508 points, or 22.6%, in its largest one-day percentage fall. Major markets in Hong Kong, Europe, Australia, and elsewhere also suffered steep losses, making the event global rather than solely American.
Several forces were associated with the crash, including rising interest rates, valuation concerns, trade tensions, and the growing use of computerized portfolio-insurance strategies. Those automated sell orders could amplify falling prices, although no single cause explains the entire event.
Black Monday is often compared with the 1929 crash, but the economic aftermath was different. The United States did not enter a Great Depression after 1987, and coordinated action by central banks helped stabilize financial markets. The name can also refer to later market disasters, so the year matters.