The 1987 Black Monday stock-market crash began on 19 October 1987 in Hong Kong before spreading worldwide.
Hong Kong’s Hang Seng Index fell sharply that day, helping trigger a chain of market declines across Asia, Europe, and North America. By the end of the trading day in New York, the Dow Jones Industrial Average had lost 508 points, or 22.6 percent—its largest one-day percentage fall.
The name “Black Monday” is also used for other market disasters, so the year is important. The 1987 crash was not the same event as the 1929 Wall Street Crash or the 1987 New Zealand market collapse. Concerns about overvalued shares, trade deficits, interest rates, and computerized portfolio insurance all contributed to the panic.
Central banks responded with emergency liquidity and reassuring statements. Trading rules were later changed, including circuit breakers designed to pause markets during exceptionally rapid falls. The Dow eventually recovered its pre-crash level, but the episode permanently changed how exchanges manage systemic selling.