The worldwide stock-market crash of 19 October 1987 is known as Black Monday. On that day, the Dow Jones Industrial Average plunged 508 points, or 22.6 percent, its largest one-day percentage loss ever.
Selling spread rapidly through interconnected markets. Hong Kong fell first, followed by Europe and the United States, while Australia and New Zealand also suffered heavy losses. Program trading, portfolio insurance and fears about an overvalued market intensified the decline.
The crash did not cause a prolonged economic depression. Central banks supplied liquidity, and the U.S. Federal Reserve publicly signaled that it would support the financial system. A common mistake is to confuse Black Monday with the October 1929 crash days, which had different dates and causes.