The extreme U.S. stock-market plunge that began on October 19, 1987, is called Black Monday.
In the United States, the Dow Jones Industrial Average fell 22.6% on October 19, 1987. The decline followed large losses in Asian and European markets and was amplified by automated trading systems. Investors were also concerned about interest rates, currency tensions, and a widening U.S. trade deficit.
The crash exposed weaknesses in market infrastructure. Trading volumes overwhelmed systems, and many investors struggled to execute orders at expected prices. In response, U.S. regulators created market-wide circuit breakers that can temporarily halt trading when indexes move by specified amounts.
Black Monday is sometimes described as a repeat of 1929, but the aftermath was different. The United States did not enter a Great Depression after 1987, and the economy continued to grow. Federal Reserve Chair Alan Greenspan also signaled that the central bank was prepared to support the financial system, helping calm markets.