Black Monday was the October 1987 event that caused the Dow Jones Industrial Average to lose 22.6% in one trading session.
The crash occurred on October 19, 1987, when markets around the world plunged. The Dow’s one-day percentage decline remains the largest in its history. Hong Kong markets fell first in the global sequence, followed by major declines in Europe and North America.
Several factors contributed, including slowing economic expectations, high valuations, rising interest rates, and automated portfolio-insurance strategies that accelerated selling. The precise combination matters: no single announcement fully explains the worldwide collapse.
Unlike the 1929 crash, Black Monday was followed by a relatively rapid recovery in the United States. The Federal Reserve, led by Alan Greenspan, signaled that it was ready to provide liquidity to the financial system. Regulators later introduced circuit breakers and other market safeguards.