Which date is known as Black Monday, when global stock markets crashed on 19 October 1987?

Black Monday occurred on 19 October 1987, when global stock markets suffered an extraordinary one-day collapse.

The Dow Jones Industrial Average fell 22.6% that day, its largest one-day percentage decline in history. Markets in Hong Kong, Australia, the United Kingdom, and other countries also recorded severe losses, making the event international rather than solely American.

Several factors contributed, including concern about overvalued shares, trade tensions, rising interest rates, and the growing use of computer-driven portfolio insurance. Researchers have debated the precise balance among these causes. The crash was not simply a repeat of the 1929 Wall Street collapse, although the nickname deliberately echoed earlier terminology.

Regulators responded with measures including trading halts, commonly called circuit breakers, designed to give investors time to assess rapidly falling prices. The Dow later recovered, and the crash did not produce a depression comparable to the 1930s.