The global stock-market crash that began on October 19, 1987, was nicknamed Black Monday.
The name refers to the dramatic losses recorded that day, especially in the United States. The Dow Jones Industrial Average fell 22.6%, while other major markets also suffered steep declines. Because financial markets operate across time zones, the selling moved from one exchange to another and became a worldwide event.
The term can be confusing because several market crises have acquired similar weekday names. Black Tuesday usually refers to October 29, 1929, and Black Thursday commonly refers to October 24, 1929. The 1987 episode is specifically associated with Black Monday.
After the crash, regulators examined trading systems, derivatives, and automated selling programs. Exchanges later adopted circuit breakers designed to pause trading when prices move too far too quickly. These measures were intended to give investors time to assess information instead of selling in a feedback loop.