Which stock exchange suffered the greatest one-day percentage fall during the 1987 Black Monday crash?

The Hong Kong Stock Exchange suffered the greatest one-day percentage fall during the 1987 Black Monday crash.

Hong Kong’s market fell 45.8% between October 19 and October 26, 1987, as the international sell-off spread through interconnected financial centers. Trading was suspended for several days after the collapse, reflecting the extreme disruption and operational pressure.

The global sequence began with heavy selling in Hong Kong before moving through Europe and North America. London’s market fell sharply, and the Dow Jones Industrial Average later recorded its then-largest one-day percentage decline. Investors were reacting to valuation concerns, currency tensions, interest rates, and automated trading strategies.

The Hong Kong collapse is sometimes overlooked because the New York decline became the best-known symbol of Black Monday. However, the event was global rather than exclusively American. Its scale encouraged exchanges to coordinate more closely and develop mechanisms for pausing trading during disorderly markets.