Which stock exchange recorded the largest single-day percentage fall during Black Monday in 1987?

The Hong Kong Stock Exchange recorded the largest single-day percentage fall during the worldwide Black Monday turmoil in 1987.

Hong Kong’s market fell 45.8% between October 19 and October 26, 1987, as trading was suspended for several days amid extreme volatility. The collapse began before the major United States decline and helped demonstrate how closely financial markets had become connected.

The United States received the most attention because the Dow Jones Industrial Average fell 22.6% on October 19, the largest percentage drop in its history. London also suffered a major decline, while other markets in Europe and the Pacific region were affected as investors reacted to global selling.

The Hong Kong figure is often missed because “Black Monday” is commonly used as shorthand for the New York event. In a global-market context, however, Hong Kong’s percentage loss was substantially larger. The episode encouraged exchanges and regulators to develop circuit breakers and other trading safeguards.