The 1987 crash that produced a global modern stock-market meltdown, including a 45.5% fall in Hong Kong, was Black Monday.
The name usually refers to October 19, 1987, when markets around the world plunged. Hong Kong’s Hang Seng Index fell 45.5%, Australia’s main market fell 41.8%, the United Kingdom’s FTSE 100 fell 26.4%, and the Dow Jones Industrial Average fell 22.6%.
The episode was unusual because the losses were rapid and internationally synchronized. Portfolio-insurance strategies and computerized trading programs placed or intensified sell orders as prices declined, while investors also worried about valuations, interest rates, and exchange-rate tensions.
The crash did not produce a depression comparable to the 1930s. Central banks supplied liquidity, and U.S. regulators introduced market-wide circuit breakers designed to pause trading during extreme declines.