Hong Kong’s October 1987 stock-market crash, which spread through global markets, was known as Black Monday.
The term is most strongly associated with October 19, 1987, when stock markets around the world plunged. Hong Kong’s market had already fallen sharply before the US market suffered its historic one-day decline, and the shock moved rapidly across international financial centers.
Several factors contributed, including overvalued shares, rising interest rates, investor anxiety, and the growing use of computerized portfolio insurance. These systems could generate additional sell orders as prices dropped, intensifying the downward movement.
Black Monday is sometimes confused with other market days carrying the same nickname. The name is also used for crashes in 1929 and 1987, so the year and location matter when identifying the event.