The 1987 stock-market crash day associated with the first major collapse in Hong Kong was called Black Monday.
On October 19, 1987, the Dow Jones Industrial Average plunged 22.6%. The crisis was international: Hong Kong’s market fell sharply before selling spread through Europe and North America. Because markets operate across time zones, events in one financial center can influence the opening mood and trading decisions in another.
The phrase Black Monday is not exclusive to 1987. It has also been used for other severe market declines, so the year is essential when identifying this crash. The 1987 episode is generally called Black Monday, while October 28, 1929, is known as Black Monday in the earlier Wall Street crash.
The 1987 collapse led regulators and exchanges to reconsider automated trading, market liquidity, and coordinated responses. Circuit breakers, which temporarily halt trading after extreme moves, became an important post-crash safeguard.