Which 1987 crash saw Hong Kong's Hang Seng Index fall 45.5% in four days?

Black Monday refers to the 1987 crash in which Hong Kong's Hang Seng Index fell 45.5% in four days.

The global sell-off began on 19 October 1987, when the Dow Jones Industrial Average dropped 22.6%, the largest one-day percentage decline in its history. Hong Kong's market suffered an especially severe fall over the surrounding trading days, and the stock exchange temporarily closed from 20 to 23 October.

Concerns about overvalued shares, rising interest rates, trade imbalances, and computerized trading strategies all featured in explanations of the crash. No single cause completely explains the international chain reaction.

Black Monday is a specific name for the 1987 episode, although other market crashes have also been nicknamed Black Monday. The Hong Kong statistic is often quoted as a four-day decline rather than a single-session percentage, which helps distinguish it from the famous Wall Street figure.