Hong Kong’s Hang Seng Index fell 45.8% during the 1987 global stock-market crash.
The decline unfolded before and around the October 19 collapse in the United States. Hong Kong’s market had already been weakened by investor anxiety, and trading was suspended for several days after the exchange experienced extreme volatility. Its loss was among the largest recorded by a major stock index during the episode.
The crash then moved through international markets, including Australia, Britain, Canada, and the United States. The worldwide sequence demonstrated how closely connected exchanges had become through capital flows, news, and trading activity.
The Hang Seng’s 45.8% fall is distinct from the Dow’s 22.6% one-day percentage loss on Black Monday itself. Comparing those figures requires care: the Hong Kong number describes the market’s crash-period decline, while the Dow figure refers to one trading day.