During the October 1987 global stock-market crash, which Hong Kong index fell 45.8%?

During the October 1987 global stock-market crash, the Hang Seng Index fell 45.8%.

The decline occurred as the crash spread across international markets after the U.S. market collapse on October 19, 1987. Hong Kong’s exchange was closed for several days after the initial turmoil, then reopened on October 26 amid intense selling pressure. The Hang Seng’s cumulative loss for that period reached 45.8%, one of the steepest falls recorded by a major stock index during the episode.

The crash was not confined to the United States. Markets in Australia, the United Kingdom, Canada, and many European countries also suffered sharp losses. The Hang Seng’s result is sometimes confused with the much smaller one-day percentage decline in the Dow Jones Industrial Average, which fell 22.6% on Black Monday itself.

The 1987 crash later prompted reforms in market structure, including the wider adoption of circuit breakers designed to pause trading during exceptionally rapid declines.