Which 1997 Asian financial crisis stock exchange suffered a one-day fall of about 15% on October 28?

The Hong Kong Stock Exchange suffered a one-day fall of about 15% on October 28, 1997, during the Asian financial crisis.

Hong Kong's Hang Seng Index had reached a record high in August 1997, shortly after the territory returned to Chinese sovereignty. As regional currencies and markets came under pressure, investors attacked Hong Kong's linked exchange-rate system and sold equities heavily.

The October collapse was especially dramatic because it followed steep declines elsewhere in Asia. Authorities defended the Hong Kong dollar and used financial measures during the crisis, while the Hong Kong Monetary Authority later intervened directly in the stock market in August 1998.

The crisis began in Thailand in July 1997 after pressure forced the baht to float. It spread through Indonesia, South Korea, Malaysia, and other economies. The Hong Kong market's decline was therefore part of a regional financial shock, not an isolated local crash.