The Hang Seng Index fell 33.3% on October 26, 1987.
Hong Kong had closed its stock and futures markets for four trading days after the global panic began. When trading resumed on October 26, selling intensified immediately: the index lost more than 650 points within its first 15 minutes and finished down 1,120.7 points, or 33.33%.
The date matters because several percentages from the same crash are easy to mix up. On October 19, often called Black Monday, the Hang Seng fell 420.81 points, while the index’s broader decline during the October crash is often reported as roughly 45.8%. The 33.3% figure refers specifically to the extraordinary single-day fall on October 26.
The turmoil exposed weaknesses in Hong Kong’s market infrastructure and contributed to later financial reforms, including the creation of the Securities and Futures Commission. It also illustrates why a quiz question must distinguish a one-day percentage loss from a cumulative decline.