The Nikkei 225’s largest one-day percentage loss in its history was 14.9%, recorded during the 1987 global crash.
On October 20, 1987, Japan’s Nikkei 225 fell sharply as the shock that had struck Wall Street and other markets spread across the world. The decline followed the Dow Jones Industrial Average’s 22.6% fall on October 19, known as Black Monday.
The Japanese market’s percentage drop was smaller than Wall Street’s, but it was still an extraordinary move for a major national index. The episode demonstrated how increasingly connected financial markets could transmit selling pressure across time zones within hours.
The 1987 crash is sometimes described as a purely American event because Black Monday is associated with the New York market. In reality, stock exchanges in Europe, Asia, and elsewhere also suffered severe losses. The crisis encouraged improvements in trading systems, coordination among regulators, and automatic trading halts.