The biggest one-day sell-off associated with the 2015 Chinese stock-market crash was called Black Monday. On August 24, 2015, China’s Shanghai Composite Index fell 8.49%, while markets worldwide also declined sharply.
The sell-off followed a major drop in Chinese share prices that had begun after the Shanghai Composite peaked in June 2015. Concerns included slowing Chinese economic growth, high valuations, forced selling by investors using borrowed money, and uncertainty over government efforts to stabilize the market.
The term Black Monday was not unique to China. It had already been used for major market falls, especially October 19, 1987, in the United States and other countries. In the 2015 episode, the label specifically refers to August 24, when the Shanghai market’s fall helped trigger a broad international risk-off movement.