What event caused the worldwide stock-market crash that began in February and March 2020?

The COVID-19 pandemic caused the worldwide stock-market crash that began in February and March 2020.

As the virus spread internationally, governments introduced travel restrictions, lockdowns, and other measures that sharply reduced economic activity. Investors rapidly revised expectations for company earnings, employment, energy demand, and global growth.

Major indexes fell into bear-market territory at exceptional speed. On March 9, March 12, and March 16, 2020, U.S. markets triggered circuit breakers after severe declines. The Federal Reserve and other central banks cut interest rates or expanded emergency support, while governments introduced fiscal relief programs.

The crash was followed by a rapid rebound in many markets, supported by policy measures and expectations for vaccines and economic reopening. The initial sell-off is distinct from the later inflation and interest-rate turbulence that also affected markets after the pandemic began.