Which global health event triggered the 2020 stock-market crash?

The COVID-19 pandemic triggered the 2020 stock-market crash.

As the novel coronavirus spread internationally in early 2020, governments imposed travel restrictions, business closures, and stay-at-home measures. Investors rapidly reassessed corporate earnings, economic activity, and energy demand. Major stock indexes fell sharply in February and March.

The World Health Organization characterized COVID-19 as a pandemic on March 11, 2020. The S&P 500 entered a bear market after falling at least 20% from its recent high, and several U.S. market-wide trading halts were triggered as prices dropped. Oil prices also suffered severe stress during the same period.

The crash was unusually rapid, but markets recovered later in 2020 after central banks and governments supplied substantial support and vaccine development raised expectations for reopening. The pandemic remained a public-health event as well as an economic shock. A common mistake is to treat the crash as caused by one announcement; it developed through the rapid spread of disease, policy responses, and changing economic expectations.