The COVID-19 pandemic was the global health event associated with the 2020 stock-market crash and the fastest bear market in U.S. history.
As COVID-19 spread internationally in early 2020, governments introduced travel restrictions, lockdowns, business closures, and other measures to slow transmission. Investors rapidly lowered expectations for economic activity and corporate profits. Financial markets experienced extraordinary volatility, with several U.S. trading sessions halted by circuit breakers.
The S&P 500 entered bear-market territory on March 12, 2020, and reached its initial pandemic-era low on March 23. From its February 19 peak to that low, the index fell about 33.9%. Central-bank support, government stimulus, and changing expectations about the pandemic then helped markets rebound sharply.
The crash was not caused by the virus alone. An oil-price dispute between Saudi Arabia and Russia added pressure in March, while markets had already become concerned about slowing growth. The episode is best understood as a shock combining public health, economic shutdowns, energy-market stress, and an exceptionally rapid policy response.