Which event caused the fastest U.S. bear market in history during March 2020?

The COVID-19 pandemic caused the fastest U.S. bear market in history during March 2020.

The 2020 stock-market crash began as investors reacted to the rapid global spread of COVID-19, business closures, travel restrictions, and fears of a deep recession. The S&P 500 entered a bear market on March 12, 2020, after falling at least 20% from its February record close.

The decline was unusually rapid: the S&P 500 lost about 34% from its February 19 peak to its March 23 low. Trading halts, known as circuit breakers, were triggered several times. Central banks and governments then introduced large monetary and fiscal responses, helping markets rebound quickly.

The crash is sometimes conflated with the oil-price shock of March 2020. A dispute between Saudi Arabia and Russia contributed to an oil sell-off, but the pandemic was the central cause of the broad global market panic.