March 12, 2020, marked the fastest U.S. bear-market entry, when the S&P 500 fell at least 20% during the COVID-19 crash.
The S&P 500 closed 9.51% lower on March 12, 2020, its largest one-day percentage drop since Black Monday in 1987. That close placed the index more than 20% below its February 19 record close, meeting the commonly used definition of a bear market. The move came amid escalating concern about COVID-19, travel restrictions, business shutdowns, and economic disruption.
The decline was exceptionally rapid: only 16 trading days separated the record high from bear-market territory. The Federal Reserve and governments later introduced major monetary and fiscal support. March 23 became the crash’s closing low for the S&P 500, but it was not the date the index first entered bear-market territory. This episode is commonly called the 2020 stock-market crash.