In what month and year did the COVID-19 crash begin its fastest US bear market?

The COVID-19 crash began its fastest US bear market in February 2020.

The S&P 500 entered a bear market on March 12, 2020, but the sharp decline began in February as investors recognized that the coronavirus outbreak could disrupt global supply chains, travel, employment, and consumer demand. From its February 19 record close to its March 23 low, the index fell about 34%.

The decline was historically rapid: the S&P 500 reached bear-market territory in 16 trading days, commonly described as the fastest bear-market entry in its history. Governments and central banks responded with emergency interest-rate cuts, asset purchases, fiscal relief, and public-health restrictions.

Markets rebounded sharply after March 23, although the economy experienced a severe recession and millions of workers lost jobs. The episode is distinct from the 2008 crash because its initial trigger was a pandemic and the economic shutdowns used to contain it. February 2020 identifies the beginning of the market slide, while March 2020 contains the most dramatic daily moves and the trough.