During the COVID-19 market crash, the S&P 500 took 16 trading days to fall into a bear market in 2020.
The index entered bear-market territory on March 12, 2020, after reaching its record closing high on February 19. A bear market is conventionally defined as a decline of at least 20% from a recent closing high, so this was an exceptionally rapid descent.
The sell-off reflected fears about the coronavirus pandemic, business shutdowns, disrupted supply chains, falling economic activity, and uncertainty about energy markets. Central banks and governments responded with emergency measures, including interest-rate cuts, asset purchases, fiscal support, and public-health restrictions.
Markets later rebounded strongly, but the economic effects were uneven. The crash was unusually fast compared with many historical declines, while the subsequent recovery also moved quickly in some major indexes.