The COVID-19 crash produced a U.S. bear-market decline that was reached in 33 days.
The S&P 500 entered bear-market territory on March 12, 2020, after the spread of COVID-19 caused abrupt changes in economic expectations. The index had reached its pre-crash closing high on February 19, so the move from that high to the bear-market threshold took only 16 trading days; the full decline to the March 23 low unfolded over 33 calendar days.
The sell-off reflected uncertainty about business closures, travel restrictions, unemployment, supply chains, and the public-health response. Oil prices also plunged after a breakdown in cooperation between major producers. Central banks and governments introduced exceptionally large monetary and fiscal measures, helping markets rebound after the March low.
This episode is often called the 2020 stock-market crash or the COVID-19 crash. It was unusually rapid, but its causes differed from those of the 2008 crisis, which centered on housing finance and bank solvency.