In the 2020 COVID-19 market crash, the S&P 500 took 16 trading days to fall into a bear market.
The index entered bear-market territory on March 12, 2020, defined as a decline of at least 20 percent from a recent closing high. Its previous record closing high had been set on February 19, so the transition occurred after only 16 trading sessions.
The speed reflected the sudden global shock caused by the COVID-19 pandemic. Governments imposed restrictions, travel collapsed, businesses closed, and investors rapidly revised expectations for earnings and economic activity. Oil prices also fell sharply during the same period.
The S&P 500 reached its closing low on March 23, 2020, then rebounded as governments and central banks introduced large fiscal and monetary measures. The crash is notable for its speed, while the subsequent recovery was also unusually rapid compared with many earlier bear markets.