How many trading days did the 2020 S&P 500 bear market take to begin?

The 2020 S&P 500 bear market began after 16 trading days of decline from its record high.

The S&P 500 reached a record closing high on February 19, 2020, then fell rapidly as the COVID-19 pandemic disrupted travel, commerce, supply chains, and expectations for corporate earnings. On March 12, the index entered a bear market, generally defined as a decline of at least 20 percent from a recent closing high. This was the fastest such descent in the index’s history at that time.

The Federal Reserve, U.S. government, and other authorities introduced extraordinary fiscal and monetary measures. The S&P 500 reached its pandemic-era closing low on March 23, after which it rebounded sharply, although economic damage and market effects continued.

The 16-trading-day figure describes the time from the February 19 closing high to the March 12 bear-market entry. It is different from the 33 calendar days often cited for the complete peak-to-trough decline.