March 2020 was the first month of the 2020 COVID-19 stock-market crash in which the S&P 500 entered a bear market.
The S&P 500 entered bear-market territory on March 12, 2020, after the index fell at least 20% from its February record close. The sell-off reflected rapidly spreading COVID-19 infections, business closures, travel restrictions, and uncertainty about the economic consequences.
March also included several extraordinary trading sessions and emergency actions by central banks and governments. The Federal Reserve cut interest rates, expanded lending support, and later introduced large-scale asset purchases.
A bear market is generally defined as a decline of 20% or more from a recent peak. It is different from a market crash, which has no single universally fixed percentage definition. The S&P 500 later recovered much of its loss as vaccines, fiscal support, and economic reopening changed expectations.