The S&P 500 entered a bear market on March 12, 2020, during the 2020 COVID-19 crash.
A bear market is commonly defined as a decline of at least 20% from a recent closing high. On March 12, the S&P 500 closed 9.5% lower and stood more than 20% below its February 19 peak. This made it the fastest move from a record high into bear-market territory in the index’s history at that time.
The sell-off reflected growing evidence that COVID-19 was spreading internationally, along with travel restrictions, business closures, and fears of a global recession. The World Health Organization characterized COVID-19 as a pandemic on March 11.
The market’s decline continued until March 23, when the S&P 500 reached its closing low for the crash. Massive fiscal support, central-bank action, and improving expectations later helped produce a powerful rebound. The March 12 date is about the bear-market threshold, not the ultimate low.