The S&P 500 entered a bear market on March 12, 2020, during the COVID-19 crash.
A bear market is commonly defined as a decline of at least 20% from a recent peak. The S&P 500 reached a record close on February 19, 2020, then fell rapidly as the coronavirus spread and governments introduced restrictions that disrupted economic activity.
On March 12, the index closed 9.99% lower, its worst single-day percentage loss since the 1987 crash. The Federal Reserve and governments later introduced major monetary and fiscal responses. Markets also recovered unusually quickly compared with many earlier crashes.
The S&P 500 is a broad index of large U.S. companies, while the Dow tracks 30 companies and the Nasdaq Composite has a stronger technology concentration. All three fell sharply during the pandemic shock, but they are different benchmarks.