Which 2020 event caused the fastest bear-market decline in U.S. stock-market history?

The COVID-19 pandemic caused the fastest bear-market decline in U.S. stock-market history.

As the virus spread internationally in early 2020, governments introduced travel restrictions, business closures, and stay-at-home measures. Investors rapidly repriced expectations for corporate earnings and economic activity. The S&P 500 entered a bear market on March 12, 2020, after falling at least 20% from its February peak.

The decline from the S&P 500’s February 19 peak to its March 23 low took only 33 calendar days. That was unusually fast compared with earlier bear markets. Financial stress also appeared in credit and money markets, while an oil-price dispute added pressure.

Central banks and governments responded with emergency interest-rate cuts, asset purchases, lending facilities, and fiscal support. The market recovery was also unusually rapid, although the pandemic recession caused severe disruption and unemployment. The crash and the later rebound were parts of the same extraordinary episode.