Which 2020 event triggered the fastest bear-market entry in S&P 500 history?

The COVID-19 pandemic triggered the fastest bear-market entry in S&P 500 history in 2020.

The crash developed as the coronavirus spread internationally, governments introduced travel restrictions and business closures, and investors reassessed corporate earnings and economic growth. The S&P 500 entered a bear market on March 12, 2020, after falling more than 20 percent from its February 19 record in only 16 trading days.

Markets also faced an oil-price shock in March when negotiations between major oil producers broke down. Central banks and governments responded with emergency interest-rate cuts, asset purchases, fiscal aid, and lending programs. The S&P 500 reached its closing low on March 23 before beginning a powerful recovery.

The 2020 crash was unusually rapid in both directions. It is often confused with the 2008 crash because both produced global recession fears and extraordinary policy responses, but their immediate triggers differed: the 2020 event began with a public-health emergency, while 2008 centered on financial and housing-system failures.