What event triggered the global stock-market crash that began in February 2020?

The COVID-19 pandemic triggered the global stock-market crash that began in February 2020.

As the virus spread internationally, investors reacted to lockdowns, travel restrictions, factory closures, disrupted supply chains, and expectations of a severe economic contraction. The S&P 500 entered a bear market on 12 March 2020, and global markets reached a major low on 23 March.

The sell-off was intensified by an oil-price shock in March after Russia and Saudi Arabia disagreed over production cuts. Falling energy prices added pressure to already stressed markets and raised concerns about highly indebted energy companies.

Governments and central banks responded with emergency measures, including interest-rate cuts, asset purchases, fiscal support, and business aid. Those actions helped fuel a rapid rebound from the March low, although the pandemic's economic and human effects continued long afterward.