Which event caused the global stock-market crash of March 2020?

The COVID-19 pandemic caused the global stock-market crash of March 2020.

As the virus spread internationally, governments introduced travel restrictions, business closures, and other measures that sharply changed expectations for economic activity. Investors sold stocks rapidly, especially in sectors exposed to travel, energy, retail, and in-person services. The crash was intensified by uncertainty about the disease and the scale of the economic response.

The S&P 500 entered a bear market on March 12, 2020, and reached its pandemic-era low on March 23. Oil-market tensions, including a breakdown in cooperation between Saudi Arabia and Russia, added pressure earlier in the month. Central banks and governments then announced extensive monetary and fiscal support.

The 2020 crash was unusually fast compared with many earlier bear markets. It should not be confused with the 2008 financial crisis, which centered on credit and housing-market failures. The pandemic crash was driven primarily by a public-health emergency and its economic consequences.