March 12, 2020, is known as Black Thursday in the 2020 stock-market crash caused by COVID-19 panic.
On that day, the Dow Jones Industrial Average fell 2,352.60 points, or 9.99%, its largest one-day point drop at the time. The S&P 500 and Nasdaq also suffered major losses as governments imposed restrictions, businesses closed, and investors assessed the rapidly spreading pandemic.
The crash was part of a sequence of extreme sessions. March 9, March 12, March 16, and March 18 were especially severe days for U.S. markets, and trading halts were triggered repeatedly by market-wide circuit breakers.
The sell-off was followed by an unusually rapid rebound from the March lows, supported by large fiscal and monetary responses. Black Thursday refers specifically to March 12, not to the entire 2020 market decline.