March 9, 2020, was the first 2020 U.S. stock-market crash day to trigger the modern circuit-breaker system. Trading in the S&P 500 was halted after the index fell 7% shortly after the opening bell.
The sell-off reflected growing fears about the economic consequences of COVID-19, together with a collapse in oil prices after a breakdown in cooperation between major oil producers. The Dow Jones Industrial Average fell more than 2,000 points, its largest point decline at that time.
Additional U.S. trading halts followed on March 12 and March 16, when the market again reached the Level 1 threshold. These pauses were designed to give investors time to absorb information and reduce panic-driven order flows.
Circuit breakers had been created after the 1987 crash, but the 2020 episode was the first time the system was triggered in the United States since 1997. The crash developed into a global market collapse before a powerful rebound later that year.