During the 2020 COVID-19 stock-market crash, the S&P 500 triggered a circuit breaker four times in March.
The halts occurred on March 9, March 12, March 16, and March 18, 2020. Each was activated after the index fell 7% from its previous close, reaching the U.S. market’s Level 1 threshold. Trading paused for 15 minutes, except when the trigger occurred near the close.
The extraordinary sequence reflected fear about the COVID-19 pandemic, collapsing economic activity, and an oil-price dispute between Saudi Arabia and Russia. The S&P 500 entered a bear market rapidly and reached its initial pandemic-era low on March 23.
Circuit breakers are designed to slow panic and give market participants time to process information. They do not guarantee that prices will recover, and they are different from exchange-specific halts on individual stocks. The March 2020 episode was the first time the modern U.S. index-wide mechanism had been used repeatedly in such a short period.