During the 2020 COVID-19 crash, U.S. market-wide circuit breakers triggered four times.
The halts occurred on March 9, March 12, March 16, and March 18, 2020, as the S&P 500 fell rapidly. Each event activated the Level 1 mechanism, which pauses trading after a 7% decline from the previous close.
The triggers reflected fears about the coronavirus pandemic, restrictions on economic activity, falling energy prices, and uncertainty about corporate earnings. The Federal Reserve and governments introduced extraordinary measures as the crisis developed.
Circuit breakers were designed after the 1987 crash to slow panic selling and give market participants time to absorb information. They pause trading; they do not prevent prices from falling later. The U.S. market reached its bear-market low on March 23, 2020, before recovering strongly.