The S&P 500 triggered the first U.S. stock-market circuit breaker during the March 2020 crash.
On March 9, 2020, the S&P 500 fell 7% shortly after trading opened, activating a Level 1 circuit breaker. Trading on major U.S. exchanges paused for 15 minutes. The halt was designed to give investors time to absorb information and reduce the risk of disorderly panic selling.
The crash reflected rapidly changing expectations about the economic effects of COVID-19, including travel restrictions, business closures, supply disruptions, and falling energy demand. An oil-price dispute between Saudi Arabia and Russia added another shock to financial markets.
Additional circuit breakers were triggered on March 12 and March 16 as the S&P 500 continued to fall. The 2020 episode is sometimes confused with the 2010 Flash Crash, but the causes and market-wide context were different. U.S. circuit breakers had been introduced after the 1987 crash and were later revised.