U.S. stock-market circuit breakers halted trading four times during the March 2020 crash.
The New York Stock Exchange triggered its Level 1 circuit breaker four times in March 2020: March 9, March 12, March 16 and March 18. Each halt followed a 7% decline in the S&P 500 from the previous closing level and lasted 15 minutes under the rules then in effect.
The halts occurred as investors reacted to the economic shock associated with COVID-19, an oil-price dispute between Saudi Arabia and Russia, and rapidly changing expectations for business activity. The repeated triggers showed how quickly selling pressure spread across global markets.
Circuit breakers are designed to provide a short pause, allowing investors to absorb information and reducing the risk of disorderly trading. They do not prevent a market from falling after trading resumes. The March 2020 halts were the first U.S. stock-market circuit-breaker events since 1997.