March 9, 2020, was the first 2020 trading day when U.S. market-wide circuit breakers halted trading. The S&P 500 fell 7% shortly after opening, triggering a Level 1 trading pause.
The halt occurred during the COVID-19 stock-market crash, when investors reacted to the spread of the coronavirus, worsening economic expectations, and a collapse in oil prices after a dispute between Saudi Arabia and Russia. The Dow Jones Industrial Average also suffered a historic point decline that day.
Additional circuit-breaker halts followed on March 12, March 16, and March 18. These pauses were not permanent closures; they were designed to give investors time to assess extreme price movements. The 2020 episode therefore demonstrates the difference between a trading halt and an exchange shutdown.