What automated safeguard halted trading after the Dow Jones fell 7.79% on 9 March 2020?

A circuit breaker halted trading after the Dow Jones fell 7.79% on 9 March 2020.

The 9 March 2020 sell-off was the first of several severe market drops during the COVID-19 stock-market crash. The Dow Jones Industrial Average fell 2,013.76 points, or 7.79%, and trading on the New York Stock Exchange was halted for 15 minutes under its Level 1 market-wide circuit breaker.

Circuit breakers are automatic safeguards designed to pause trading when prices move too rapidly. They give investors and trading systems time to process information and can reduce panic-driven feedback loops. U.S. market-wide thresholds are based on percentage declines in the S&P 500, with different pause rules at different levels.

The halt was not a permanent closure and did not prevent further volatility. On 16 March 2020, another large decline triggered a circuit breaker, showing how quickly the pandemic shock continued to affect markets.