Betty Liu, Executive Vice Chairman for NYSE Group, explains:
Why did trading halt momentarily on Monday, March 9?
So, on Monday, what happened was the markets opened and the S&P 500 immediately fell more than 7 percent. That triggered what we call the market wide circuit breaker, and that halts trading for 15 minutes. It allows time for market participants to assess the market conditions and make decisions accordingly. That process worked exactly as designed.
Is this a first time a circuit breaker has been triggered?
So, the modern market wide circuit breaker was put in place back in 2013. And yes, it is the first time that it was triggered. Prior to that in 1997, was the last time we saw a market wide circuit breaker triggered.