During times of stock market volatility and big daily drops, one term that gets bandied about is "circuit breaker." But many investors and others may not know what the market circuit breaker is and ...

U.S. stocks had gone more than 20 years without a market-wide trading halt. We've now tripped the so-called circuit breakers two times in four days. On Monday, March 9, the S&P 500 fell 7% within ...