Here's what to know about so-called “circuit breakers" and when they're used to halt trading on stock markets.

Stocks fell sharply again Thursday, with declines nearing levels that would trigger a marketwide trading halt. These are the ...

The Thursday selloff has torched more than $2.5 trillion in market value so far, but the stock market is still ways away from a trading halt. The S&P 500 was recently down 4.1%. It would need to fall ...