If losses in the U.S. stock market worsen, keep in mind there might be a 15-minute break.

The New York Stock Exchange said it will halt trading for 15 minutes if the Standard & Poor's 500 Index drops 7 percent.

The stock exchange will pause trading if the benchmark for U.S. equities slumps to 1,832.92 before 3:25 p.m. New York time, Sara Rich, a NYSE spokeswoman said in an e-mail.

The S&P 500 slid 3.9 percent to 1,894.93 at 9:42 a.m. in New York as markets were convulsed by a surge in selling.