Screens show that the stock trade is halted at the New York Stock Exchange (NYSE) in New York, the United States, on March 12, 2020. U.S. stocks extended their losses following a 15-minute trading halt on Thursday morning. The S&P 500 declined 7 percent shortly after the opening bell, triggering a key circuit breaker that halted trading for 15 minutes. It was Wall Street's second 15-minute halt this week. (Xinhua)

NEW YORK, March 12 -- U.S. stocks plunged on Thursday with all the three major indexes declining more than 7 percent shortly after opening as an address from U.S. President Donald Trump failed to calm markets on potential economic damages from the coronavirus epidemic.

The S&P 500 declined 7 percent shortly after the opening bell, triggering a key circuit breaker that halted trading for 15 minutes.

Wall Street extended losses with the S&P 500 down more than 8 percent after the trading was resumed.