Passengers wearing face masks walk past the New York Stock Exchange building, U.S., March 18, 2020. NYSE will temporarily close its trading floor and move to electronic trading on March 23 as a precautionary step after two employees were tested positive for COVID-19. /Xinhua

A New York Stock Exchange trader at work, U.S., March 18, 2020. /Xinhua

Wall Street's main indexes slumped as rapid spread of COVID-19 around the globe has sparked fears. /Xinhua

The S&P 500 plunged over 7% on March 18 and hit the level one circuit breaker, marking the forth halted trading in U.S. stocks within two weeks. /Xinhua