After Trump's speech last night -- one that was immediately corrected by his own administration -- the markets were not reassured. Via CNBC:

U.S. stocks hit critical circuit breaker levels on Thursday minutes after the opening bell for the second time this week as global markets plunged amid investor fears about the coronavirus global pandemic.

Just as they did on Monday, the S&P 500 hit exchanges’ 7% threshold decline in morning trading, halting trade during regular market hours for 15 minutes to ensure order in the marketplace.

Trading resumed at 9:50 a.m. ET, with both the S&P 500 and Dow Jones Industrial Average extending losses immediately after the restart. The S&P 500 was last seen down 8% and the Dow was down 9%.