The New York Stock Exchange will temporarily shut its trading floors starting Monday and move to fully electronic trading after an employee and a person who worked on the floor both tested positive for coronavirus this week.

The exchange’s equities and options trading floors in New York will close, as will its options trading pit in San Francisco, according to a statement by NYSE owner Intercontinental Exchange Inc.

The company said in a notice to traders that two individuals were screened on Monday and tested positive for coronavirus. The NYSE employee and the person who worked on the trading floor both were barred from entering the building this week and were last inside on Friday.

Traders work on the floor of the New York Stock Exchange (NYSE) in New York, U.S., on Friday, Sept. 23, 2016. U.S. stocks slipped as investors considered whether shares have climbed too far too fast, after a rally spurred by central-bank optimism put the S&P 500 Index on track for its best weekly advance in two months.

“Our markets are fully capable of operating in an all-electronic fashion to serve all participants, and we will proceed in that manner until we can re-open our trading floors to our members,” said NYSE President Stacey Cunningham. “While we are taking the precautionary step of closing the trading floors, we continue to firmly believe the markets should remain open and accessible to investors. All NYSE markets will continue to operate under normal trading hours despite the closure of the trading floors.”

The site will remain open this week. On Tuesday, it was “thoroughly sanitized using treatments recommended by federal agencies” and will be again Wednesday evening.

“This is a big deal,” said independent analyst Larry Tabb. “The question is, does the floor provide a differentiated process or just differentiated marketing? I guess we will find out, if after this is over, the floor opens back up, or if they stay electronic and save the tremendous cost of operating.”

The U.S. equity market closed for two days in 2012 in the aftermath of Hurricane Sandy. NYSE had previously shut for four trading days after the terrorist attacks on Sept. 11, 2001.

Wild swings in equity markets and thousands in the financial industry working from home have led to questions about whether stock exchanges should remain open. But top regulators -- including Treasury Secretary Steven Mnuchin and Securities and Exchange Commission Chairman Jay Clayton -- and executives of exchange firms have come out in favor of keeping markets open.

The NYSE is home to 25% of share-trading for companies listed there. It also hosts more than 36% of block trades comprising 10,000 shares or more, according to the company.