(Reuters) - Exchange operator CME Group Inc said on Wednesday it would close its Chicago trading floor after business hours on Friday to reduce large gatherings that can contribute to the spread of the coronavirus.

The outbreak of the coronavirus, which can cause a sometimes fatal flu-like respiratory illness, has roiled equities and commodities prices worldwide.

“The reopening of the trading floor will be evaluated as more medical guidance on the coronavirus becomes available,” CME Group, which owns the Chicago Board of Trade and Chicago Mercantile Exchange, said in a statement.

No coronavirus cases have been reported on the trading floor or in the Chicago Board of Trade building, and the markets will remain available for trading electronically, it said.

The floor closure comes as markets are unusually volatile.

“The electronic market fails when the markets get crazy. Look at Sunday night - violent swings,” said PJ Quaid, an independent open-outcry corn options broker on the CME floor.

“Market-makers on the screen just turn off their markets when things get bad. The pit does not do that,” Quaid said, adding: “My customers still believe in the open-outcry market.”

The New York Stock Exchange said in an internal memo on Wednesday that it had taken measures to help keep its floor open, including mandating separate entrances and eating spaces for floor traders and staff, and employees of NYSE and parent company Intercontinental Exchange Inc who work in the office tower at 11 Wall Street.

CME closed most futures pits in 2015 after the practice declined because of computerized trading. Products like Eurodollar and grain options are still traded in pits, however. Cboe Global Markets Inc and The London Metal Exchange have said they also have contingency plans.