US markets should stay open despite intense volatility, the head of the Securities and Exchange Commission said on Monday, quashing industry speculation that the government might shut down the country’s exchanges to stop a plunge in stock prices.

“Markets should continue to function through times like this,” SEC Chair Jay Clayton told CNBC in a phone interview, adding that the SEC was closely monitoring markets and was working with exchanges and market infrastructure providers to ensure they could continue to function.

US stocks plunged on Monday morning on mounting fears the coronavirus pandemic will cause a global recession, again triggering a circuit breaker that temporarily suspends trading.

The turmoil prompted the Federal Reserve on Sunday to take aggressive action to buttress the economy and financial system, slashing interest rates to near zero, pledging hundreds of billions of dollars in asset purchases and backstopping foreign authorities with the offer of cheap dollar financing.

Some analysts speculated Monday that closing the markets altogether might be the next step for regulators, who are rapidly running out of tools to arrest the turmoil.

“One might not be faulted to assume that a next major step might be to shut the stock markets to prevent a further, self-fueling sell-off,” William O’Donnell, an analyst at Citigroup Global Markets, wrote in a note on Monday.

Closing the markets is rare but not unprecedented.

The New York Stock Exchange, which is now owned by Intercontinental Exchange Inc., most recently closed on Oct. 29-30, 2012, during Hurricane Sandy and before that on Sept. 11-14, 2011, following the terrorist attacks on the US, according to its website. It also shut for four months during the outbreak of World War I, the longest closure on record.

“This is a World War against the virus, so maybe it’s not such a crazy idea?” O’Donnell wrote.

The NYSE trading floor remained open Monday, but the bourse was taking additional precautions, requiring people entering the building to disclose whether they had been exposed to the virus and to submit to a temperature check, according to a Reuters reporter present. Those entering the floor were given stamps on their forearm to indicate they’d been checked.

Speaking to Fox News on Monday, NYSE president Stacey Cunningham said closing the markets would be the “wrong response,” adding: “It’s important that investors have access to their money.” Nasdaq chief executive Adena Friedman also told CNBC on Monday it was “critically important” that markets remained open.

The European Union’s markets watchdog said Monday it was lowering the threshold for reporting short-selling, whereby traders profit by betting stocks will fall, to regulators for the next three months as current trading conditions posed a “serious threat” to “fragile” markets.

Clayton said the US markets overall had continued to function well, reopening in an orderly manner following the triggering of circuit breakers last week.

“Things have been functioning well in our markets over the past two weeks of a very volatile time,” he added.