President Donald Trump wants to fire Federal Reserve Chairman Jerome Powell for raising interest rates, according to one report, an unprecedented action by a president against the independent body and one that could undermine confidence in a financial system already under the strain of a vicious equity sell-off.

Trump has privately discussed firing Powell because of his frustration with stock market losses in recent months, according to Bloomberg News, which cited four people familiar with the situation. The president’s frustration intensified in recent days, with him discussing the firing “many times” during that time, according to the report.

The Dow Jones Industrial Average dropped 7 percent this week, its worst week in 10 years, on fears the Fed is unnecessarily slowing the economy as the central bank on Wednesday raised its benchmark interest rate for a fourth time this year. The Dow, which Trump cheered when it was at record highs earlier this year, is now down 9 percent for 2018.

The report said Trump’s advisers have warned him against such a move, which has never been done by a president and it’s not even clear whether he has the legal authority to do so. White House and Fed spokespeople declined to comment to Bloomberg.

Can he fire him?

Powell became Fed chair in February of this year after Trump nominated him to take over from Janet Yellen. He was easily confirmed in the Senate and has a four-year term.

While the president appoints the Fed’s board of governors, including the chairman, the central bank “derives its authority from the Congress, which created the System in 1913 with the enactment of the Federal Reserve Act,” according to the Fed’s website.

“The Board reports to and is directly accountable to the Congress but, unlike many other public agencies, it is not funded by congressional appropriations,” the site says.

“The President can nominate a chair but once the chair is confirmed, the president is out of it and the only way you can remove a chair from office is literally if they broke the law. Congress will have to find a cause to remove them from office through a vote and a procedure,” Ellen Zentner, Morgan Stanley’s chief U.S. economist, told CNBC in October.

But Trump has already broken with precedent through his repeated criticism in the second half of this year of the Fed and the chairman to the press and via Twitter, including this week before the central bank hiked rates. Other presidents privately tried to influence the Fed, but none did so in such a public and forceful matter.

‘Gone crazy’

“I think the Fed is making a mistake. They are so tight. I think the Fed has gone crazy,” the president told reporters in October.

The independence of the Fed is one of the pillars of confidence global investors have in the U.S. financial system. Powell’s removal would undermine that confidence because it would now seem the most important central bank was now under the control of a politician, who may not always have the best interests of the economy at heart. Sometimes it’s necessary to raise interest rates to keep inflation in check. The Fed has a dual mandate: to maximize employment and stabilize inflation.

After Trump first began his criticism of the Fed in July, former Dallas Fed President Richard Fisher told CNBC the president was out of line.

“One of the hallmarks of our great American economy is preserving the independence of the Federal Reserve. No president should interfere with the workings of the Fed,” Fisher said. “Were I Chairman Powell, I would ignore the president and do my job and I am confident he will do just that.”

The S&P 500 sits less than 3 percent away from a bear market, pushed there by Fed fears, but also by the trade battle Trump has waged with China and turmoil within his own administration. Contrary to what occurred when he first took office, the president’s comments and actions have now turned into a negative for the stock market, because of the uncertainty he is causing.

If Trump were to try to remove Powell or force his resignation it could cause the market to drop at least another five percent, according to Jeff Kilburg, CEO of KKM Financial in Chicago.

But Trump may want to wait and see, Kilburg said, as the Fed is likely to be less aggressive with rate hikes next year.

“Powell will only go one or two times in 2019,” he said.