Sentiment took a hit Tuesday after Trump released a letter on social media announcing Cook’s removal, effective immediately.

Trump said the firing was tied to allegations of mortgage fraud, and that there was “sufficient cause” for her removal. The allegations were raised earlier in August by Federal Housing Finance Agency Director William Pulte. 

Cook denied the allegations, and had stated that she would not be bullied out of her position.

But Trump’s announcement of her removal marks his latest attack against the Fed, with the president seen repeatedly attempting to exert more influence over the central bank. Cook is a member of the Fed’s seven-member rate-setting board. 

Trump’s moves sparked heightened uncertainty over the Fed’s independence, with political interference in the central bank threatening to undermine U.S. economic credibility. The Fed has traditionally operated outside the government’s sphere of influence. 

Trump had earlier this year also attempted to remove Fed Chair Jerome Powell, who had largely rejected the president’s calls to cut rates immediately.