In a letter to Fed Chairman Jerome Powell, Warren said Sloan, a 30-year veteran of Wells, is "deeply implicated" in prior bank misconduct, and it is untenable for him to remain at the bank as the Fed seeks a drastic overhaul of its operations.

"The Wells Fargo Board of Directors cannot plausibly claim that it is 'ensuring senior management's ongoing effectiveness in managing the firm's activities' while retaining a CEO that helped oversee this much misconduct," she wrote.