In addition to Warren, who this week called for the resignation of Wells Fargo Chief Executive John Stumpf, the letter was signed by Democrats Sherrod Brown of Ohio, Jack Reed of Rhode Island, Robert Menendez of New Jersey, Jeff Merkley of Oregon, Kirsten Gillibrand of NY and Mazie Hirono of Hawaii.
Eight U.S. Democratic senators asked the Labor Department on Thursday, Sept. 22, to launch a probe into whether Wells Fargo may have violated wage and working hour laws by failing to pay overtime to tellers and sales representatives who stayed late to meet sales quotas.
"You haven't resigned, you haven't returned a single nickel of personal earnings, haven't fired a single senior executive... it's gutless leadership", Warren told Stumpf during the Senate Banking Committee's session Tuesday.
Faced with the unrealistic sales expectations and close tracking of their sales by managers, employees looked for ways to manipulate Wells' sales system.
The cross-selling program incentivized employees to create more and more accounts for customers-if they opened enough new accounts, they received a bonus.
Separately, a top banking regulator is expected to tell lawmakers at the same hearing that his agency should have acted more quickly to catch misconduct at Wells Fargo.
John Stumpf, chairman and CEO of Wells Fargo, testifies about the unauthorized opening of accounts by Wells Fargo during a Senate Banking Committee hearing.
Buffett's silence has also reinforced the notion that Berkshire is stepping away from Wells Fargo in the eyes of some investors.
"I am deeply sorry that we failed to fulfill our responsibility to our customers, to our team members, and to the American public", he said in his prepared remarks.
Yesterday, Sen. Elizabeth Warren told Stumpf that he should resign his position, and that's apparently not just a partisan position.
Ms. Warren added: "Your definition of accountability is to push this on your low-level employees".
Thomas Curry, the Comptroller of the Currency, said in prepared testimony that his agency is considering action against individual Wells Fargo executives.
What went wrong at Wells Fargo?
Wells Fargo claims it does business with one in three United States households.
However, the pressure to sell its customers new services was exposed this month.
In the short term the giant lender, with assets of $1.9tn and a stock market value of $231bn, has ridden out the storm. But many analysts say the firm, which made a $23bn profit previous year, is still a good bet.