BOSTON (Reuters) - Vanguard Group, one of the world’s biggest fund managers, voted against three directors at Wells Fargo & Co this year, including Chairman Stephen Sanger, according to U.S. filings, a rare rebuke from the bank’s second-largest shareholder.

A Wells Fargo bank sign is pictured in downtown Los Angeles, California, U.S. August 10, 2017. REUTERS/Mike Blake

The lack of support from Vanguard was disclosed on Wednesday and Thursday, just as Wells Fargo announced it had uncovered more than a million additional accounts potentially opened without customers’ knowledge in a drawn-out scandal that has already resulted in a $190 million settlement with regulators and the ouster of its chief executive officer.

Investors are concerned that as the sales scandal deepens it will make it more difficult to restore the San Francisco bank’s once-pristine brand. Shares in Wells Fargo fell 0.6 percent on Thursday to close at $51.07. They are down 7.3 percent so far this year.

Vanguard said it voted against certain directors at "a U.S. financial company that was fined for fraud" in an annual voting report on Thursday. (vgi.vg/2gm2Ltx)

Vanguard executives, including Investment Stewardship Officer Glenn Booraem, declined to confirm the language referred to Wells Fargo. According to filings with the Securities and Exchange Commission, Vanguard funds supported 12 of 15 Wells Fargo directors on the ballot, and backed the company’s management on all nine shareholder proposals up for a vote at the April meeting.

Wells Fargo declined to comment on the investor votes.

Mutual funds, often the largest owners of U.S. corporations, wield decisive clout through their proxy voting over governance questions like the election of directors or the setting of executive pay.

But while the majority of the votes take place during the springtime annual meeting season, the funds rarely detail any of their votes until securities filings appear in late August. The fund firms also generally support corporate boards -- Vanguard said it backed director put up for election by management 96 percent of the time at U.S. companies in the most recent proxy season.

In the case of Wells Fargo, it was clear that many shareholders were displeased, with only three of 15 directors receiving more than 90 percent support from voting shareholders at the bank’s annual meeting on April 25. Sanger received just 56 percent.

Vanguard’s regulatory filings showed funds like Vanguard Total Stock Market Index Fund voted against Wells Fargo directors including Federico Pena, chair of its Corporate Responsibility Committee; Enrique Hernandez, who had chaired its risk committee, and Sanger.

Other funds that voted critically at Wells Fargo included American Funds like Income Fund of America, which did not support nine of 15 directors, filings show.

American Funds representatives did not respond to a request for comment.

Wells Fargo said this month that former Federal Reserve governor Elizabeth Duke will replace Sanger on Jan. 1, and two other directors will also retire.

Hernandez and Pena remain on the board but Hernandez will no longer chair its risk committee and Pena and Sanger are leaving the committee.

In its annual voting report, Vanguard wrote of its votes at the financial company: “...we concluded that certain directors had fallen short of their responsibility to understand the risks and culture of the company and to challenge management when necessary.”

Vanguard’s report stated that while it supported the changes made by the company’s board since the vote, “we will continue to engage to ensure ongoing progress.”

According to Thomson Reuters data, Vanguard holds a 6 percent stake in Wells Fargo second only to the 9 percent stake held by Warren Buffett’s Berkshire Hathaway Inc which has supported the bank.