The additional refunds amount to a tiny fraction of the bank's quarterly earnings, but investors who spoke to Reuters in recent weeks said they were less worried about the hard costs than a degradation of the bank's once-pristine brand.
They also expressed concern about Wells becoming an easy political target, going into the midterm elections.
Warren Buffett, who runs Wells Fargo's largest investor, Berkshire Hathaway Inc, said this week he still considers it a great bank despite selling some of his holdings. But he acknowledged the bank will likely find more problems now that it is shining a light in dark places.
"There's never just one cockroach in the kitchen," he said on CNBC.
This article was provided by Reuters.