Wells Fargo & Co.'s disclosure that it may have pushed thousands of car buyers into loan defaults and repossessions by charging them for unwanted insurance is raising doubts about the bank's ability to put proper controls in place.

“The steady drip of revelations is concerning as it makes quantifying and qualifying the extent of the internal control failures difficult,” Isaac Boltansky, an analyst at Compass Point Research & Trading, said Friday in an email. “Which is worrisome for both Washington and Wall Street.”

An internal review of the bank's auto lending found more than 500,000 clients may have unwittingly paid for protection against vehicle loss or damage while making monthly loan payments, even though many drivers already had their own policies, Wells Fargo said in a statement late Thursday. The firm said it may pay as much as $80 million to affected clients — with extra money for as many as 20,000 who lost cars, “as an expression of our regret.”