Two regulators signed off on the $35 billion deal, which the banks say will create a competitor to Visa and Mastercard. But consumer advocates warn that the deal may raise costs.

The merger, announced last year, would mark the establishment of the largest U.S. credit card company by balances if it goes through successfully.

Capital One's planned $35.3 billion acquisition of a rival credit card company, Discover, was approved by two regulators, Federal Reserve and the Office of the Comptroller of the Currency, on Friday.