The European Commission said it had fined Mastercard 570.6 million Euro for limiting the possibility for merchants to benefit from better conditions offered by banks elsewhere in the European Union.

“By preventing merchants from shopping around for better conditions offered by banks in other member states, Mastercard’s rules artificially raised the costs of card payments, harming consumers and retailers in the EU,” European Competition Commissioner Margrethe Vestager said in a statement, Reuters reads.

The Commission granted Mastercard a 10 percent fine reduction for cooperating with its investigation.

The fine is the latest in a series of actions over the past decade that the Commission, acting as the antitrust regulator for the 28-member European Union, has taken to reduce card fees for merchants.