The European Commission has fined Mastercard €570.6m 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.
The Commission granted Mastercard a 10% 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 competition regulator for the 28-member European Union, has taken to reduce card fees for merchants.
It has, for example, taken decisions to make legally binding commitments by Visa Europe to cap the levels of interchange fees for all debit and credit card transactions within the European Economic Area.
It has also looked into the fees charged on card payments made by tourists visiting the European Union.