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The regulator’s formal investigation into Mastercard and Visa and their alleged anti-competitive practices in the global card payments market is the latest challenge to the card networks’ operations.
The Competition Board has announced that it launched the probe in June 2025 under decision number 25-23/552-M. It aims to assess whether the companies and their Turkish operations have violated Article 4 and/or Article 6 of Türkiye’s Competition Act No. 4054.
The investigation targets Mastercard Europe SA and its Istanbul Liaison Office, both of which are ultimately controlled by Mastercard Incorporated, and Visa Europe Limited, Visa Europe Services LLC and their Türkiye Representative Office, all ultimately controlled by Visa Inc.
According to the regulator, the investigation will examine whether the companies and their affiliates restricted competition by obstructing the activities of payment service providers (PSPs) offering international payment solutions.
Specifically, the case concerns allegations that Mastercard and Visa prevented overseas firms from accessing payment and point-of-sale (POS) infrastructure provided by Turkish banks regulated under the Banking Law No. 5411.
Vixio approached both entities for comment, with a spokesperson for Visa stating that the firm “always fully cooperates with any regulatory process and upholds the highest ethical, legal and regulatory standards everywhere we do business.”
Investigation ongoing
Despite the launch of the investigation, the competition authority has stressed that this does not necessarily imply wrongdoing by either of the card schemes.
“Investigation decisions taken by the Competition Board are announced to the public following the notification of the decision to the undertakings or associations of undertakings under investigation,” the regulator said.
“These declarations, which are made within the framework of informing the public on Competition Board decisions, cannot be interpreted to mean that the undertakings or associations of undertakings under investigation have violated the Act no 4054 and that they have faced or will face sanctions under the Act.”
A growing trend
The Turkish investigation is another example of regulators applying greater scrutiny to the major US card networks’ practices.
In June 2025, the UK Competition Appeal Tribunal (CAT) ruled that Visa and Mastercard's multilateral interchange fees breach European competition law.
This could have a significant impact on how competition law applies to payment schemes in the UK and beyond, particularly in relation to non‑negotiable, collectively agreed pricing structures.
It could also lead to claims from retailers across Europe that have been paying what can now be considered excessive fees.
This came a month after the CAT approved a £200m settlement in a class action against Mastercard, with the card network found to have imposed unlawfully high fees between 1997 and 2008.
In addition, in April 2025, the UK Payment Systems Regulator (PSR) proposed a set of remedies, having reached the conclusion that the country’s card market is not working effectively and that consumers are being charged excessively high fees due to a lack of competitive constraints.
And in its quarterly report for Q3 2024, Mastercard disclosed that it is cooperating with the European Commission on an antitrust investigation relating to its conduct in the EU and the European Economic Area (EEA).
There is growing concern that Visa and Mastercard’s dominance allows them to charge consumers excessive fees and impose unfair terms on users.
This combines questions of consumer protection with the need to ensure that markets function effectively, so it is no surprise that regulators are seeking to act.
So far, the card networks have faced adverse rulings, although both maintain that they have acted lawfully.
In this context, it will be interesting to see what the Turkish regulator’s investigation uncovers.
The other aspect to the scrutiny of Visa and Mastercard’s activities is the growing concern around payments sovereignty, with the EU particularly concerned that relying on US-based providers may no longer be prudent.
The bloc is looking for other options, whether homegrown alternatives to the US networks or the implementation of a digital euro, and allegations of wrongdoing on the part of the incumbents will only accelerate this shift.
