The aim of this article is to analyse the threats to contestability and fairness in the artificial intelligence (AI) value chain from the perspective of EU competition law and the Digital Markets Act (DMA). In particular, it assesses the impact of resource concentration – including compute, data, and human capital – as well as vertical integration along the AI value chain, understood as the sequence of stages and inputs required to design, train, deploy, and commercialise foundation models and generative AI services. The article discusses exclusionary practices that may restrict access to key resources and entrench dominant positions, highlighting the limitations of Article 102 Treaty on the Functioning of the European Union (TFEU) in addressing structural risks. It also evaluates the preventive potential of the DMA and identifies its limitations in the context of emerging technological architectures. The conclusion calls for deeper regulatory reflection and a possible revision of existing legal instruments to preserve the conditions of contestability and fairness in the rapidly evolving AI ecosystem.

Antitrust authorities face the challenge of adapting traditional legal frameworks to the dynamically changing realities of digital markets. Given the unique characteristics of these markets, a flexible interpretation of traditional principles may be crucial, allowing for the adequate application of Article 102 TFEU in a manner that reflects the intent of this provision. This article examines whether online platforms – viewed as digital infrastructure (applications, websites) that enable businesses to reach customers – can, under certain circumstances, be considered essential facilities. The analysis will focus on behaviours involving the refusal of access to this infrastructure, which must meet the stringent criterion of indispensability.

The P2B Regulation lays down the principles of fair and transparent treatment of business users using online platforms (online intermediation services). This legal act, addressing many anti-trust issues, is the first step towards creating ex ante regulatory instruments for online platforms. To contribute to the discussion on the need and possible shape of online platforms regulation, the aim of the research is: (i) to indicate the interaction between the P2B Regulation and antitrust law, with particular emphasis on the importance of antitrust law for the future ex ante regulation of large online platforms, as well as (ii) to determine the desired standard of intervention, including an effective enforcement mechanism, with regard to harmful practices of online platform operators (i.e. entrepreneurs which provide online intermediation services on the platform) identified on the basis of the P2B Regulation. Arguments for the legitimacy of public intervention in the operation of online platform operators in the case of: (i) significant bargaining power of the online platform operator over business users and (ii) damage to the public interest will be elaborated.