This installment of Steptoe’s antitrust and artificial intelligence series examines how the unilateral deployment of artificial intelligence tools by firms with strong market presence can reinforce market power and risk monopolization. The authors note that digital markets are fast moving and that artificial intelligence systems can micro-target customers and operate at a speed and scale that is difficult for enforcers to analyze in real time. Antitrust authorities in the United States, the United Kingdom and the European Union recognize these risks but operate under different legal tests and enforcement tools. The piece contrasts the EU presumption of dominance at a 50 percent market share with the US doctrines that also recognize attempted monopolization, which captures anticompetitive conduct aimed at securing monopoly power before completion.
The article highlights challenges in defining relevant markets in the digital economy given multi-sided platforms and limited information, and it stresses how data accumulation and network effects create self-reinforcing advantages. It cites the European Commission’s Google Search and Google Android findings and the August 2024 US district court ruling that Google monopolized the general search market through default agreements. Those network effects informed a September 2025 remedy requiring Google to make certain search index and user-interaction data available to rivals. The authors explain that extensive data control allows firms to refine algorithms and personalize services in ways that raise barriers to entry and can foreclose competition even before consumer harm is readily observable.
To address these structural risks, enforcers are using sector inquiries and ex-ante regulatory measures. The EU adopted the Digital Markets Act, which uses quantitative gatekeeper thresholds rather than traditional dominance tests, and the EU Artificial Intelligence Act aims to set rules for certain artificial intelligence systems that complement competition law. The UK moved toward ex-ante oversight through the Digital Markets, Competition and Consumers Act 2024 and designated Google and Apple with Strategic Market Status. Market-wide investigations such as the EU Digital Markets Inquiry and the UK digital advertising study have informed these measures. The authors conclude that data accumulation combined with network effects will remain central to investigations and regulatory reform as authorities seek tools to prevent firms from leveraging artificial intelligence to entrench monopoly positions.
