Brussels widens AI antitrust scrutiny to the full stack — chips, cloud, models

European Commission competition chief Teresa Ribera has used a series of recent appearances to outline an enforcement posture that goes substantially further than the headline DMA cases of 2024 and 2025. The thesis, summarised: artificial intelligence is being shaped by a handful of vertically integrated companies whose control reaches from chip licensing to cloud to model weights to consumer distribution — and that integration, more than any single product behaviour, is the competition risk worth investigating.

In parallel, the U.S. Federal Trade Commission has opened a probe into Arm Holdings, focused on whether the company's licensing practices in the semiconductor IP layer are foreclosing competition. The two investigations look unrelated. They are not.

#The "full stack" thesis

Ribera's framing — repeated almost verbatim in Bloomberg's March reporting and in subsequent Commission statements — is that the AI stack now includes chips, cloud capacity, training data, models, and the application surfaces where users meet AI. A small number of firms touch most or all of those layers. The regulatory question is whether competition can exist meaningfully at any one of them when the firm controlling the layer also controls the one above and below.

That is a more ambitious enforcement theory than 'this company is abusing its app store.' If it holds up, the remedies it implies — structural separation, mandatory interoperability, licensing covenants — are likewise more ambitious.

#The Arm angle

The FTC's Arm investigation looks narrow but it sits at exactly the chokepoint where the EU's theory is most testable. Arm licenses the instruction set that underpins essentially every mobile and most edge AI accelerator. If a U.S. regulator concludes that Arm's licensing practices distort the chip market, the analytical road from that conclusion to the EU's stack-level thesis is short.

#What to watch

Two near-term signals will tell us whether this remains rhetoric or becomes enforcement: a formal Article 102 case filing in Brussels against an integrated AI provider, and any indication that the FTC's Arm investigation broadens beyond licensing terms into the wider IP-to-fab pipeline. Both are plausible inside this year.