- SMS Designation: Under the 2024 DMCC Act, the CMA has officially designated Google with Strategic Market Status, granting regulators unprecedented power to enforce “Conduct Requirements” across its ad tech stack.
- Monopoly Precedent: This secondary probe follows the landmark April 2025 US federal ruling which found Google held an illegal monopoly in publisher ad servers and exchange markets.
- Market Impact: With the UK digital advertising market projected to hit £45 billion in 2026, regulators are investigating if Google’s self-preferencing is artificially inflating costs for advertisers and deflating revenue for independent publishers.
The walls are closing in on the “black box” of digital advertising. In a move that signals a decisive shift in European regulatory strategy for 2026, the UK’s Competition and Markets Authority (CMA) has formally expanded its investigation into Google’s dominance over the ad tech stack. This escalation isn’t just another legal hurdle; it is an existential challenge to how the tech giant mediates the flow of billions of pounds between advertisers and the open web.
The probe centers on whether Google is leveraging its end-to-end control of the advertising ecosystem—from the tools used by publishers to sell space to the platforms used by advertisers to buy it—to suppress competition. This “self-preferencing” allegedly forces a “Google tax” on the industry, a concern that has gained momentum following a wider crackdown on anti-competitive behavior across the global technology sector.
The New Regulatory Arsenal: DMCC Act 2024
Unlike previous investigations that relied on legacy antitrust frameworks, this probe is the first to utilize the full weight of the UK’s Digital Markets, Competition and Consumers (DMCC) Act 2024. Under this legislation, the CMA has designated Google as having Strategic Market Status (SMS). This status allows Sarah Cardell, the CMA’s Chief Executive, to impose proactive “Conduct Requirements” rather than waiting years for a court to prove past harm.
“We are concerned that Google may be using its position in ad tech to favor its own services to the detriment of its rivals, its customers, and ultimately, the consumers who rely on a free and open internet,” Cardell stated in a recent briefing.
The CMA is specifically scrutinizing three pillars of Google’s operation:
- Interoperability Restrictions: Allegations that Google limits the ability of third-party ad servers to work seamlessly with its dominant ad exchange (AdX).
- Contractual Tying: Forcing publishers to use Google’s publisher ad server (Google Ad Manager) to gain full access to its vast pool of advertiser demand.
- Self-Preferencing in the Auction: Investigating if Google’s Demand-Side Platforms (DSPs) give preferential treatment to its own exchange, bypassing more competitive bids from rivals.
2026 Ad Tech Landscape at a Glance
| Metric | 2019 Data | 2026 Projection |
|---|---|---|
| UK Digital Ad Spend | £15.7 Billion | £45.2 Billion |
| Google’s Stack Revenue | £1.8 Billion | £5.4 Billion (est.) |
| Regulatory Framework | Competition Act 1998 | DMCC Act 2024 (SMS) |
The Global Ripple Effect: From DC to London
The CMA’s move does not exist in a vacuum. On April 17, 2025, Judge Leonie Brinkema of the U.S. District Court ruled that Google held an illegal monopoly in the ad tech market, validating years of complaints from state attorneys general. This U.S. verdict has provided a roadmap for British regulators, who are now looking to ensure that the UK’s £45 billion advertising market remains competitive.
As the industry shifts toward AI-integrated advertising—where “AI Overviews” and conversational search results change the very nature of ad placement—the CMA is wary of Google extending its monopoly into the next generation of tech. This focus on future-proofing the market is essential, especially as security and data integrity in AI accounts become paramount for both users and advertisers.
What This Means for Publishers and Consumers
For independent newsrooms and content creators, the outcome of this probe could be a lifeline. The CMA estimates that “weakening competition” in the ad tech stack directly reduces the ad revenues available to publishers. When Google takes a larger-than-necessary cut of every pound spent, publishers are often forced to implement aggressive paywalls or reduce the quality of their journalism to survive.
For the consumer, the impact is more subtle but equally pervasive. Higher advertising costs are ultimately passed down by brands to the prices of goods and services. A more competitive ad tech market could, in theory, lead to lower prices at the checkout and a more diverse, better-funded ecosystem of free information online.
Google has consistently maintained that its tools help publishers grow and provide value to advertisers. In a formal response to the CMA’s Statement of Objections, the company argued that the ad tech industry is more crowded and competitive than regulators suggest, citing the rise of Amazon and TikTok as significant challengers to its throne.
However, with the 2026 regulatory climate favoring intervention over “wait-and-see” approaches, the CMA appears ready to force structural changes. Whether this results in a mandatory “breakup” of the ad tech stack or stringent interoperability mandates, the status quo of the digital advertising world is nearing its end.
