The UK Competition Appeal Tribunal has published a formal notice confirming the receipt of a massive collective proceedings application against Alphabet Inc. and its subsidiary Google entities. Filed by AGC Collective Actions Limited, a special-purpose entity directed by Adam Grant Collinson, the opt-out class action seeks aggregate damages provisionally estimated between £1.827 billion and £3.173 billion, including interest, for alleged anti-competitive abuses in the digital advertising market.
Represented by London-based law firm KP Law Limited, the lawsuit aims to represent a proposed class of roughly 205,000 to 250,000 UK-domiciled advertisers. The claim covers businesses that paid for open-web display advertising services, either directly or through media agencies, during a relevant period spanning from October 2015 to the present.
The core of the legal challenge targets Google’s dual dominance across the programmatic advertising supply chain. The claim form alleges that Google abused its monopoly power by deliberately steering transactions away from rival supply-side platforms (SSPs) and channelling them exclusively through its own supply-side platform, AdX. The claimants argue that Google engaged in distortive “buy-side” tactics by using its dominant ad-buying tools, Google Ads and DV360, to artificially inflate advertiser bids on AdX to entice publishers, while simultaneously penalizing bids submitted through rival platforms with higher fees.
On the “sell-side,” the lawsuit claims Google weaponized its dominant publisher ad server, DoubleClick for Publishers (DFP), to insulate AdX from market competition. This allegedly included giving AdX a controversial “Last Look” advantage, allowing it to view competitor bids before an auction closed and clear them by a marginal fraction. The claim also targets unified pricing rules that blocked publishers from setting higher price floors on AdX relative to other platforms, alongside dynamic revenue-sharing schemes designed to systematically undercut competing platforms.
According to the filing, this exclusionary behavior inflicted distinct financial harms on British businesses. By choking off competing advertising inventory networks, Google allegedly reduced the overall volume and relevance of available web space, lowering total returns on investment. Concurrently, the lack of market competition forced advertisers to pay inflated premiums for their digital placements.
The case surfaces amidst escalating global regulatory pressure on Google’s advertising technology ecosystem. In certifying the claim, the tribunal application points to a recent European Commission antitrust decision against Google, a matching certified class action brought on behalf of UK publishers, and a formal statement of objections from the UK Competition and Markets Authority, which provisionally found that Google abused its dominant position. Given the sheer volume of affected small and medium-sized British businesses, the class representative argues that a collective opt-out proceeding is the only economically viable path to secure legal recourse.
