Google is under investigation amid allegations that it unlawfully monopolized key parts of the display advertising “ad tech” stack—tools that match advertisers with ad space on third‑party websites and run real-time auctions to decide which ads are shown. According to the claims being examined, Google leveraged dominance in search and search ads to expand control across “all stages” of display advertising, including advertiser tools, publisher ad servers, and ad exchanges, while also selling ads on its own properties like YouTube and Google Maps. Investigators are scrutinizing tactics such as acquiring and bundling competing services (e.g., consolidating products into Google Ad Manager and Display & Video 360), allegedly steering advertisers into Google’s ecosystem to access valuable data or inventory, making rival ad tech less compatible, and using auction mechanisms—like alleged artificial floor prices—that could push advertisers to pay more than they would in a truly competitive market.

The investigation has been initiated because these practices, if proven, could violate federal and state antitrust laws designed to prevent a single firm from using market power to exclude rivals and inflate prices. Attorneys are gathering advertisers for coordinated legal action via mass arbitration rather than a traditional class action, largely because Google’s advertising terms reportedly require disputes to be handled in arbitration; the significance is that many individual claims filed at once can pressure discovery and accountability even when court class actions are procedurally constrained. The inquiry also matters beyond individual refunds because antitrust statutes can allow treble (triple) damages and could reshape how dominant platforms structure ad auctions, data access, and interoperability.

Broader implications extend across the digital advertising industry, where a small number of intermediaries can simultaneously represent buyers, sellers, and the auction venue—creating potential conflicts of interest and opacity around pricing “take rates,” auction rules, and routing of bids. Similar concerns have fueled multiple U.S. and European enforcement actions and private lawsuits examining whether Google’s integrated control of ad buying tools, selling tools, and exchanges forecloses competition; regulators such as the U.S. Department of Justice, state attorneys general, and the European Commission have pursued parallel theories in other matters involving online advertising and platform dominance, reflecting a wider push to police exclusionary conduct, self-preferencing, and consolidation in high‑velocity ad markets governed by competition law rather than sector-specific ad pricing regulation

Defendant Companies: Google

Alleged Violations: Alleged violations of federal antitrust laws (monopolization of the digital/display advertising services market), Alleged violations of state antitrust laws, Alleged anticompetitive conduct including acquiring/eliminating competitors, tying/conditioning access to search and YouTube data on use of Google's ad services, and designing incompatibilities to hinder rivals, Alleged manipulation of ad auctions through artificial reserve/floor prices leading to inflated advertiser costs

Case Status: Under Investigation

Affected Product or Service: Google Display Ads / Google display advertising services and ad-tech stack (e.g., Google Ad Manager, Display & Video 360) used to buy and place display ads on third-party sites and Google platforms (including YouTube)

Eligibility Requirements: Purchased Google Display Ads on or after May 27, 2016, Total spend on Google Display Ads was between $5,000 and $543,000, Advertiser believes they may have paid inflated prices due to Google’s alleged anticompetitive conduct

Source: https://www.classaction.org/google-display-ads-network-antitrust/