Index Exchange files antitrust lawsuit against Google over ad tech monopoly

Index Exchange filed a comprehensive antitrust complaint against Google on November 10, 2025, seeking monetary damages and injunctive relief following a federal court's determination that Google illegally monopolized digital advertising technology markets. The 56-page lawsuit alleges that Google's systematic anticompetitive conduct prevented the Canadian ad exchange from competing fairly in markets worth over $104 billion annually.

The complaint, filed as Case No. 1:25-cv-02003 in the U.S. District Court for the Eastern District of Virginia, builds directly on Judge Leonie Brinkema's April 17, 2025 ruling that found Google "willfully engaged in a series of anticompetitive acts to acquire and maintain monopoly power" in publisher ad server and ad exchange markets for open-web display advertising. Index Exchange CEO Andrew Casale had previously testified during the government's antitrust trial that concluded with that landmark ruling.

According to the filing, Index Exchange has operated in programmatic advertising since 2003, initially as an ad network before pivoting exclusively to ad exchange operations in 2015. The company established its market position through commitments to transparency, detailed pricing information, and lower transaction fees than Google's AdX platform, which maintained a 20% take rate throughout the relevant period.

Google's ad exchange maintained market share between 54% and 65% despite charging prices significantly above competitive levels, demonstrating monopoly power that this court previously found violated federal antitrust law. Index Exchange alleges that Google's conduct artificially suppressed its growth and forced the company to invest substantial resources in developing workarounds to Google's anticompetitive restrictions.

The ad tech stack and Google's dominance

The lawsuit provides detailed technical explanation of the "ad tech stack," the collection of software products that negotiate billions of display ad sales daily across the open web. Publishers use ad servers to manage their available advertising space, while advertisers work with demand-side platforms to purchase impressions. Ad exchanges like Index Exchange and Google's AdX sit between these two sides, conducting auctions that match advertiser bids with publisher inventory.

Google acquired its dominant position in publisher ad servers through its 2008 purchase of DoubleClick for $3.1 billion, obtaining the platform then known as DoubleClick for Publishers with 60% market share. The acquisition price exceeded Google's internal valuations by $1 billion, but the strategic purchase gave Google control over the crucial final step in ad sales—the publisher's decision about which advertiser wins each impression.

According to the complaint, Google leveraged its early monopoly in internet search to establish control over a large pool of advertisers through its AdWords product. The company then forced publishers to adopt DoubleClick for Publishers by making it the only ad server that could access real-time bids from AdX and the unique advertising demand from AdWords.

The filing states that Google's publisher ad server achieved 90% or more market share worldwide by the late 2010s, up from 60% at acquisition. This dominance provided Google with extraordinary power over how, when, and to whom ad impressions are sold across the open web.

Systematic manipulation through multiple policies

Index Exchange's complaint details a series of policies that Google implemented to favor its own ad exchange over competitors. The lawsuit alleges these policies were often concealed from market participants, making it impossible for rival exchanges to formulate effective competitive strategies.

Google introduced "First Look" in 2010 through its Dynamic Allocation program, giving AdX the first opportunity to acquire any impression before other exchanges could bid. The policy meant that AdX received access to the majority of impressions available for programmatic ad sales across the entire web before Index Exchange or other competitors could evaluate the opportunity.

According to the filing, First Look combined with Google's refusal to share user data created substantial advantages. AdX received real-time bid data associated with available ad space and user information, allowing it to cherry-pick the most desirable impressions. Competing exchanges received only historical estimates of what they might bid rather than actual impression data.

The lawsuit states that Index Exchange conducted extensive testing to understand why its sales remained stagnant despite offering lower fees and superior transparency. At one point, the company reduced its take rate to zero, passing 100% of advertiser offers through to publishers. Sales experienced no material increase. Only through compelled discovery in litigation did the actual explanations emerge.

Google replaced First Look with "Last Look" as header bidding technology threatened its dominance. The new policy gave AdX the final opportunity to generate a winning bid after all other exchanges had competed and their highest bid was visible to Google. "In what was otherwise a sealed auction, Last Look let AdX open the envelope for the winning bid, know what the winning bid was and be able to bid after everybody else," according to Judge Brinkema's previous ruling quoted in the complaint.

The lawsuit alleges Google exploited this information advantage through "Sell Side Dynamic Revenue Share," a policy that adjusted AdX's take rate on individual transactions to manipulate advertiser bids. When AdX had a buyer whose net bid was slightly below the competing header bid, Google could lower its commission to boost the net bid enough to win the impression. The company then increased its take rate on other transactions where it had bids significantly exceeding competing offers, making up for lost fees while claiming additional market share.

Project Poirot's bid manipulation

The complaint describes "Project Poirot," a 2017 initiative that Google concealed even from affected customers. The program relied on discrimination between bids that Google's DV360 demand-side platform generated for rival exchanges versus bids for the same impression offered through AdX.

Google undertook massive analysis of pricing data from rival exchanges to identify which were conducting first-price auctions and therefore presumably engaged in header bidding. According to the lawsuit, Google then caused DV360 to "shade" or materially reduce bids for any exchange identified as holding first-price auctions. When the same impression was offered through AdX, DV360 submitted full-price bids.

The filing states that transactions on rival exchanges decreased by an average of 10% as a result of Project Poirot. Google subsequently introduced "Poirot 2.0" with amplified parameters, reportedly shading bids through first-price exchanges by as much as 90%. This caused DV360 transactions on rival exchanges to decrease by an average of 15%.

Index Exchange operated a first-price model because its business focused on header bidding. The company began losing sales to AdX following initial success with its proprietary header bidding wrapper. Because Google concealed Project Poirot, Index Exchange invested substantial resources in data analysis and testing of various bid optimization techniques without identifying the actual cause of its declining performance.

Header bidding as competitive response

The lawsuit explains how Index Exchange and other market participants developed header bidding technology as a workaround to Google's self-preferencing of AdX. Header bidding allows publishers to conduct real-time auctions between multiple exchanges before the publisher's ad server is called, mitigating the advantages that Google gave AdX through First Look and similar policies.

Index Exchange joined with other non-Google market participants to lead header bidding development starting around 2014. The company developed its own proprietary wrapper and later supported the open-source Prebid technology. According to the complaint, header bidding was popular because it worked—increasing publisher revenue and yields by broadening real-time bid competition beyond AdX.

The filing states that despite header bidding's strengths, it remained a compromise solution that failed to put competitor exchanges on truly equal footing with Google. Publishers had to update their configurations twice—once for the ad server and again for the wrapper—creating ongoing maintenance burdens. The need to contend with "website drift" as publishers' pages evolved was a direct result of Google's refusal to allow rival ad exchanges to compete fairly within DoubleClick for Publishers.

Google responded to header bidding's threat by introducing "Open Bidding" in 2018, marketed as an alternative that would generate simultaneous real-time bids from multiple exchanges. The lawsuit alleges this was another attempt to create a system favoring Google's ad tech. Open Bidding extracted at least a 5% fee from transactions on non-Google exchanges while charging nothing for sales on AdX, lowering competitive bids and reducing rivals' opportunities to win impressions.

Unified Pricing Rules and ongoing harm

In 2019, as Google faced increasing antitrust scrutiny, the company announced it would end Last Look. Simultaneously, Google implemented "Unified Pricing Rules" that prohibited publishers from offering lower floor prices to rival ad exchanges than they offered to AdX. Publishers were allowed to offer lower floors to AdX than to competitors—the policy only restricted preferential treatment of non-Google exchanges.

According to the complaint, many publishers had expressed preference for Index Exchange and its features by setting lower floor prices for the exchange than for AdX. Unified Pricing Rules eliminated this option. The filing quotes Judge Brinkema's previous finding that "Unified Pricing Rules increased the number of impressions AdX won and the revenue it received, while decreasing impressions won and revenue received by third-party exchanges."

The lawsuit states that Index Exchange offered significantly more transparent pricing models and materially lower take rates than AdX's 20% fee. Despite these lower costs and clear advantages flowing from the company's transparency, data-sharing policies, and commitment to quality, AdX continued to dominate programmatic ad sales. Judge Brinkema previously found that Google's ability to charge prices "significantly above competitive levels" demonstrates monopoly power in the ad exchange market.

Market definitions and monopoly power

Index Exchange's complaint relies on market definitions and findings already established through Judge Brinkema's April 2025 ruling. The relevant geographic market for both publisher ad servers and ad exchanges is worldwide, reflecting the borderless nature of internet publisher content and open-web display advertising.

Publisher ad servers constitute a distinct product market because they are uniquely suited for managing ad inventory for large web publishers, are priced differently than other ad tech tools, and are recognized as distinct products by industry participants. Other ad tech tools are not reasonably interchangeable with publisher ad servers.

Google possesses monopoly power in the worldwide market for publisher ad servers with a 91% market share. High barriers to entry support the durability of this position, including technical and practical difficulties of convincing publishers to switch ad servers and enormous capital and labor costs needed to develop and maintain publisher ad servers.

Ad exchanges for open-web display advertising likewise constitute a distinct product market. They are the only ad tech tools through which publishers can auction their inventory at scale and in real-time to the largest sources of programmatic advertising demand. Most programmatic ad spending flows through ad exchanges. Google possesses monopoly power in the worldwide ad exchange market with market share roughly nine times greater than its next-largest competitor.

Specific antitrust violations alleged

The complaint brings a single claim for monopolization of the ad exchange market in violation of Section 2 of the Sherman Act. Index Exchange alleges that Google unlawfully monopolized both global and United States ad exchange markets through exclusionary conduct including the tying of real-time bids from AdX to the use of Google's publisher ad server, tying of AdWords demand to AdX, First Look, Last Look, Sell-Side Dynamic Revenue Share, Project Poirot, Open Bidding's additional fees for non-Google exchanges, and Unified Pricing Rules.

The filing states that Google's conduct serves no legitimate or pro-competitive purpose that could justify its anticompetitive effects. Index Exchange is a competitor in both global and United States markets for ad exchanges for open-web display advertising, having operated its own exchange competing directly with AdX since 2011.

According to the complaint, Google's exclusionary conduct materially harmed Index Exchange's ability to compete. The conduct impaired the company's growth by limiting business volume and revenues to levels materially lower than they would have been in a genuinely competitive market. It forced Index Exchange to invest in developing technology like header bidding that would not have been necessary absent Google's abuse of market power, consuming investment resources that could have been allocated to more valuable innovation.

The lawsuit states that Google's restrictions required Index Exchange to engage in sales, marketing, and customer maintenance efforts far exceeding what would have been required in a competitive market. Google's restrictions on access to advertisers through AdWords forced Index Exchange to expend efforts developing liquidity that would have been unnecessary in a fair market. Research efforts to understand factors influencing auction results were required only because Google partially or fully concealed its anticompetitive policies.

Remedy requests and jury demand

Index Exchange requests that the court issue an injunction prohibiting Google's anticompetitive conduct and mandating that Google take all necessary steps to cease such conduct and restore competition. The company seeks a declaration that the restraints are unlawful.

As monetary relief, Index Exchange requests compensatory, consequential, and punitive damages including treble damages for injuries directly and proximately caused by Google, as proved at trial, along with costs of suit including attorney's fees. The complaint demands a jury trial on all claims.

The lawsuit joins a series of private antitrust actions filed against Google following Judge Brinkema's April 2025 liability ruling. OpenX Technologies filed suit on August 4, PubMatic on September 8, Magnite on September 16, and Raptive on October 17. All cases rely on the Eastern District of Virginia's liability determination to establish the foundation for financial recovery.

The Department of Justice and Google filed final post-trial briefs and proposed remedies on November 3, 2025, with closing arguments scheduled for November 17. The DOJ seeks structural remedies including complete divestiture of AdX and open-sourcing of DoubleClick for Publishers' auction logic. Google proposes behavioral remedies including real-time bid sharing and removing discriminatory policies.

On October 27, 2025, the Southern District of New York granted summary judgment to private plaintiffs using Virginia findings, establishing that Google is precluded from relitigating whether its conduct unlawfully obtained and maintained market power in ad exchange and publisher ad server markets.

Timeline

• 2003: Index Exchange founded, initially operating as ad network before pivoting to exchange operations
• 2008: Google acquires DoubleClick for $3.1 billion, obtaining dominant publisher ad server with 60% market share
• 2010: Google introduces First Look through Dynamic Allocation, giving AdX first opportunity to acquire impressions
• 2011: Index Exchange releases programmatic ad exchange with real-time bidding capability
• 2014-2015: Header bidding emerges as publishers seek to mitigate Google's advantages in ad tech stack
• 2015: Index Exchange pivots exclusively to ad exchange operations
• 2017: Google implements Project Poirot to adjust DV360 bids in ways benefiting AdX over rival exchanges
• 2018: Google launches Open Bidding as alternative to header bidding, charging 5% fee on non-Google exchanges
• 2019: Google ends Last Look but implements Unified Pricing Rules restricting publishers' ability to offer preferential pricing to non-Google exchanges
• January 2023: Department of Justice files antitrust lawsuit against Google for monopolizing digital advertising technologies
• April 17, 2025: Judge Brinkema rules Google violated antitrust laws by monopolizing publisher ad server and ad exchange markets
• August 4, 2025: OpenX files follow-on antitrust lawsuit
• September 8, 2025: PubMatic files antitrust lawsuit
• September 16, 2025: Magnite files antitrust complaint
• October 17, 2025: Raptive files lawsuit seeking billions in damages
• October 27, 2025: SDNY grants summary judgment binding Google to Virginia court findings
• November 3, 2025: DOJ and Google file final remedies proposals 
• November 10, 2025: Index Exchange files lawsuit as Case No. 1:25-cv-02003
• November 17, 2025: Closing arguments scheduled in remedies phase

Summary

Who: Index Exchange Inc., an Ontario corporation headquartered in Toronto operating as an independent ad exchange platform since 2003, filed the lawsuit against Google LLC. Index Exchange CEO Andrew Casale previously testified in the government's antitrust trial. Judge Leonie M. Brinkema is assigned to the case with referral to Magistrate Judge Ivan D. Davis.

What: A 56-page antitrust complaint alleging Google illegally monopolized ad exchange markets through systematic anticompetitive conduct including First Look policies giving AdX first opportunity to acquire impressions, Last Look allowing AdX to bid after seeing competing offers, Sell-Side Dynamic Revenue Share manipulating transaction fees to favor Google, Project Poirot reducing bids on rival exchanges through DV360, Open Bidding charging additional fees only on non-Google exchanges, Unified Pricing Rules prohibiting preferential pricing for competitors, and tying arrangements forcing publishers to use Google's ad server to access AdWords demand.

When: Filed November 10, 2025, following Judge Brinkema's April 17, 2025 ruling that established Google violated antitrust laws by monopolizing publisher ad server and ad exchange markets through over a decade of exclusionary conduct spanning Google's 2008 DoubleClick acquisition through present operations.

Where: U.S. District Court for the Eastern District of Virginia as Case No. 1:25-cv-02003, the same court that ruled against Google in the government's antitrust action. The relevant markets are worldwide in scope for both publisher ad servers and ad exchanges serving open-web display advertising, reflecting the borderless nature of internet publisher content and programmatic advertising infrastructure.

Why: Index Exchange seeks to recover substantial damages for harm caused by Google's conduct that artificially suppressed the company's growth, forced expensive development of workarounds like header bidding technology, required excessive sales and marketing efforts, and prevented the company from reaching its full competitive potential in markets worth over $104 billion annually. The lawsuit aims to obtain injunctive relief ending Google's anticompetitive conduct and restore competitive conditions in digital advertising markets where Google maintained market share exceeding 90% in publisher ad servers and 54-65% in ad exchanges through exclusionary practices rather than superior performance.