In ruling against Google, Judge Leonie Brinkema specifically found that the company violated Section 2 of the Sherman Act by illegally monopolizing the open-web display publisher ad server market and the open-web display ad exchange market.12 The court also determined that Google violated both Sections 1 and 2 of the Sherman Act by unlawfully tying its publisher ad server (DFP) and ad exchange (AdX) products together.13 This ruling marks Google's second major antitrust loss, following an earlier decision that found the company had illegally monopolized the general internet search market.24

The Sherman Act prohibits monopolization and anticompetitive business practices, with potential penalties including fines of up to $100 million for corporations and $1 million for individuals, along with prison sentences of up to 10 years.5 While the court rejected claims that Google monopolized advertiser ad networks,24 it found sufficient evidence that Google's control over publisher-side ad tech constituted illegal monopolization.2 The judge will now set a briefing schedule to determine appropriate remedies, which could potentially include forcing Google to divest parts of its advertising business.23

Google's 2007 acquisition of DoubleClick for $3.1 billion marked a pivotal moment in the company's path to ad tech dominance. This purchase gave Google control of DoubleClick's dominant publisher ad server and ad exchange, vaulting it into a commanding position with access to both sides of the advertising marketplace12. Though the Federal Trade Commission initially approved the deal, concluding it was "unlikely to substantially lessen competition"3, the Department of Justice later argued this acquisition fundamentally altered the competitive landscape by allowing Google to control multiple critical stages of the ad delivery supply chain4.

Following the DoubleClick purchase, Google strategically acquired additional ad tech companies including Invite Media (2010) and AdMeld (2011), further consolidating its market power56. The DOJ alleges that Google then engaged in anticompetitive behavior by making DoubleClick available only to advertisers using Google's internal ad buying tools and implementing exclusive agreements that forced publishers to use its products4. These actions allegedly helped Google increase its market share for publisher ad servers from 60% in 2008 to approximately 90% by 20154, allowing it to capture at least 30 cents of every dollar spent on online advertising while raising costs for advertisers and reducing revenue for publishers7.

Google's antitrust troubles extend beyond ad tech to its search business, where Judge Amit Mehta ruled that Google violated Section 2 of the Sherman Act through exclusive distribution agreements that maintained its search monopoly. These agreements, which cost Google a staggering $26 billion in 2021 alone (nearly four times more than all other search-specific costs combined), ensured Google was the preloaded default search engine on browsers and devices from partners like Apple, Mozilla, and Android manufacturers12. The court found these agreements foreclosed approximately 50% of the general search market, depriving competitors of the scale needed to effectively compete3.

In response to the ruling, Google has proposed remedies that would modify rather than eliminate these agreements. The company's proposal would allow browser companies to continue making Google their default search provider while permitting them to strike deals with different search engines across various devices and browsing modes45. Google has also proposed that these agreements be non-exclusive, terminable annually, and subject to increased transparency56. However, critics argue these concessions don't go far enough to address the monopolistic behavior that allowed Google to capture over 89% of the general search market and 94.9% on mobile devices2.