In a landmark decision, a US District Judge has ruled that Google illegally monopolized the ad tech market. A federal judge in Virginia has found that the tech giant established “monopoly power” for two online advertising markets: publisher ad servers and ad exchanges that sit between buyers and sellers. The ruling in the second-largest antitrust case of the century could mean that Google will have to break up its advertising products or change its business practices. Google is said to have earned nearly $265 billion in 2024 alone through ad placement and sales. The company has said it will appeal the decision. Google was previously the center of the century’s largest antitrust case, and was found guilty of being a “monopolist” with its search business. The US Department of Justice (DOJ) has made it clear that it wants the company to sell off its Chrome browser. That issue goes to trial next week. Thursday’s ruling will likely have a significant impact on the ad tech market, not to mention on Google’s business model and structure. That being said, the lengthy appeals process means the market isn’t going to feel seismic changes anytime soon. “Google’s integration across ad serving, exchange, and buying platforms created efficiency, but it also limited competition and transparency,” said Julie Geller, principal research director at Info-Tech Research Group. “This decision forces a closer look at how market power is exercised through vertical control.” Decision: monopoly in two of the three areas The core of the case was Google’s alleged monopoly over three markets in the ad tech space — one for publishers, one for advertisers, and one that connects the two. US District Judge Leonie Brinkema ruled today that Google had a monopoly on two of those markets (the publisher market and the ad exchange market), but sided with Google in finding that there is no separate advertiser market for online ads. She also ruled that the company’s acquisition of  advertising company DoubleClick in 2008 was not anticompetitive. Google took this as a partial win, with the company’s VP for regulatory affairs, Lee-Anne Mulholland, stating: “We won half of this case and we will appeal the other half. The Court found that our advertiser tools and our acquisitions, such as DoubleClick, don’t harm competition. We disagree with the Court’s decision regarding our publisher tools. Publishers have many options and they choose Google because our ad tech tools are simple, affordable, and effective.” Geller called the ruling a “major inflection point” for digital advertising, as it confirms that Google’s dominance wasn’t just about market share: It was reinforced by unlawful practices like tying DoubleClick for Publishers (DFP) with Google Ad Exchange. “Structural separation is no longer theoretical, it’s moving forward,” she said. “For advertisers and publishers, the implications are real.” She pointed out that a breakup would reshape how media is bought, how value flows, and how trust is built across the ad ecosystem, and potentially, search as well. “It’s not just about Google,” said Geller. “It’s about whether the digital market can evolve toward something more open, accountable, and competitive.” Bid to ‘restore competition’ to the web The US Department of Justice (DOJ) and a coalition of eight states initially brought the case against Google in 2023, saying the tech giant engaged in monopolistic behavior, strategically acquiring particular companies and controlling the industry’s most popular tools and exchanges. The lawsuit sought to “restore competition” to the web. The company avoided a jury trial, instead going before a judge only in a “bench trial,” by making a roughly $2.3 million payment to the DOJ that covered a portion of damages to the plaintiffs. The trial took place last fall, with lawyers for the government arguing that Google has been looking to monopolize control of the ad network, server, and exchange markets since its DoubleClick purchase. This and other moves gave Google a monopoly over the three markets in the ad tech space, the DOJ alleged. Google, for its part, argued that the feds didn’t understand advertising market economics and were just focusing on a narrow sliver of it (banner ads at the top and sides of web pages). The company described the industry as “intensively competitive” and claimed that its share in the market has decreased even as its revenues have increased.