Google fights to shield ad tech unit as antitrust trial kicks off

Google has entered a critical legal battle in Virginia, as US antitrust regulators push for a break-up of its core advertising technology business. The case centres on AdX, Google’s ad exchange platform that processes billions in ad auctions and is accused of cementing the company’s dominance in digital advertising.

Supported by other states, the US Department of Justice (DOJ) argues that Google's dominance over the ad buying chain, from publisher tools to the exchange where ads are sold, stifles fair competition.  Publishers presently pay AdX about 20% to run auctions in milliseconds after a page loads.  Regulators contend that the only way to bring the market back into balance is for Google to sell out AdX and expose the auction mechanism to external inspection.

Judge Leonie Brinkema, who is presiding over the trial, has already determined that Google unlawfully tied AdX to its publisher ad server. DOJ attorney Julia Tarver Wood stressed that allowing Google to keep both businesses would risk a repeat of past monopolistic practices.

Google, however, is resisting the divestiture push. Its lawyer Karen Dunn described the DOJ’s demands as “reckless,” cautioning that a forced sale would disrupt the advertising ecosystem and reduce market stability. Instead, Google has floated policy reforms aimed at making it easier for publishers to integrate with competing platforms, though regulators argue these measures fall short of meaningful change.

Publishers, news outlets, and ad tech competitors are carefully monitoring the trial as many of them have filed separate lawsuits seeking damages.  Some industry voices, like Advance Local executives, maintain that leveling the playing field requires structural adjustments rather than changes to the law.

This case is part of a larger US effort to rein in Big Tech, alongside ongoing proceedings against Meta, Amazon and Apple. The outcome could reshape how digital advertising operates worldwide and determine whether Google’s $200 billion ad business retains its central grip on the industry.