A US judge has ordered Google to overhaul parts of its online advertising business after finding that it unlawfully maintained a monopoly in open-web display advertising. The ruling aims to increase competition in a market that helps fund publishers, including news organisations, whose advertising income is under pressure from artificial intelligence and changing online habits.

Google must separate its publisher ad server from AdX, share more data, end preferential auction practices and provide greater transparency. A monitoring committee will oversee compliance for six years, potentially longer, while Google must appoint an internal antitrust monitor; the US Department of Justice described the decision as a significant victory, although Google disputes the findings and plans to appeal.