The Google ad exchange favored its own platforms, limiting the ability of other exchanges to compete fairly in bidding for ad inventory. https://www.justice.gov/archives/opa/pr/justice-department-s...
In limiting the number of bidders, Google inflated the prices for ad inventory. https://www.abc.net.au/news/2024-11-26/closing-arguments-giv...
Google engaged in bid rigging where competitors agree on who will win a bid, again to inflate prices. https://www.justice.gov/atr/preventing-and-detecting-bid-rig...
Google entered market allocation agreements to create an unfair playing field. https://www.winston.com/en/insights-news/avoiding-antitrust-...
This part doesn't make sense to me. Limiting bidders should drive the price down, because fewer advertisers are competing for the same potential ad impression. The article describes Google's influence as "Google controls the auction-style system," which is a bit more open-ended about the specific alleged practices.
"The US argues that Google used its financial power to acquire potential rivals and corner the ad tech market, leaving advertisers and publishers with no choice but to use its technology."