> In limiting the number of bidders, Google inflated the prices for ad inventory.
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.
> It was argued that this approach allows Google to charge higher prices to advertisers while sending less revenue to publishers such as news websites.
It could depend on how they 'limit the number of bidders'. If they sell seats to be able to bid, then the bids are lower to account for that, and publishers get a share of the bid, not the fee bidders pay. I'm guessing though...
You could limit to one mark and a bunch of planted bidders in an attempt to control competition. If you win with your plants, you get to pay yourself anyway.
I think they meant that Google managed to limit the number of bidders for ad placement - they shut out other advertising groups -, so they could then charge what they want to those who need to advertise their business or perish, and take what they want from websites that publish ads as well (take a larger cut from the 'ad inventory' understood either as ad space or ads to be published). In this sense the linked article states:
"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."
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.