Google owns Google Ad Manager (the tool third-party website and app publishers like NyTimes use to show ads on their properties), Google Ads (the place advertisers like Nike go to run ad campaigns across both Google properties and also these third party sites), and AdX the ad exchange that runs the auction that sits between Ad Manager and Google Ads.

The lawsuit is specifically about googles ownership of the auction and the ownership of the relationship on either side of the auction. The AdX auction also contains demand (ads from places besides google ads) and inventory (ad slots outside of ad manager). Website publishers allege that Google uses this ownership to artificially deflate the value of ads on third party websites.