X has settled its long-running legal battle with the World Federation of Advertisers, ending a case that accused brands including Mars and Shell of illegally coordinating a boycott of the platform. The suit was the most aggressive test yet of a theory that has been circulating in advertising for several years: that when brands act collectively through an industry body to withhold spending from a platform over content standards, the coordination itself can constitute an antitrust problem rather than a series of independent commercial decisions.