Elon Musk's X is asking the US Court of Appeals for the 5th Circuit to revive its antitrust lawsuit against a group of major advertisers, after a district judge dismissed the case in March. The company argues that advertisers colluded in an illegal boycott that damaged X's revenue and allowed rival platforms to charge above-competitive rates, calling it "an unusually brazen group boycott" that has drawn scrutiny from regulators and Congress.

US District Judge Jane Boyle threw out the original case, ruling that advertisers simply chose competing platforms over X, which does not amount to an antitrust violation. Although X recently settled with the World Federation of Advertisers, the trade body linked to the Global Alliance for Responsible Media (GARM) brand-safety initiative, it is still pursuing other defendants including Mars, CVS Health, Nestlé, Abbott Laboratories, Colgate-Palmolive, Lego, Pinterest, Tyson Foods, Shell and Ørsted. The case stems from a sharp fall in advertising revenue at X (formerly Twitter) following Musk's 2022 takeover and subsequent changes to content moderation, with legal experts previously describing X's underlying case as weak.