Firms including Apple, Disney and IBM have paused advertising on X amid an antisemitism storm on the site.
This comes after X owner Elon Musk amplified an anti-Semitic trope on the platform formerly known as Twitter.
The boycott has also been picking up steam in the wake of an investigation by a US group which flagged ads appearing next to pro-Nazi posts on X.
Mr Musk has denied his post was anti-Semitic and has threatened to sue over the advertising investigation. Mr Musk said on Saturday that X would file a “thermonuclear lawsuit” against Media Matters “the split second court opens on Monday”.
He came under fire on Wednesday after he replied to a post sharing an anti-Semitic conspiracy theory, calling it “actual truth”.
The billionaire Tesla and SpaceX entrepreneur denied he is anti-Semitic and later said his comments referred not to all Jewish people but to groups like the Anti-Defamation League and other unspecified “Jewish communities”.
The White House denounced Mr Musk’s endorsement of the post.