Firms including Apple, Disney, and IBM have paused advertising on X amid an antisemitism storm on the site.
It comes after X owner Elon Musk amplified an antisemitic 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 that flagged ads appearing next to pro-Nazi posts on X.
Mr Musk has denied his post was antisemitic and has threatened to sue over the advertising investigation.
Left-leaning pressure group Media Matters for America said it had identified ads bought by high-profile firms next to posts including Hitler quotes, praise of Nazis and Holocaust denial.
A spokesperson for X told the BBC that the company does not intentionally place brands “next to this kind of content” and the platform is dedicated to combatting antisemitism.
Mr Musk said on Saturday that X would file a “thermonuclear lawsuit” against Media Matters “the split second court opens on Monday”.
He said the group’s report had “misrepresented the real user experience of X” in order to “undermine freedom of speech and mislead advertisers”.
On Wednesday, Mr Musk replied to a post sharing a conspiracy theory which accused Jewish communities of pushing hatred against white people, calling it “actual truth”.
The billionaire Tesla and SpaceX entrepreneur later said his comments referred not to all Jewish people but to groups like the Anti-Defamation League (ADL) and other unspecified groups.