Companies including Apple, Disney, and IBM have suspended advertising on X following a barrage of anti-Semitism on the site.
This comes after X owner Elon Musk intensified his anti-Semitic tone on the platform formerly known as Twitter.
The boycott movement also gained momentum following an investigation by a US group that placed advertisements next to pro-Nazi posts about advertising investigations.
The left-leaning advocacy group Media Matters for America said it had identified ads purchased from high-profile companies, along with posts containing Hitler quotes, praising the Nazis and denying the Holocaust.
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, acalling 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.
The White House denounced Mr Musk’s endorsement of the post.
“We condemn this abhorrent promotion of antisemitic and racist hate in the strongest terms,” said spokesperson Andrew Bates.
On Thursday, IBM became the first company to pull its advertising from the site following the Media Matters investigation, saying the juxtaposition of its ads with Nazi content was “completely unacceptable”.
The European Commission, Comcast, TV network Paramount and movie studio Lionsgate have also pulled ad dollars from X.
On Friday, as controversy over the pro-Nazi posts mounted, Mr Musk announced new steps to combat what he described as “calls for extreme violence” against Israel.
In a post on X, he said anyone using such phrases as “from the river to the sea” – which the ADL considers to be a coded call for Israel`s destruction – would be suspended from the platform.
The ADL, one of the most vocal critics of how X moderates incendiary content, offered rare praise for Mr Musk. Its chief executive Jonathan Greenblatt said the announcement was “an important and welcome move”.
X chief executive Linda Yaccarino posted on Friday evening that the platform had been “extremely clear about our efforts to combat antisemitism and discrimination. There’s absolutely no place for it anywhere in the world”.
The platform argues it has stronger brand safety controls than other social networks and that hate speech and extremism have fallen on the platform despite large cuts to the company’s safety team.
Several outside groups disagree with that assessment and say that such content has increased under Mr Musk’s leadership.
It is unclear how much of X’s revenue currently comes from ads, because it’s now a private company and no longer publishes quarterly reports.
But before Mr Musk took over the firm, advertising made up about 90% of Twitter revenue.
Mr Musk has attempted to change its reliance on ad dollars by trying to create a paid-membership tier.
If you pay a monthly fee, you can have a blue tick by your name and your content will be boosted. Yet that still makes up a tiny fraction of revenue.
In an interview with the BBC in April, Mr Musk said “almost all of them [advertisers] have either come back or they’re going to come back”.
Three months later he acknowledged in a post on X that ad revenue had fallen by 50%.
His appointment of Ms Yaccarino, a former ad executive, was widely seen as an attempt to smooth relations with advertisers.