IBM on Thursday said it has stopped advertising on X due to a report its ads were shown next to pro-Nazi posts on the platform formerly known as Twitter.

The move came as X owner Elon Musk faced criticism for endorsing an unfounded antisemitic conspiracy theory on the service.

Nonprofit Media Matters on Thursday reported that it found Apple, Oracle, and IBM ads displayed next to posts touting Hitler and the Nazi Party on X.

"IBM has zero tolerance for hate speech and discrimination and we have immediately suspended all advertising on X while we investigate this entirely unacceptable situation," the New York-based tech firm said in response to an AFP inquiry.

An X executive told AFP that it did a "sweep" of accounts pointed out by Media Matters and they will no longer be able to make money from ads.

The posts themselves will be labeled "sensitive media," according to the executive.

"Ads follow the people on X, in this case, the Media Matter's researcher that was going to actively look for this content – that's how user targeting works," the executive said in an emailed reply.

In the year since taking over Twitter, now rebranded as X, Musk has gutted content moderation, restored accounts of previously banned extremists, and allowed users to purchase account verification, helping them profit from viral — but often inaccurate — posts.

Musk has also promoted Community Notes, in which X users police the platform, as a tool to combat misinformation. 

A recent study by the disinformation monitoring group NewsGuard found that paying subscribers at X were the big spreaders of misinformation about the Israel-Hamas war. 

"During all of this Musk-induced chaos, corporate advertisements have also been appearing on pro-Hitler, Holocaust denial, white nationalist, pro-violence, and neo-Nazi accounts," Media Matters said in a post displaying samples of what it found at X.

Musk caused an uproar on Wednesday by endorsing an antisemitic post on X that falsely claimed members of the Jewish community were stoking hatred against white people.

The tycoon later turned his criticism to the Anti-Defamation League, the nonprofit that fights antisemitism that he has accused of chasing advertisers from X.