Tesla and xAI CEO Elon Musk has fired off a legal threat at Apple, accusing the company of antitrust violations over its App Store rankings – reigniting his ongoing feud with OpenAI CEO Sam Altman.

Musk claims Apple unfairly favours OpenAI’s ChatGPT app, making it “impossible for any AI company besides OpenAI to reach number one” on the App Store.

In a series of posts on X on Monday, Musk said both his social media platform X and xAI’s Grok chatbot were excluded from Apple’s “Must Have” app lists, despite Grok ranking fifth overall and X topping the news app charts.

“Are you playing politics?” Musk demanded, warning that xAI would pursue “immediate legal action” against Apple for the alleged antitrust breach.

OpenAI’s Sam Altman hit back swiftly, accusing Musk of manipulating X’s algorithms to promote his own interests and harm rivals.

Altman challenged Musk to sign an affidavit denying interference with X’s algorithm, promising to apologise if Musk proved truthful.

OpenAI CEO Sam Altman

The spat between two former business partners (Musk co-founded OpenAI but left in 2018) quickly devolved into a public clash over social media reach and accusations of dishonesty.

Musk’s legal threats come amid growing regulatory scrutiny of Apple’s App Store practices.

The US Department of Justice is currently suing Apple over its smartphone market dominance, while the EU recently fined the company €500 million (A$893 million) for antitrust violations.

Apple has integrated ChatGPT across its devices since mid-2024, a move Musk has previously criticised as a “security violation” that could lead to banning Apple products at his companies.

As of Tuesday, Apple’s App Store showed ChatGPT holding the top free app spot in the US, with Grok close behind.