Elon Musk has announced plans to sue Apple Inc. over the fact that the iOS version of ChatGPT is the top-ranked app in the App Store.

“Apple is behaving in a manner that makes it impossible for any AI company besides OpenAI to reach #1 in the App Store, which is an unequivocal antitrust violation,” Musk wrote in a late Monday post on X. “xAI will take immediate legal action.”

Below the post, X users pointed out that DeepSeek’s namesake artificial intelligence service briefly surpassed ChatGPT as the most popular App Store app in the U.S. Perplexity AI Inc.’s search engine reached the top spot in India last month.

In March 2023, Musk launched an AI startup called xAI Holdings Corp. that competes with OpenAI. The company offers a large language model series called Grok and a chatbot of the same name. Earlier this year, xAI acquired X in a $33 billion all-stock deal.

“Why do you refuse to put either X or Grok in your ‘Must Have’ section when X is the #1 news app in the world and Grok is #5 among all apps? Are you playing politics?” Musk wrote on X.

Last Monday, CNBC reported that ChatGPT was poised to top 700 million weekly active users. Market intelligence company Sensor Tower Inc. estimates that xAI’s Grok app had 4 million downloads in July. Similarweb Inc, in turn, measured about 900,000 daily visits to the Grok website earlier this year.

OpenAI Chief Executive Officer Sam Altman responded to Musk’s posts by writing on X that “this is a remarkable claim given what I have heard alleged that Elon does to manipulate X to benefit himself and his own companies and harm his competitors and people he doesn’t like.”

It’s unclear whether Musk’s lawsuit will focus solely on ChatGPT’s App Store ranking or also the partnership between OpenAI and Apple. Last year, the iPhone maker inked a deal to integrate OpenAI language models into Siri. Additionally, Apple is using ChatGPT to power its Writing Tools proofreading and text generation features.

If the partnership will be a focus of the lawsuit, Musk may name OpenAI as a defendant in the case. He is already suing the ChatGPT developer for allegedly misleading him about its AI development plans.

OpenAI launched in 2015 with funding from Musk and other technology executives. According to Musk’s lawsuit, the AI developer pledged to operate as a nonprofit and make its LLMs available for free when it raised the funds. The complaint charges that OpenAI breached those commitments. 

In April, OpenAI filed a countersuit that accuses Musk of attempting to slow down market competition. The ChatGPT developer recently asked xAI to share internal documents that may be relevant to the litigation. The case is set to go to trial next spring. 

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