How Elon Musk and Sam Altman went from besties to bitter rivals

Combination photo shows OpenAI CEO Sam Altman (L) on April 28, 2026, and Elon Musk on April 29, 2026, during the hearing of his lawsuit regarding the for-profit conversion of OpenAI at a federal courthouse in Oakland, California, USA.
Manuel Orbegozo | Reuters
In December 2015, Elon Musk and Sam Altman met for an interview at the Vanity Fair Startup Summit in San Francisco and publicly announced their new partnership as co-heads of a new artificial intelligence research lab.
Musk was a multibillionaire because of his shares Tesla’sIt went public five years ago, and Altman was running the famed startup incubator Y Combinator. The two were working closely that year on an artificial intelligence initiative they hoped would prevent Google from establishing monopoly control over powerful technology. Their non-profit project was called OpenAI.
Over the past three weeks, the collapse of the once-tight bond between two of the most prominent figures in artificial intelligence has become the subject of a high-profile lawsuit in Oakland, California, after Musk sued Altman and OpenAI for allegedly violating their commitment to maintain OpenAI as a nonprofit through 2024. OpenAI is currently valued at over $850 billion, and Musk’s SpaceX was valued at $1.25 trillion after merging with artificial intelligence lab xAI in February.
Both companies are vying for the public market, and SpaceX is expected to unveil its promotional brochure as soon as this week, ahead of what could be a record offering next month. Before addressing eager investors, Musk had to testify before a jury in downtown Oakland to prove his case and deal a major blow to OpenAI’s ambitious plans if he succeeded.
“What you can’t do is have your cake and eat it too,” Musk said in response to questions from OpenAI’s lawyer on April 29. He accused Altman and Greg Brockman, OpenAI’s president and co-founder, of trying to enrich themselves from a charity while also capitalizing on the positive connotations that come with running a nonprofit.
Musk used his time on the witness stand to highlight a message he’s been shouting for years on social media app X, now owned by SpaceX: OpenAI wouldn’t exist without him.
“I came up with the idea and the name, hired the key people, taught them everything I knew, secured all the initial financing,” Musk said.
Altman stated last week that he and his co-founders had not made any commitments to Musk about the company’s corporate structure.
He has argued from the early days that a big problem was that Musk felt too strongly about having complete control over OpenAI, at least initially, in part because Musk did not trust other people to make decisions.
“I was extremely uncomfortable with it,” Altman testified of Musk’s quest for power.
Lawyers for Musk and OpenAI wrapped up their closing arguments on Thursday after three weeks of hearings. The jury will begin deliberations on Monday to determine the validity of Musk’s claims and whether OpenAI, Altman and Brockman can be held liable for breach of charitable trust and unjust enrichment.
Whatever the final outcome, neither tech mogul will win publicly, said Stavros Gadinis, a professor at the University of California, Berkeley, School of Law.
“After weeks of damaging statements, the public has been forced to choose between two dueling billionaires, each convinced that he is the true guardian of transformative technology,” Gadinis said by email. “The answer most people will arrive at is: none.”
How did it start
The partnership began 11 years ago, in May 2015, when Altman emailed Musk and asked if it would be a good idea for Y Combinator to launch a “Manhattan Project for AI.” Musk said the idea was “probably worth talking about.”
OpenAI launched In December 2015, Musk pledged to fund up to $1 billion to the charity.
“I’m more impressed than everyone else so far,” Musk wrote to Altman in November 2015, according to emails made public as part of discovery in the case. “This is a great team.”
Cracks started to appear in 2017.
Although OpenAI had made progress in research and development, Musk had demanded that Altman and other co-founders, including Brockman and Ilya Sutskever, compile a list of employees and their significant contributions and fire anyone who did not make the grade immediately, according to the applications.
OpenAI was burning through cash and needed significantly more in computing resources. Leaders discussed turning the lab into a for-profit facility. The question of who would be CEO and who would own controlling shares was of great importance, especially for Musk, who wanted up to 90% ownership of a for-profit entity.
Altman and the other co-founders rejected the proposal, arguing that no person or group should have unilateral control over “artificial general intelligence” technology that could prove smarter than humans.
A major point of tension in the relationship emerged in June 2017, when Tesla poached Andrej Karpathy, an artificial intelligence researcher, from OpenAI. In text messages between Musk and his employees, including OpenAI board member Shivon Zilis and project director Sam Teller, Musk’s team applauded the hire, according to correspondence made public in the discovery.
Lawyer Steven Molo questions his client Elon Musk as OpenAI CEO Sam Altman watches; Courtroom sketch of Musk at his trial hearing before U.S. District Judge Yvonne Gonzalez Rogers regarding the for-profit conversion of OpenAI, at a federal courthouse in Oakland, California, U.S., April 29, 2026.
Vicki Behringer | Reuters
Zilis, who has four children with Musk, took the stand earlier this month and was questioned by attorneys on both sides about conversations she made in 2017 and 2018 about OpenAI’s corporate structure, as well as whether Tesla tried to poach OpenAI employees while she was on the board.
After an OpenAI lawyer showed Zilis messages congratulating Karpathy on accepting Musk’s job offer, Zilis acknowledged that Musk was the first to approach Karpathy.
During his testimony, Brockman recalled that Musk later offered “an apology and a confession” to the OpenAI co-founders.
While the internal drama unfolded, OpenAI’s technology continued to advance. As of August 2017, their system was able to beat the world’s best players in Dota 2, a multiplayer action game. Musk was promoted Success on Twitter.
“OpenAI is the first to beat the world’s best players in competitive eSports,” Musk wrote. “It’s much more complex than traditional board games like Chess and Go.”
A month later, he sent an email to Altman and other OpenAI leaders, saying “that’s enough.” If he couldn’t gain control over OpenAI, he was ready to walk.
“Either do something on your own or continue OpenAI as a nonprofit,” Musk wrote in an email disclosed in the court filing. “I will no longer fund OpenAI until you make a firm commitment that you will stay, otherwise I would be a fool to essentially give you free funding to start a startup.”
Musk ended his monthly contribution to the company. Far from putting in $1 billion, his donations totaled $38 million.
‘Tesla is an automobile company’
With OpenAI in need of support, Musk, Zilis, and Teller made a last-ditch attempt to bring the lab under Musk’s control, suggesting that the lab should be incorporated into Tesla. In an attempt to impress Altman, Musk’s team invited him to tour a Tesla factory and promised him a board seat at Tesla.
Altman said during his testimony that he didn’t think this was the right choice and was concerned that the nonprofit would be effectively destroyed if it became part of Tesla.
“Tesla is a car company and does not have the OpenAI mission,” Altman said at the podium. “I don’t think we have the ability to make sure the mission is accomplished.”
After the merger effort was rejected, Musk wrote in a December 2018 email to Altman and OpenAI leadership that “the likelihood assessment that OpenAI will be relevant to DeepMind/Google without a dramatic change in execution and resources is 0%, not 1%.”
Musk left the OpenAI board in 2018, as he said in a speech at OpenAI. blog post As Tesla began to focus more on artificial intelligence, it was necessary to “eliminate a potential future conflict for Elon.”
For the next five years, Musk rarely mentioned OpenAI in public. The cracks in his relationship with Altman were largely absent from social media.
Altman regularly praised Musk on Twitter. don’t write “Betting against Elon is historically a mistake” in 2019 and sending In October 2022, Musk said it served as “a reminder of how much one person can do.”
The second post came a month before OpenAI introduced ChatGPT. That’s when everything changed; The productive AI boom has led to increased investment in the field. In January 2023, Microsoft He pumped $10 billion into OpenAI and made it clear that the race to commercialization is on. OpenAI had already established a non-profit subsidiary.
Microsoft CEO Satya Nadella (right) greets OpenAI CEO Sam Altman at the OpenAI DevDay event in San Francisco on November 6, 2023.
Justin Sullivan | Getty Images News | Getty Images
Musk began crushing Altman and OpenAI online. In a post on Twitter, which Musk had by then acquired and later renamed X, he said the following about the startup’s financing and partnership with Microsoft:
“OpenAI was created as an open source company (which is why I call it ‘Open’ AI), a for-profit company, and to serve as a counterbalance to Google, but has now become a closed-source, max-profit company effectively controlled by Microsoft,” Musk wrote. to mail In February 2023. “It was not at all what I intended.”
Altman responded with a text released in the court file.
“I’m extremely grateful for everything you’ve done to help – I don’t think openai would happen without you – and it really hurts that you’re publicly attacking openai,” Altman wrote Amulet.
Musk was undecided. In March 2023, it acquired xAI, aiming to become a direct competitor to OpenAI and even actively recruit from the company. At that point, Zilis, who had children with Musk, resigned from the OpenAI board.
He was headed in that direction when he texted a friend last month: “There’s nothing to be done when your babies’ daddy starts a competitive endeavor and starts recruiting from OpenAI.”
Since filing his lawsuit in 2024, Musk has escalated his war of words with the OpenAI co-founders, mostly over his preferred platform
“I could have founded OpenAI as a for-profit company,” he wrote in one post. to mail While the full hearing was in progress in X. “Instead, I started it, funded it, hired critical talent, and taught them everything I knew about how to make a startup successful FOR THE PUBLIC GOOD. Then they stole the charity.”
—CNBC’s Kate Rooney contributed to this report.
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