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

A combination photo shows CEO of OpenAI Sam Altman (L) on April 28, 2026 and Elon Musk on April 29, 2026 during the trial in Elon Musk's lawsuit over OpenAI for-profit conversion at a federal courthouse in Oakland, California, U.S. Manuel Orbegozo | Reuters In December 2015, Elon Musk and Sam Altman sat together at the Vanity Fair New Establishment Summit in San Francisco for an interview, publicly touting their new partnership as co-chairs of a fledgling artificial intelligence research lab. Musk was a multibillionaire due to his stake in Tesla , which had gone public five years earlier, and Altman was running famed startup incubator Y Combinator. The pair had been working closely that year on an AI initiative they hoped would prevent Google from establishing monopoly control over the powerful technology. Their project, a nonprofit, was called OpenAI. Over the past three weeks, the collapse of the once-tight bond between two of the most prominent names in AI has been the subject of a high-profile trial in Oakland, California, after Musk sued Altman and OpenAI in 2024 for allegedly violating their commitment to keep OpenAI as a nonprofit. OpenAI is now valued at over $850 billion, and Musk's SpaceX has a valuation of $1.25 trillion after merging with his AI lab, xAI, in February. Both companies are racing for the public market, with SpaceX expected to disclose its prospectus as soon as this week, ahead of what could be a record offering next month. …