The U.S.-based billionaire has alleged that both companies derived “wrongful gains” from his early backing
Elon Musk is seeking $134 billion in damages from OpenAI and Microsoft, as per a court filing submitted by his attorney on Friday. The U.S.-based billionaire asserts that the firm behind ChatGPT secured “wrongful gains” through his initial financial support.
The tech entrepreneur was reportedly defrauded of the $38 million in seed funding he contributed to OpenAI in 2015, the filing states, arguing he is now entitled to a portion of the company’s current $500 billion valuation.
OpenAI reaped between $65.5 billion and $109.4 billion from that investment, the filing notes. Microsoft, which has invested in the company since 2019 and holds a 27% stake in OpenAI Group PBC, gained between $13.3 billion and $25.1 billion, the document indicates.
“Without Elon Musk, there would be no OpenAI. He provided the majority of the seed funding, lent his reputation, and shared all he knows about scaling a business,” the billionaire’s lead trial attorney, Steven Molo, told Reuters, referencing estimates from expert witness and financial economist C. Paul Wazzan, who is cited in the document.
The ChatGPT developer dismissed Musk’s claims as “baseless” and labeled them part of a “harassment” campaign. Microsoft declined to comment on the compensation matter.
The two co-defendants filed a separate document on Friday requesting the judge to disregard Wazzan’s analysis, deeming it “fabricated” and “unverifiable.”
Musk co-founded OpenAI in 2015, contributing around $45 million in total, but exited the board in 2018 amid strategic disputes with its CEO, Sam Altman. The billionaire has since become a vocal critic of OpenAI’s commercialization endeavors and its close partnership with Microsoft.
In February 2025, he proposed purchasing OpenAI for $97.4 billion to counter its shift to a for-profit model. Altman rejected the offer and sarcastically suggested buying Musk’s social media platform, X, for $9.74 billion instead.
OpenAI overtook Musk’s SpaceX as the world’s most valuable private tech company in October, reaching a $500 billion valuation after current and former employees sold approximately $6.6 billion in shares to a group of investors.