Elon Musk has sought damages amounting to $134 billion from OpenAI and Microsoft, alleging that the artificial intelligence company behind ChatGPT derived “wrongful gains” from his early financial backing.
The claim was made in a court filing submitted on Friday by Musk’s legal team. According to the filing, the US-based billionaire was allegedly defrauded of the $38 million in seed funding he provided to OpenAI in 2015.
Musk’s lawyers argue that he is now entitled to a share of the company’s current valuation of approximately $500 billion. The document claims that OpenAI generated gains ranging between $65.5 billion and $109.4 billion from Musk’s early investment.
Microsoft, which began investing in OpenAI in 2019 and currently holds a 27% stake in OpenAI Group PBC, is estimated to have gained between $13.3 billion and $25.1 billion.
“Without Elon Musk, there’d be no OpenAI. He provided the bulk of the seed funding, lent his reputation, and taught them all he knows about scaling a business,” Musk’s lead trial lawyer, Steven Molo, told Reuters. The estimates cited in the filing are attributed to expert witness C. Paul Wazzan, a financial economist.
OpenAI has rejected Musk’s claims, describing them as “baseless” and part of a broader “harassment” campaign. Microsoft declined to comment on the compensation issue.
In a separate filing submitted on Friday, OpenAI and Microsoft asked the court to exclude Wazzan’s analysis, calling it “made up” and “unverifiable.”
Musk co-founded OpenAI in 2015 and invested approximately $45 million in total but stepped down from its board in 2018 following strategic disagreements with chief executive Sam Altman. Since then, he has been a vocal critic of the company’s shift towards commercialisation and its deepening partnership with Microsoft.
In February 2025, Musk offered to acquire OpenAI for $97.4 billion in an attempt to counter its transition to a for-profit model. Altman rejected the proposal and responded by jokingly suggesting the purchase of Musk’s social media platform, X, for $9.74 billion.
OpenAI surpassed Musk’s SpaceX in October to become the world’s most valuable private technology firm after reaching a $500 billion valuation. The valuation followed a transaction in which current and former OpenAI employees sold around $6.6 billion worth of shares to a consortium of investors.