Microsoft’s OpenAI stake is worth $228 billion

Microsoft’s early OpenAI stake has turned into a monster-sized paper win. A leaked cap table shows the software giant’s stake is now worth $228.3 billion, making it the biggest winner in the company’s investor roster by a very wide margin.

The document, compiled from public filings and secondary-market disclosures, lands at a moment when OpenAI’s valuation has reportedly climbed to $852 billion after a $122 billion funding round. That kind of number does more than make spreadsheets sweat: it also helps explain why OpenAI’s next corporate step is being watched so closely by every investor who missed the bus.

Microsoft’s OpenAI stake dwarfs everyone else’s

Microsoft first put $13 billion into OpenAI in 2019 and later added another $10 billion four years after that. In exchange, it ended up with a 26.79 percent stake that now towers over the rest of the reconstructed cap table, which lists 29 investors.

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If OpenAI does go public later this year or in early 2027, as expected, Microsoft stands to get even richer. That is the kind of optionality public markets love to price in and regulators tend to study with a frown.

Sam Altman and Ashton Kutcher are the oddest names on the list

The leaked document’s most surprising detail is that OpenAI chief executive Sam Altman appears to hold zero equity in the company he launched as a nonprofit in 2015. Another eyebrow-raiser: Sound Ventures, the firm co-founded by Ashton Kutcher, shows up near the bottom of the list with a 0.15 percent stake valued at $1.3 billion.

• Microsoft stake: 26.79 percent, worth $228.3 billion
• OpenAI Foundation stake: 25.8 percent, worth $219.8 billion
• Sound Ventures stake: 0.15 percent, worth $1.3 billion
• By one estimate, Kutcher’s share of that position is worth about $400 million

The nonprofit still has a huge claim on OpenAI

OpenAI shifted from nonprofit to capped-profit in 2019 and became a public benefit corporation in 2025, but its nonprofit arm, OpenAI Foundation, still holds a 25.8 percent stake worth $219.8 billion. That makes the foundation the second-biggest beneficiary on the cap table, which is a neat reminder that corporate structures can be wildly more lucrative than they sound in a press release.

Elon Musk has argued that OpenAI’s nonprofit roots were part of the deal when he donated $38 million to the foundation. He has sued three times, accusing the company of breach of contract and fraud, and is seeking damages ranging from $79 billion to $139 billion. The trial is scheduled for April 27 in Oakland, California.

The bigger question now is whether OpenAI can keep growing fast enough to justify these paper fortunes without turning every governance decision into a courtroom hobby. With Microsoft already sitting on a massive stake and a public offering still looming, the company’s capital structure may end up being as closely watched as its models.