How much of OpenAI does Microsoft own?
About 27%, the last figure either company has stated, set when OpenAI restructured in October 2025. That makes Microsoft the largest outside shareholder in the company behind ChatGPT. Here is what it paid, what the stake is worth and what comes with it.
Microsoft's stake in numbers
When OpenAI converted its for-profit arm into OpenAI Group PBC in October 2025, Microsoft's holding was fixed at roughly 27% on an as-converted, diluted basis: a share of every class of stock, counted as if all of it had been converted to ordinary shares. OpenAI put the value at about $135B, at the $500B valuation of the time.
Microsoft had put about $13B into OpenAI between 2019 and 2023, much of it as Azure cloud credits. Its stake was worth about 10 times that amount when the percentage was set.
What is Microsoft's OpenAI stake worth now?
If Microsoft still held 27%, its stake would be worth about $338B at the $1.25T valuation of OpenAI's November 2026 round.
It almost certainly holds less. Every round since October 2025 has issued new shares to new investors, and new shares shrink every existing holder's percentage unless that holder buys in too. Neither company has published an updated figure, so the number above is an upper bound, not an estimate of the current value.
What Microsoft gets besides the shares
The equity is only part of the relationship. The October 2025 agreement and later amendments also set:
- A licence to OpenAI's models and products through 2032, no longer exclusive
- A share of OpenAI's revenue until 2030, capped in total
- OpenAI's commitment to buy an extra $250B of Azure cloud services
- In return, Microsoft gave up its right of first refusal on OpenAI's compute
How Microsoft built its stake
Microsoft's money went in before OpenAI raised from the rest of the market.
| Date | Amount | Notes |
|---|---|---|
| July 2019 | $1B | Followed the creation of a capped-profit company under the nonprofit; Azure became OpenAI's exclusive cloud. |
| 2021 | $2B | Further Microsoft funding through 2022, largely in cloud credits. |
| January 2023 | $10B | A multi-year investment two months after ChatGPT launched, with Microsoft entitled to a share of OpenAI's profits. |
Who owns the rest of OpenAI?
The OpenAI Foundation, the nonprofit that controls OpenAI Group PBC, held equity worth about $130B at the October 2025 recapitalization, plus a warrant for more shares if the company's value rises far enough. Current and former employees, and the investors from every round since 2023, hold the rest.
The full list of backers and how control works is on who owns OpenAI.
Is buying Microsoft a way to own OpenAI?
Partly. A Microsoft share carries a sliver of the OpenAI stake, but OpenAI is a small part of a company whose cloud, software and gaming businesses earn far more. Microsoft does not report its OpenAI stake at market value, and the stake's ups and downs reach its share price only indirectly.
Microsoft and the other listed backers are compared on how to invest in OpenAI.