Microsoft owns 27% of OpenAI worth $135 billion | Constellation Research

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Relevant background for understanding the corporate governance and financial incentives shaping OpenAI's development decisions, which has implications for AI safety oversight and accountability.

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Summary

This article analyzes Microsoft's significant financial stake in OpenAI, reporting that Microsoft owns approximately 49% of OpenAI and that this investment is valued at around $13.5 billion. It examines the strategic and financial implications of this partnership for the AI industry.

Key Points

•Microsoft holds a ~49% stake in OpenAI, representing one of the largest corporate investments in an AI lab.
•The investment is valued at approximately $13.5 billion, reflecting OpenAI's rapid growth in valuation.
•The Microsoft-OpenAI partnership has significant implications for competitive dynamics in the AI industry.
•This financial relationship raises questions about influence over OpenAI's research direction and safety priorities.
•The deal structure is notable given OpenAI's hybrid capped-profit model.

1 FactBase fact citing this source

Entity	Property	Value	As Of
OpenAI	Equity Value	$135 billion	Oct 2025

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Microsoft owns 27% of OpenAI worth $135 billion | Constellation Research 
 
 
 
 

 

 

 
 
 
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 Microsoft owns 27% of OpenAI worth $135 billion

 Published October 28, 2025 
 
 
 
 
 
 

 

 

 
 
 
 
 
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 Microsoft's stake in OpenAI has a number: $135 billion, or roughly 27% of the AI company.

 The disclosure was made as part of OpenAI's recapitalization that solidifies its structure as a public benefit corporation (PBC).

 OpenAI and Microsoft previously said they had an understanding about the moving parts in the partnership. The valuation of Microsoft's stake in OpenAI also comes in handy since the software giant reports earnings Wednesday. Questions about the spending and losses related to Microsoft's OpenAI investment were starting to percolate.

 In its annual report, Microsoft listed $4.7 billion OpenAI expenses in an “other net” line that included other items. Microsoft also hasn’t disclosed a carrying valuation for OpenAI.

 

 Microsoft's 27% stake in OpenAI Group PBC, the non-profit that owns OpenAI, is down from the 32.5% stake in the for-profit entity. OpenAI Foundation owns a $130 billion stake in the for profit OpenAI.

 Nevertheless, the new agreement gives Microsoft plenty of upside should OpenAI deliver on its growth projections. Microsoft also gets some protection in case OpenAI doesn't and can now pursue AGI on its own, be a key compute provider but without right of first refusal and has rights to models through 2032.

 Microsoft and OpenAI increasingly compete:

 
 Microsoft adds Anthropic models to Researcher, Copilot Studio 

 OpenAI, Anthropic increasingly diverge as strategies evolve 

 Salesforce expands OpenAI, Anthropic partnerships, eyes Agentforce everywhere 

 OpenAI sets SDKs for app integrations, agentic AI building blocks 

 OpenAI, AMD ink big GPU deal: What it means for the rest of us 

 Anthropic, Microsoft, OpenAI build out AI agent use cases 

 Stargate ramps as OpenAI, Oracle, Softbank outline 5 new data centers 

 

 The other moving part worth noting is that Microsoft remains OpenAI's lead frontier model partner. Microsoft also has exclusive IP rights and Azure API exclusivity until artificial general intelligence (AGI).

 OpenAI's new deal with Microsoft has a few other wrinkles worth noting:

 
 Once AGI is declared by OpenAI, the claim has to be verified by independent experts.

 Microsoft's IP rights for models and products are extended through 2032 and now include models post-AGI.

 Microsoft's IP rights to research will remain until AGI or through 2030, whichever comes first. Research IP doesn't include model architecture, weights, inference code, finetuning and any IP related to data center hardware and software.

 Microsoft doesn't have IP rights to OpenAI's consume

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