Microsoft has finalized an investment that strengthens its position within OpenAI, the company everyone knows as the force behind ChatGPT.
This deal, announced recently, brings the value of Microsoft’s stake to $135 billion, representing 27% of OpenAI’s equity. The Yiaho team took a close look at the details.
Microsoft and OpenAI: Details of the $135 billion deal
The negotiations, launched in January 2024 following the internal crisis at OpenAI (and extended by tensions over governance and investments), stretched over twenty-two intense months, culminating on October 28, 2025 in a historic agreement.
They involved a series of confidential meetings in Redmond and San Francisco, legal arbitration with firms such as Goldman Sachs for OpenAI’s board, and near-daily virtual exchanges between the legal, financial, and technical teams on both sides, with Sam Altman conducting the orchestra.
These talks focused on key points: OpenAI’s valuation (set at $500 billion as part of the recapitalization), governance safeguards to preserve scientific independence (with a mixed board dominated by the nonprofit foundation), and the terms for integrating OpenAI’s technologies into Microsoft’s Azure ecosystem, including a massive $250 billion cloud services contract through 2032.
Microsoft, which injected an initial $1 billion into OpenAI as early as 2019, followed by several additional rounds totaling more than $13 billion, is now strengthening its position by becoming the main shareholder with around 27% of the stake.
Also read on this topic: GAFAM to invest $400 billion in AI in 2025
A restructured model
This strategic deal allows OpenAI to deeply restructure its model: the original nonprofit entity (renamed OpenAI Foundation) retains legal control through its board, while handing operational control to a for-profit subsidiary structured as a public benefit corporation (PBC), named OpenAI Group PBC.
This shift aims to speed up funding for ambitious projects such as the development of GPT-6 and to attract new talent in a hyper-competitive market dominated by rivals like Google DeepMind or Anthropic.
Impact on the markets
The announcement triggered an initial 4% rise in Microsoft’s share price at the opening of Wall Street trading on Tuesday. That gain then eased over the course of the day.
The market capitalization of the Redmond-based company topped $4 trillion. OpenAI is valued at $500 billion as part of this transaction.
Expected reactions to this deal
This change in OpenAI’s status, from a nonprofit organization to a more profit-oriented entity, could draw sharp criticism, notably from Elon Musk, an original co-founder who left the company in 2018 due to strategic disagreements.
He has repeatedly expressed, on social media and in interviews, his fierce opposition to OpenAI’s commercial shift, which he accuses of betraying its original mission to develop open AI that benefits all of humanity, in favor of financial interests dominated by major investors.
At the same time, this deal significantly strengthens the already close ties between Microsoft and OpenAI in artificial intelligence. By injecting billions of dollars and integrating OpenAI’s technologies into flagship products like Azure and Copilot, Microsoft not only cements its position as the undisputed leader in AI-driven cloud computing, but also accelerates the widespread adoption of these tools by businesses and individuals.
Source: Reuters
