Microsoft and OpenAI keep competing for the same customers, yet one is still writing the other very large checks. Microsoft disclosed in a regulatory filing that it booked $10 billion in revenue from OpenAI arrangements in the quarter ended September 30. That is nearly 11% of its $92.3 billion total for the period.
The quarter is the first of Microsoft’s fiscal 2027. For all of fiscal 2026, OpenAI-related revenue came to $24.1 billion. At the latest pace, the annual figure would be about $40 billion. Receivables tell a similar story: OpenAI owed Microsoft $7.2 billion at the end of September, up from $6 billion in June. That is money owed for past transactions, not new revenue, but the direction is worth watching.
What we don’t know is the split. The filing doesn’t say how much came from revenue-sharing payments versus Azure compute. That matters. Leaked documents reported by TechCrunch in November 2025 put net revenue-sharing payments at $865.8 million for the first nine months of that year, which suggests Azure spending is doing most of the lifting. OpenAI reportedly shares 20% of its revenue with Microsoft, though neither company has confirmed that number.
The bigger picture is a partnership being slowly unwound without anyone losing money. In October 2025, Microsoft gave up its exclusive hold on OpenAI so the startup could use other cloud providers. In return, OpenAI committed to buy an additional $250 billion in Azure services. An April 2026 agreement keeps revenue sharing going through 2030, subject to a cap, even though OpenAI can now work with Microsoft’s cloud rivals like Google and Amazon.
Microsoft’s ownership stake is shrinking too. It slipped from about 25% in June to 24% in September, and it was roughly 27% after the October 2025 recapitalization. Microsoft didn’t say what caused the dilution.
So is this a big deal? Yes, mostly as a measure of dependence. Roughly one dollar in nine of Microsoft’s revenue now traces back to a company that sells products against Copilot and Azure AI. Investors who like Microsoft’s AI story should recognize how much of it rides on OpenAI continuing to grow and keep paying. Compare that with Amazon, whose Anthropic ties are far smaller relative to its revenue, or Google, which mostly builds its own models.
The hedge is obvious. Microsoft is building in-house models and courting other labs, while OpenAI is shopping for compute elsewhere. But the cap on revenue sharing and the stake dilution show the relationship tilting toward OpenAI over time. For now, the cash keeps flowing, and that’s the part worth tracking.
