Microsoft disclosed Wednesday in a regulatory filing that it generated $10 billion in revenue from its commercial arrangements with OpenAI - including revenue-sharing payments - in the quarter ended September 30. That's nearly 11% of Microsoft's total quarterly revenue of $92.3 billion, a handy reminder that the two companies are locked in a deeply lucrative embrace even as they increasingly elbow each other for the same customers.

A note for the calendar-impaired: Microsoft's fiscal year starts in July, which makes the quarter ended September 30, 2026 the first quarter of its fiscal 2027. Time is a flat circle, but the accounting is quarterly.

For the full 2026 fiscal year, OpenAI-related revenue reached $24.1 billion. At the latest quarterly pace, Microsoft would haul in $40 billion annually from these arrangements - a nice little side business attached to the side business.

Microsoft also reported $7.2 billion in outstanding receivables from OpenAI at the end of September, up from $6 billion at the end of June. That's money OpenAI owes for previous transactions, not fresh revenue - an important distinction for anyone tempted to double-count their way to a headline.

How much of the $10 billion came from revenue-sharing payments versus Azure cloud computing services remains unclear; TechCrunch has asked for more information. For context, in November 2025 TechCrunch reported, citing leaked documents, that Microsoft had received $865.8 million in net revenue-sharing payments from OpenAI during the first nine months of that year.

OpenAI reportedly shares 20% of its revenue with Microsoft under a previous deal in which the software giant invested more than $13 billion in the AI startup - a percentage neither company has publicly confirmed. Under an April 2026 agreement, OpenAI must keep sharing revenue with Microsoft through 2030, subject to a cap, even as it's free to work with competing cloud providers.

The once-exclusive partnership began loosening in October 2025, when Microsoft relinquished its hold on OpenAI to give the startup more freedom to partner with other cloud providers. In exchange, OpenAI committed to buying an additional $250 billion in Azure services as part of that October 2025 agreement.

Meanwhile, Microsoft's ownership stake in OpenAI slipped from about 25% in June to 24% in September - continuing a gradual decline from roughly 27% following the October 2025 recapitalization. Microsoft did not specify what caused the dilution, leaving observers to enjoy the mystery.