Buried in Microsoft’s fiscal 2026 annual report is a line the company has never had to write before: revenue from commercial arrangements with OpenAI, inclusive of revenue-sharing payments, of $24.1 billion for the year ended June 30. Accounts receivable from OpenAI on that date: $6.0 billion.
Microsoft did not volunteer this. OpenAI is an equity-method investee, which makes it a related party under ASC 850 — and ASC 850 requires disclosure of revenue and receivable balances with related parties. The number exists because an accounting standard demanded it, which is exactly why it’s useful. It is the first hard figure anyone outside either company has had for the commercial spine connecting them.
Set it against Microsoft’s own scale and the proportion is modest: $331.8 billion of total FY26 revenue, up 18%. OpenAI is about 7% of the whole company. Set it against the part of the company everyone actually pays a multiple for, and it is not modest at all.
The denominator nobody publishes
Microsoft has disclosed a complete AI sales figure roughly twice, and both times as an annualized run rate rather than a total — the last being an AI business run rate above $37 billion as of the March quarter, growing 123% year over year. Bloomberg, extending that growth through June, estimates Microsoft’s AI business took in something near $34 billion across the full fiscal year.
That is an estimate, not a disclosure, and it deserves to be labeled as one. But it is the only denominator available — and $24.1 billion into roughly $34 billion is around 70%. More than half of Microsoft’s AI revenue, on the best public math, comes from a single counterparty.
The composition makes it stranger. That $24.1 billion bundles Azure capacity OpenAI bought, revenue-sharing payments flowing back from OpenAI products, and other commercial agreements. Microsoft does not break it out. So the largest customer in Microsoft’s AI business is also a company Microsoft has committed $13.0 billion to fund — $11.9 billion of it already wired as of June 30 — and holds an equity stake in.
The receivable is the sharper number
$6.0 billion outstanding against $24.1 billion billed is roughly 91 days of sales sitting uncollected at year-end — about a quarter of the year’s revenue from this customer, unpaid when the books closed.
Nothing improper in that. Contracts this size settle on long terms, and a fast-growing customer always shows a receivable weighted toward its most recent quarters. But it is worth watching rather than waving through, because the counterparty’s cash needs are famously enormous and Microsoft is itself partly supplying the funding.
Our take: Every hyperscaler has spent two years reporting “AI revenue” as an undifferentiated growth number, and investors have paid for it as though it were a broad market forming. This disclosure is the first time one of them has been forced to show the customer list, and the customer list is short. That does not make the $24.1 billion less real — OpenAI paid it, and Azure delivered against it. It makes it a different asset than the market has been pricing. Diversified platform revenue and a single-name supply contract carry the same dollars and completely different risk. The tell to watch isn’t Microsoft. It’s whether Amazon, Google and Oracle now face the same question about their own anchor tenants — and whether any of them has an accounting rule that makes answering mandatory.
What to watch
- Next year’s comparative. ASC 850 disclosure recurs. FY27 shows whether $24.1 billion grew — and whether the receivable grew faster than the revenue. The second is the one that matters.
- Whether Microsoft publishes a real AI total. Run rates were convenient while the mix was unexamined. Less so now that a numerator is public and the denominator isn’t.
- Peer disclosure. Related-party treatment turns on the equity stake. Cloud providers invested in their largest AI customers may face the same requirement; ones at arm’s length won’t.
- The $1.1 billion left to fund. $13.0 billion committed, $11.9 billion delivered. What happens at the end of that commitment is an open question about the structure itself.
Microsoft reported a record quarter last week — Azure past $100 billion, Cloud revenue of $59.3 billion, commercial RPO up 84% to $678 billion. None of that is in doubt. The 10-K just added a footnote naming who a large share of the AI part is, and the answer is one company.