Microsoft said in its quarterly report filed on 28 October 2026 that, for the three months to 30 September, it recorded revenue from commercial arrangements with OpenAI, inclusive of revenue-sharing payments, of $10.0 billion. Its income statement puts total revenue for the quarter at $92.3 billion.
By our arithmetic, that makes OpenAI about 10.8% of Microsoft’s revenue in the quarter. For the fiscal year to 30 June 2026, Microsoft’s annual report put revenue from OpenAI at $24.1 billion and total revenue at $331.8 billion; by our arithmetic, that is about 7.3%.
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The key insight: By our arithmetic from Microsoft’s 10-Q, OpenAI accounted for about 10.8% of Microsoft’s revenue in the quarter to 30 September 2026, up from about 7.3% for fiscal 2026.
The 10-Q says Microsoft holds an equity method investment that represents an approximate 24% interest in OpenAI on an as-converted basis. Because OpenAI is an equity method investee, the filing treats it as a related party and discloses revenue and accounts receivable from transactions with it.
Accounts receivable from OpenAI were $7.2 billion on 30 September 2026 and $6.0 billion on 30 June 2026, according to the filing. By our arithmetic, that is a rise of $1.2 billion in the quarter, and the September balance equals about 72% of the quarter’s OpenAI revenue.
Microsoft revenue from commercial arrangements with OpenAI, inclusive of revenue-sharing payments, as a share of total revenue: fiscal year to 30 June 2026 ($24.1 billion of $331.8 billion) and the quarter to 30 September 2026 ($10.0 billion of $92.3 billion). Shares are our arithmetic. Sources: Microsoft FY2026 Form 10-K and Form 10-Q filed 28 October 2026.
Against Last Fiscal Year
The annual report gives only a full-year figure for fiscal 2026, $24.1 billion. By our arithmetic, that averages about $6.0 billion a quarter, so the $10.0 billion recorded in the September quarter is about two-thirds above that average.
The Investment Line
Separately from revenue, Microsoft records gains and losses from its investments in OpenAI in other income (expense), the filing says. The 10-Q says other income included $272 million of net gains for the September 2026 quarter and $4.1 billion of net losses a year earlier from investments in OpenAI. It says the gains raised net income by $207 million, or $0.03 a share, and that a year earlier the losses lowered net income by $3.1 billion, or $0.41 a share.
Microsoft’s non-GAAP figures exclude these gains and losses. By our arithmetic, the $272 million gain was about 0.6% of the quarter’s $46.0 billion of income before taxes; a year earlier, the $4.1 billion loss equalled about 12% of $34.3 billion.
Earlier filings show larger amounts. Microsoft’s December 2025 quarterly report recorded $10.0 billion of net gains for that quarter, and its fiscal 2026 annual report says the year’s $6.5 billion of net gains primarily related to the dilution gain from OpenAI’s recapitalisation.
Stake and Funding
Microsoft’s September 2025 quarterly report said that after OpenAI’s recapitalisation Microsoft held approximately 27% of the new public benefit corporation on an as-converted diluted basis, and that under a new agreement OpenAI had contracted to purchase an incremental $250 billion of Azure services. The filings put the interest at approximately 25% in June 2026 and approximately 24% in September 2026.
The filings put Microsoft’s total funding commitments at $13 billion, of which $11.6 billion had been funded by 30 September 2025 and $12.0 billion by 30 September 2026. By our arithmetic, about $1.0 billion remains to be funded.
As we read the filings, the two OpenAI lines differ greatly in size: the 10-Q records $10.0 billion of revenue from OpenAI in the quarter and $272 million of net gains on the investment.
By our arithmetic, accounts receivable from OpenAI rose $1.2 billion in the quarter, to $7.2 billion, equal to about 72% of the quarter’s OpenAI revenue.
The filings put Microsoft’s interest at approximately 27% after OpenAI’s recapitalisation in October 2025, approximately 25% in June 2026 and approximately 24% in September 2026.
Microsoft Form 10-Q, quarter to 30 September 2026, business overview
“Microsoft is a major investor in OpenAI and will continue to receive revenue-sharing payments”
Three Implications
FOR REVENUE Microsoft recorded $10.0 billion of revenue from commercial arrangements with OpenAI in the quarter, inclusive of revenue-sharing payments, according to its 10-Q; by our arithmetic that is about 10.8% of total revenue.
FOR THE BALANCE SHEET OpenAI owed Microsoft $7.2 billion on 30 September 2026, against $6.0 billion on 30 June, the filing says.
FOR EARNINGS The OpenAI investment line added $207 million to net income this quarter, the filing says, against a $3.1 billion reduction a year earlier.
The framework argues: “The $1T capex cycle is being underwritten by a $1T concentrated demand commitment from two counterparties whose combined free cash flow is deeply negative.” It names those counterparties as OpenAI and Anthropic.
Microsoft’s 10-Q now puts a number on one side of that relationship: $10.0 billion of revenue from OpenAI in a single quarter. The framework was published in May 2026 and does not discuss this figure.
What Is Not Established
The 10-Q does not split the $10.0 billion between cloud services and revenue-sharing payments, and it does not explain why the figure rose. Microsoft did not disclose quarterly OpenAI revenue for fiscal 2026, so the comparison with the fiscal 2026 average is approximate.
The filing says Microsoft calculates its equity method income or loss using the hypothetical liquidation at book value method, so the investment line is not a simple share of OpenAI’s profit or loss. Microsoft’s release says it gives forward-looking guidance on its earnings call; nothing from the call is included here.
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Microsoft recorded $10.0 billion of revenue from commercial arrangements with OpenAI in the quarter to 30 September 2026, inclusive of revenue-sharing payments, according to its 10-Q. By our arithmetic, that is about 10.8% of its $92.3 billion in revenue, against about 7.3% for fiscal 2026. OpenAI owed Microsoft $7.2 billion at the end of the quarter, the filing says, up from $6.0 billion in June.
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A note on sourcing. All OpenAI figures come from the related-party, equity method and other-income disclosures in Microsoft’s Forms 10-Q for September 2025, December 2025, March 2026 and September 2026 (the last filed on 28 October 2026) and its fiscal 2026 Form 10-K. Shares of revenue and pretax income, differences and averages are our arithmetic; linked earlier pieces carry their own sources.
Gennaro Cuofano is a CRO and tech executive who has worked in AI since late 2015, starting with bringing NLP, natural-language generation, voice and chatbot products to the marketing industry. His background is in law and finance: he holds a Master's degree in Law and an International MBA with an emphasis on corporate finance (LUISS Business School and the University of San Diego, 2012), and worked as a financial analyst at a real-estate investment firm in San Diego and as an assistant controller. His work focuses on business model strategy, business engineering and, more broadly, structural analysis: how companies make money, read from their own filings. He created FourWeekMBA and leads research there and at The Business Engineer, his newsletter on AI and business strategy, with over 95,000 subscribers and more than 1,000 published analyses. His writing has also appeared on Entrepreneur (for example, How to Digitize a Family Business in Europe) and HackerNoon. Find him on LinkedIn and Substack. See how we source.
