Regulatory filings submitted by Microsoft last week revealed startling data: in the fiscal year ending this June, Microsoft recorded revenue of $24.1 billion from OpenAI. According to Bloomberg estimates, this figure accounted for about 70% of Microsoft's AI business revenue, indicating that the growth engine of this tech giant's AI is largely driven by a single partner.

For a long time, the market has questioned the true composition of Microsoft's AI revenue, and this data has now revealed the concentration of the core driving force. Jackson Ader, an analyst at KeyBanc, pointed out that a key unresolved issue remains: how much of the $24.1 billion comes from cloud computing services and how much from revenue-sharing agreements.

The partnership structure comes to light, with service income and investment returns to be broken down

According to the agreement between the two companies, OpenAI pays Microsoft for computing power costs, AI model development expenses, and a percentage of its revenue. Microsoft confirmed that the $24.1 billion includes all sales and revenue-sharing from OpenAI. Ader emphasized that a higher proportion of service income better reflects true commercial delivery capability rather than book contributions from financial arrangements.

Previously, CEO Satya Nadella mentioned that Microsoft's AI business had an annualized revenue run rate of approximately $37 billion as of the end of the March quarter. However, it is worth noting that Microsoft has only publicly disclosed the overall scale of its AI business at two points in time—$13 billion in the December 2024 quarter and $37 billion in the March 2025 quarter. The rapid growth impressed the market, but the specific weight of OpenAI remained hidden until this document was released.

Efforts to reduce dependence have limited impact; IPO approach increases demand for transparency

In response to concerns about over-reliance on a single source, Microsoft has been trying to reduce its dependence on OpenAI in recent years, investing in Anthropic and accelerating its own AI model development. However, according to the latest data, these efforts have not yet resulted in sufficient diversification in revenue. While OpenAI accounts for less than 10% of total revenue, it remains the largest contributor to annual order volume growth.

The timing of this detailed disclosure is also quite delicate. Olga Usvyatsky, founder of Nonlinear Analytics and an accounting researcher, pointed out in her research report that the information release may be related to OpenAI's plan to go public. Previously, Microsoft had never explicitly released complete revenue data from OpenAI. As OpenAI moves toward the public market, the financial relationship between the two companies will face stricter scrutiny. Affected by this news, Microsoft fell 0.5% during trading on Wednesday, as investors continue to digest the transparency and sustainability of the partnership structure.