Most of Microsoft's AI revenue comes from OpenAI, new disclosures show. A Bloomberg report puts the figure at $24.1 billion during the fiscal year ending in June, roughly 70 percent of Microsoft's total AI revenue. CEO Satya Nadella said in late March the AI business was on track to top $37 billion annually. Under their agreement, OpenAI pays Microsoft for computing power, model development costs, and a revenue share.

That reliance explains a lot about Microsoft's recent messaging. The same company long known for vendor lock-in has been championing open-weight models and warning against a few proprietary AI models capturing the value of entire industries. Nadella also criticized AI labs like OpenAI and Anthropic for opposing "distillation," the practice of training models on proprietary model outputs to build competitors with less effort. Chinese manufacturers have reportedly been especially aggressive with this approach. Meanwhile, Microsoft has been steadily swapping in its own AI models across Office products.

Bloomberg