Microsoft has figured out it's better positioned as an AI orchestrator than as an OpenAI reseller.

The company is now actively pushing for open-weight models. In an open letter titled "Open Weights and American AI Leadership," which Microsoft signed alongside Meta, Nvidia, Hugging Face, Mistral, and more than 20 other companies, the group argues that "leadership will be judged not by one frontier AI model, but by whether the United States builds a strong, open ecosystem that diffuses into every sector."

Open-weight models are supposed to spur innovation and reduce dependence on a handful of providers. The letter also frames "distillation," in which a smaller AI model learns from a more capable model's output, as a legitimate way to build AI. "It reflects a long tradition of learning from, building upon, and improving existing technologies, a tradition that has helped drive innovation since the rise of the open-source software movement," the letter states.

Chinese providers have faced particular criticism for using distillation, while the Trump administration reportedly plans to take action against Chinese open-weight models. That's likely the main reason Microsoft and the other signatories are speaking up now.

The company that invented software lock-in now champions open AI to preserve it

Microsoft's enthusiasm for openness makes more sense when you look at its business model. The company makes money from cloud infrastructure on Azure and the lock-in created by its Windows and Office ecosystem. More models on Azure give customers fewer reasons to use rival AI platforms. Relying less on expensive models from OpenAI and Anthropic also improves Microsoft's margins.

A fragmented model market also stops any single AI lab from becoming powerful enough to threaten Microsoft's cloud and operating system businesses. CEO Satya Nadella wrote on LinkedIn that the key is using "the right model for each task" while keeping costs down. He had previously warned that a few AI models could absorb the value of entire industries.

Microsoft's savings may come at customers' expense

Microsoft is also replacing OpenAI and Anthropic models in GitHub Copilot, Excel, and Outlook with its in-house MAI family. Whether customers benefit from that swap is questionable. Independent benchmarks put MAI well behind OpenAI and Anthropic, with performance roughly matching Deepseek V3.2.

Copilot customers are getting weaker AI for the same price, while Microsoft pockets better margins. The company claims MAI performs just as well or better, but only compares it against smaller, less powerful models like GPT-5.4 Mini, Anthropic's Haiku, and "GPT-5.6" without specifying whether that means Sol, Terra, Luna, or which reasoning mode it runs at. That's not how you do benchmarks, and Microsoft's "superintelligence team," which made the comparison, certainly knows it.

Microsoft doesn't even try to hide that this is about cutting costs. The company states on its own blog that the smaller MAI model runs on older Nvidia GPUs like the H100 and A100 instead of requiring the latest accelerators, which "significantly lowers the cost of deployment for Microsoft." More MAI models are planned for Copilot Chat, Outlook, and PowerPoint.

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