Microsoft replacing OpenAI, Anthropic models, and CEO Satya Nadella explains why

Microsoft is routing work inside GitHub Copilot, Excel and Outlook away from OpenAI and Anthropic models, towards its own MAI family. Satya Nadella explained the shift on X: use frontier models only for frontier problems, push everything else to cheaper in-house models. Microsoft's Excel model matches GPT 5.4 at 10 times the efficiency. Copilot Chat and PowerPoint are next in line.