Microsoft is replacing AI models from OpenAI and Anthropic with its own in-house MAI models across several Copilot products, including Excel and Outlook, to cut costs. The MAI models are already processing tens of thousands of requests per week in Excel and Outlook, though they still handle only a small fraction of total requests. The MAI models are also available in GitHub Copilot, and a proprietary transcription model is expected to ship in Teams soon. At the Build conference, Microsoft unveiled seven new AI models, including MAI-Thinking 1, its first reasoning model. Microsoft claimed it could match Sonnet 4.6 and Opus 4.6 in coding based on human evaluations, but benchmarks showed Thinking-1 trailing the competition from OpenAI and Anthropic by a wide margin and landing roughly on par with Deepseek V3.2. Microsoft's head of AI, Mustafa Suleyman, acknowledged in June: "We pay a lot of money to Anthropic—so our goal is to reduce and ultimately eliminate that cost." Microsoft CEO Satya Nadella hinted that AI billing could shift toward usage-based pricing, with cheaper MAI models as the default and third-party models as premium add-ons. Microsoft claimed the MAI models are trained on clean, commercially licensed data, but the technical paper noted use of the Common Crawl dataset.