Microsoft Replaces OpenAI and Anthropic Models in Excel and Outlook with In-House MAI Models
Taylor Wilson
Microsoft is swapping OpenAI and Anthropic models for its own MAI models inside Excel, Outlook, and other core Office apps, already handling tens of thousands of AI prompts per week. This means → Microsoft is shifting from AI buyer to AI builder, and its suppliers' pricing leverage is starting to erode.
Where is the swap already happening?
Excel and Outlook previously relied heavily on OpenAI and Anthropic models; both have now partially switched to Microsoft's in-house MAI models.
Tens of thousands of AI prompts per week are already processed by MAI — a scale never publicly disclosed before.
Microsoft declined to comment; the report comes from Bloomberg, citing people familiar with the matter.
What did Suleiman say — and why so bluntly?
Microsoft's AI-models chief Mustafa Suleiman said at the June Build conference: "We pay Anthropic a lot of money — our goal is to reduce and ultimately eliminate that cost."
In plain terms = Microsoft doesn't just want to save money; it wants to downgrade external AI vendors from "must-have" to "nice-to-have."
At the same event Microsoft unveiled seven new AI models, one of which reportedly matches Anthropic's older Opus 4.6 model in coding ability — at lower cost.
Why is Microsoft in such a hurry?
Microsoft currently gets discount pricing through a long-term deal with OpenAI, but that deal has an expiration date.
This means → if Microsoft lacks sufficient in-house capability when the agreement lapses, it will be forced to accept market pricing from external AI vendors — with zero negotiating leverage.
Suleiman's team is racing to build scale and capability before that window closes.
Where else will MAI models show up?
GitHub Copilot, Microsoft's developer assistant, already supports MAI model calls.
A proprietary speech-transcription model will be integrated into Teams video conferencing and other products within months.
MAI still accounts for a small share of Microsoft's total AI usage, but its presence in core productivity apps signals a structural narrowing of dependence on outside AI suppliers — putting pricing pressure on both OpenAI and Anthropic.
Content is for reference only, not financial advice.