Microsoft shares climbed 1.75% on Tuesday, marking an outperformance versus a broadly sluggish Nasdaq, after reports emerged that the company is shifting away from expensive third-party AI models in favor of internally developed systems.
Those reports indicate Microsoft has quietly introduced its MAI models into key Office applications, placing them inside Excel and Outlook to handle AI-driven tasks. An anonymous source familiar with the matter told reporters the behind-the-scenes change is already managing tens of thousands of AI prompts each week across the spreadsheet and email environments.
Until this deployment, Microsoft’s flagship productivity tools largely relied on external AI providers such as OpenAI and Anthropic. The recent internal rollout is notable because it is the first time the scale of Microsoft’s proprietary MAI integration into its workplace apps has been described publicly.
The tactical move reflects an emphasis on lowering the substantial infrastructure costs associated with operating artificial intelligence, while seeking to keep the company’s core software suite operating at full capacity. The company’s aim, as described in the reports, is to aggressively reduce the cost burden of AI infrastructure without degrading the functionality of its productivity applications.
Details in the reporting are limited to the scope described above: the presence of MAI models inside Excel and Outlook, the current volume of prompts being handled measured in the tens of thousands per week, and the broader strategic goal of cutting infrastructure expenses. The accounts do not provide additional figures on cost savings, timelines for wider rollout, or how existing arrangements with external providers will be adjusted.
Context and implications
The reported change documents a material operational adjustment in how Microsoft runs AI features within its core productivity apps. By routing a substantial number of prompts to in-house models, the company appears to be prioritizing control over key AI workloads and attempting to reduce the heavy infrastructure spending that accompanies large-scale AI services.
While the immediate market reaction was positive for Microsoft’s stock, the reporting stops short of detailing the full breadth of the transition or any contractual or technical ramifications with prior third-party suppliers.