OpenAI has moved to reassure the market that its partnership with Microsoft remains intact, announcing that GPT 5.6 will serve as the “preferred model” for Microsoft 365 Copilot even as reports circulate that the software giant is turning to its own in-house AI to cut costs.
The announcement came during the launch of OpenAI’s GPT 5.6 family of models on Thursday. In a blog post, OpenAI stated that GPT 5.6 would be the preferred model powering Copilot across Word, Excel, PowerPoint, and the newly launched Cowork application.
“Our partnership with Microsoft has always been about bringing the benefits of advanced AI to more individuals and organizations, and we’re excited to continue building on that shared commitment,” the company wrote.
The statement was a direct response to a Bloomberg report earlier this week that revealed Microsoft was increasingly relying on its own MAI models in applications like Word and Excel to reduce its dependency on OpenAI’s more expensive technology. The report had triggered widespread speculation about a potential rift, or even a breakup, between the two companies, whose relationship has been described as a “situationship” in recent financial analysis.
The term “preferred model” leaves room for interpretation. It does not mean GPT 5.6 is the exclusive model powering Copilot. Microsoft could still deploy its own MAI models for certain tasks while using OpenAI’s models for others. The phrasing appears designed to signal continuity without contradicting the cost-cutting narrative that Bloomberg originally reported.
The arrangement reflects a broader industry trend: as AI infrastructure costs balloon, enterprises are seeking more flexible, multi-model strategies rather than exclusive partnerships. Microsoft’s dual-track approach, using both OpenAI and its own models, may become the norm rather than the exception.
Sources: OpenAI says GPT 5.6 is the preferred model for Microsoft Copilot 365 amid breakup chatter (TechCrunch, Jul 9, 2026)