OpenAI's GPT 5.6 named preferred model for Microsoft 365 Copilot amid breakup rumors

Earlier this week, Bloomberg reported that Microsoft was increasingly relying on its own in-house AI models, called MAI, to power apps like Word and Excel, aiming to reduce costs. This sparked speculation that the close partnership between Microsoft and OpenAI—historically seen as inseparable—might be drifting apart. The report raised questions about the future of their multi-billion dollar alliance, especially as Microsoft has invested heavily in OpenAI while also developing its own AI capabilities.

Now, OpenAI is pushing back. During the launch of GPT 5.6 on Thursday, the company announced that the new model would become the 'preferred model' powering Microsoft 365 Copilot across productivity apps including Word, Excel, PowerPoint, and Cowork. In a blog post, OpenAI stated: '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.' However, the term 'preferred model' remains ambiguous—it doesn't confirm exclusivity or replace existing arrangements. Notably, the announcement does not negate the earlier reporting that Microsoft is developing its own models to reduce dependency on OpenAI's expensive software. The situation suggests a complex co-opetition dynamic rather than a clean break.