OpenAI says GPT 5.6 is the ‘preferred model’ for Microsoft Copilot 365 amid breakup chatter

OpenAI announced that its new GPT 5.6 model will be the "preferred model" for Microsoft's 365 Copilot productivity suite, including Word, Excel, PowerPoint, and Cowork. This announcement comes after reporting that Microsoft was increasingly using its own in-house models, called MAI, to power some of these applications in an effort to reduce costs. OpenAI framed the announcement as a continuation of its partnership with Microsoft and a shared commitment to bringing advanced AI to organizations. The exact meaning of "preferred model" remains unclear, though the disclosure does not contradict earlier reports that Microsoft was reducing its reliance on OpenAI's software.