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

Earlier this week, Bloomberg reported that Microsoft was replacing some OpenAI software with its own internal models in an effort to cut costs. These internal models, known as MAI, are increasingly being used to run applications like Word and Excel, the outlet noted.

This story raised an increasingly popular question about the two companies, which were once inseparable and have recently sent mixed signals about their status: Were the two companies diverging?

Now, OpenAI is trying to put to rest any hints of such a malfunction. During OpenAI’s launch of GPT 5.6 on Thursday, the company announced that it will become the “preferred model” running Microsoft’s 365 Copilot software.

GPT 5.6 will support Microsoft users across the company’s suite of productivity applications, including Word, Excel, PowerPoint, and Cowork, OpenAI noted in a blog post published Thursday.

“Our partnership with Microsoft has always been about bringing the benefits of advanced AI to more people and organizations, and we are excited to continue building on this shared commitment,” OpenAI wrote in a blog post.

What the “preferred model” actually means isn’t entirely clear, other than that OpenAI will continue to run Microsoft applications.

However, it was never reported that ChatGPT would stop running Microsoft applications — just that Microsoft was increasingly relying on its own software in an attempt to reduce costs. The revelation of the new “preferred model” does not seem to negate this previous report.