Earlier this week Bloomberg reported that Microsoft had begun replacing some OpenAI software with its own in‑house models to reduce costs. Those internal models were referred to as MAI, and the report said they were increasingly being used to power applications such as Word and Excel.
That coverage renewed questions about the relationship between OpenAI and Microsoft—once seen as tightly linked—raising speculation that the two might be drifting apart. OpenAI sought to address those implications at the GPT‑5.6 launch.
On Thursday, OpenAI announced that GPT‑5.6 would be the “preferred model” for Microsoft 365 Copilot. In a blog post published the same day, OpenAI said GPT‑5.6 will support Microsoft users across the company’s productivity suite, including Word, Excel, PowerPoint and Cowork.
OpenAI wrote in the blog post: “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 did not fully define what being the “preferred model” entails in practice, other than indicating that OpenAI’s technology will continue to power Microsoft’s apps. Earlier reporting never claimed that ChatGPT‑based software would be completely removed from Microsoft’s products; it only described Microsoft’s growing reliance on its own models as a cost‑saving measure.
Thus, while OpenAI’s announcement confirms ongoing ties and the continued presence of its models in Microsoft 365 Copilot, it does not necessarily contradict Bloomberg’s reporting about Microsoft’s increased deployment of MAI models.
