OpenAI has announced that its newly launched GPT 5.6 will be the "preferred model" powering Microsoft's 365 Copilot, a move widely read as an attempt to dampen speculation that the two companies are drifting apart. The declaration, made during Thursday's launch of the GPT 5.6 family, follows a Bloomberg report earlier in the week that Microsoft was increasingly using its own in-house "MAI" models to power apps such as Word and Excel in a bid to cut costs. The public reaffirmation matters because OpenAI and Microsoft have long been seen as close partners, and recent signals had raised questions about the health of that relationship.

According to OpenAI's blog post, GPT 5.6 will support Microsoft users across productivity apps including Word, Excel, PowerPoint and Cowork, with the company stressing its "shared commitment" with Microsoft to bringing advanced AI to more users. However, TechCrunch notes that the meaning of "preferred model" remains unclear beyond confirming that OpenAI's software will keep powering Microsoft's apps. Crucially, the original reporting never claimed OpenAI would be dropped entirely — only that Microsoft was leaning more on its own models to save money — so the new announcement does not appear to contradict earlier coverage.