Microsoft reportedly plans to start using Anthropic models to power some of Office 365's Copilot features

Microsoft is reportedly planning to start using Anthropic's latest Claude models to power some of the Copilot features in its Office 365 apps. This decision comes as a potential sign of a growing split between Microsoft and its long-time partner, OpenAI, which currently provides the majority of AI features for Word, Excel, Outlook, and PowerPoint. Microsoft denies that the move is motivated by animosity, stating that OpenAI will continue to be a partner on frontier models. However, the tech giant is said to be partly motivated by the belief that Claude 4 Sonnet "performs better in subtle but important ways" than GPT-5, particularly in generating more aesthetically pleasing PowerPoint presentations. The decision to use Anthropic's models is notable as Microsoft will have to pay Amazon, Anthropic's primary cloud provider, for access to Claude Sonnet 4, unlike with OpenAI's models, which Microsoft can access at no additional cost due to its investment in the company.