Microsoft is expanding its AI capabilities by integrating Anthropic's AI models into its Copilot assistant, previously powered mainly by OpenAI. This move signifies a shift in Microsoft's reliance on OpenAI, following a recent deal to use Anthropic's AI in Office 365 apps. Copilot business users can now choose between OpenAI's models and Anthropic's Claude Opus 4.1 and Claude Sonnet 4 for tasks such as complex research and building custom AI tools. Opus 4.1 is suited for reasoning and coding, while Sonnet 4 is better for data processing and content generation.