Microsoft adds xAI's Grok to Copilot for Word, Excel and PowerPoint

The integration marks a shift toward multi-model Copilot environments with seamless model switching, letting M365 users pick Grok for tasks inside core Office apps. Grok arrives via the Frontier Program preview alongside Microsoft's existing OpenAI-powered Copilot, signaling Microsoft's intent to be a model-agnostic platform rather than an OpenAI-exclusive shop.

Grok 4.6 (released August 12) anchors the offering with a 500,000-token context window and a new 'xhigh' reasoning tier atop the existing low/medium/high options. Satya Nadella's terse endorsement — 'More model choice coming to Copilot. Welcome Grok!' (7,467 likes) — underscores how normalized the xAI-Microsoft relationship has become despite Musk's ongoing litigation with OpenAI, Microsoft's other partner.

The deal deepens the awkward triangle: Microsoft now ships models from both OpenAI and its founder-turned-rival's company inside the same product. For enterprises, more model choice is a clear win; for the ecosystem, it's another sign that Microsoft is hedging its OpenAI dependency. It also lands the same week Musk endorsed Amodei's slowdown essay — Grok expanding into Office while its CEO calls to pace the frontier is the week's neatest contradiction.