The announcement was made at Microsoft’s Build developer conference on Monday, and was notable given Microsoft’s partnership with OpenAI. Musk founded xAI, the startup behind Grok, but he has also been locked in a feud with OpenAI since stepping down from its board in the late 2010s, citing disagreements over its leadership direction.

Musk’s deal means that the latest versions of xAI’s Grok models will be hosted on Microsoft’s Azure cloud computing platform, alongside competing models from OpenAI and other companies, including Facebook parent Meta Platforms.