On his 55th birthday, Elon Musk turned to X with a challenge for OpenAI's Sam Altman and Anthropic's Dario Amodei: starting next month, his AI team will ship a brand-new, trained-from-scratch foundation model every month through year's end. First up is Grok 4.5, a 1. 5T-parameter model now in private beta that he claims rivals—or perhaps beats—Anthropic's Claude Opus.

A 2T model lands in August.