Grok 4.5 is better than Anthropic's Opus model: Musk
What's the story
Elon Musk has announced that his artificial intelligence (AI) company, xAI, has entered the private beta phase for its latest model, Grok 4.5. The testing is being conducted at SpaceX and Tesla facilities. Early internal evaluations show that Grok 4.5 performs similarly to or even better than Anthropic's Opus model in some cases.
Model evolution
Grok 4.5 is trained on Cursor data
Musk revealed that Grok 4.5 is based on xAI's 1.5 trillion parameter (1.5T) V9 foundation model, which has been enhanced with Cursor data during supplemental training. The additional Cursor data, obtained from developer workflows, multi-file edits, refactors, and iterative correction cycles, is intended to improve the model's coding capabilities. SpaceX had agreed to acquire Cursor earlier in June for its AI coding assistant capabilities.
Model refinement
SpaceX will launch new model every month
Musk also revealed that reinforcement learning is continuously improving Grok 4.5, and "Grok Build," xAI's coding-agent harness, is being refined daily. He described the deployment at SpaceX and Tesla as an internal proving ground before any wider release. Musk further stated that SpaceX will launch a completely new model, trained from scratch, every month for the rest of this year.
Strategic move
SpaceX to acquire Anysphere for $60 billion
In a strategic move to bolster its position in the lucrative enterprise AI tools market, SpaceX has agreed to acquire Anysphere, the startup behind the popular AI coding agent Cursor. The all-stock deal is worth $60 billion. The acquisition will give xAI a stronger foothold in coding, one of the first areas where companies have been able to monetize AI technology.
Twitter Post
Musk's post
Grok 4.5, based on our 1.5T V9 foundation model, with Cursor data added in supplemental training, is now in private beta at SpaceX & Tesla. Early evals show performance close to, perhaps exceeding Opus.
— Elon Musk (@elonmusk) June 28, 2026
RL is continuing to significantly improve the model, and the Grok Build…