BREAKING: Elon Musk announced that Grok 4.5 is now in private beta at SpaceX and Tesla, with early evaluations showing performance "close to, perhaps exceeding Opus" Grok 4.5 is based on the V9 foundation model, which has 1.5 trillion parameters. That is 3 times the size of the V8 model currently serving all Grok production traffic. The model was trained with a large amount of Cursor developer workflow data in supplemental training. Opus refers to Anthropic's Claude Opus 4.6, one of the leading general-purpose AI models alongside GPT-5.5. Musk's comparison is the first public benchmark claim against a frontier rival for Grok 4.5. Musk also said that SpaceX will release a completely new foundation model, trained from scratch, every month for the rest of 2026. That cadence is unprecedented. OpenAI, Anthropic and Google currently release major frontier models every 3 to 6 months. The private beta at Tesla and SpaceX is the first internal deployment of Grok 4.5. Reinforcement learning continues to improve the model. V9 foundation model training completed on May 26, 2026. SpaceX acquired Cursor for $60 billion earlier this month. (Source: @elonmusk on X, June 28, 2026)