Musk says xAI’s Grok 4.5, trained on Cursor data, launches Thursday

Elon Musk announced on Tuesday that SpaceXAI will release Grok 4.5, the company's latest large language model, to the public on Thursday, July 9, following an 11-day private beta with SpaceX and Tesla ↘ 3.22% teams. The model marks the first major product milestone since SpaceX ↘ 1.02% agreed to acquire Cursor maker Anysphere for $60 billion in June.reuters+3

A Bigger Model With Cursor in the Mix

Grok 4.5 is built on xAI's new V9 foundation architecture with roughly 1.5 trillion parameters — about three times the scale of the V8-small architecture that powered earlier Grok 4 variants. The model was supplemented during post-training with data from Cursor, the AI coding tool, to sharpen its coding and technical reasoning capabilities.felloai+2

Musk described the model on X as "Opus-class, but faster, more token-efficient and lower cost," a reference to Anthropic's Claude Opus line of models. No independent benchmarks have yet scored Grok 4.5, and xAI's internal claims of parity with top-tier reasoning models remain unverified by third parties.x+2

From Acquisition to Integration

SpaceX announced its all-stock acquisition of Anysphere on June 16, days after the rocket company's IPO, in what became the largest deal in AI developer tooling history. The transaction, valued at $60 billion, is expected to close in the third quarter of 2026.cosmicjs+1

Under SpaceX's plans, Grok will become the default model inside the Cursor IDE, and the company intends to ship its Grok Build developer platform within the editor. An xAI engineer confirmed that Cursor session data was used in a supplemental training stage rather than initial pre-training, a distinction that tempers expectations for how deeply coding expertise is embedded in the model.buildthisnow+2

What Comes Next

Grok 4.5 is an interim release, not xAI's next flagship. The company has seven models training concurrently on its Colossus 2 supercomputer, including Grok 5 variants at six trillion and ten trillion parameters. Pricing for Grok 4.5 has not been confirmed, though its predecessor, Grok 4.3, set an aggressive benchmark at $1.25 per million input tokens. The model is expected to be available through X for Premium+ and SuperGrok subscribers as well as through the xAI API.mindstudio+2