Cursor and SpaceXAI Release Grok 4.5, Their First Joint Model
SpaceXAI and Cursor have jointly launched Grok 4.5, a 1.5-trillion-parameter coding model available now across all Cursor plans at $2/$6 per million tokens — weeks before their $60B acquisition deal closes.
Image by SpaceX
Cursor and SpaceXAI Release Grok 4.5, Their First Model Trained Together
Cursor and SpaceXAI jointly launched Grok 4.5 on July 8, the first AI model the two companies have built together. The release is available now across all Cursor plans and from the SpaceXAI console, weeks before SpaceX's $60 billion acquisition of Cursor formally closes.
SpaceX announced the acquisition of Cursor's parent company Anysphere in mid-June at a $60 billion valuation. The deal is expected to close in Q3 2026. In the meantime, SpaceXAI — the AI unit that emerged when SpaceX absorbed xAI in February — and Cursor have moved ahead with a joint model trained on Cursor's development workflow data and SpaceXAI's Colossus compute infrastructure.
What Grok 4.5 Is
Grok 4.5 is a mixture-of-experts model built on a 1.5-trillion-parameter V9 foundation. SpaceXAI describes it as an Opus-class model designed primarily for software engineering, legal work, financial analysis, and agentic tasks — rather than general-purpose chat. Elon Musk framed it on X as "an Opus-class model, but faster, more token-efficient and lower cost."
On coding benchmarks, SpaceXAI's evaluations put Grok 4.5 at 83.3% on Terminal-Bench 2.1, competitive with Fable 5 at 84.3% and GPT-5.5 at 83.4%. On SWE Marathon pass@1, it scores 29.0%, ahead of Opus 4.8 at 26% and Fable 5 at 24%. SWE Bench Pro resolution rate comes in at 64.7%, behind Fable 5 at 80.4% and Opus 4.8 at 69.2%. These are vendor-run benchmarks and independent verification is pending.
The pricing is the sharpest differentiator. Grok 4.5 is priced at $2 per million input tokens and $6 per million output tokens. A faster premium variant runs at $4/$18. By comparison, Claude Opus 4.8 is priced at $5 input/$25 output, and GPT-5.6 Sol at $5/$30. SpaceXAI is offering free Grok 4.5 usage for a limited period in Grok Build and Cursor.
What Changes for Cursor Users
Grok 4.5 is available immediately in Cursor across desktop, web, iOS, CLI, and the Cursor SDK on all plans. The model is live in Grok Build and the SpaceXAI console via API key. EU availability is expected in mid-July.
For developers already working inside Cursor, Grok 4.5 sits alongside Composer 2.5 — Cursor describes the two as different model weight classes aimed at different task profiles. The key differentiator is that Grok 4.5 was trained with data from Cursor's real developer workflows, agentic sessions, and multi-file editing traces — meaning this is the first model specifically shaped by how Cursor users actually code rather than a general-purpose model integrated as a third-party option.
SpaceXAI has also committed to shipping new foundation models roughly monthly through the end of 2026. Grok 4.5 is the first public proof point of that cadence and the first to carry Cursor data as a co-development input rather than a downstream integration.
What the Acquisition Means for the Product
The Cursor acquisition has not yet formally closed, but the joint model launch makes the product relationship concrete before the corporate one is finalized. Reports indicate Grok 4.5 was trained partly using the same compute capacity SpaceXAI simultaneously leases to Anthropic and Google — a detail that underscores the infrastructure leverage SpaceXAI is building into its competitive position.
For Cursor users, the practical question is how the SpaceX acquisition will affect model availability, pricing, and product independence over time. The current message from both companies is continuity: all plans get Grok 4.5 access, existing settings carry over, and the model is pitched on price-to-performance rather than exclusivity. Whether that holds after the deal closes in Q3 is what developers should track closely.
