SpaceXAI today released Grok 4.6, a large language model that it says can outperform Anthropic PBC’s Claude Fable 5 in some areas.

The company was known as xAI until last month. The Elon Musk-founded artificial intelligence provider rebranded in connection with its acquisition by SpaceX Corp. In June, the combined company listed its shares on the Nasdaq via the biggest initial public offering on record.

Grok 4.6 is rolling out only a month after SpaceXAI released its previous flagship LLM. According to the company, one of the main improvements is that its engineers spent more time training the former model. The extended training run used an AI-generated dataset designed to improve Grok 4.6’s reasoning capabilities. SpaceXAI also provided the model with access to “high-quality engineering data.”

The initial training run was followed by two additional development steps. The first used a training method called supervised fine-tuning, or SFT, while the second used reinforcement learning.

An SFT training run refines an LLM’s output using a set of sample prompts and pre-packaged answers. Engineers mainly use the technique to ensure that LLM prompt responses are outputted in a user-friendly format. SpaceXAI used Grok 4.5, the predecessor of Grok 4.6, to optimize the latter model’s SFT training phase. The optimization workflow focused on improving its ability to tackle science and programming tasks.

SpaceXAI evaluated Grok 4.6 using the Artificial Analysis Intelligence Index. It’s a dataset that combines nine popular AI benchmarks spanning fields such as science, coding and financial services. Grok 4.6 scored 61, which put it on par with OpenAI Group PBC’s flagship GPT-5.6 Sol model and one point behind Claude Fable 5.

The company also compared the models across nine other benchmarks. Grok 4.5 managed to outperform Claude Fable 5 in three. One of the benchmarks, AA-Briefcase, evaluates LLMs’ ability to perform knowledge work projects that would take a human weeks to complete. The other two evaluations comprised tasks spanning more than a half-dozen industries.

Grok 4.5 is particularly adept at generating software prototypes based on high-level descriptions, according to SpaceXAI. Additionally, it’s better than its predecessor at creating visual assets such as interfaces. The model is also more likely to check its work for errors when working on long-horizon projects.

The standard version of Grok 4.6 is priced at $2 per million input tokens and $6 per million output tokens. SpaceXAI also offers a faster edition that costs twice as much. The LLM is available through Cursor, the vibe coding platform that the company bought for $60 billion in June, and an internally developed programming tool called Grok Build.

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