Mistral AI Drops ‘Le Chonk’: A Massive AI Model Named After a Cat Meme

Paris-based Mistral AI launched Mistral Large 4 on Tuesday, an AI model with 1 trillion parameters. That is the kind of system behind chatbots like ChatGPT and Claude, as parameters are the adjustable numbers it tunes during training—more of them generally means more capacity to learn, and more expensive to run.

“[Mistral Large 4] is at the frontier of open models, and by far the strongest open-weight model from the US or Europe,” Mistral AI’s Chief scientist Guillaume Lample, wrote on X.

Not all of those parameters work at once. Large 4 uses a “mixture of experts” design, meaning the model routes each question to a few specialist sub-networks, so only 49 billion parameters fire per answer. Mistral’s last flagship, Large 3, did the same with 41 billion active out of 675 billion.

The whole “Le Chonk” nickname has a backstory. In June, after Mistral renamed its Le Chat assistant to Vibe, fans on Reddit and X invented a fictional model called Le Chaton Fat—roughly “the fat kitten”—with 30 trillion parameters, 1,000 meows per second, and fake benchmarks claiming it beat Claude Fable 5.

CEO Arthur Mensch played along, replying that the model was really called “le gros chaton,” French for “the big kitten.” Mistral then added a cartoon cat to its Vibe website. Its real launch post now lists the model as, “very officially,” le Chonk.

Mistral sells “sovereign AI”—models a country or company can own and run without handing its data to outside firms. Saudi Arabia’s state-backed HUMAIN signed a deal worth hundreds of millions of euros in August with this company for this exact reason.

Mistral raised a €3 billion ($3.37 billion) Series D—a funding round that sells shares to investors—in September at a valuation above €21 billion ($23.6 billion), led by Samsung. Mistral says Large 4 is the first milestone on the roadmap that money funds.

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Le Chunk costs $1.36 per million input tokens and $4.18 per million output tokens—the chunks of text, roughly three-quarters of a word each, that AI companies bill by. Claude Opus 5.5 charges $4 and $20, while GPT-6 Astra charges $10 and $50.

That puts Large 4 at about a third of Opus 5.5’s price on input and a fifth on output. Against Astra, it is roughly a seventh and a twelfth.

What the benchmarks say

Mistral’s announcement mostly benchmarks Large 4 against Chinese open-weight models—DeepSeek V4 Pro, Kimi K3, GLM-5.3, and Qwen3.8 Max—and “open-weight” means anyone can download and run the model. Claude and GPT show up in only a handful of comparisons, and the newest Claude, Opus 5.5, appears only in a cybersecurity claim.

In a blind human evaluation of coding quality by Surge AI, Mistral Large 4 ranked second of five models with 3.74 out of 5, behind Claude Opus 5’s 4.22.

AutomationBench hands an AI 657 chores in simulated business software—finance, HR, sales, support—and scores the share of each task’s goals it completes, with zero credit if it breaks a rule. Large 4 scored 59.9 points. On Artificial Analysis’s board, Claude Sonnet 5.5 hit 71.8, Opus 5.5 hit 69.5, and Gemini 4 Argon topped the page at 77.5 on that same benchmark.

On DeepSWE 1.1, which is one of the benchmarks developers check out when trying to assess how good a model is at coding, Large 4 scored 62. That tops GLM-5.3 at 61 and DeepSeek V4 Pro at 57 but trails Kimi K3’s 68. Datacurve’s own leaderboard has GPT-6 Astra and Claude Opus 5 at 74.

Mistral says it will release Large 4’s weights—the trained numbers that make the model work—by the end of October, which would let outside developers download the model and test those claims themselves.