Mistral Opens 1T 'Le Chonk' Large 4 Under Modified MIT License

Mistral released the weights for Mistral Large 4, a trillion-parameter multimodal mixture-of-experts model it nicknames "Le Chonk," under its Ecosystem Open-Weight license, a modified MIT with one carve-out. The company's own announcement states the pitch directly: "We release the weights of Le Chonk, advancing the frontier of open models in agentic coding and cybersecurity."

The benchmark story is the sales argument. Mistral reports 19.7% on FrontierCode 2.0 and 41% on Terminal-Bench 4.0, a 13-point jump from the earlier preview release, along with 48% on the Artificial Analysis Coding Agent Index while using 47% fewer tokens than competitors on the same task. On the security side, the model scores 51% on the Artificial Analysis Cyber Index, refuses 96.6% of malicious cyber requests, and resists 97.1% of attacks on the B3 Agent Security Benchmark. Enterprise numbers include 73.3% on FinWorkBench and 84.5% on BrowseComp.

The license is where the "open" claim gets qualified. Mistral says the model is free to use, modify, fine-tune and commercialize, with one condition: "businesses that operate a Model-as-a-Service offering must obtain a separate commercial license from Mistral before using the model commercially." The announcement does not define where SaaS wrapping ends and MaaS begins.

API access runs $0.70 per million input tokens, $0.07 per million for cached input, and $2.10 per million output. Weights sit on Hugging Face, listed as Mistral-Large-4-1T-A52B. The company also lists OpenRouter, NVIDIA endpoints, vLLM and SGLang at launch, and says the model was "developed and trained from scratch on European infrastructure" with native fluency in 160+ languages.

The release lands in a busy stretch for the lab: it is our eleventh Mistral story in 90 days, and comes a day after the open release of the Timestral family of time-series models.