Mistral releases the weights of an improved Mistral Large 4 (“Le Chonk”), a 1T-parameter MoE, under a modified MIT licence

Mistral AI published the weights of Mistral Large 4 (“Le Chonk”) on October 29, 2026, three weeks after the model went into public preview (see Mistral releases Mistral Large 4 (“le Chonk”)). The released checkpoint is not the preview: Mistral kept training it with reinforcement learning and says coding and defensive-cyber scores rose, for example Terminal-Bench 4.0 from 28% to 41%, with fewer output tokens. Reasoning now has three settings (Low, Medium, High); it can no longer be switched off.

The weights come in FP8 and NVFP4 on Hugging Face, with llama.cpp and Unsloth quantisations on the same day. They use a new “Mistral Ecosystem Open-Weight license”, described by Mistral as “a modified MIT license”: anyone may use, modify and sell products built on it, but a company that runs a model-as-a-service business must first sign a commercial licence. Hacker News commenters said that makes it “weights available” rather than open source. The API price fell to $0.70 per million input tokens and $2.10 per million output tokens, roughly half the preview’s list price.

Mistral pitches the model for agentic coding and for cyber defence, naming about ten security vendors as partners and saying the EU cybersecurity agency ENISA is testing it. It also says that while the preview was live it “carefully monitored cybersecurity-related use” and saw “a potential for uplift to conduct real attacks”, and that it is “modifying our guardrails accordingly”. A more specialised cyber variant stays with vetted design partners such as Orange Cyberdefense. Guardrails that Mistral runs on its own API do not apply to copies of the weights that others run themselves.

Benchmarks in Mistral’s post are self-reported. Artificial Analysis’s own page puts the model at 26 on its Intelligence Index v5, above the open-weight median for its size; Hugging Face calls it the fifth-best open-weight model on that index.

It is the largest open-weight model from a European lab. One Hacker News commenter argued that it “opens a lot of doors” for regulated US businesses that cannot run Chinese models and have relied on smaller US open models such as gpt-oss or Gemma. It also shows a lab publishing weights while saying it saw uplift for real attacks in its own traffic, and keeping its strongest cyber variant gated.