Explainer / Published 2026-10-29

Mistral opens the weights of its 1T-parameter flagship

Mistral released the weights of Mistral Large 4, a trillion-parameter multimodal model under a modified MIT licence with one commercial condition. Its own benchmarks lead open-weight coding.

Heavy metal weight plates rest beside an open wooden crate on a plain desk, with a small card showing a simple cat silhouette.
Conceptual illustration of released model weights; it does not depict the model, Mistral's software, or a benchmark result.

THE SHORT VERSION

  • Mistral published the open weights of Mistral Large 4 on October 29, a 1-trillion-parameter mixture-of-experts model with about 52 billion active parameters and a 1M-token context window.
  • The release license is a modified MIT license: free to use, modify, fine-tune and commercialize, except that businesses running a model-as-a-service offering need a separate commercial license.
  • Mistral reports leading open-weight results in agentic coding and defensive cybersecurity, while noting the model was trained on 3,800 Nvidia Grace Blackwell GPUs in its own European data centers.

The weights are out, after the preview

Mistral published the weights of Mistral Large 4 after releasing the model in public preview earlier this month. The company's announcement says the release follows additional reinforcement learning aimed at coding and defensive cybersecurity, and that the gains had not yet plateaued. The model is available through Mistral's API and Studio, on OpenRouter, and as a download from Hugging Face, where the model card lists deployment recipes for vLLM and SGLang. A quantized NVFP4 checkpoint for Blackwell GPUs is also published, and the card tags the release as image-text-to-text.

The model card describes a 1-trillion-parameter mixture-of-experts model with 49 billion active parameters per token, or 52 billion including embeddings and output layers. It has 128 routed experts with four active per token and one shared expert, accepts text and image input, produces text, and supports a 1-million-token context window. Its vision encoder is Pixtral-style and handles variable image sizes and aspect ratios, and the model supports native function calling and strict JSON schemas. Mistral says it trained the model from scratch on 3,800 Nvidia Grace Blackwell GPUs in its own data centers in Europe.

The license is almost MIT, with one condition

The release is not unrestricted. Mistral published the model under what it calls the Mistral Ecosystem Open-Weight License, a modified MIT license. The company says the model is free to use, modify, fine-tune and commercialize, with one condition: a business that operates a model-as-a-service offering must obtain a separate commercial license from Mistral before using the model commercially.

That condition separates two kinds of user. A company that downloads the weights to run them internally, or to build a product on top, falls under the open license. A company that resells access to the model as a service needs a deal with Mistral. The release does not say how Mistral would identify such a use, so enforcement rests on the licence terms rather than on a technical restriction. The distinction matters for cloud providers and inference startups more than for enterprises running the model in their own data centers.

Mistral's numbers put it at the open-weight top for coding

Mistral reports several benchmark results, all of which are the company's own summaries of third-party evaluations. On Cognition's private FrontierCode 2.0 benchmark, which tests whether a repository maintainer would merge an agent's change, Mistral Large 4 scores 19.7 percent, the company reports. On the Artificial Analysis Coding Agent Index, it scores 48 percent, effectively tied with GLM-5.3 while using 47 percent fewer tokens per task on average. On the Artificial Analysis Intelligence Index v5 the model scores 26, which Mistral describes as the highest among western open-weight models; Chinese open models score higher on that aggregate measure.

On Terminal-Bench 4.0, the company says the model improved by 13 percentage points over its preview to 41 percent, leading open-weight models while cutting output tokens by 30 percent. In Surge Code's blind pairwise evaluations, graders preferred Mistral Large 4 over GLM-5.3, Kimi K3 and DeepSeek V4.1 Flash, and preferred Claude Opus 5.5 over it. The announcement states that ranking itself, including the model it loses to. These are vendor-reported figures; the benchmarks are third-party, but the selection and presentation come from Mistral.

Defensive security is the other pitch

Mistral is marketing the release to security teams as much as to developers. It reports a score of 51 percent on the Artificial Analysis Cyber Index, which measures finding, reproducing, validating and patching vulnerabilities in a codebase, and says the model handles those defensive tasks without unnecessary refusals. It also reports an average refusal rate of 96.6 percent on malicious cyber requests across three jailbreak and harm benchmarks.

The company says it monitored live traffic after the preview and observed the model refusing black-box attacks against live targets while seeing potential for uplift in real attacks, and that it is adjusting guardrails. ENISA, the EU cybersecurity agency, is testing the model to identify vulnerabilities, audit code and analyse defensive logs, and Booz Allen, Cisco and Cloudflare also provided statements in the announcement. Enterprise design partners, including Orange Cyberdefense, are getting preview access to a specialized variant for penetration testing, vulnerability assessment and red-teaming, subject to vetting and contracts that restrict testing to owned or authorized systems. Mistral also says customers can tailor the model with proprietary security data through Mistral Forge.

Finance, browsing and agent security

Beyond coding, the company reports a Finch score of 73.3 percent for finance workflows, second among open models to Kimi K3, and 84.5 percent on BrowseComp for web browsing. On the B3 Agent Security Benchmark, it says the model resisted 97.1 percent of attacks, up from 93.3 percent in the preview, which the company presents as evidence that organizations can host it without additional tuning. The demos are published in a gallery that runs on the Mistral API with a small shared free budget for the first week, and each one is a company-selected task rather than a measured failure rate.

The announcement also lists demonstrations rather than benchmarks: an agent that triages vulnerability reports and iterates on a patch until a canary exploit fails, a generated 3D map of about 19,000 satellites and debris pieces, and a quantum chemistry solver checked against a standard tool. These are company-selected examples, and they show what the model can be asked to do rather than how reliably it does it.

What it costs to use, and what running it takes

On Mistral's API, the model is priced at $0.70 per million input tokens, $0.07 per million cached input tokens, and $2.10 per million output tokens. Microsoft is the first cloud provider to offer it, through Microsoft Foundry, and Nvidia hosts endpoints and publishes an optimized NIM container. The model card also notes a quantized NVFP4 checkpoint for Blackwell GPUs and an embedded speculative decoding head that Mistral says can raise throughput up to 1.9 times.

Self-hosting is the harder part. The model card's vLLM recipe uses tensor parallelism across eight GPUs, and a full-precision trillion-parameter model needs substantial memory. The license makes the weights available, and the hardware still decides who can serve them at scale. The published vLLM recipe assumes an eight-GPU node, which is the practical requirement for serving the checkpoint. That gap between an open license and a practical deployment is the part a reader should keep in view when the release is described as open. Related coverage includes the Mistral Responses API preview, Meta's open-weight Muse Spark, and Models. Another open-weight release, Reflection's Beam.

Sources & reporting limits

  1. Mistral Large 4 (Le Chonk) is now open weight
  2. mistralai/Mistral-Large-4-1T-A52B model card
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