Mistral AI Releases Small 4: 119B Parameter Open-Source Model with 256K Context Under Apache 2.0

Mistral AI has released Mistral Small 4, a 119B total parameter mixture-of-experts (MoE) model with 256K context window and native multimodal capabilities. The model uses 128 experts with 4 active per token (6B active parameters, 8B including embedding and output layers) and is released under the Apache 2.0 license.

Architecture and Specifications

Mistral Small 4 employs a mixture-of-experts architecture with 128 total experts and 4 active per token. The model has 119B total parameters with 6B active parameters per token. According to Mistral AI, the model supports a 256K context window and accepts both text and image inputs.

The model includes a configurable reasoning_effort parameter that allows users to toggle between fast responses (reasoning_effort="none") equivalent to Mistral Small 3.2's chat style, and deep reasoning mode (reasoning_effort="high") with step-by-step analysis similar to previous Magistral models.

Performance Claims

Mistral AI claims a 40% reduction in end-to-end completion time in latency-optimized setups and 3x more requests per second in throughput-optimized configurations compared to Mistral Small 3. The company states the model achieves competitive scores on benchmarks while generating significantly shorter outputs than comparable models.

On the AA LCR benchmark, Mistral AI reports a score of 0.72 with 1.6K characters of output, compared to Qwen models requiring 5.8-6.1K characters for comparable performance. On LiveCodeBench, the company claims the model outperforms GPT-OSS 120B while producing 20% less output.

Hardware Requirements

Minimum infrastructure requirements:

• 4x NVIDIA HGX H100, or
• 2x NVIDIA HGX H200, or
• 1x NVIDIA DGX B200

Recommended setup for optimal performance:

• 4x NVIDIA HGX H100, or
• 4x NVIDIA HGX H200, or
• 2x NVIDIA DGX B200

Availability and Deployment

The model is available immediately on Mistral API, AI Studio, and Hugging Face under the Apache 2.0 license. It supports inference frameworks including vLLM, llama.cpp, SGLang, and Transformers. The model is available as an NVIDIA NIM for production deployment and can be customized with NVIDIA NeMo for domain-specific fine-tuning.

Mistral AI has joined the NVIDIA Nemotron Coalition as a founding member and collaborated with NVIDIA on inference optimization for vLLM and SGLang.

What This Means

Mistral Small 4 represents the first major open-source model to unify reasoning, multimodal, and coding capabilities in a single release under a permissive license. The 256K context window and MoE architecture with 6B active parameters position it as a deployment-friendly alternative to dense models requiring more compute per token. The Apache 2.0 license allows commercial use and fine-tuning without restrictions, though real-world performance claims will need independent verification across diverse workloads. The configurable reasoning mode is a notable feature that could reduce the need for maintaining separate model deployments for different task types.