Muse Spark Open
Meta released Muse Spark Open, an 816B-parameter open-weight mixture-of-experts model with 42B active parameters, which it calls the most capable US open-weight model to date.
Muse Spark Open is Meta's largest open-weight model. It is a mixture-of-experts design that takes text, images, audio and video as input and outputs text, with a context window of up to 1 million tokens. It was trained for agentic coding and tool use, and Meta worked with Apple so it can run locally with MLX on two M5 Ultra Mac Studios.
- Date
- Thursday 15 October 2026
- Lab
- Meta
- Kind
- open-weights
- Access
- open weights (restricted license)
Figures
| Measure | Value | Measured by |
|---|---|---|
| Total parameters | about 816B about 42B active per token | company |
| Context window | up to 1M tokens | company |
| JobBench | 61.8 xhigh reasoning; GLM 5.3 61.4, Kimi K3 54.3, Qwen3.8 52.7 | company |
| MCP-Atlas | 89.2 xhigh reasoning; GLM 5.3 84.2 | company |
| Terminal-Bench 2.1 | 76.4 Kimi K3 85.0, GLM 5.3 83.9 | company |
| Artificial Analysis Intelligence Index | 39 reported on the model card; GLM 5.3 45, Kimi K3 44 | company |
| Speed on Mac M3 Ultra 512GB | 18 tokens/s 2-bit imatrix quant on llama.cpp, 304 GB used by the model | Hugging Face |
Custom license with a Built with Muse Spark Open attribution requirement and a $20 million exemption threshold described by VentureBeat. The 512GB Mac Studio configuration ships late October.
Sources
- huggingface.co/blog/meta-muse-spark-open
- venturebeat.com/technology/meta-unveils-muse-spark-open-the-new-top-u-s-open-weights-model
- techcrunch.com/2026/10/15/meta-launches-an-open-weight-model-that-runs-on-macs/
- tech.co/news/meta-challenges-china-with-new-open-weight-ai-model
- huggingface.co/nvidia/Muse-Spark-Open-816B-A42B-DFlash2
This record was partly confirmed: some claims could not be checked on 15 October 2026. How we check