Meta's Muse Spark Open scores 39 on Artificial Analysis Intelligence Index, top US open-weights model

Artificial Analysis says Meta's Muse Spark Open scores 39 on its Intelligence Index, the highest score of any US open-weights model.

The source says the 816B-parameter mixture-of-experts model, with 42B active parameters and a 1M-token context window, is weaker than leading Chinese open-weights models on agentic evaluations. It scores 22 points above Meta's 30B dense Muse Glimmer, which scored 17.

Meta released the weights on Hugging Face in BF16 and NVFP4 formats. Together AI, Fireworks and Baseten offer API access at launch at $1.25 per million input tokens and $4.25 per million output tokens, with $0.15 per million for cached input. Groq, Modal, Nebius, OpenRouter and Baseten also list API access.