Meta releases Muse Spark Open, an 816B-parameter open-weights model

Artificial Analysis says Meta’s Muse Spark Open has 816 billion total parameters, with 42 billion active, and scores 39 on its Intelligence Index—one point below Muse Spark 1.2. Among the nine highest-scoring open-weights models, it ranks last on the index’s four agentic evaluations but fourth on the other six combined. Meta says its roughly 530GB quantized checkpoint can run on four Blackwell Ultra GPUs or two 512GB M5 Ultra Mac Studios.