One-line summary
Meta announced on October 15, 2026 and released weights on October 16 for Muse Spark Open, an open-weight model: a native multimodal model with a mixture-of-experts architecture, 816 billion total parameters (42 billion active), and a 1 million token context window; optimized with Apple via the MLX framework, the full model can run on two Mac Studios with 512GB unified memory each.
Event Overview
According to Cailianshe's report of October 16, 2026, Meta released the open-weight model Muse Spark Open on Thursday (October 15) and partnered with Apple to run it locally on Mac computers. Meta AI Research's announcement calls the model "the most capable US open-weight model to date." Meta CEO Mark Zuckerberg posted on social media in the early hours of October 16 (Beijing time) that the weights were releasing that day, sharing a photo of the model running on two Mac Studios.
Key Information
| Item | Detail |
|---|---|
| Official announcement | October 15, 2026 (Meta AI Research) |
| Weights released | October 16, 2026 (Zuckerberg: weights releasing that day) |
| Architecture | Mixture-of-experts, native multimodal |
| Parameters | 816 billion total, 42 billion active |
| Context window | 1 million tokens |
| Focus | Coding and agentic tasks; long-horizon tasks, complex software engineering, multi-step reasoning |
| Claimed results | Meta's own tests rank it first in 6 comparisons (workflows, tool use, knowledge reasoning, knowledge reliability, complex visual reasoning, visual factual QA) |
| Apple collaboration | Optimized with MLX for Mac Studio with M5 Ultra; two Mac Studios with 512GB unified memory run the full model; the 512GB version is expected to go on sale in late October |
| Other support | Optimized for NVIDIA, AMD and Intel chips; compatible with multiple inference engines; available via API or self-hosted weights |