According to Ethan Mollick on X, Meta’s new Muse Spark model powers Meta AI but ships without open weights, marking a strategic departure from prior Llama releases that enabled broad open-source adoption (source: Ethan Mollick on X). According to Alexandr Wang on X, Muse Spark is the first model from Meta’s MSL, built after nine months of rebuilding the AI stack with new infrastructure, architecture, and data pipelines, and now powers Meta AI (source: Alexandr Wang on X). As reported by Ethan Mollick, the lack of open weights reduces predictability of ecosystem value creation around Spark, limiting third-party fine-tuning, on-prem deployment, and independent safety research compared to open-weight models (source: Ethan Mollick on X). For businesses, according to these sources, the closed-weight approach implies stronger control by Meta over distribution and monetization, favoring API-based integration, while potentially slowing community-driven innovation and vendor diversification opportunities that open-weight LLMs historically enabled.