Today · event date October 15

Meta releases 816B Muse Spark Open; scores are self-reported

Meta releases Muse Spark Open, an 816-billion-parameter open-weight model, and model-service sellers with over US$20M in annual revenue must sign separately with Meta

Concept illustration: a pale grey building lettered META, with a blue looped symbol beside the lettering, has a large window on the left in which stands a tall dark double-door server cabinet lettered MUSE WONDER. In the open doorway on the right, a person in a black turtleneck, wide grey-brown trousers and an ID badge on a lanyard holds the door handle, and outside to the right a table holds an orange-red laptop whose screen shows a grey speech bubble, next to a white sign reading MUSE SPARK OPEN.

Why it matters: US open-weight supply returns without Meta's frontier model, and API model sellers with over US$20M in group revenue need a separate deal.

Meta released the weights of Muse Spark Open on October 15, a model with 816 billion parameters that uses 42 billion per token (AI at Meta, 2026-10-15; Alexandr Wang, 2026-10-15; Mark Zuckerberg, 2026-10-15; Hugging Face, 2026-10-15). Companies selling model services with annual revenue above US$20M must sign separately with Meta (model page, 2026-10-15). The "most capable" claim is Meta's own.

Not proven yet: "most capable US open-weight model" is Meta's claim alone How we checked →

Judgment update: A new working read, not settled: Meta keeps its frontier model in house and opens the previous generation, and the open version carries a revenue threshold for model-service sellers. "Previous generation" is our inference from release order and naming, and confidence doesn't move. What would prove this wrong: Meta releases Wonder's weights before April 15, 2027, or Spark Open comes within 3 points of Wonder on the overall score of a single independent evaluation. The deadline and the 3-point threshold are both our own.

Source and checks

This item ran in the brief of Oct 16, 2026, alongside 19 other items. How we checked it, the quote checks and what was still missing that day are on that issue's How we checked page.

Cite this item

SecondSource (2026). "Meta releases 816B Muse Spark Open; scores are self-reported." https://secondsource.io/en/news/2026-10-16-1/. Accessed access date.