Markets put the next Claude Opus at 83% by Thursday — the name going around is 5.5

Polymarket's "Next Claude Opus released by...?" book, read directly at 06:49 UTC, September 21: 83% by September 24, 91% by September 27, 95% by September 30. Polymarket's own post about nine hours earlier had Thursday at 72%, so the number has been climbing through the day. The companion day-by-day market is sharper still: Sep 21 47%, Sep 22 32%, Sep 24 11%.

What the market is and is not pricing: it resolves on any model Anthropic explicitly names Opus and makes generally available - 5.1, 5.5, 6, anything. It does not price the name.

The name is thinner. "Opus 5.5" traces to one X account relaying a leaker, with a claimed internal codename (claude-wafer-eap) and a rumored Tuesday, September 22. A week ago the same rumor was calling it 5.2, with a September 17-18 window that closed empty. There is no model card, no API id, no price sheet, and no second outlet with the checkpoint string. Treat 5.5 as a label, not a fact.

What we read ourselves at the same time: Anthropic's own model list still tops out at claude-opus-5, and neither OpenRouter nor models.dev carries a newer Opus id. The cadence does fit: Opus 4.7 on April 16, 4.8 on May 27, 5 on July 24; today is eight and a half weeks on.

On our end: until this morning nothing on the board would have matched a claude-opus-5-5 id. The Opus 5 entry excludes point releases on purpose, and the old 4.9 hunt was retired without a successor. The next-Opus hunt is now armed on the whole range the market resolves on, and the fire drill passes on the id shapes Anthropic, OpenRouter and Bedrock would carry. The alert fires when a model answers, not when a market moves.