Anthropic Expected to Release Its Next Claude Opus Model
ESTIMATED65% CONFIDENCENo official date: September 21 is the day Polymarket's[1][2] per-day market prices highest, at 31% on its outcome row (the page header reads 30.5%), with September 22 at 25% and September 24 at 15%, and “No release by September 30” at 22%. The figures are the chance on each row, not the Buy Yes or Buy No prices in cents beside them.
Polymarket
Polymarket
Prediction-market traders expected Anthropic to ship the successor to Claude Opus 5 (released July 24, 2026) within days. On 19 September 2026 Polymarket's per-day market made September 21 the single likeliest day at 31%, ahead of September 22 at 25%, and its deadline market gave a release by September 30 an 83% chance and by October 31 98%. Anthropic had not announced the model; the “Opus 5.1” name comes from leaked early-access identifiers and early tester reports.
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