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brianletort.aiD. Brian Letort, Ph.D.

AI Market · Forecast desk · hit · software

71% · hit

Anthropic makes Claude Sonnet 5.5 or Claude Haiku 5.5 generally available on the Claude API by November 30, 2026.

Back to the bookIssue 2026-W39

Outcome

hitcalled at 71%brier contribution 0.084

Claude Sonnet 5.5 went GA on September 28 with API model id claude-sonnet-5-5 listed on the Claude Platform models page and available on Bedrock, Google Cloud and Microsoft Foundry. Haiku 5.5 remains 'coming weeks'.