This market resolves YES if credible evidence emerges that Claude Sonnet 5 was planned for release on the week starting February 2nd, but later decided to release Opus 4.6 after failed deployment attempts. NO otherwise by close date

Anthropic released Opus 4.6 on February 5, 2026. Prior to the release, there were persistent rumors of a Sonnet 5 release, with prediction markets hovering around 80% odds. Opus 4.6 is priced 66% higher than Sonnet, creating an incentive to brand a capable, but cheap to run, model as Opus. However, there haven't been any leaks calling the released model Sonnet, and multiple organizations with early access all announced Opus 4.6 upon release.

Claude itself suggested there may be some relationship between the internal codename "Fennec" (associated with Sonnet 5 leaks) and what became Opus 4.6, but acknowledged the full story is likely more complicated than a simple rebrand, and that Sonnet 5 might still release separately.