Next Mythos-Class Model released by September 7, 2026?

ResolutionResolved YES

YES payout100¢

NO payout0¢

VenuePolymarket

Realized · held to resolution+54%$100 paper stake

Polymarket65¢ → 100¢

Our position · YES65¢ → 100¢

Signal endedSep 1

Forecast updated

Aug 28 forecast

Reports of imminent Fable 5.1 testing point toward launch, so a next Mythos-class model release by the deadline is favored.

Alleged testing and reports of an imminent Fable 5.1 release suggest launch preparations may be advanced, while Anthropic previously said more capable models were coming within months. The case remains fragile because Anthropic has confirmed none of the recent claims, test candidates were reportedly withdrawn, its known stronger internal model was not cleared for release, and official release notes remained silent. A qualifying public launch is therefore favored.

Points to YES

Reported Fable 5.1 rollout activity suggests launch preparations may already be advanced enough to complete within the remaining window.
On August 27, 2026, an unconfirmed report said Anthropic could release Fable 5.1, potentially alongside Sonnet 5.1, as early as August 28.
Anthropic’s stated model roadmap makes a late-summer successor plausible rather than an unexpected acceleration.
On June 9, 2026, Anthropic said Fable 5 and Mythos 5 shared an underlying model and that more capable models were expected in the coming months.

Points to NO

The apparent launch signals could reflect speculation or inconclusive testing rather than a release candidate, creating substantial delay and misidentification risk.
On August 27, 2026, reporting said Anthropic had not confirmed Fable 5.1’s existence or timing and that alleged test models were quickly taken offline.
Anthropic’s known stronger internal candidate appears unready for external deployment, limiting evidence that a cleared successor is available now.
Coverage published August 16, 2026, said Anthropic had no current plans to release internal Model 2 externally and had not completed its full predeployment assessments.
Official release channels remained silent close to the deadline, leaving little time for announcement, qualification, and general-public access.
Anthropic’s August 2026 release notes listed an August 25 memory update but no Mythos-class model launch after Fable 5.

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