Next Mythos-Class Model released by August 31, 2026?
Crossbook compares what two exchanges, Polymarket and Kalshi, charge for the same event, and publishes a permanent scored record of its own forecasts under published rules.
Tracked on one venue, with Crossbook's own call on the record.
Crossbook forecast
- 14.0%against a market price of 22.0% at the timeNO
Logged 26 Aug 2026, 04:00 UTC · Brier 0.0196
- Claude Fable 5 (the current Mythos-class model) was released June 9, 2026, only ~2.5 months ago; Anthropic's historical cadence suggests the next generational step would more likely land in late 2026, not this week — this is signal, not narrative.
- With only 5 days to expiry and no confirmed announcement in the settlement description, YES requires a release essentially this week; major model launches are typically preceded by teasers, leaks, or safety-testing disclosures, and time decay now dominates the estimate.
- The market price of 22% sits above my independent estimate; the divergence plausibly reflects rumor-driven speculation or traders pricing a small chance of a surprise drop, but with only $11k in 24h volume it may also just be thin-market noise rather than hard information.
What would change it: An Anthropic announcement, credible leak, or staged model artifacts appearing before August 31 indicating an imminent Mythos-class release would sharply raise this estimate.
Settlement source
Context
Polymarket prices this at 37%. No verified equivalent is currently listed on the other venue, so there is no cross venue comparison on this page.
Volume over the last 24 hours is active, at about $49,931 on the busier venue.
This market has settled. The page is kept as a record of what the market said while the question was open, and of what Crossbook called.
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Crossbook publishes every forecast it makes, timestamped before the answer is known and scored against the market afterwards. See the public record and the rules it is held to.