Fable 5.2/Mythos 5.2 cut prices 30% and run 30% faster, but is the shared base model claim credible?
teortaxesTex · x · 2026-11-15
Official notes say Claude Fable and Claude Mythos are the same underlying model — Fable ships with stronger cybersecurity/biology safeguards for all users, while Mythos access goes through the expanded Life Sciences and Cyber Verification Programs. Version 5.2 generates outputs up to 30% faster than 5.1 and costs less: $8/M input, $40/M output, with an optional fast mode (2.5x speed) at $16/$80.
teortaxesTex doubts the 'same base model' framing: a price cut alone doesn't prove no change, since post-training, algorithmic gains, or supply shifts can also cut costs — and why call it 5.2 rather than 5.5? He argues that if 5.2 is a fully new base model, the qualitative jump falls far short of Opus 5 → 5.5, which would be bearish for Ant; SimpleQA divergence, though, hints Ant may have achieved a post-training breakthrough while OpenAI falls behind.
Related event: Fable 5.2 tops SimpleQA leaderboard(3 posts)→
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