Anthropic rumors point to a larger internal teacher model and a near-K3 public stack

teortaxesTex · x · 2026-07-28

A X post says the situation around Fable and Mythos is still murky, but claims to have reasonably trustworthy information that Anthropic has a larger internal teacher model.

It also says Mythos-Preview was roughly at Opus 4.8 level before much RL, and that what is currently served is not much larger than K3. The post is explicitly framed as a clarification of confusion around whether Fable 5 is simply Mythos with a classifier or a distill.

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