Claude Fable 5.2 and 4 more November updates

1MToken context window

Fable 5.2 is for demanding, multi-step work.

Anthropic released it on November 9. It shares an underlying model with Mythos 5.2, which requires verified access. Fable is generally available with additional safeguards for cybersecurity and biology. The API supports a 1 million token context window and up to 128,000 output tokens.

IPONasdaq filing

The company behind Claude is going public.

Anthropic publicly filed for an initial public offering on Nasdaq. Coverage has focused on the S-1, including questions from a US senator about how existential-risk disclosures are worded.

BetaThreads · IP allowlisting

Threads, allowlists and watermarks for builders.

The Claude Developer Platform added beta message threads in the Messages API and beta IP allowlisting in the Console, plus watermarking of generated text for several models. Fast mode on an older Opus model is being retired on November 30.

Arrow's take

What it means for brands

• Start with Opus 5.5 for most coding or knowledge work. Try Fable 5.2 on a difficult migration, a long research task or a technical analysis when a simpler run falls short.
• Compare the two on the same inputs, with the same access and acceptance criteria. Score evidence coverage, corrections, time and cost before changing your default.
• For API use, Fable 5.2 costs $8 per million input tokens and $40 per million output tokens at standard rates. Opus 5.5 costs $4 and $20 respectively. Check your data-retention requirements before running sensitive work.