# Anthropic extends text watermark to four Claude models, with a loophole on two

> Original title: Anthropic's watermark rollout leaves a loophole on two older Claude models

- Source: The Decoder
- Published: 2026-10-31T19:20:55.000Z
- Bad Influence: https://badinfluence.news/items/c7b6nzrbohlwnu6d52iyoxqjb
- Original: https://the-decoder.com/anthropics-watermark-rollout-leaves-a-loophole-on-two-older-claude-models/

## Summary

Anthropic says it will watermark Claude Mythos 5, Claude Opus 4.7, Claude Opus 4.6, and Claude Sonnet 4.6 in an email to API customers. On Claude Opus 4.6 and Claude Sonnet 4.6, changing any one of the temperature, top_p, or top_k sampling parameters from its default removes the watermark. Anthropic ties the rollout to the EU AI Act's December deadline.