— The model must be released publicly to qualify, i.e. if Opus 5 gets a limited release (similar to what's been going on with Mythos and GPT-5.6) followed by a GA release of Haiku, the latter will be considered as having been released first.

— The existing version(s) of Mythos will qualify if released into general access before any other qualifying model.

— Any 4.x versions, in case Anthropic decides to continue that branch for some reason, will not qualify.

The most recent release as of this market's creation date is Sonnet 5, which is the third release in the Claude 5 series following Mythos 5 and Fable 5.