**Anthropic’s rapid cadence on Mythos-class frontier models, combined with its August 2026 internal “Model 2” disclosure, is positioning early September as the leading window for the next public release.** The company shipped its first widely available Mythos-tier model (Claude Fable 5, with the restricted Mythos 5 variant) on June 9, 2026, after earlier restricted previews, then restored broader access by early July following U.S. regulatory adjustments. Traders see the internal Model 2—described in Anthropic’s mid-August risk report as a modest but measurable improvement over Mythos 5 on coding, research, and agentic tasks—as evidence of ongoing training and evaluation progress that typically precedes a public rollout. This aligns with Anthropic’s pattern of iterating every 4–8 weeks on high-capability systems while refining safety classifiers for cybersecurity and biology risks. Market-implied odds cluster highest around September 1–3 (37% and 27%) and mid-September dates (25–26%), reflecting expectations of a near-term announcement once post-release monitoring and safeguards stabilize. Lower probabilities for late September or “no release by September 30” (around 15–22.5%) acknowledge that timelines can slip due to regulatory reviews, benchmark validation, or competitive timing against OpenAI and Google releases. The closely contested probabilities underscore trader caution around the exact public availability date for the next Mythos-class system.