**Trader sentiment for Anthropic’s next Mythos-class model (post-June 2026 Fable 5/Mythos 5) reflects tight uncertainty around a fall release window, with clustered probabilities in early-to-mid September and a substantial share on no release by September 30.** Anthropic’s June launch of the safeguarded Fable 5 (public) and restricted Mythos 5 (via Project Glasswing for cyber partners) reset expectations after U.S. government restrictions were eased in late June/early July. No official announcements or credible leaks have emerged since, leaving the market pricing historical cadence—frontier models often ship every 3–5 months—against potential delays from safety evaluations, regulatory scrutiny on cybersecurity capabilities, and compute allocation. Competitive pressure from OpenAI’s phased GPT-5.6 rollout and activity at Google DeepMind or xAI adds urgency, yet Anthropic’s emphasis on safeguards for Mythos-class models (which excel at vulnerability discovery) favors measured pacing over rushed deployment. The near-even distribution across late-August and September dates versus the “no release by Sept 30” outcome highlights trader disagreement on whether internal progress or external factors will tip the timeline, with capital at risk enforcing disciplined assessment of verifiable signals like executive statements or benchmark leaks.