Anthropic’s next Mythos-class model faces tight release timing odds because the lab must balance rapid capability gains against heightened U.S. government scrutiny of cybersecurity and biological risks. The June 9 launch of Claude Fable 5 and limited Mythos 5 established a template of safeguard classifiers that fallback to Opus 4.8 on sensitive queries, yet regulators have already paused and selectively restored access, slowing broader rollout. Competitive pressure from OpenAI’s phased GPT-5.6 family and ongoing benchmark gains by other labs add urgency, while Anthropic’s trusted-access program and IPO preparations create incentives to demonstrate progress without triggering new restrictions. Traders see roughly equal chances of an end-of-August drop versus a mid-to-late September release, reflecting uncertainty over whether additional safety work or external approvals will slip the schedule.