Google's September 30, 2026 limited release of Gemini 4 Argon as its new flagship model—larger than prior Pro variants and focused on long-horizon reasoning, coding, and cybersecurity—serves as the main catalyst for trader sentiment on whether the next Gemini Pro debuts prominently on Humanity’s Last Exam. As of mid-October 2026, Gemini variants lead select HLE subsets like the verified leaderboard (Gemini 3.8 Flash at 54.9%), yet Anthropic’s Claude Opus 5.5 and Fable 5.1 hold the top spots on AA-HLE (61.4%) and standard HLE evaluations. Rapid frontier iteration, tool-augmented scoring gains, and Google’s canceled 3.5 Pro plans add uncertainty around timelines, with potential full Gemini 4 availability or new benchmark reports as key near-term swing factors.