**Anthropic leads trader sentiment for second-best AI lab at end of October, with a 64% implied probability, driven by its Claude models topping multiple October 2026 leaderboards.** Claude Opus 5.5, Sonnet 5.5, and Fable 5.1 consistently rank first or near the top on Artificial Analysis, BenchLeader, SuperIndex, and consensus blends, ahead of OpenAI’s GPT-6 Astra and GPT-6.1 Sol. Recent releases—including Claude Haiku 5.5 on October 7 and Sonnet 5.5 in late September—have reinforced this edge in reasoning, agentic tasks, and efficiency benchmarks. OpenAI’s strong but secondary positioning explains its low 1.1% odds for second place. Google’s Gemini 4 Argon and 3.8 Flash trail in most composites, supporting its 23.5% share, while other labs remain further back amid rapid iteration cycles that can shift standings quickly before month-end.