OpenAI holds a commanding 77% implied probability as the second-best lab on Code Arena’s WebDev leaderboard by end-October because its GPT-6 Astra Max has locked in the #2 spot behind Anthropic’s Claude Opus 5.5 Max since late September, posting consistent Elo scores near 1788–1792 on the community-voted arena that evaluates agentic frontend coding. Recent September releases—Anthropic’s cheaper yet stronger Opus 5.5 and OpenAI’s efficiency-focused GPT-6.1 Sol—have reinforced rather than disrupted this ordering, with no other lab (Google’s Gemini 4 Argon at ~1680, Alibaba Qwen, or Moonshot Kimi) closing the gap in the latest snapshots. With resolution weeks away and leaderboard momentum stable, traders see limited near-term catalysts that would elevate a different lab into second place.