**Anthropic’s recent release of Claude Opus 5.5 on September 22 drives the 56% market-implied odds for claude-opus-5.5-high.** The model matches or exceeds Claude Fable 5.1 performance on most agentic coding, computer-use, and knowledge-work benchmarks while cutting typical run costs by roughly 40% versus Opus 5, with independent evaluations such as Artificial Analysis placing it at a leading 58-point Intelligence Index score. Fable 5.1, released earlier in September as Anthropic’s highest-capability offering for long-horizon tasks, retains a 12.5% share due to its strength on demanding workloads but faces pressure from the newer, more efficient Opus variant. With no major competing releases expected before October 12, traders are pricing the cost-performance edge and fresh benchmark leadership as decisive factors for the snapshot evaluation.