This market will resolve to the highest 50% time horizon, as reported by METR, for the first Claude Opus 4.8 model to appear on METR's graph. Claude Opus 4.8.x variants count for the purpose of this market. 4.7 or earlier would not count. Opus 5 or later would not count. Sonnet would not count.

50% time horizon is a measure of AI autonomy based on the length of tasks that AI can do: roughly, it is the time that humans take to complete tasks that an AI system can successfully do 50% of the time. See METR's Time Horizon 1.1 update for the technical definition. As of May 2026, frontier time horizons are around 12 hours, with a doubling time of roughly 4 months.

Left bounds inclusive, right bounds exclusive.