Overnight, two key developments emerged: Opus 5.5 rose to first place, and GPT-6 slashed costs for comparable offerings by half.

Beating AI Express News: Artificial Analysis has completed third-party testing of several new AI models released overnight. Claude Opus 5.5 max scored 58 points on the Intelligence Index v4.3, currently ranking first. GPT-6 Astra and Fable 5.1 both scored 53 points, while Opus 5 scored 51 points. Opus 5.5 max took the top score in 6 of the 10 tests. However, achieving these top scores required more tokens: Opus 5.5 max generates an average of around 119,000 tokens per task, roughly 60% more than Opus 5’s 73,000 tokens per task. Thanks to a 20% API price cut and 60% reduction in cache read costs, its per-task cost came to $5.98, almost on par with Opus 5’s $5.86. The more practical medium-tier model scored 51 points, matching Opus 5 max, with a per-task cost of just $1.34. OpenAI took a different approach: GPT-6 Sol and Luna delivered Intelligence Index performance close to their GPT-5.6 predecessor, but at significantly lower prices. Sol max’s per-task cost dropped from $1.99 to $1.06, while Luna’s fell from $0.18 to $0.07. In coding agent tests, Sol’s score rose from 55 to 57 points, with its cost cut by roughly half; Luna’s score dipped from 43 to 41 points, but its per-task cost is about 60% lower. The two companies’ strategies are starting to diverge: Opus 5.5 pushes performance limits higher with more inference, while GPT-6 Sol and Luna focus on making existing capabilities cheaper. On Artificial Analysis’s performance-cost chart, both companies’ new models occupy the new Pareto frontier.