OpenAI's new flagship model, GPT-5.6 Sol, performs almost as well as Fable 5 in benchmarks but costs only one-third as much.

According to the independent AI evaluation platform Artificial Analysis, GPT-5.6 Sol (max) scores 59 points on the Intelligence Index, just one point behind Claude Fable 5 (max). In Artificial Analysis's new Coding Agent Index, Sol (max) takes the top spot with 80 points when running in OpenAI's Codex environment, beating every other model. In the AA-Briefcase benchmark for realistic office tasks, Sol earns the highest "Presentation Elo" of all models but still trails Fable 5 in the overall ranking.

OpenAI takes on Anthropic on price

Sol costs $1.04 per task, about one-third of what Fable 5 charges. The smaller variants, Terra and Luna, cost 50 and 80 percent less than Sol, respectively. According to Artificial Analysis, Sol "defines a new Pareto frontier of Intelligence vs Output Tokens per Task." The full benchmark data is available here.

GPT-5.6 also introduces a cache-write fee for the first time, pushing prices down further. Token prices per million are $5/$30 (Sol), $2.50/$15 (Terra), and $1/$6 (Luna) for input/output. Cache reads get a 90 percent discount. Sol also burns fewer output tokens than models with similar performance, up to 54 percent fewer for agentic coding tasks, according to OpenAI CEO Sam Altman.

Pricing pressure is building across the AI industry. Chinese open models, Meta with Muse 1.1, and xAI with Grok 4.5 are all pushing established AI labs to cut rates. OpenAI is still pricier than those competitors but is now squeezing Anthropic from another angle. Anthropic will need to respond. But this race to the bottom on pricing could end up hurting the entire industry.