Weekly LLM benchmark digest
GPT-5.6 arrives, locked behind a preview
OpenAI previewed GPT-5.6 Sol, Terra, and Luna on June 26, undercutting Anthropic’s flagship by half on price. The catch: it shipped to roughly 20 government-approved partners under a limited preview, so most teams could not use it yet. Claude Mythos 5 still led at 99, with Fable 5 at 95, while Z.AI’s GLM-5.2 entered the top five at 91. The issue examined what the 17-day gap between those launches suggested about the market.
Leaderboard movers
Claude Mythos 5
Anthropic · 99 overall
#1
Held #1
Claude Fable 5
Anthropic · 95 overall
#2
Held #2
GLM-5.2
Z.AI · 91 overall
#4
New to top five
Analysis worth opening
Fable 5 vs GPT-5.6: Two Bets on Where the Frontier Goes NextAnthropic shipped Fable 5 and Mythos 5 broadly at $10/$50. OpenAI previewed GPT-5.6 at half the price, but only a limited group could use it.How We Keep a Benchmark Site HonestHow live benchmark and pricing tables are collected and monitored without maintaining a dedicated scraper for every source.
This issue in numbers
- 124
- Models ranked
- 3
- New that week
- $23.92
- Average output price per 1M tokens
- 99
- Top overall score
New on BenchLM
GPT-5.6 Sol, Terra, and LunaThe new family was tracked with pricing and preview notes, pending an independent benchmark suite at general availability.GLM-5.2 entered the top fiveZ.AI’s release reached 91 overall and was the highest-ranked open-weight model on the board.Cost calculator updatedThe GPT-5.6 tiers were added so readers could price Sol against Mythos 5 using their own token mix.