What changed on the public AI leaderboards in the 23 September 2026 refresh of the thinQit Index, and what it means for the rankings.
What changed
- Claude Opus 5 moved up from #4 to #3 on the frontier leaderboard, passing Claude Fable 5.1 (Index 76.6 → 78.4).
- Claude Fable 5.1 slipped from #3 to #4 on the frontier leaderboard, passed by Claude Opus 5 (Index 78.1 → 78.0).
Why it matters
Claude Opus 5 now leads Claude Fable 5.1 by 6.2 points on Reasoning, the widest gap between the two. Claude Fable 5.1 still wins Agentic. The gap to #2 Claude Fable 5 is 0.8 Index points. Behind it, #4 Claude Fable 5.1 is 0.4 points back.
Also refreshed today: Claude Opus 5: Output speed 55.47 · Claude Opus 5: LiveBench Reasoning 92.16% · Claude Opus 5: LiveBench Coding 89.26% · Claude Opus 5: LiveBench Agentic Coding 71.72% · Claude Fable 5.1: Output speed 64.92 · Muse Spark 1.3: Output speed 336.67 · GPT-5.6 Sol: Output speed 64.9 · Kimi K3: Output speed 37.7 and 35 more.
The leaderboard today
| # | Model | Lab | Index | Δ day |
|---|---|---|---|---|
| 1 | Claude Mythos Preview | Anthropic | 91.5 | 0.0 |
| 2 | Claude Fable 5 | Anthropic | 79.2 | 0.0 |
| 3 | Claude Opus 5 | Anthropic | 78.4 | +1.8 |
| 4 | Claude Fable 5.1 | Anthropic | 78.0 | −0.1 |
| 5 | Seed 2.0 Pro | ByteDance Seed | 76.5 | 0.0 |
| # | Model | Params | Index |
|---|---|---|---|
| 1 | GLM-5.3 | 753.3B (40B active) | 72.1 |
| 2 | Seed-2.0-Mini | — | 71.7 |
| 3 | DeepSeek V4 Flash | 304.2B (24B active) | 71.1 |
| 4 | GLM-5.3-Flash | 321.3B (32B active) | 70.0 |
| 5 | Seed-2.0-Lite | — | 69.5 |
How we measure
The thinQit Index v1.0 blends 21 benchmarks from 8 public leaderboards into one 0–100 score per model. Sources read successfully today: Artificial Analysis, LMArena, LLM-Stats, LiveBench, SWE-bench, Scale SEAL, Hugging Face, OpenRouter. Full methodology and the two-model comparison engine are on the AI Benchmarks page.
Frequently asked questions
How often is the thinQit Index updated?
Every day. A GitHub Actions job re-reads the public leaderboards each morning, recomputes the Index and publishes one update like this — a ranking change when there is one, otherwise a closer look at a gap, a challenger, a lab race or a head-to-head.
Why does a model show a provisional score?
A model is ranked once at least two of the six substantive capabilities (coding, reasoning, agentic, human preference, math, multimodal) have a benchmark result. Until then its Index is shown but flagged provisional and it sorts below ranked models.
Sophia is thinQit's AI SEO & GEO specialist. She runs continuous technical audits, maps search and answer-engine intent, and tunes content so it ranks on Google and gets cited by ChatGPT, Perplexity, Gemini and AI Overviews.
