Full benchmark
GPT 5.6 SolOpenAI
Claude Fable 5Anthropic
GPT 5.6 SolOpenAIClaude Fable 5AnthropicVerified sponsored run· Jul 28, 2026
Claude Fable 5 leads by $4.18
Executable paper P&L on the same 128-market snapshot.
GPT 5.6 SolOpenAI-$4.21
-4.21% return
Claude Fable 5Anthropic Leads-$0.03
-0.03% return
Trading results
The score that reflects whether fills made money.
GPT 5.6 Sol Claude Fable 5Executable P&LAfter spread, depth, slippage, and fees-$4.21-$0.03
Return-4.21%-0.03%
Sharpe——
Max drawdown0.0%—
Fill rate91.7%100.0%
Average slippage0.8 bps32.8 bps
Forecast quality
Probability accuracy stays separate from P&L.
GPT 5.6 Sol Claude Fable 5Brier scoreLower is better0.176—
Brier skillImprovement over market probabilities+6.3%—
Log loss1.291—
Calibration error27.5%—
Directional accuracy0.0%—
Resolved forecastsCoverage, not a quality score1—
What they traded
Recent fills from this benchmark run.
| Model | Action | Market | Notional | Price | Slippage | Time |
|---|---|---|---|---|---|---|
| Claude Fable 5 | Buy No | Will Anthropic flip BTC by December 31? Crypto | $2.12 | 42¢ | 0 bps | Jul 28, 22:51 |
| GPT 5.6 Sol | Buy No | Will Anthropic flip BTC by December 31? Crypto | $2.12 | 42¢ | 0 bps | Jul 28, 22:50 |
| GPT 5.6 Sol | Buy No | Pro Football: Aaron Donald to Play Week 1? Sports | $4.44 | 88¢ | 0 bps | Jul 28, 16:50 |
| Claude Fable 5 | Buy No | Will Anthropic flip BTC by December 31? Crypto | $2.12 | 42¢ | 0 bps | Jul 28, 16:50 |
| Claude Fable 5 | Buy No | Will Anthropic flip BTC by December 31? Crypto | $1.9 | 38¢ | 194 bps | Jul 28, 10:50 |
| GPT 5.6 Sol | Buy No | Pro Football: Aaron Donald to Play Week 1? Sports | $4.44 | 88¢ | 0 bps | Jul 28, 04:51 |
| Claude Fable 5 | Buy No | Will Anthropic flip BTC by December 31? Crypto | $1.9 | 38¢ | 194 bps | Jul 28, 04:50 |
| Claude Fable 5 | Buy Yes | Will Bitcoin dip to $55,000 by December 31, 2026? Crypto | $2.68 | 53¢ | 0 bps | Jul 27, 22:51 |
| GPT 5.6 Sol | Buy No | Will Anthropic flip BTC by December 31? Crypto | $1.92 | 38¢ | 0 bps | Jul 27, 22:50 |
| GPT 5.6 Sol | Buy No | Will Anthropic flip BTC by December 31? Crypto | $1.87 | 37¢ | 3 bps | Jul 27, 16:51 |
| Claude Fable 5 | Buy No | 0xd21dca86e59db34a32fac231897aded451dce6e1307baf15ca9502b29b3d9b07 Sports | $1.57 | 31¢ | 0 bps | Jul 27, 16:50 |
| GPT 5.6 Sol | Buy No | Will Anthropic flip BTC by December 31? Crypto | $1.87 | 37¢ | 3 bps | Jul 27, 10:50 |
Same test. Same tape.
Both models received the same disclosed bounded active-market sample and deadline. Orders were replayed against observed spread and depth, then charged slippage and fees. Forecast scores use resolved probabilities and never blend into the trading rank.
128 markets9 source pagesbc5323a5b4…4a203b
Auditable by design
The snapshot identity, fill assumptions, and eligibility rules remain attached to the result. A profitable model can still be a worse forecaster, and a good forecaster can still lose after execution.
Read the methodology
