Benchmark Almanac

Prophet Arena

Claude Opus 5.5 86.0 leads since Sep 2026 In use

Models and agents forecast open Kalshi prediction-market events and are scored once the events resolve. The live board ranks a difficulty-adjusted Arena score and also reports calibration error and market return.

ICLR 2026. Models appear once they reach 50 resolved events, in fixed-context and agentic harness tracks.

In the authors’ words

Forecasting is not only a fundamental intellectual pursuit but also is of significant importance to societal systems such as finance and economics. With the rapid advances of large language models (LLMs) trained on Internet-scale data, it raises the promise of employing LLMs to forecast real-world future events, an emerging paradigm we call "LLM-as-a-Prophet". This paper systematically investigates such predictive intelligence of LLMs. To this end, we build Prophet Arena, a general evaluation benchmark that continuously collects live forecasting tasks and decomposes each task into distinct pipeline stages, in order to support our controlled and large-scale experimentation. Our comprehensive evaluation reveals that many LLMs already exhibit impressive forecasting capabilities, reflected in, e.g., their small calibration errors, consistent prediction confidence and promising market returns. However, we also uncover key bottlenecks towards achieving superior predictive intelligence via LLM-as-a-Prophet, such as LLMs' inaccurate event recalls, misunderstanding of data sources and slower information aggregation compared to markets when resolution nears.

Abstract of LLM-as-a-Prophet: Understanding Predictive Intelligence with Prophet Arena (arXiv:2510.17638, CC0)
Made by UChicago SIGMA Lab with Kalshi Released Oct 2025 Real-world events All tasks public Last in a launch post Jul 2026 Last model added Sep 2026 Scores refreshed 2 Nov 2026
Level
Expert Specialists with years of training, often over hours of work
Scored
Settled by events Predictions are scored against what later happens.
Answers
Prediction Probabilities for events that have not happened yet.
19
Entries on its own leaderboard, 18 models we track
1
Launch post lists it, from 1 lab

Claude Opus 5.5 leads with 86.0

Best score per entry from the benchmark's own leaderboard, read on 2 Nov 2026. Where a model ran with several settings or harnesses, we keep its best. Names in gray aren't in our model list: fine-tunes, agent systems, products and older models. They don't count toward leaders.

  1. 1 Claude Opus 5.5 86.0
  2. 2 GPT-6 Astra 85.9
  3. 3 Gemini 4 Argon 85.9
  4. 4 GPT-6.1 Sol 85.7
  5. 5 Claude Fable 5.1 85.6
  6. 6 Gemini 3.8 Flash 85.6
  7. 7 GLM-5.3 85.5
  8. 8 DeepSeek V4.1 Flash 85.4
  9. 9 Grok 4.6 85.4
  10. 10 GPT-6 Luna 85.1
  11. 11 Kimi K3 85.1
  12. 12 Gemini 3.1 Pro 85.0
  13. 13 GLM-5.2 85.0
  14. 14 Claude Fable 5 84.8
  15. 15 GPT-5.6 Sol 84.7
  16. 16 DeepSeek V4 Pro 0813 84.4
  17. 17 Tencent Hy3 84.4
  18. 18 Qwen 3.8 Max 84.3
  19. 19 Foresight V3 84.2
#EntryScoreSettingDateSource
1 Claude Opus 5.5 86.0 OpenCode Harness Sep 2026 Official leaderboard
2 GPT-6 Astra 85.9 OpenCode Harness Sep 2026 Official leaderboard
3 Gemini 4 Argon 85.9 OpenCode Harness Sep 2026 Official leaderboard
4 GPT-6.1 Sol 85.7 OpenCode Harness Sep 2026 Official leaderboard
5 Claude Fable 5.1 85.6 OpenCode Harness Sep 2026 Official leaderboard
6 Gemini 3.8 Flash 85.6 OpenCode Harness Sep 2026 Official leaderboard
7 GLM-5.3 85.5 OpenCode Harness Aug 2026 Official leaderboard
8 DeepSeek V4.1 Flash 85.4 OpenCode Harness Sep 2026 Official leaderboard
9 Grok 4.6 85.4 OpenCode Harness Aug 2026 Official leaderboard
10 GPT-6 Luna 85.1 OpenCode Harness Sep 2026 Official leaderboard
11 Kimi K3 85.1 OpenCode Harness Jul 2026 Official leaderboard
12 Gemini 3.1 Pro 85.0 OpenCode Harness Feb 2026 Official leaderboard
13 GLM-5.2 85.0 OpenCode Harness Jun 2026 Official leaderboard
14 Claude Fable 5 84.8 Fixed Context Jun 2026 Official leaderboard
15 GPT-5.6 Sol 84.7 Fixed Context Jul 2026 Official leaderboard
16 DeepSeek V4 Pro 0813 84.4 Fixed Context Aug 2026 Official leaderboard
17 Tencent Hy3 84.4 Fixed Context Jul 2026 Official leaderboard
18 Qwen 3.8 Max 84.3 Fixed Context Aug 2026 Official leaderboard
19 Foresight V3 84.2 Fixed Context Official leaderboard

Labs report scores for 1 model in their cards. We plot every source in the charts below.

7 models have held number one since its release in Oct 2025

Lab claims count from the day the card came out, independent runs from the model’s release.

Google DeepMind Moonshot AI xAI Z.ai Anthropic OpenAI
Own leaderboard 7 leaders

Scores over time

All the scores we have, one dot each, so a model tested at several settings appears more than once.

On the benchmark’s own leaderboard Reported by the lab in its model card
0.00 20.0 40.0 60.0 80.0 100.0 2026 0.00 20.0 40.0 60.0 80.0 100.0 2026

One lab put it in a launch post in the last six months

Launch posts from every lab that has listed it, one tick per post. Tall colored ticks include it, and short gray ones leave it out.

Thinking Machines
DateLaunch postScoreAs the post writes it
30 Jul 2026 Inkling-Small 0.124 Prophet Arena Brier Score (lower is better)

More in Forecasting

All 12 in Forecasting
  • ForecastBench In use Models give probabilities for 500 auto-generated questions per round about future events, drawn from prediction markets and time-series datasets. Forecasts are scored with difficulty-adjusted Brier scores once the questions resolve. Claude 3 Haiku 44.7
  • Echo General AI Prediction Leaderboard Not in model cards Models forecast unresolved events drawn from prediction markets, synthesized news questions and expert-written questions. Forecasts made at aligned times are compared in pairwise battles, and an Elo fit ranks the models. DeepSeek-V4-Pro 1,018
  • Human Behavior Bench Not in model cards Models predict how specified groups of U.S. adults answer closed survey questions, as a distribution over options. Scored as 1 minus total variation distance. Gemini 4 Argon 80.6
  • BTF-3 Not in model cards Agents forecast already-resolved binary and numeric questions while researching a frozen snapshot of the web. Scoring pools Brier and ranked probability scores. Claude Opus 5 0.12
  • BackSearch Not in model cards Paid API that searches a frozen web archive as of a given date, for forecasting backtests and reproducible web-enabled evals. A tool, not a benchmark.
  • BallotBench Not in model cards Nine frontier agents forecast 863 contests in the 2026 US midterms each day until polls close. Proper scoring rules grade forecasts against certified results, beside Kalshi, Polymarket and expert ratings.