Best AI Model This Month? Prediction Market Odds

Anthropic breaks Google’s winning streak in the #1 AI model market

Kalshi and Polymarket both run monthly markets on which company holds the top-ranked AI model on the Arena leaderboard. For February, the two sites agreed: Anthropic’s Claude Opus 4.6 is #1 and the market is pricing it as settled with Kalshi at 99% and Polymarket at 98%. Unless something drastic happens in the next 24 hours, this market will resolve as is. It will also end Google’s six-month streak as the leading AI model.

One difference worth noting: Kalshi resolves to the specific model (gemini-3-pro, claude-opus-4-6), while Polymarket resolves to the company (Google, Anthropic). Kalshi also runs both variants — a model-level market and a company-level market. Our charts are aggregating data from the model market.

Monthly AI prediction results

How to bet on AI prediction markets

Each company (or model, on Kalshi) gets its own contract. You pick Yes or No on whether that AI company will hold #1 at the end of the month. Only one can win, so in practice this is a winner-take-all contract. If you buy Anthropic Yes at 98¢ and Anthropic holds #1 on February 28, the contract pays $1.00 and every other company’s contract resolves No.

The contracts trade between 1¢ and 99¢. With only one day left in February and Anthropic at 97-99%, there isn’t much edge left to gain this month. The opportunity is in forward months where the outcome is less certain, particularly if GPT-5.3 or Grok 5 launches and disrupts the leaderboard.

The two platforms handle timing differently. Kalshi opens each month’s market on the 1st, so you can only trade the current month. Polymarket lists future months alongside the active one — March, June, and beyond are already tradeable. That means Polymarket lets you take a position on where the leaderboard will be months from now, while Kalshi is limited to the race in progress.

For a full comparison of where to trade, see our list of prediction market apps.

Anthropic beats Google for the first time in six months

Claude Opus 4.6 launched on February 5 and took #1 on Arena by February 6, dethroning Gemini 3 Pro. The thinking variant hit 1506 Elo, the standard version 1502. It’s held the top spot for three weeks with no serious challenger, which is why pricing has converged toward certainty on both markets.

The Polymarket chart tells the story clearly. Google led early February around 75%, Claude spiked past it around Feb 5-6, dipped briefly mid-month, then locked in above 90% by Feb 20. On Kalshi, the interesting dynamic is the internal Claude race — opus-4-6 (standard) started behind opus-4-6-thinking but has pulled ahead to 85% vs 17% as the month closes.

The March market is already shaping up differently. On Polymarket, Anthropic opened the month at 54% with Google at 24%, OpenAI at 12%, and xAI at 5.5% — with $3.13 million in early volume. The market is pricing meaningful confidence in multiple contenders, a sharp contrast to the 90%+ dominance Google held in most prior months.

What to watch this month

Several releases could reshape the March market and beyond:

• Google’s Gemini 3.1 Pro launched on February 19 and is already within 4 Elo points of Claude Opus 4.6 on Arena. As more votes accumulate through March, the gap could narrow further or flip entirely — making Google the most immediate threat to Anthropic’s lead.
• OpenAI’s GPT-5.3 general model is still expected in Q1 2026. The coding variant (GPT-5.3-Codex) shipped in early February, but the full model hasn’t arrived on Arena yet. If it launches in March, OpenAI becomes a real contender.
• xAI’s Grok 5 is confirmed for Q1 2026 with a public beta likely landing in March or April. Grok 4.1 briefly held Arena #1 at its November 2025 launch before Gemini 3 dethroned it a day later, so the gap is closable.

The volume trend is also worth watching. Polymarket’s monthly AI market peaked at $36.33 million in December and has been declining — $28.97 million in January, $21.66 million in February. A competitive March could reverse that trend. Track live volume across Kalshi and Polymarket on our prediction markets dashboard.

How do these markets resolve?

Kalshi and Polymarket both resolve against the Arena leaderboard, but they use different columns — which means they could theoretically resolve to different winners.

• Kalshi checks the “Rank (UB)” column on the text leaderboard with Style Control removed on the last day of the month. Tiebreaker goes to highest Arena Score, then most votes, then earliest release.
• Polymarket checks the “Arena Score” column on the Leaderboard tab at 12:00 PM ET on the last day of the month with style control off. Tiebreaker is alphabetical.

Rank (UB) reflects the upper bound of a model’s confidence interval, while Arena Score is the raw Elo. In a tight race where two models are separated by a few points, one platform could resolve to a different winner than the other — use our arbitrage calculator to compare pricing across platforms.

How Arena ranks AI models

Kalshi and Polymarket both resolve against the Arena leaderboard, formerly known as the LMSYS Chatbot Arena. Arena presents users with a prompt and two anonymous model responses side by side. The user picks which response is better without knowing which model produced it. Over 5.3 million of these blind comparisons have been collected, and each model receives an Elo rating derived from its win rate against other models in the pool.

Style Control is a leaderboard filter that adjusts for formatting bias — models that use more markdown, bullet points, or longer responses tend to score higher in raw comparisons even when the underlying reasoning is equivalent. With Style Control on, Arena isolates substance from presentation. Both Kalshi and Polymarket require Style Control off in their resolution criteria, meaning the raw Elo without formatting adjustment is what determines the winner.

Related AI prediction markets

• “Which companies will have a top-ranked AI model this year?” on Kalshi. An annual market with 12 active contracts ($832K volume). Unlike the monthly markets, these resolve Yes if a company reaches #1 at any point during 2026. Google and Anthropic have already resolved Yes. OpenAI leads the remaining contracts at 62%, xAI at 55%.
• “AI capability growth before July?” on Kalshi. A related bet on whether any model will hit an Arena Score of 1550 or higher before July ($77K volume). Currently pricing 46% for 1550 and 30% for 1575. Claude Opus 4.6 sits at 1506 today, so this is effectively a bet on the next generation of models.
• “When will Claude 5 be released?” on Polymarket. Currently pricing 36% for April 30. If Claude 5 arrives and tops Arena, Anthropic could hold #1 for consecutive months.
• “When will GPT-5.3 be released?” on Polymarket. Directly relevant to whether OpenAI can challenge for March. If GPT-5.3 launches and climbs Arena, expect the monthly market to move in tandem.
• EU AI Act compliance deadline arrives August 2, 2026. If a lab delays a frontier model release to meet compliance requirements, that’s one fewer chance to top the leaderboard within a given month.

Liquidity varies significantly across these markets. Polymarket’s monthly AI market routinely draws $20-36 million per month, making it one of the deeper non-political betting markets on the platform. Kalshi’s monthly markets are thinner at $2-3 million but growing — February volume nearly doubled January. The annual and milestone markets on either site are much smaller, typically under $1 million, so larger positions may face slippage.

The fee structures are quite different between Kalshi and Polymarket and can affect net returns, particularly on lower-volume contracts. If you’re new to betting on Kalshi or Polymarket, you will also want to learn how order books work and market resolution before making your first trade.

FAQ

What does “best AI model” mean in these markets?

The company (or model) that holds the top rank on the Arena text leaderboard at the end of the month. Kalshi uses the Rank (UB) column, Polymarket uses Arena Score.

Can Kalshi and Polymarket resolve to different winners?

In theory, yes. They use different columns from the same leaderboard. In practice, the #1 model under Rank (UB) and Arena Score has been the same, but a tight race could produce a split.

Why is Polymarket’s volume so much higher than Kalshi’s?

Polymarket generally carries more liquidity on AI-related markets and draws a larger crypto-native trading audience. Kalshi is a regulated US exchange that has been expanding internationally, while Polymarket US continues to roll out to domestic traders.

Why is Anthropic favored for March but not dominant?

Anthropic opened March at 54% because Claude Opus 4.6 is the incumbent — it holds Arena #1 at 1506 Elo with a large gap over Gemini 3 Pro. Google sits at 24% partly because Gemini 3.1 Pro launched on February 19 and is already within 4 Elo points of Opus 4.6 on Arena. As more votes accumulate through March, that gap could close. OpenAI is at 12% because the general GPT-5.3 model is expected in Q1 2026 — the coding variant (GPT-5.3-Codex) shipped in early February, but the full model hasn’t launched yet. If it arrives in March and climbs Arena, OpenAI could become a real contender. xAI rounds out at 5.5% with Grok 5 confirmed for Q1 2026, though a public beta likely lands closer to March or April.

How often do these markets run?

Monthly on Kalshi and Polymarket. New contracts open as the prior month’s market approaches resolution. Polymarket has results going back to at least August 2025, Kalshi to at least August 2025 as well.