Is sports arbitrage on prediction markets the same as sportsbook arbitrage?

The idea is the same: cover both outcomes for a combined cost below the payout. The mechanics differ. Prediction markets are order books where prices are cents on a $1.00 contract, there is no bookmaker margin to overcome in the same way, and fees are stated per platform. The main risks shift from account limits to matching and settlement rules.

What is the biggest risk in sports arbitrage on Kalshi and Polymarket?

Resolution rules. Two contracts that look like the same game can differ on what happens after overtime, a postponement, a draw or an abandoned match. If one platform voids or settles differently, the position is no longer hedged. Read both rule sets for every pair.

Are there many sports arbitrage opportunities between Kalshi and Polymarket?

Fewer than most people expect. The two platforms list overlapping events unevenly, game-day markets move fast, and thin books limit size. Net edges after fees are small, as on any other category, and the live figures are on /proof.

Sports Arbitrage on Prediction Markets

Sports arbitrage on prediction markets means buying YES on one platform and NO on the other for the same game, so that one leg pays $1.00 whichever team wins and the combined cost is below $1.00 after fees. It is the same logic as sportsbook arbitrage, but it runs on exchange-style order books, with different costs and, more importantly, different risks.

This article is about how the Kalshi and Polymarket version works, where it differs from the sportsbook version, and what tends to go wrong. If you want the underlying concept first, start with how prediction market arbitrage works.

The mechanics for a single game

Take a game with two outcomes. On Kalshi you can buy YES on the home team; on Polymarket you can buy the contract that pays if the away team wins. Exactly one of those pays $1.00. If the two together cost $0.97 before fees, the gross edge is $0.03 per contract. The numbers are illustrative, not a live trade, and they only hold if both legs fill at those prices and both contracts settle on the same terms.

From the gross edge you subtract each platform's fees. The Polymarket side is worked through in how to calculate net edge after fees on Polymarket. Whatever is left, measured against what you put in, is the net edge.

How it differs from sportsbook arbitrage

No bookmaker margin to beat. A sportsbook builds its margin into the odds, so a sportsbook arbitrage usually needs two books to disagree by more than their margins. Exchange-style order books price each side directly, and the cost to subtract is a stated fee. Our comparison of arbitrage betting software covers the sportsbook tools if that is the route you are weighing.
Different account risk. Sportsbook arbitrage is known for accounts being restricted. We looked at what is and is not documented for these two platforms in do prediction markets limit winning traders.
You are not choosing from a menu of bookmakers. There are two main venues here, so the number of pairs is much smaller than a scanner across dozens of books.
Prices are cents on a contract, which makes the arithmetic simple but means depth at each price level matters as much as the price itself. See why liquidity caps your profit.

Why matching is the hard part

Both platforms word sports markets differently. One may ask whether a team wins, another whether it wins by a margin, another about a season total. Team names and abbreviations differ too. The arbitrage only exists if the two contracts are really complements of the same event, so every pair needs checking, ideally against the written rules of both. This is the part of the job where a model helps and where a wrong answer is expensive, because a bad match turns a hedged position into a directional bet.

Resolution rules are the real risk in sports

Sports have more edge cases than most categories. Ask of every pair:

Does the contract count overtime or extra time, or only regulation?
What happens on a draw, a postponement, a suspended or abandoned game?
Do both platforms settle on the same official source and on the same timing?

If one platform settles on the final result and the other voids after a delay, or one counts extra time and the other does not, the two legs can both lose. That is resolution risk, and it is the main reason a screen showing a gap is not the same as a trade worth taking.

Execution risk is sharper on game day

Sports prices move on events: a goal, an injury, a lineup announcement. A leg that fills while the other does not leaves you holding a directional bet on a game that is already moving. This is the two-leg execution problem in its most acute form. Pre-game markets are calmer than live ones, and a gap that sits for hours is more often a rules mismatch than a mispricing. For the general case, see how to arbitrage Polymarket vs Kalshi.

What to expect

Sports is not a separate pool of larger edges. Across the pairs we track, the median is roughly 0.7% net per position after fees, with capital held until the contract resolves, which annualises to about 1.1% a year at the median. Short-dated sports contracts resolve sooner than the median, but they are fewer, thinner and faster-moving. The live numbers are on /proof, and the honest range is in how much you can make with prediction market arbitrage.

Where Arbitrage Agent fits

Arbitrage Agent uses AI matching with every pair validated, then applies fixed rules for spread, fees and depth. The product today is signals: a live feed and a step-by-step guide with both legs ready to place, and you place the orders yourself. Alerts are part of the Operator plan, which is coming soon. You can start with the Starter plan or compare the plans.

Key terms: Surebet · Resolution Risk · Two-Leg Execution

Sports Arbitrage on Prediction Markets: How It Differs From Sportsbook Arbitrage (2026)