Prediction market arbitrage is one of the purest forms of risk-free profit available to retail traders. When the same binary event is priced differently on Polymarket and Kalshi, buying both sides simultaneously locks in a guaranteed return — regardless of which way the market resolves.
What is prediction market arbitrage?
Every contract on Polymarket and Kalshi resolves to either $1 (YES wins) or $0 (NO wins). If you can buy YES on one platform and NO on the other for a combined cost below $1.00, you profit on every outcome. For example:
- Buy YES on Polymarket at 47¢
- Buy NO on Kalshi at 51¢
- Total cost: 98¢ → guaranteed payout: $1.00 → +2% edge
Why does the arbitrage exist?
Polymarket and Kalshi have different liquidity pools, different user bases, and different fee structures. Prices diverge constantly — especially around breaking news events. The window to capture the spread is typically 30–200 seconds before market makers close it.
How to find Polymarket vs Kalshi arbitrage manually
- Open both platforms and search for the same event.
- Note the best ask price for YES on one platform and NO on the other.
- Add the two prices. If the sum is below 1.00 (accounting for fees), an opportunity exists.
- Execute both legs as quickly as possible — ideally within seconds of each other.
Why use an automated Polymarket arbitrage agent?
Manual arbitrage is nearly impossible to scale. By the time you identify an opportunity, compare prices, and place both orders, the spread has usually collapsed. A Polymarket arbitrage agent like Arbitrage Agent monitors thousands of markets simultaneously and alerts you instantly with both legs ready to place (automated execution in final testing).
How the Kalshi arbitrage agent works
Arbitrage Agent connects to both platforms via official APIs. It continuously polls order books, calculates net edges after fees, and fires both orders atomically when a profitable spread is detected. Kelly criterion sizing ensures each position is sized relative to your bankroll.
Key risks to understand
- Leg risk: If one order fills but the other doesn't, you hold a directional position. Arbitrage Agent retries the second leg aggressively and includes a kill switch.
- Fee drag: Both platforms charge maker/taker fees. Always calculate edge after fees.
- Jurisdiction restrictions: Both venues restrict access by country, and the lists change. You need accounts on both to run this strategy at all — check your own country against both before committing capital.
Getting started with the prediction market arbitrage tool
Arbitrage Agent offers a dry-run mode where all signals are logged but no real money is deployed. Start there, verify the edge calculations, then flip to live trading when you're confident. Join the waitlist to get early access.