Prediction markets do not always agree on the probability of an event. When Kalshi prices an election outcome at 62 cents and Polymarket has the same outcome at 57 cents, that 5-cent gap represents real money. Arbitrage is the strategy of systematically finding and exploiting these price differences. It is one of the most reliable approaches in prediction markets because your profit does not depend on correctly forecasting the outcome — it depends on identifying pricing inefficiencies.
What Is Arbitrage?
Arbitrage is the simultaneous purchase and sale of the same asset in different markets to profit from a price difference. The concept dates back centuries in traditional financial markets, but prediction markets create uniquely fertile ground for it because dozens of platforms now list contracts on the same real-world events.
In its simplest form, prediction market arbitrage works like this: Platform A sells YES on "Will the Fed cut rates in June?" at $0.58. Platform B sells NO on the same event at $0.38. Since YES and NO must add up to $1.00, the combined cost is $0.96. You buy both, spend $0.96, and are guaranteed to receive $1.00 when the event resolves — locking in a $0.04 profit per contract pair regardless of what the Fed actually does.
This 4-cent spread might sound small, but at scale it adds up. Buy 500 contract pairs and that is $20 in guaranteed profit. If the event resolves in two weeks, you have earned a roughly 4.2% return in 14 days, which annualizes to over 100%.
How to Spot Opportunities
Arbitrage opportunities arise from structural differences between platforms. Here are the main sources of price divergence:
Regulatory fragmentation. CFTC-regulated exchanges (Kalshi, Robinhood) serve different user bases than crypto-native platforms (Polymarket). Retail traders on Robinhood may push prices differently than crypto whales on Polymarket.
Liquidity differences. A contract with $2 million in open interest on Polymarket will be more efficiently priced than the same contract with $50,000 on a smaller exchange. Thinner markets move more slowly.
Geographic restrictions. Polymarket is not available to US residents on certain contract types, while Kalshi is US-only. This geographic segmentation means information does not flow evenly across platforms.
Timing differences. Breaking news hits different platforms at different speeds. A trader on Kalshi may react to a GDP release before the same information is reflected on Polymarket, creating temporary mispricings.
To spot opportunities manually, open the same market on two or more platforms side by side and compare prices. A price difference of 3 cents or more is worth investigating. You can also use our arbitrage finder tool to automate this scanning process across major platforms.
Cross-Platform Arbitrage
Cross-platform arbitrage is the most common form. You buy a contract on the cheaper platform and sell (or buy the opposite side) on the more expensive platform.
Real example: In March 2026, the contract "Will Congress pass a TikTok ban by June 30?" was priced at YES $0.35 on Kalshi and YES $0.42 on Polymarket. A trader could buy YES at $0.35 on Kalshi and buy NO at $0.58 on Polymarket (since NO = $1.00 minus the YES price of $0.42). Total cost: $0.93 per pair. Guaranteed payout: $1.00. Profit: $0.07 per pair, a 7.5% return.
The mechanics require maintaining funded accounts on multiple platforms. Most dedicated arbitrage traders keep capital on at least three exchanges to maximize the surface area for finding mispriced contracts.
Execution speed matters. Prices converge quickly as other traders spot the same opportunities. When you identify a gap, execute both sides as close to simultaneously as possible. Even a 60-second delay can see the spread narrow enough to eliminate your profit.
YES/NO Spread Arbitrage
You do not always need two platforms. Sometimes a single platform offers arbitrage within its own order book. This happens when the YES and NO prices on the same market do not add up to $1.00.
If a market shows YES at $0.54 and NO at $0.43, buying both costs $0.97 and guarantees a $1.00 payout — a $0.03 profit per pair. This type of arbitrage is rarer on well-functioning exchanges because market makers quickly close these gaps, but it does appear during volatile moments when order books become thin.
Check the bid-ask spreads as well. The displayed price may show a gap, but if you factor in the actual execution price (accounting for the spread), the opportunity might vanish. Always calculate your real cost including fees before placing the trade.
Risks and Limitations
Arbitrage in prediction markets carries risks that do not exist in traditional financial arbitrage:
Resolution differences. Two platforms may word the same event differently. Kalshi might settle "Will Bitcoin hit $100K in 2026?" based on CoinDesk's price at 11:59 PM ET, while Polymarket uses a Chainlink oracle with different timing. These subtle differences mean you could win on one platform and lose on the other.
Withdrawal timing. After a contract resolves, it can take 1-5 business days to withdraw funds, depending on the platform. Your capital is locked during this period, reducing your effective annualized return.
Platform risk. If a platform becomes insolvent, freezes accounts, or delays payouts, your "risk-free" trade becomes very risky. Diversify across regulated and established platforms to mitigate this.
Fee erosion. Transaction fees (typically 1-3% on some platforms) eat into thin arbitrage spreads. A 5-cent opportunity becomes 2-3 cents after fees. Always calculate net profit after all fees.
Capital requirements. Because individual arbitrage profits are small (2-8%), you need meaningful capital deployed to generate worthwhile absolute returns. A $100 account earning 5% on a trade yields $5 — useful for learning, but not a strategy you can live on without scale.
Getting Started
If you want to pursue arbitrage in prediction markets, follow this progression:
Week 1-2: Set up accounts. Create and fund accounts on at least Kalshi and Polymarket. If you already use Robinhood, enable the sports/events section. Verify your identity and make test deposits on each platform.
Week 3-4: Monitor manually. Pick 5-10 high-profile markets that exist on multiple platforms. Check prices daily, noting any differences. Use a spreadsheet to track spreads over time.
Month 2: Execute small trades. When you spot a spread of 5 cents or more, execute a small arbitrage (10-20 contract pairs). Track your actual execution prices versus the quoted prices to understand slippage.
Month 3 and beyond: Scale and automate. Increase position sizes as you gain confidence. Consider using the arbitrage finder tool or building custom monitoring scripts using platform APIs.
The key to successful arbitrage is discipline. You are not predicting outcomes — you are hunting for pricing errors and executing quickly. Keep your emotions out of it, track every trade meticulously, and never risk more capital than you can afford to have locked up across multiple platforms for extended periods.