Two exchanges now dominate prediction markets: Polymarket, the crypto-native giant settling on Polygon, and Kalshi, the CFTC-regulated US contract market. They trade many of the same questions at different prices — and the live spreads below are exactly why traders watch both.
| Event | Outcome | Polymarket | Kalshi | Diff |
|---|---|---|---|---|
| Solana price target by end of 2026 | ↑ 300 | 7¢ | 16¢ | −10¢ |
| 2028 US Presidential Election Winner | Marco Rubio | 10¢ | 16¢ | −5¢ |
| Bitcoin price target by end of 2026 | ↑ 110,000 | 25¢ | 30¢ | −5¢ |
| 2026 MLB World Series | New York Yankees | 11¢ | 15¢ | −4¢ |
| 2026 MLB World Series | Atlanta Braves | 10¢ | 13¢ | −3¢ |
| 2028 US Presidential Election Winner | JD Vance | 21¢ | 19¢ | +3¢ |
| 2028 Democratic Presidential Nominee | Jon Ossoff | 6¢ | 9¢ | −2¢ |
| 2027 NFL Super Bowl Winner | Dallas Cowboys | 2¢ | 5¢ | −2¢ |
Polymarket and Kalshi both let you trade binary YES/NO contracts on real-world events, but they come from opposite ends of the regulatory and technical spectrum. Understanding that split is the key to knowing which venue suits which trade.
Polymarket is a decentralized prediction market built on Polygon. Trades settle in USDC through Gnosis' Conditional Token Framework, the orderbook lives at clob.polymarket.com, and you hold your own funds in a Polygon wallet. It historically served a non-US user base and focuses on breadth: crypto, macro, politics, sports, and culture.
Kalshi is a CFTC Designated Contract Market — the only federally regulated event exchange in the United States. Accounts are KYC'd, funding is USD via ACH or wire, and contracts settle to 0 or 100 cents through a traditional clearinghouse. Kalshi's 2024 court win opened the door to election markets, and sports followed soon after.
Because the two venues serve different user bases with different capital costs, identical markets often trade at meaningfully different odds. 'Will the Fed cut in December?' on Polymarket can settle at a different implied probability than the Kalshi equivalent for hours or days — which is the entire reason arbitrage discussions dominate r/PredictionMarkets.
Polymarket acquired QCX in 2025 to obtain a CFTC license and re-enter the US, while Kalshi has pushed aggressively into crypto deposits and sports. The venues are converging on surface area, but their liquidity pools, fee models, and settlement rails remain distinct — and that is what keeps price divergences alive.
Neither platform is strictly better — it depends on where you live, how you custody money, and what you are trying to trade. Here is how experienced users actually split their activity.
The differences that actually decide where to route an order — regulation, fees, listing speed, liquidity, and API surface, all in one scannable table.
| Factor | Polymarket | Kalshi |
|---|---|---|
| Federal legality | CFTC-approved Sept 2025 Entered the US through the QCX (OCEX) acquisition; federal approval landed in September 2025. | CFTC-approved since 2020 Native CFTC Designated Contract Market — the first federally regulated US event exchange. |
| State availability | US rollout in waitlist (Feb 2026) Global platform open to non-US users; US platform approved but staged. | Live in 40+ US states Directly available in most US states (NY, NV and a handful remain restricted). |
| Registration & KYC | Full KYC on US platform Global platform allows on-chain pseudonymous trading; US (OCEX) entity requires full identity verification. | Full identity verification SSN, government ID, and address verification required for every account. |
| Settlement asset | USDC wallet balance Settles in USDC on Polygon; funds are self-custodied in a user's wallet. | USD at a regulated clearinghouse Settles in US dollars held with a traditional clearinghouse, funded via ACH, wire, or debit card. |
| Fees | 0% global · 0.10% US taker Global CLOB is fee-free — you pay only Polygon gas (~$0.01). US platform charges 0.10% taker. | 0.07 × P × (1−P) Per-contract fee that scales with price and peaks near $0.50 — usually a few cents per share. |
| Market creation speed | Minutes · global No regulatory gate on new questions — breaking-news markets can go live in minutes. | Weeks · CFTC self-cert Every contract must clear CFTC self-certification, so breaking-news listings lag noticeably. |
| 2025 trading volume | $33.4B Deepest global liquidity in long-dated political, crypto, and macro markets. | $43.1B Edged past Polymarket in 2025 after regulated sports event contracts went live. |
| API & data access | CLOB + Gamma + on-chain CTF Public Gamma discovery API, CLOB with EIP-712 signed orders, and indexable on-chain CTF events. | REST + WebSocket + SDKs API-key auth with official Python and TypeScript SDKs — no wallet signing required. |
For active traders the fee schedule often decides whether a strategy is profitable. Here are each platform's tiers alongside worked examples — the numbers that matter when you are arbitraging tight spreads.
Global CLOB is fee-free · US platform 0.10% taker
Price-tiered per-contract fee with 0.25% maker on major events
Real threads about Polymarket and Kalshi arbitrage from r/algotrading, r/Polymarket, r/Kalshi, and r/PredictionMarkets. Short verbatim quotes; full discussions on Reddit.
consistent arbitrage opportunities sitting there in plain sight.
Found 5¢ arbitrage spreads in prediction markets expiring tomorrow
finding the spread is easy, executing it before it closes is the hard part.
Automating the Prediction Market Arb: Programmatically capturing the 5% spread
Feels like there should be a single place to see all the prices at once.
Anyone else cross-referencing Poly and Kalshi on the same market to find better odds?
If the same event is priced differently on Kalshi vs Polymarket that's free edge.
How I research Kalshi and Polymarket markets before placing a trade
consistent arbitrage opportunities sitting there in plain sight.
Found 5¢ arbitrage spreads in prediction markets expiring tomorrow
finding the spread is easy, executing it before it closes is the hard part.
Automating the Prediction Market Arb: Programmatically capturing the 5% spread
Feels like there should be a single place to see all the prices at once.
Anyone else cross-referencing Poly and Kalshi on the same market to find better odds?
If the same event is priced differently on Kalshi vs Polymarket that's free edge.
How I research Kalshi and Polymarket markets before placing a trade
When the same outcome trades at different prices on each venue, that gap is an arbitrage window. We surface the largest live spread, refreshed hourly from the table above.
The questions new traders ask first — including the ones that dominate the arbitrage threads on r/PredictionMarkets.
Parlay watches both exchanges at once, normalizes their markets, and highlights where prices disagree. Spot arbitrage candidates, track liquidity, and let your agents trade the whole prediction-market landscape — not just one venue.