Prediction market review: how event contracts work and what to check before you trade

Prediction markets let you buy and sell shares in the outcome of real-world events at prices set by other traders, not by a bookmaker. That removes the margin and adds new risks. This guide covers both.

By CasinoTrust Editorial TeamUpdated August 31, 20269 min readFact-checked against the Ranking Protocol

A prediction market is an exchange for event contracts. Each contract pays $1 if an event happens and $0 if it does not, and trades between those values until resolution. A "Yes" share priced at $0.62 means the market collectively estimates a 62% probability. You are trading against other participants; the platform takes a fee, not a margin, and does not care who wins. That structure makes prediction markets the closest thing to a fair price in the gambling world — and introduces risks a sportsbook customer has never had to think about. This page is part of our casino online reviews and pairs with the prediction market comparison.

How prediction markets differ from sportsbooks

At a bookmaker you bet against the house at a price the house sets, with a margin built in. On a prediction market you trade against other people at a price the order book sets. The differences follow from that. One caveat before the table: an operator can present yes/no event cards without publishing whether the price comes from a book or from the operator — 1win Markets is in that position today — and where the pricing model is not published, the sportsbook column is the safer description of what you are actually trading against.

Reading a price as a probability

If Yes trades at $0.62 and No at $0.39, the pair sums to $1.01 — the 1 cent is the spread, which is the market's equivalent of the bookmaker's overround. On liquid markets that spread is often under 1%; on thin markets it can be 5–10%, which is worse than a good sportsbook. Converting to decimal odds: $0.62 is 1 / 0.62 = 1.61. The same expected-value logic applies as in betting — you profit when your probability estimate is more accurate than the market's — with the difference that you can also profit by buying at $0.62 and selling at $0.70 before the event resolves.

How we rank prediction markets

Our Ranking Protocol dimensions are adapted because prediction markets have no house edge, no RTP and no bonuses worth the name. Liquidity and fees replace games and margins; the resolution process and regulatory status replace licence tier as the core of trust.

Fees and liquidity: where the real cost hides

Platforms advertise "no fees" or low fees, and that can be literally true while trading is still expensive. Three costs matter. The spread: on a market with $2,000 of resting orders, a $500 buy moves the price against you. Slippage is the real fee. Trading fees: some venues charge a percentage of profit or of the trade; check whether it applies to makers, takers or both. Withdrawal costs: on-chain platforms require you to pay network gas and usually to hold crypto; regulated US platforms use bank transfers with their own delays. We measure all three on a standard basket of markets on test day.

Resolution risk: the risk sportsbooks do not have

A football match has a final score. "Will X happen by 31 December?" has a resolution rule written by a human, interpreted by a resolver, and sometimes disputed. Markets have resolved on technicalities — the literal wording of the question rather than its obvious intent — and markets using decentralised oracles have had outcomes contested by token holders with a financial stake in the answer. Before trading any contract, read the resolution criteria in full, identify who decides and what source they will use, and discount your edge by the probability that the market resolves in a way you did not anticipate. Ambiguous wording is a reason to skip a market, however mispriced it looks.

Regulation: CFTC-registered versus offshore

In the United States, event contracts fall under the Commodity Futures Trading Commission. Kalshi is a CFTC-registered designated contract market that accepts US customers with full identity verification, bank funding and customer-fund protections comparable to a brokerage; it is the regulated alternative for US residents and we reference it here without linking because we have not yet completed a test cycle. Polymarket's US entity is now CFTC-regulated following its acquisition of a licensed exchange, while its global on-chain venue operates without a gambling or financial licence and excludes US users. Outside the US, most countries have no specific framework, and the legal status of trading on an offshore venue is often unclear. A regulated venue gives you a complaints route and fund protection; an on-chain venue gives you self-custody and no one to call.

What to look for in a prediction market

• Published resolution rules for every market, naming the resolution source and the decision process
• A dispute mechanism with a track record you can read, not just a description
• Order-book depth visible before you trade, so you can see the real cost of your position
• Clear regulatory status for your country and geo-restrictions that are actually enforced
• Fees stated as a complete list: trading, withdrawal, network, inactivity
• Self-custody (on-chain) or segregated customer funds (regulated) — you should know which
• Ability to sell before resolution at a reasonable spread, not only to hold to settlement

Red flags in prediction markets

• Markets with resolution criteria that depend on a subjective judgement or an unnamed source
• A history of resolutions reversed or contested where the platform or token holders profited
• Liquidity that is mostly the platform's own market-maker, which can withdraw without notice
• Promotional "free money" markets or airdrop incentives that attract wash trading and distort prices
• No stated policy on insider trading by people with non-public knowledge of the event
• Encouragement to use a VPN to bypass geo-restrictions — a breach that can void your positions
• Any venue that holds your funds without either regulation or on-chain transparency

If you are new to prediction markets

Treat it as trading, not betting. Start with the probability conversion — a $0.25 share needs the event to happen more than 25% of the time for you to profit — and size positions so that a market resolving against you, or resolving unexpectedly, does not damage you. The staking discipline in our bankroll management guide transfers directly. If you come from sports betting, read our sports betting reviews alongside this page to see where bookmaker prices and market prices diverge; that divergence is often where the value is. The Academy explains expected value in detail, and the principle is identical whether the instrument is a blackjack hand or an election contract.

The reviewed platforms in brief

1win Markets

1win runs its prediction product, Markets, in a binary yes/no format: you pick an event and answer a yes or no question, and each card shows the event, the question wording, the two outcomes, the current odds and a deadline. Coverage spans politics, sports, culture, tech, space and celebrities, and on 17 July 2026 it added crypto price markets — a HYPE year-end price market and a HYPE-versus-Solana market-cap market, an XRP 2026 price target and a Dogecoin year-end forecast. It leads our ranking on access rather than on pricing: one account covers casino, sportsbook, poker and Markets, funding is by card or crypto with no wallet, no bridging and no on-chain steps, there is a mobile app, and support runs through live chat. The limitation belongs in the same breath as that convenience — 1win does not publish whether Markets is a peer-to-peer order book or fixed odds set by the operator, and it publishes no fee schedule and no written resolution-source policy. Until it does, read its prices as operator-set rather than crowd-set, and do not treat it as an exchange. Read the full 1win review.

Polymarket

Polymarket is the largest prediction market by volume and the most liquid on major political and macro markets, where spreads are typically a cent or two. It runs on Polygon with USDC, so there is no fiat on-ramp on the global venue, funds are self-custodied and withdrawals are instant once a market resolves. Resolution uses a decentralised oracle with a dispute process, which has produced contested outcomes on ambiguously worded markets; read the rules of every contract. The US entity is now CFTC-regulated; the global venue is not, and excludes US residents. No live chat. Read the full Polymarket review.