How Prediction Markets Work: Contracts, Prices & Probability
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A prediction market lets people trade contracts on the outcome of a future event — an election, a Fed decision, a championship. The price of a contract is, in effect, the market’s estimate of how likely the outcome is.
They look different from sportsbooks but answer the same question — what are the odds? — through a market of buyers and sellers rather than a bookmaker setting a line.
Contracts priced 0 to 1
Most markets trade binary “Yes/No” contracts that settle at $1 if the event happens and $0 if it does not. A contract trading at 62¢ implies the market thinks there is roughly a 62% chance of “Yes”.
That price is the implied probability directly — no conversion needed. It is what makes prediction markets so easy to compare against de-vigged sportsbook odds.
Where the price comes from
Unlike a sportsbook, no house sets the number. Traders post buy and sell orders, and the last traded price is the market’s consensus. As new information arrives, traders move the price.
Liquidity matters: a market with deep order books and high volume gives a more reliable price than a thin one, where a single trade can swing the quote.
Buying the cheaper side
For a buyer, the “best” price is the lowest one — the cheapest way to back an outcome means the biggest payout if it hits. This mirrors line shopping for the best sportsbook odds.
When the same event trades on multiple platforms, the prices can differ. OddsGrab surfaces the best available price per outcome and flags meaningful gaps.
- Yes + No prices should sum to roughly $1; the small overage is the spread.
- Play-money venues (e.g. Manifold) are a signal, not a tradeable price.
- Fees, funding method, and regional access all affect your real cost.
Frequently asked questions
- What does a prediction market price mean?
- The contract price is the market’s implied probability of the event. A contract at 62¢ implies about a 62% chance, and pays $1 if the outcome happens or $0 if it does not.
- How are prediction markets different from sportsbooks?
- A sportsbook sets the odds and takes the other side of your bet; a prediction market matches you against other traders, and the price is set by supply and demand. The price is already an implied probability, so the two can be compared directly.
- Can prices differ between platforms?
- Yes. The same question can trade at different prices on Polymarket, Kalshi, and others because of separate order books, fees, and access. Comparing them is exactly how you find the best price.
- What happens when a market resolves?
- At resolution the winning contracts pay out $1 each and the losing side settles at $0. Every market publishes resolution criteria up front; read them carefully, because ambiguous wording is the main source of disputes.
- Are prediction markets the same as gambling?
- They share mechanics with betting, but regulated venues like Kalshi are structured as event-contract exchanges overseen by the CFTC. Either way, you can lose your stake, so treat position sizing the same way you would any speculative bet.
- Why might a market price be more accurate than a poll?
- Traders have money at stake, so they are incentivised to price in all available information rather than just state a preference. Liquid markets tend to be well-calibrated, though thin ones can be noisy or manipulated.
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Educational content for informational purposes only. Not betting or financial advice. Please gamble responsibly. 21+ where applicable.