How Do Prediction Markets Work? Event Contracts Explained
A prediction market takes a question about the future, one with a clean yes-or-no answer, and turns it into a price you can trade. That price is the single most important thing to understand here, because it is not an opinion or a marketing number. It is the crowd's live estimate of how likely the event is to happen, expressed in cents. Learn to read that one number and the rest of the machine explains itself: why the price moves, why there is no bookmaker taking the other side, and why the whole thing is regulated as a financial contract rather than a sports bet.
That is the thread of this guide. We will start with what an event contract actually is, watch a price behave like a probability, then follow that same price through the order book, through the news that moves it, and all the way to settlement. By the end the promise is simple. You will be able to glance at any prediction market and know exactly what it is telling you.
In Summary (TL;DR)
- A prediction market lets people trade event contracts: yes/no contracts on a future outcome that settle at $1 if the event happens and $0 if it does not.
- The price in cents equals the market's implied probability. A contract at 60 cents means the crowd thinks the event is about 60% likely.
- Prices are set by an order book, with buyers and sellers matched directly, not by a bookmaker baking in a margin. That is the structural difference from a sportsbook.
- Prices Move when new information arrives or when order flow tips the balance of buyers and sellers.
- Settlement is the moment the outcome is known: the contract resolves to $1 or $0 against a pre-defined source.
- Leading platforms operate as CFTC-regulated event contracts, not sports betting: Kalshi as a CFTC-designated contract market, Polymarket back in the U.S. under a CFTC order. It is a legal distinction that matters, and one whose state-by-state availability changes often.
What Is An Event Contract?
An event contract is a legally binding agreement to pay out based on whether a specific, verifiable event occurs. Each contract has two possible ends. If the event happens, the contract is worth $1. If it does not, the contract is worth $0. There is no middle ground and no gray area, which is exactly why these markets only work on questions with an unambiguous answer and a clear resolution date.
Because the payout is always one dollar or zero, the price the market charges you today has to sit somewhere between those two poles, and where it sits is the whole story. A contract trading at 60 cents can only rise to a dollar or fall to zero, so paying 60 cents is a statement about how confident the market is that you will collect the full dollar.
On the leading platforms, Kalshi lists these contracts as a CFTC-designated contract market, and Polymarket returned to the U.S. under a CFTC order. Either way they are regulated as financial contracts, which is why the industry calls them event contracts rather than bets. We will come back to that regulatory label, because it is where most of the confusion (and the compliance risk) lives.
How Prediction Market Pricing Works: Price Is Probability
Here is the payoff on the promise from the intro. The reason the price is so powerful is that it converts directly into a probability, no math degree required. Divide the price in cents by 100 and you have the market's implied chance of the event happening.
| Contract Price | Implied probability | What the crowd is saying |
|---|
| 10¢ | ~10% | Long shot, probably won't happen |
| 25¢ | ~25% | Unlikely, but live |
| 50¢ | ~50% | A genuine coin flip |
| 75¢ | ~75% | Likely, priced as the favorite |
| 90¢ | ~90% | Heavy favorite, the market is confident |
The most interesting row is the 50-cent line. A contract sitting at exactly 50 cents is the market throwing up its hands and calling the outcome a true coin flip, the point of maximum uncertainty, where the crowd sees the two outcomes as equally likely. Every other price is the crowd leaning one way, and the further from 50 it drifts, the more one-sided the information has become.
Say a market asks whether a particular team will win its league championship, and the contract is trading at 20 cents. That is a clearly illustrative number, not a live quote, but read it the way the market intends. The crowd is pricing that team at roughly a 20% chance to win it all. Buy at 20 cents, and if the team wins you collect a dollar for every contract; if it loses, the contract expires at zero. Your profit and your risk are both baked into that entry price the moment you trade.
This is also why prediction market prices are so useful even if you never trade them. They are a real-time, money-backed forecast. People are putting capital behind their estimate, which tends to keep the number honest.
New to reading probabilities off a price? OddsShopper's odds screen does the same translation for sportsbook lines. It strips each book's margin out and shows you the fair, no-vig probability behind every number, so you can compare a market's implied chance against what the books are quoting for the same event.
Order Books Vs. The Sportsbook's Vig
Now follow that price one level down, into the machinery that sets it, because this is where a prediction market stops resembling a sportsbook. When you bet a moneyline at a sportsbook, the book is your counterparty. It sets both sides of the line and builds in a margin, called the vig (or juice, or hold), so that the two prices add up to more than 100%. That extra slice is the book's edge, and you pay it on every bet whether you win or lose.
A prediction market works differently. It runs an order book, the same mechanism a stock exchange uses. Traders who want to buy a contract post the price they are willing to pay; traders who want to sell post the price they will accept. When a bid and an ask meet, a trade happens. The platform is not taking the other side of your position. It is matching you against another trader and typically charging a transparent fee rather than an embedded margin.
That structural difference has a practical consequence. On a sportsbook, the "yes" and "no" prices are deliberately padded so they sum past 100%, and that gap is the vig. In a healthy prediction market order book, the yes and no prices tend to sit much closer to summing to exactly 100%, because no house is padding both ends. It does not mean trading is free. Spreads and fees are real, and we cover them below, but the cost structure is out in the open rather than hidden inside the line. (If the phrase "no-vig price" is new, our positive expected value guide walks through why stripping the margin out is the first step to finding a fair number.)
See both numbers side by side. OddsShopper's Sharp Action tool surfaces where the sharp money, including exchange and prediction-market flow, is landing, and the odds screen shows the fair, no-vig probability behind every sportsbook line, so you can set it beside a prediction market's price for the same event. New to OddsShopper? It scans the market and shows you the fair, no-vig price so you can see exactly who is offering the better number. Try OddsShopper Pro free for 7 days, and code PREDMARKET20 takes 20% off your first month of OS Pro or OS Core if you subscribe: Start your free trial.
Why Prediction Market Prices Move
A price that started as a probability does not sit still, and the reasons it moves are the same two forces that move any market: information and flow.
New information is the big one. Anything that genuinely changes the odds of the event, such as a result, an announcement, a report, or a shift in conditions, pushes traders to reprice. If the crowd learns something that makes an outcome more likely, buyers rush in, bids climb, and the contract ticks up toward a dollar. Bad news for that outcome does the reverse. Because the price is a probability, watching it move is watching the crowd update its forecast in real time.
Order flow is the quieter force. Even without fresh news, a wave of buyers with no matching sellers will lift a price simply because demand outruns supply, and the opposite pushes it down. In a thin market, one without many traders, a single large order can move the price more than the underlying odds justify, which is one of the liquidity risks we flag later.
Recall the coin-flip market from earlier, the one sitting at 50 cents. The instant real information arrives, that perfect balance breaks: the side the news favors gets bid up, the other side sags, and the 50-50 standoff resolves into a lean. The price was never frozen. It was just waiting for someone to know something.
What Settlement Means
Every event contract ends the same way, at settlement, the moment the real-world outcome becomes known and the contract pays out. If the event happened, holders of "yes" collect $1 per contract; if it did not, "yes" settles at $0 and the "no" side collects instead.
What keeps settlement honest is that each market defines its resolution source up front, the specific, agreed-upon authority that determines the answer. A well-built market spells out exactly what counts as a yes, what counts as a no, and which source is the referee, so there is no argument when the moment comes.
Key takeaway: before you trade any contract, read its resolution terms first. Know what counts as a yes, what counts as a no, and which source decides. The price only matters once you know exactly what has to happen to collect on it.
Settlement is also why the price converges on a dollar or zero as the event nears. As uncertainty drains away, the probability the price represents marches toward 100% or 0%, and at resolution it snaps to one end. The number that started as a forecast finishes as a fact.
Prediction Markets Vs. Sports Betting: The Legal Distinction
This is the part to get right, because it is where the mechanics meet the law. Prediction markets on platforms like Kalshi and Polymarket operate as CFTC-regulated event contracts. They are not sports betting as a legal category, and the two should never be treated as the same thing. The Commodity Futures Trading Commission oversees them as financial instruments, the same regulator that governs commodity and futures markets. (Our prediction markets vs. sports betting guide goes deeper on how the two differ in practice.)
That distinction has real consequences for where you can and cannot participate, and the map does not match the sportsbook map at all. Event contracts can be available in states where sportsbooks are not, and blocked in states where sportsbooks are live. Availability is also platform-specific and changes frequently, so treat any snapshot as a starting point, not gospel.
As of July 2026, here is the lay of the land. Verify each platform's current eligibility on its own site before doing anything:
- Kalshi operates as a CFTC-designated contract market and is available in most U.S. states, with restrictions or limits in several, including Arizona, Massachusetts, Maryland, Michigan, Montana, New Jersey, Nevada (where sports contracts are paused), and Ohio.
- Polymarket returned to the U.S. through the QCEX acquisition in July 2025 and a CFTC Amended Order in November 2025. Its U.S. exchange has been live since December 2025, the waitlist was removed in May 2026, and it is currently iOS-only. It is blocked in states including Arizona, Illinois, Massachusetts, Maryland, Michigan, Montana, Nevada, and Ohio.
- Minnesota is the one to underline: participating in these markets becomes a felony there effective August 1, 2026. If you are in Minnesota, do not trade event contracts. This guide is not encouraging you to.
Because these rules shift, always date what you read ("as of July 2026") and check the platform's own eligibility tool for your state before you act. Nothing here is legal advice; it is a plain-language summary of a fast-moving regulatory picture.
Fees, Spreads, And Liquidity: The Real Costs
The order-book structure removes the sportsbook's hidden vig, but trading event contracts is not free, and pretending otherwise would be dishonest. Three real costs deserve your attention:
- Trading Fees. Platforms charge fees on trades, and the exact structure varies by platform and market. Read the fee schedule the way you would read the resolution terms, before you trade, not after.
- The Spread. The gap between the best bid and the best ask is a cost you pay to get in and out. Wider spreads in thinner markets eat into any edge.
- Liquidity Risk. A market with few active traders can be hard to enter or exit at a fair price, and a single large order can swing it. Thin liquidity is the quiet tax on niche markets.
None of these make prediction markets bad. They make them markets. The point is simply that the cost moved from a hidden margin to visible fees and spreads, and a careful trader accounts for all three before deciding a price is worth taking.
How OddsShopper Fits In
You do not need a prediction-market account to get value out of one. The most useful thing an event contract gives you is that clean, real-money probability, and the sharpest way to use it is to hold it up against what the sportsbooks are quoting for the same event.
That side-by-side is exactly what OddsShopper is built to show. Three tools do the heavy lifting:
- The odds screen strips the vig out of every sportsbook line and reports the fair, no-vig probability, so you can compare a market's implied chance against the books directly.
- The Sharp Action tool tracks where sharp money, including exchange and prediction-market flow, is moving, so you can see which number the informed side is backing.
- The Line-Movement History lets you watch how a price has traveled over time, the same way the "why prices move" section described, but across the whole market rather than one contract.
Put those together and you are doing, in seconds and automatically, the exact thing this guide taught you to do by hand: read a price as a probability, then find who is offering the better number on it.
Frequently Asked Questions
What is a prediction market in simple terms?
It is a marketplace where people trade yes/no contracts on future events. Each contract settles at $1 if the event happens and $0 if it does not, and the price you pay in cents equals the market's estimate of how likely the event is.
How is a prediction market price a probability?
Because a contract can only end at $1 or $0, its price has to sit between them. A price of 70 cents means the market is pricing roughly a 70% chance the event happens. Divide the cent price by 100 to read the implied probability.
Are prediction markets the same as sports betting?
No. Platforms like Kalshi and Polymarket operate as CFTC-regulated event contracts, a financial-market category, not sports betting. Their legality is governed differently and varies by state, so always check each platform's eligibility for your location.
Are prediction markets legal in my state?
It depends on the platform and your state, and the rules change often. As of July 2026, availability is restricted in several states and, importantly, participation becomes a felony in Minnesota on August 1, 2026. Verify current eligibility on the platform's own site before doing anything.
Do prediction markets charge a vig like a sportsbook?
Not in the same way. Instead of a bookmaker padding both sides of a line, prediction markets use an order book that matches traders directly, typically charging transparent fees. You still pay costs (fees, the bid-ask spread, and liquidity risk), but they are visible rather than hidden inside the price.
What does it mean when a contract "settles"?
Settlement is when the real-world outcome is known and the contract pays out, $1 to the correct side and $0 to the other, against a pre-defined resolution source that each market names in advance.
Read a price as a probability, follow it through the order book to settlement, and a prediction market stops looking like a mystery and starts looking like what it is: a live, crowd-sourced forecast with money on the line. The mechanics are the easy part. The discipline is what helps you navigate these markets carefully: reading the resolution terms, accounting for fees and spreads, and knowing the rules where you live before you ever trade. Understand the number first, and the decisions that follow it are better informed.
New to OddsShopper? It scans the market, strips out the vig, and shows you the fair probability behind every line, so you can put a prediction market's number next to every sportsbook's and see who has the better one. Start free for 7 days to see it in action, then keep going for 20% off your first month of OS Pro or OS Core with code PREDMARKET20: Start your free trial.
