World Cup Prediction Markets Explained: Essential Terms for Polymarket and Kalshi

For those who have been following the 2026 FIFA World Cup with any real interest, a particular shift in how people engage with the tournament has been difficult to ignore. Prediction markets are pulling billions of dollars away from traditional sportsbooks, and the terminology they use comes from a very different world. Terms like event contract, CLOB, resolution source, and implied probability belong to the language of finance, not sports betting, and misunderstanding any one of them can, as many traders have discovered the hard way, cost you real money. What follows is a complete glossary of the terms you need to navigate prediction markets during the World Cup, with real examples drawn from live markets on Polymarket and Kalshi as of early June 2026. Prices change constantly. The definitions do not.

How to Use This Glossary

Each entry includes a clear definition, a worked example using actual World Cup 2026 market data where possible, and cross-references to related terms. Terms are grouped by category rather than alphabetically, so they can be absorbed in a logical order. For those looking for a specific term, a simple search will locate it quickly.

Market Structure Terms

These are the terms that describe how prediction markets work at a mechanical level. For those who have only ever placed bets through a sportsbook app, this is where the biggest conceptual shift happens, and it is worth taking the time to understand it properly.

Event Contract

A binary financial instrument that pays out a fixed amount, usually 1.00, if a specified event occurs, and 0.00 if it does not. This is the fundamental building block of regulated prediction markets, and everything else in this glossary builds upon it.

Binary Outcome

A market with exactly two possible results, Yes or No. Most World Cup prediction markets are structured this way. Will France win the World Cup? resolves to Yes 1.00 or No 0.00. There is no partial payout, no push, and no dead heat. Some markets may appear to be multi-outcome, such as Who wins Group A?, but they are actually constructed as bundles of binary contracts, one per team. You buy the Germany wins Group A binary or the Scotland wins Group A binary, and each settles independently at 1.00 or 0.00.

Outcome Share

The unit you actually buy and sell on Polymarket. It is functionally identical to an event contract, but denominated in USDC, a dollar-pegged stablecoin, rather than U.S. dollars. When you buy a Yes share in Polymarket’s Brazil to win the World Cup market at 0.085, you are paying 8.5 cents in USDC per share for a contract that pays 1.00 in USDC if Brazil wins. The distinction between an outcome share and an event contract is mostly regulatory and platform-specific. The maths works the same way.

Central Limit Order Book, CLOB

The matching engine that is known to connect buyers and sellers on both Polymarket and Kalshi. When you want to buy 100 shares of England to win the World Cup at 0.11, your order goes into the book. If someone is willing to sell at 0.11, the trade executes. If not, your order sits in the book until someone matches it or you cancel it. This is the same system used by the New York Stock Exchange, Nasdaq, and every major commodity exchange. Prices are set by supply and demand between traders, with no bookmaker deciding the line. A CLOB displays two prices for every market: the bid, which is the highest price someone is willing to pay, and the ask, which is the lowest price any trader is willing to sell at. The gap between them is the spread.

Automated Market Maker, AMM

An alternative to the CLOB model where a smart contract, a self-executing program on a blockchain, sets prices using a mathematical formula rather than matching individual buyers and sellers. Polymarket used an AMM model in its early days before switching to its current CLOB system in 2023. The most common AMM formula is the constant product function x×y=kx \times y = kx×y=k, where xxx and yyy represent the quantities of Yes and No shares in a liquidity pool. As traders buy Yes shares, the pool’s Yes reserves decrease, automatically pushing the Yes price up. AMMs solve liquidity problems in low-volume markets because there is always a price available. The tradeoff is slippage: large orders move the price against you because the formula adjusts in real time. On a CLOB, a large resting limit order fills at one price. On an AMM, a 10,000 buy might start at 0.15 and finish at 0.19. Most serious prediction markets now use CLOBs. AMMs still power some decentralised markets like Augur v2 and smaller Polygon-based platforms.

Resolution Source

The data feed or authority that determines whether a market’s event occurred. This is one of the most overlooked terms in prediction market trading and, for those who take the time to understand it, one of the most important. Polymarket’s World Cup Winner market specifies its resolution source in the market rules. For tournament outcomes, the resolution source is typically FIFA’s official match results. If FIFA declares Spain the winner, the Spain contract resolves to 1.00. Where resolution sources become contentious, however, is in player-level markets. Will Mbappé score five or more goals in the World Cup? might resolve based on FIFA’s official statistics, the Opta data feed, or another source. Different sources occasionally disagree on whether a deflected shot counts as a goal for the shooter or an own goal by the defender. It is worth checking which source your market uses before committing capital. Kalshi publishes resolution sources for every contract on its terms page. Polymarket includes them in each market’s description. If you cannot find the resolution source, it is best not to trade the market.

Resolution Rules

The complete set of conditions that govern how a market settles. Broader than the resolution source, resolution rules cover edge cases: what happens if the World Cup is suspended due to a natural disaster, what if a team is disqualified after the final, what if the tournament format changes mid-competition. A real example from Polymarket’s World Cup markets is this: if FIFA awards the tournament to a team through a ruling rather than on-field play, say a doping disqualification of the winner, the market typically still resolves based on FIFA’s official declaration of the champion. The contract does not care about asterisks. Reading the resolution rules before placing any trade above 50 is, as any experienced trader will quietly confirm, the prediction market equivalent of reading the fine print.

Pricing and Probability Terms

These terms explain how prediction market prices translate into probabilities and expected returns. For those coming from sports betting, this is where the maths diverges considerably from what you may be used to.

Implied Probability

The market-derived likelihood of an event occurring, expressed as a percentage. On a prediction market, implied probability equals the contract price. A contract trading at 0.16 implies a 16 percent chance of that event happening. On sportsbooks, calculating implied probability from American odds requires a formula. For negative odds, implied probability equals the absolute value of the odds divided by the absolute value of the odds plus 100. For positive odds, implied probability equals 100 divided by the odds plus 100. Spain at +450 on DraftKings: 100 divided by 550 equals 18.2 percent implied probability. Spain at 0.16 on Polymarket: 16.0 percent implied probability. The 2.2 percentage point difference represents the sportsbook’s margin.

True Probability

A theoretical concept representing the actual likelihood that an event will occur, independent of any market’s pricing. Nobody knows the true probability that Spain will win the World Cup. The best approximation comes from large, liquid markets where thousands of traders with real money at stake are converging on a price. When you see an opportunity in prediction markets, you are making a judgment that the market’s implied probability is wrong and the true probability is higher, if you are buying, or lower, if you are selling. That, in essence, is the core skill of prediction market trading.

Overround, Vigorish, Vig, Juice

The total margin built into a sportsbook’s odds. It is calculated by summing what we call the implied probabilities of all outcomes in a market. If the sum exceeds 100 percent, the excess is the overround. In a perfectly fair World Cup Winner market, the implied probabilities of all 48 teams should sum to exactly 100 percent, since one team must win. On Polymarket, the sum hovers near 100 percent, sometimes dipping slightly below due to market mechanics. On DraftKings and FanDuel, the sum lands between 120 and 125 percent. That 20 to 25 percent overround means sportsbook bettors collectively pay 120 to 125 in implied risk for every 100 in actual outcomes. It is a tax that does not exist on prediction market exchanges because there is no house setting the odds. A specific example makes this clearer. If the fair odds for every team summed to 100 percent and FanDuel’s odds sum to 122 percent, then on average, every dollar wagered at FanDuel carries about 18 percent in embedded cost. Prediction market traders paying near 100 percent in total implied probability carry close to zero percent embedded cost, minus platform fees.

Spread, Bid-Ask Spread

The difference between the highest price any buyer is willing to pay and the lowest price a seller is willing to accept for a contract. On Polymarket’s World Cup Winner market, a popular contract like France might show a bid of 0.159 and an ask of 0.161. That is a 0.2-cent spread, which is extremely tight. A less-traded contract like Saudi Arabia might show a bid of 0.005 and an ask of 0.009. That is a 0.4-cent spread, but it represents an 80 percent price gap relative to the contract’s value. Tight spreads mean you can enter plus exit positions without losing much to the gap. Wide spreads mean you are paying a hidden cost on every round trip. On the France contract, buying at 0.161 and immediately selling at 0.159 loses you 0.002 per share, about 1.2 percent of your position. On the Saudi Arabia contract, the same round trip loses 0.004, about 44 percent of your position. Spread width is, in short, a direct indicator of market liquidity.

Slippage

The difference between the price you expected to pay and the price you actually received when your order executes. Slippage is most common in two situations: illiquid markets with thin order books, and large orders that eat through multiple price levels. If you want to buy 10,000 shares of Argentina to win and only 3,000 shares are available at 0.088, the next 4,000 might be priced at 0.089, and the final 3,000 at 0.091. Your average fill price is 0.0893, not the 0.088 you saw on screen. That 0.0013 per share difference, multiplied by 10,000 shares, is 13.00 in slippage. On sportsbooks, slippage does not exist in the same way because the house always fills at the posted line, up to their limit. On prediction markets, you control slippage by using limit orders instead of market orders.

Limit Order

An instruction to buy or sell contracts at a specific price or better. If you place a limit buy for France at 0.155, your order only fills if someone is willing to sell at 0.155 or lower. If the current ask is 0.161, your order sits in the book, unfilled, until the price drops to your level or you cancel it. Limit orders give you price control at the cost of execution certainty. You might not get filled at all if the market moves away from your price.

Market Order

An instruction to buy or sell immediately at whatever price is currently available. A market buy takes the best available ask price. If there are not enough shares at that price to fill your full order, it moves up to the next price level, and then the next, until it is filled. Market orders guarantee execution but not price. In liquid markets, like Polymarket’s top World Cup contracts, the difference is negligible. In thin markets, it can be considerable.

Depth

The total volume of resting orders at each price level in the order book. Depth tells you how much you can buy or sell at a given price before the price moves. 10,000 shares at 0.16, 8,000 shares at 0.161, and 5,000 shares at 0.162 is an example of three levels of depth on the ask side. Polymarket’s World Cup Winner market has roughly 362 million in total liquidity across all outcomes. That depth means you can place six-figure trades on top teams without moving the price significantly. Smaller markets, such as Will there be a red card in USA vs Mexico?, might have only a few thousand dollars of depth, making large trades impractical.

Trading and Position Management Terms

Once you understand how prices work, these terms cover what you can actually do with your positions during the tournament.

Long Position

Holding Yes shares, or buying event contracts, with the expectation that the price will go up or the event will occur. If you buy 1,000 shares of Germany to win the World Cup at 0.057, you are long Germany. You profit if Germany wins, earning 0.943 per share after the 1.00 payout minus your 0.057 cost, or if the contract price rises before the tournament ends and you sell at the higher price.

Short Position

Holding No shares or selling Yes shares you do not own, with the expectation that the price will go down or the event will not occur. If you short Germany to win at 0.057, you receive 0.057 per share up front and owe 1.00 per share if Germany wins. Your maximum profit is 0.057 per share if Germany does not win and the contract settles at 0.00. Your maximum loss is 0.943 per share if Germany wins and the contract settles at 1.00. On Polymarket, you can go short by buying No shares. On Kalshi, you sell the Yes side of the contract. The economic exposure is identical. Shorting favourites before they are eliminated is a common World Cup strategy. If France is trading at 0.16 and loses in the quarterfinals, the contract drops to 0.00, and a short position opened at 0.16 earns 0.16 per share, a 100 percent return on margin.

Exit, Close Position

Selling a position before the market resolves. This is one of the core advantages prediction markets hold over sportsbooks. If you bought Brazil at 0.085 before the tournament and Brazil beats Germany 3-0 in the round of 16, the contract price might spike to 0.14. You can sell your shares at 0.14, locking in a 64.7 percent gain, without waiting to see if Brazil actually wins the whole tournament. On a sportsbook, your futures bet is locked in until the event concludes. If Brazil gets knocked out in the next round, your profit disappears. On prediction markets, you can take profit at any point.

Position Sizing

How much of your total trading capital you allocate to a single market. This concept is not unique to prediction markets, but it matters considerably more here because binary contracts can go to zero overnight. If you put 80 percent of your bankroll on Argentina at 0.088 and Argentina loses in the group stage, you have lost 80 percent of your capital in a single resolution. A common framework, and one that most experienced traders follow, is to risk no more than two to five percent of your total capital on any single contract. With a 5,000 account, that is 100 to 250 per position. This lets you survive a string of incorrect predictions without losing everything.

Hedging

Opening a second position that offsets the risk of your first position. If you are long Spain at 0.16 and Spain reaches the semifinal, with the contract now at 0.35, you could short Spain at 0.35 on the same platform or buy the opposing team’s contract to lock in a guaranteed profit regardless of the result. Worked example: you own 1,000 Spain shares bought at 0.16, costing 160. Spain reaches the semifinal, and the price rises to 0.35. You sell 600 shares at 0.35, receiving 210. You have already recovered your entire 160 cost plus 50 in profit, and you still hold 400 shares that pay 400 if Spain wins the tournament. Your downside is now zero. This is a partial hedge, and it is, for many traders, one of the most powerful tools available.

Arbitrage

Buying and selling the same outcome across different platforms, or within the same platform, to lock in a risk-free profit from price discrepancies. If Polymarket prices England to win at 0.111 and Kalshi prices the same outcome at 0.108, you could theoretically buy on Kalshi and sell on Polymarket, pocketing the 0.003 difference per contract. In practice, cross-platform arbitrage in prediction markets is harder than it might sound. Withdrawal times, gas fees on blockchain platforms, and the illiquidity of selling at the exact displayed price all eat into the theoretical profit. True arbitrage opportunities in major markets are rare and close within minutes. Within a single platform, arbitrage can exist when the sum of all outcome prices in a multi-outcome market falls below 1.00. If Polymarket’s World Cup Winner market momentarily prices all 48 teams at prices summing to 0.97, you could buy every outcome for 0.97 total and guarantee a 1.00 payout, a 3.1 percent risk-free return.

Paper Trading

Simulating trades without real money to test strategies. Neither Polymarket nor Kalshi offers a formal paper trading mode, but you can track hypothetical positions in a spreadsheet. Record the price when you would have bought, check it daily, and calculate your profit and loss. Doing this for the group stage before risking real capital in the knockouts is, as most experienced traders will advise, time well spent.

Market Types and Contract Structures

World Cup prediction markets are not all about who wins the tournament. Here are the specific contract types you will encounter, each with its own characteristics and considerations.

Futures Market, Outright Winner

A market on which team wins the entire tournament. This is the highest-volume World Cup prediction market on both Polymarket and Kalshi. Prices are lowest, and potential returns highest, before the tournament starts, then rise for advancing teams and drop to 0.00 for eliminated ones. Polymarket’s World Cup Winner market has crossed 2 billion in total trading volume as of June 2026, with over 1,100 traders holding open positions. By volume, this is the largest single prediction market in history outside of U.S. presidential elections, a hardly surprising distinction given the global appeal of the tournament.

Match Market, Game-Level

A market on the outcome of a single game. Will Brazil beat Serbia in their Group G opener? resolves independently of the overall tournament. Match markets typically feature three outcomes: Win, Draw, and Loss, structured as separate binary contracts. Kalshi lists match markets for every World Cup game. Polymarket has them for the more prominent matchups. Match markets resolve faster, within 90 minutes of kickoff plus stoppage time, and trade at higher implied probabilities than futures because they are simpler events.

Prop Market, Player or Event Specific

Markets on specific events within the tournament. Will Mbappé score the most goals? Will there be a VAR controversy in the final? Will a host city match be postponed due to weather? Prop markets are where prediction markets become particularly creative. They tend to be less liquid, carry wider spreads, and present more resolution risk because the resolution criteria can be ambiguous. They also, however, tend to offer more mispriced opportunities, precisely because fewer sophisticated traders are monitoring them.

Conditional Market

A market that only activates or resolves based on the outcome of another event. If the USA advances to the quarterfinals, will they beat the Group E winner? These are less common on major platforms but appear in specialised prediction market communities. The pricing of conditional markets bakes in the probability of the conditioning event. If the market implies a 30 percent chance that the USA beats the Group E winner, but there is only a 40 percent chance the USA advances to face them, the unconditional probability is 12 percent.

Multi-Leg Parlay Equivalent

Combining positions across multiple markets. On sportsbooks, this is a parlay. Prediction markets do not offer built-in parlay functionality, but you can construct the equivalent by buying contracts in separate markets. The advantage is notable: on sportsbooks, parlays carry compounded vig across each leg. If each individual leg has 5 percent vig, a four-leg parlay might carry 18 to 20 percent effective vig. On prediction markets, each leg is priced at near-zero margin, so a self-constructed parlay carries only the individual spreads and fees of each contract.