World Cup 2026 Prediction Market Glossary: Every Term a Trader Needs to Know

Prediction markets are pulling billions of dollars away from traditional sportsbooks during the 2026 FIFA World Cup. But the vocabulary is different. Terms like “event contract,” “CLOB,” “resolution source,” and “implied probability” come from finance, not sports betting, and misunderstanding any one of them can cost you money. This is the complete glossary, with real examples from live World Cup markets on Polymarket and Kalshi.

How to Use This Glossary

Each entry includes a plain-English 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 you can absorb them in logical order. If you’re looking for a specific term, use Ctrl+F.

The data referenced throughout comes from Polymarket and Kalshi World Cup markets as of early June 2026, unless otherwise noted. Prices change constantly. The definitions don’t.

Market Structure Terms

These are the terms that describe how prediction markets work at a mechanical level. If you’ve only ever placed bets through a sportsbook app, this section is where the biggest conceptual shift happens.

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 doesn’t. This is the fundamental building block of regulated prediction markets.

On Kalshi, an event contract for “Spain wins the 2026 FIFA World Cup” trading at $0.169 means you pay 16.9 cents per contract. If Spain wins, each contract pays $1.00. If they don’t, it pays nothing.

Event contracts are regulated by the CFTC under the Commodity Exchange Act, putting them in the same legal category as crude oil futures or S&P 500 options. They are not “bets” in the legal sense, which matters for taxation and state-by-state availability. More on that under Section 1256 Contract.

Binary Outcome

A market where there are exactly two possible results: Yes or No. Most World Cup prediction markets are structured this way. “Will France win the World Cup?” resolves Yes ($1.00) or No ($0.00). There’s no partial payout, no push, no dead heat.

Some markets seem like they should be multi-outcome (e.g., “Who wins Group A?”) but 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. Each settles independently at $1.00 or $0.00.

Outcome Share

The unit you actually buy and sell on Polymarket. 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 on Polymarket’s “Brazil to win the World Cup” market at $0.085, you’re paying 8.5 cents in USDC per share for a contract that pays $1.00 in USDC if Brazil wins.

The distinction between “outcome share” and “event contract” is mostly regulatory and platform-specific. The math works the same way.

Central Limit Order Book (CLOB)

The matching engine that connects 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.

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 (highest price someone is willing to pay) and the ask (lowest price someone 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 = k, where x and y 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’s 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 (Polymarket, Kalshi, Betfair Exchange) now use CLOBs. AMMs still power some decentralized 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 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. Full stop.

Where resolution sources become contentious: player-level markets. “Will Mbappé score 5+ 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. Check which source your market uses before buying.

Kalshi publishes resolution sources for every contract on its terms page. Polymarket includes them in each market’s description. If you can’t find the resolution source, don’t 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?

Real example from Polymarket’s World Cup markets: 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 doesn’t care about asterisks.

Read the resolution rules before placing any trade above $50. This is 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. If you’ve come from sports betting, this is where the math diverges from what you’re 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% chance of that event happening.

On sportsbooks, calculating implied probability from American odds requires a formula:

For negative odds: Implied probability = |odds| / (|odds| + 100)

For positive odds: Implied probability = 100 / (odds + 100)

Spain at +450 on DraftKings: 100 / (450 + 100) = 18.2% implied probability. Spain at $0.16 on Polymarket: 16.0% implied probability. The 2.2 percentage point difference represents the sportsbook’s margin (the overround, covered below).

True Probability

A theoretical concept. 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’re making a bet that the market’s implied probability is wrong and the true probability is higher (if you’re buying) or lower (if you’re selling). This is the core skill of prediction market trading.

Overround (Vigorish / Vig / Juice)

The total margin built into a sportsbook’s odds. Calculate it by summing the implied probabilities of all outcomes in a market. If the sum exceeds 100%, 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% (since one team must win). On Polymarket, the sum hovers near 100%, sometimes dipping below due to market mechanics. On DraftKings and FanDuel, the sum lands between 120% and 125%.

That 20–25% overround means sportsbook bettors collectively pay $120-$125 in implied risk for every $100 in actual outcomes. It’s a tax that doesn’t exist on prediction market exchanges because there’s no house setting the odds.

A specific example: if the fair odds for every team summed to 100%, and FanDuel’s odds sum to 122%, then on average, every dollar wagered at FanDuel carries about 18% in embedded cost (1–100/122 = 0.18). Prediction market traders paying near 100% in total implied probability carry close to 0% embedded cost, minus platform fees.

Spread (Bid-Ask Spread)

The difference between the highest price a buyer is willing to pay (bid) and the lowest price a seller is willing to accept (ask) 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’s a 0.2-cent spread, extremely tight. A less-traded contract like Saudi Arabia might show a bid of $0.005 and an ask of $0.009. That’s a 0.4-cent spread, but it represents an 80% price gap relative to the contract’s value.

Tight spreads mean you can enter and exit positions without losing much to the gap. Wide spreads mean you’re paying a hidden cost on every round trip (buy then sell). On the France contract above, buying at $0.161 and immediately selling at $0.159 loses you $0.002 per share, about 1.2% of your position. On the Saudi Arabia contract, the same round trip loses $0.004, about 44% of your position.

Spread width is 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 doesn’t 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.

Limit orders give you price control at the cost of execution uncertainty. 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 aren’t enough shares at that price to fill your full order, it moves up to the next price level, and the next, until it’s 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 severe.

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, 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 (e.g., “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’re long Germany. You profit if Germany wins ($1.00 payout minus $0.057 cost = $0.943 profit per share) or if the contract price rises before the tournament ends and you sell.

Short Position

Holding No shares or selling Yes shares you don’t own, with the expectation that the price will go down or the event won’t occur. If you sell (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 (Germany doesn’t win, contract settles at $0.00). Your maximum loss is $0.943 per share (Germany wins, 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 the same.

Shorting favorites before they get 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. A short position opened at $0.16 earns $0.16 per share, a 100% return on margin.

Exit (Close Position)

Selling a position before the market resolves. This is one of the core advantages prediction markets have 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% 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 isn’t unique to prediction markets, but it matters more here because binary contracts can go to zero overnight. If you put 80% of your bankroll on Argentina at $0.088 and Argentina loses in the group stage, you’ve lost 80% of your capital in a single resolution.

A common framework: risk no more than 2–5% of your total capital on any single contract. With a $5,000 account, that’s $100-$250 per position. This lets you survive a string of incorrect predictions without blowing up.

Hedging

Opening a second position that offsets the risk of your first position. If you’re long Spain at $0.16 and Spain reaches the semifinal (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 (cost: $160). Spain reaches the semifinal, price rises to $0.35. You sell 600 shares at $0.35 (revenue: $210). You’ve 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.

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 sounds. 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% 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 P&L. Do this for the group stage before risking real capital in the knockouts.

Market Types and Contract Structures

World Cup prediction markets aren’t all “who wins the tournament.” Here are the specific contract types you’ll encounter.

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. Over 1,100 traders hold open positions. This is, by volume, the largest single prediction market in history outside of U.S. presidential elections.

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 have three outcomes (Win, Draw, Loss) structured as separate binary contracts.

Kalshi lists match markets for every World Cup game. Polymarket has them for marquee matchups. Match markets resolve faster (within 90 minutes of kickoff plus stoppage time) and trade at higher implied probabilities than futures because they’re simpler events.

Prop Market (Player/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 get creative. They tend to be less liquid, have wider spreads, and carry more resolution risk (because the resolution criteria might be ambiguous). They also tend to offer more mispriced opportunities, because fewer sophisticated traders are monitoring them.

Conditional Market

A market that only activates or resolves based on the outcome of another event. “If USA advances to the quarterfinals, will they beat the Group E winner?” These are less common on major platforms but appear in specialized prediction market communities.

The pricing of conditional markets bakes in the probability of the conditioning event. If the market implies a 30% chance the USA beats the Group E winner, but there’s only a 40% chance the USA advances to face them, the unconditional probability of “USA beats Group E winner in the quarters” is 0.30 × 0.40 = 12%.

Multi-Leg (Parlay Equivalent)

Combining positions across multiple markets. On sportsbooks, this is a parlay. Prediction markets don’t offer built-in parlay functionality, but you can construct the equivalent by buying contracts in separate markets.

The advantage: on sportsbooks, parlays carry compounded vig across each leg. If each individual leg has 5% vig, a four-leg parlay might carry 18–20% 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.

Fee and Cost Terms

Every platform charges something. Knowing exactly what costs you’ll pay, and where they’re hidden, determines whether a trade is actually profitable.

Trading Fee (Transaction Fee)

The percentage charged on winning trades by the platform. On Polymarket, the fee parameter θ (theta) is set to 0.05, meaning 5% of your net profit on winning contracts. If you bought Spain at $0.16 and Spain wins, your gross profit is $0.84 per share. Polymarket takes 5% of $0.84 = $0.042. Your net profit is $0.798 per share.

Kalshi uses θ = 0.07 (7% of net profit on winning trades).

On the same Spain contract bought at $0.169, gross profit is $0.831, fee is $0.058, net profit is $0.773 per share.

If you sell a position before resolution at a profit, the same fee applies to your realized gain.

Gas Fee

The blockchain transaction cost paid to process trades on Polymarket’s on-chain version. Gas fees on Polygon (Polymarket’s blockchain) are typically fractions of a cent per transaction, often $0.001-$0.01. This is negligible for any trade above a few dollars.

On Ethereum mainnet (where some prediction markets like Augur operated), gas fees could exceed $50 per transaction during network congestion. This is one reason Polymarket chose Polygon.

Kalshi has no gas fees because it runs on traditional financial infrastructure, not a blockchain.

Maker-Taker Fee Model

A fee structure where “makers” (traders who post limit orders that add liquidity to the book) pay lower fees than “takers” (traders who place market orders that remove liquidity from the book). Polymarket currently uses a flat fee model, but other exchanges (including some crypto prediction platforms) incentivize makers with zero or negative fees to encourage deeper order books.

If you always use limit orders on platforms with maker-taker pricing, your trading costs can drop by 30–70% compared to market orders.

Funding Fee (Deposit/Withdrawal Cost)

The cost of moving money into and out of the platform. Polymarket accepts USDC deposits on Polygon (near-zero cost), ACH transfers (free, 1–3 day settlement), and debit card deposits (variable, usually 2–3% processor fee). Withdrawals in USDC are instant. ACH withdrawals take 1–3 business days.

Kalshi offers ACH (free), wire transfer ($25–30 per wire), and debit card (variable fee). Apple Pay is available for both platforms.

If you’re funding with a credit card or debit card, the 2–3% processing fee is an invisible cost that eats into your returns. A $1,000 deposit via debit card might cost you $25–30 in processor fees before you’ve placed a single trade. ACH is almost always cheaper.

Regulatory and Tax Terms

Prediction markets sit at the intersection of finance, gambling, and technology. The regulatory terms aren’t optional reading. They affect which platforms you can use, how your profits are taxed, and whether you might lose access mid-tournament.

CFTC (Commodity Futures Trading Commission)

The federal agency that regulates prediction markets in the United States. The CFTC oversees Kalshi directly as a Designated Contract Market (DCM) and regulates Polymarket US through its acquisition of QCEX, also a CFTC-registered DCM.

The CFTC’s jurisdiction over event contracts was contested for years but solidified through a series of rulings in 2023–2025. The key precedent: the Third Circuit’s 2024 decision that event contracts on elections (and by extension, sports) can be regulated as commodities derivatives rather than gambling.

DCM (Designated Contract Market)

A CFTC classification for exchanges authorized to list and trade futures and options contracts. The CME Group, CBOE, and Kalshi are all DCMs. Being a DCM means the platform meets specific capital requirements, reporting standards, and consumer protection rules.

For traders, trading on a DCM provides legal clarity, bankruptcy protection for segregated customer funds, and consistent rules enforcement. If Kalshi goes bankrupt, your funds in segregated accounts are protected by the same framework that protects futures traders on the CME.

Section 1256 Contract

An IRS tax classification that applies to certain futures contracts, including regulated event contracts on DCMs. Section 1256 provides a tax advantage: regardless of how long you held the contract, profits are taxed at a blended rate of 60% long-term capital gains and 40% short-term capital gains.

For a trader in the 37% federal income tax bracket, the Section 1256 blended rate works out to about 26.8% (60% × 20% + 40% × 37%). Without Section 1256, all short-term trading profits would be taxed at the full 37%.

Whether Polymarket contracts qualify for Section 1256 treatment depends on whether the trade was executed through the US-regulated arm (QCEX/DCM) or the international on-chain version. Consult a tax professional, but the distinction matters: on a $10,000 profit, the tax difference between 26.8% and 37% is over $1,000.

KYC (Know Your Customer)

Identity verification required before you can trade. Both Polymarket US and Kalshi require government-issued ID, Social Security number, and proof of address. Verification typically takes 1–24 hours.

Polymarket’s international (non-US) version has lighter KYC requirements, which has contributed to its higher volume but also raised regulatory questions. If you’re a U.S. resident, use only the regulated US version.

Geofencing

Platform restrictions based on your physical location, enforced via IP address, GPS, or device-level location services. Kalshi is available in all US states but faces active litigation in Nevada, Maryland, Massachusetts, and Ohio. A court order in any of those states could temporarily block access.

If you hold open World Cup positions and your platform gets geofenced in your state mid-tournament, you may be unable to exit your positions. This is a real risk, not theoretical. In 2024, Kalshi was temporarily blocked in several states during the election cycle.

Mitigation: don’t allocate more than you can afford to have locked up for 4–6 weeks (the duration of the World Cup). If geofencing hits, your positions still resolve at maturity. You just can’t trade them actively.

Blockchain-Specific Terms

These apply primarily to Polymarket and other crypto-native prediction markets. If you’re only trading on Kalshi, you can skip this section, but roughly 60% of World Cup prediction market volume flows through blockchain-based platforms.

USDC (USD Coin)

A stablecoin pegged 1:1 to the U.S. dollar, issued by Circle. USDC is the denomination currency for all Polymarket trades. 1 USDC = $1.00 (maintained through reserves held in Treasury bills and cash at regulated financial institutions).

You don’t need to own crypto to use Polymarket. Debit card and ACH deposits automatically convert to USDC at a 1:1 rate. When you withdraw, USDC converts back to dollars.

Polygon (Network)

The Layer 2 blockchain where Polymarket operates. Polygon processes transactions at high speed (2-second block times) and low cost ($0.001-$0.01 per transaction), compared to Ethereum’s 12-second blocks and variable gas fees that can spike during network congestion.

For traders, this means Polymarket trades confirm in about 2 seconds and cost virtually nothing in gas. You won’t notice the blockchain infrastructure unless you’re depositing USDC directly from an external wallet.

Smart Contract

A self-executing program on a blockchain that automatically settles prediction market contracts. When Polymarket’s resolution oracle confirms that Spain won the World Cup, a smart contract automatically distributes $1.00 per share to all Yes holders and $0.00 to No holders. No human intervention, no delayed payouts, no counterparty risk.

The smart contract’s logic is publicly auditable (the code is open-source on Polymarket’s GitHub), which means anyone can verify that the settlement rules match what the market description says. This transparency is a structural advantage over traditional sportsbooks, where the settlement process happens behind closed doors.

Oracle

A system that feeds real-world data into blockchain smart contracts. Since a blockchain can’t independently verify that Spain won the World Cup (it only knows about on-chain data), an oracle bridges the gap by confirming the real-world outcome and triggering contract settlement.

Polymarket uses UMA’s Optimistic Oracle, where outcomes are proposed and then subject to a dispute period. If no one challenges the proposed outcome within the dispute window (typically 2–4 hours), the result is accepted and contracts settle. If someone disputes, it goes to UMA token holders for a vote.

In practice, high-profile World Cup markets resolve without disputes because the outcomes are publicly verifiable (FIFA announces the winner on live television). The oracle dispute mechanism matters more for ambiguous prop markets.

Liquidity Pool

A pool of funds deposited by liquidity providers to facilitate trading in AMM-based markets. Since Polymarket now uses a CLOB, liquidity pools are less relevant to World Cup trading specifically, but you’ll encounter the term on other platforms and in DeFi prediction markets.

Liquidity providers earn fees from traders who use the pool but face impermanent loss if the market moves significantly in one direction, meaning their deposited funds become worth less than if they’d simply held them.

Statistical and Analytical Terms

These terms help you analyze markets, identify edges, and make better trading decisions during the World Cup.

Expected Value (EV)

The average profit or loss per trade if you repeated it many times. Calculated as: (probability of winning × profit if you win) — (probability of losing × loss if you lose).

If you believe Spain has a 20% chance of winning (your personal estimate) and the contract is priced at $0.16:

Probability of winning: 20%

Profit per share if Spain wins: $1.00 — $0.16 = $0.84, minus 5% fee = $0.798

Probability of losing: 80%

Loss per share if Spain doesn’t win: $0.16

EV = (0.20 × $0.798) — (0.80 × $0.16) = $0.1596 — $0.128 = +$0.0316 per share

A positive EV trade is one where your estimated probability exceeds the market’s implied probability by enough to cover fees. In this case, 20% vs 16% gives you a positive expected value of about $0.03 per share.

Kelly Criterion

A formula that calculates the optimal fraction of your bankroll to bet based on your edge and the odds offered. The formula is: f* = (bp — q) / b, where b is the decimal odds minus 1, p is your estimated probability, and q is 1 — p.

Using the Spain example: b = (1/0.16) — 1 = 5.25, p = 0.20, q = 0.80.

f* = (5.25 × 0.20–0.80) / 5.25 = (1.05–0.80) / 5.25 = 0.0476, or 4.76% of your bankroll.

Most practitioners use “fractional Kelly” (half or quarter Kelly) because the formula assumes you know the true probability perfectly, which you never do. Half Kelly on this trade would be 2.38% of your bankroll.

Calibration

How well a trader’s (or model’s) probability estimates match actual outcomes over time. If you assign 20% probability to events and those events happen 20% of the time, you’re well-calibrated. If they happen 30% of the time, you’re systematically underconfident.

During the World Cup, track every probability estimate you make. After the tournament, plot your estimates against actual results. This calibration exercise is the single best way to improve at prediction market trading long-term.

Line Movement

The change in a contract’s price over time, driven by new information or shifts in trader sentiment. If England’s contract moves from $0.11 to $0.14 after they beat Germany 4–1 in a pre-tournament friendly, that $0.03 move reflects updated expectations.

Tracking line movement tells you where informed money is flowing. A sudden, large price move with high volume often means someone with inside information (injury news, tactical changes, weather data) is trading aggressively. A slow drift on low volume is usually organic reassessment.

Volume

The total number of contracts traded in a market over a given period. High volume means active trading, tight spreads, and reliable price signals. Low volume means the price may not reflect the market’s true consensus.

Polymarket’s World Cup Winner market has over $2 billion in cumulative volume. Daily volume during the tournament will likely exceed $50–100 million. By comparison, niche prop markets might see $10,000-$50,000 in total volume, making their prices much less reliable as probability estimates.

Open Interest

The total number of outstanding contracts that haven’t been settled or closed. Different from volume: if you buy 100 shares and then sell them, volume increases by 200 (one buy, one sell) but open interest is unchanged (you opened and then closed your position).

Rising open interest alongside rising prices is a bullish signal: new money is entering the market and betting on that outcome. Rising prices with falling open interest means existing holders are selling to new buyers at higher prices, a weaker signal.

World Cup-Specific Terms

Terms that aren’t unique to prediction markets but have specific meaning when trading World Cup outcomes.

Group Stage Pricing

The dynamics of contract prices during the World Cup’s group stage (first 14 days). During the group stage, all 48 teams are still alive. Futures prices move based on results: a team that wins all three group games sees its contract price rise. A team that draws two and loses one sees its price drop, often sharply.

The group stage is where the most volatile price swings happen, because results eliminate the widest range of scenarios. Once the bracket is set, prices converge more predictably.

Knockout Premium

The tendency for contracts to jump in price disproportionately when a team advances to the knockout round, beyond what the remaining probability math would justify. This happens because casual traders flood in after exciting results, pushing prices above fair value.

If you’re a disciplined trader, knockout premiums can be selling opportunities. When the crowd overpays for a team that just won a thrilling round-of-16 game, selling at the inflated price and buying back after the excitement fades can capture 5–10% returns in 48 hours.

Dead Heat Rule

A sportsbook rule that reduces payouts when two or more selections tie for a position. Some prediction market prop contracts (e.g., “Top Scorer”) include dead heat provisions. If Mbappé and Kane both finish with 6 goals, contracts on each might settle at $0.50 instead of $1.00.

Check the resolution rules for any player-market contract to see whether dead heat rules apply. On some platforms, tied outcomes void the market entirely and return all funds. On others, the payout is split proportionally.

Home Advantage Factor

The statistical edge gained by teams playing in the host country. The 2026 World Cup is hosted across the United States, Mexico, and Canada. Historical data shows host nations outperform their pre-tournament odds by 15–30% in knockout rounds, partly due to crowd support, travel advantage, and familiarity with venues.

Prediction markets tend to be better at pricing home advantage than sportsbooks because the trader base includes quantitative analysts who model these factors explicitly. But even prediction markets may underprice the home crowd effect in matches played in Mexico City’s Estadio Azteca, where altitude (2,240 meters above sea level) creates a measurable physiological disadvantage for non-acclimatized teams.

Quick Reference: Common Abbreviations

What This Glossary Doesn’t Cover

This glossary focuses on terms you need for trading prediction markets during the World Cup. It doesn’t cover general sports betting terminology (moneyline, point spread, over/under) because those concepts don’t map cleanly onto binary event contracts. It doesn’t cover DeFi yield farming, liquidity mining, or other crypto-native concepts that sit outside the prediction market core.

If you’re brand new to prediction markets, start with five terms: event contract, implied probability, CLOB, resolution rules, and expected value. Those five will carry you through your first hundred trades. The rest of this glossary becomes useful as you scale your positions and encounter edge cases.