Glossary

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Market Structure & Hierarchy

Category: Broadest classification level organizing instruments by event type (e.g., Sports, Politics, Crypto, Culture). Series: More specific classification within each category, such as sports leagues or specific topics (e.g., NFL, NBA, US Presidential, Bitcoin). Event: Specific occurrence with multiple possible outcomes. Each event consists of one or more instruments representing the complete set of tradable outcomes. Product: Type of contract structure used to format instruments (e.g., Athletic Event Contract, Election Winner Contract, Total Score Contract). Instrument: The tradable symbol representing a specific outcome for an event. Follows consistent naming conventions for easy identification. Also called a market. Participant: The possible outcomes in an instrument. The long participant represents the “Yes” outcome, while positions on the opposing outcome are achieved by selling (shorting) the long participant. Market: Same as an instrument. A tradable outcome with defined resolution criteria and sources. Contract: An instance of an instrument. You trade contracts in quantities (e.g., buying 100 contracts of an instrument). Each contract settles at $1.00 if the outcome occurs and $0.00 if it does not.

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Trading Basics

Long position: Buying contracts of an instrument, betting the outcome will occur. You pay the current price per contract and receive $1.00 per contract if the outcome happens. Short position: Selling (shorting) contracts of an instrument, betting the outcome will not occur. You receive the current price per contract but must cover potential losses if the outcome happens. Long position: Buying an instrument, betting the outcome will occur. You pay the current price and receive $1.00 if the outcome happens. Short position: Selling (shorting) an instrument, betting the outcome will not occur. You receive the current price but must cover potential losses if the outcome happens. Order: A request to buy or sell contracts at a chosen price. Order book: List of bids and asks showing available prices and size for each level. Bid: Highest price buyers are willing to pay. Ask: Lowest price sellers are willing to accept. Spread: Gap between the bid and the ask. Size: Number of contracts available to buy or sell at a given price. Liquidity: How much size is available to trade at listed prices.

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Order Execution

Fill: When your order completes, fully or partially. Partial fill: When only part of your order fills. Execution price: The price at which your order fills. Fill price: Average price you receive when your order fills across multiple levels. Marketable limit order: Order that fills at the best available price shown on your screen. Price impact: How much your fill price changes because of limited liquidity. Slippage: Difference between expected and actual execution price. Maker: Trader who adds liquidity by placing an order on the book. Taker: Trader who removes liquidity by filling an existing order.

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Positions & Account

Open position: Contracts you currently hold. Closed position: A position you no longer hold because you sold it or the market has resolved. Position value: Real-time value in dollars of your open positions. Cash balance: Funds in your account not tied to open positions. Buying power: Cash available to open new positions after margin is applied. Instant buying power: Part of your deposit that becomes available to trade immediately. Margin: Funds locked to cover the maximum possible loss of a short position. Equal to $1.00 per contract shorted. Max gain: The most you can earn on a position. Max loss: The most you can lose on a position.

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Market Lifecycle

Clarification: Extra context added to explain how rules should be understood. Resolution: When Polymarket determines the final outcome of a market using the sources listed in the rules. Settlement: Final payout of $1.00 for winning contracts and $0.00 for losing contracts.

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Fees & Display

Fees: Trading or platform fees applied to executed orders. Odds display: How prices are shown, such as price, percent chance, or American odds. Open order: Order waiting on the book to be filled. Order status: Whether an order is open, filled, or partially filled. History: Section showing your past filled orders and closed positions.