How Does Polymarket Work? From Buying Shares to Settlement

Polymarket lets you trade shares tied to event outcomes: you can sell your position before resolution or hold it for a payout determined by the market’s rules. Your result depends on your purchase price, the price you receive if you sell, or the outcome used for settlement.

To understand the mechanics, follow one hypothetical football market: “Will the home team win?” In this example, a winning share pays $1 and a losing share pays $0. All prices, quantities and results below are illustrative, not live market data, and calculations exclude fees and other execution costs.

What are you buying when you buy an outcome share?

An outcome share is a position whose settlement value depends on a defined event. In our example, buying Yes means buying exposure to the home team winning under the contract’s rules. Buying No means taking the opposite outcome. Neither position is ownership of the team or a claim on its revenue.

• A Yes share bought for $0.60 costs 60 cents and pays $1 if Yes is the resolved outcome.
• A No share bought for $0.40 costs 40 cents and pays $1 if No is the resolved outcome.
• The losing outcome pays $0 in this hypothetical binary contract.

A $0.60 price on a $1-payout share corresponds to a 60% price-implied probability. That is an interpretation of the price, not proof that the home team has a 60% chance. The prices actually available to buy and sell can also differ, so there need not be one executable “market probability.”

The Federal Reserve Bank of San Francisco paper Interpreting Prediction Market Prices as Probabilities explains that prediction-market prices can provide useful, sometimes biased estimates of average beliefs under certain conditions. Treat price as information to assess, not an authoritative forecast.

Who takes the other side of your trade?

A purchase needs matching selling interest; wanting to buy does not by itself create a completed trade. The other side might be someone reducing an existing position or someone willing to supply the outcome at that price. You do not need to share their reasoning for your orders to match.

Imagine an order book with a best Yes buy offer of $0.58 and a best Yes sell offer of $0.60. The $0.02 difference is the spread. Suppose the seller offers 200 shares at $0.60. Your request to buy 200 shares can match that offer if it remains available when your order arrives.

1. You submit an order specifying the outcome, quantity and any price condition.
2. Compatible buying and selling interest matches, subject to available quantity.
3. The matched portion becomes a trade; an unmatched request is not yet a position.

If only 80 shares are available at your acceptable price, do not assume all 200 shares will trade there. Depending on the order instructions, you may receive a partial fill, wait for more matching interest or pay different prices for additional shares. A displayed price alone does not establish the cost of your entire order.

Why would traders disagree? In the model described in Opinion Dynamics Explain Price Formation in Prediction Markets, agents buy below their own probability estimate and sell or short-sell above it. That is a theoretical explanation of trading incentives, not a description of available Polymarket short-selling tools or its exact matching implementation.

How much does buying a position cost?

Assume your full purchase fills: 200 Yes shares at $0.60 each cost $120 before costs. The calculation is entry cost = shares × purchase price. You now have 200 shares, not a guaranteed $200 balance. Their eventual settlement value depends on the outcome, while their resale value depends on available buyers.

Keep share quantity separate from money committed. The same $120 would buy a different number of shares at another price. Before confirming an order, check its quantity and total cost, rather than judging the exposure from the quoted probability alone.

What happens if you sell before the market resolves?

Selling before resolution exchanges your shares for the price another participant will pay now. You no longer hold the sold shares for settlement. This means a trade can make money or lose money without waiting for the final match result.

• If all 200 shares sell at $0.66, proceeds are $132 and profit is $12 before costs.
• If all 200 shares sell at $0.53, proceeds are $106 and the loss is $14 before costs.
• If only some shares sell, the unsold shares remain exposed to subsequent prices and settlement.

For a fully closed position, trading profit before costs equals shares sold × (sale price − purchase price). A price rise on a chart is not itself a completed profit: you need an executable sale. Conversely, selling at a loss ends your exposure on those shares even if the home team later wins.

What happens if you hold shares until settlement?

Holding to settlement means accepting the payout associated with the resolved outcome instead of selling to another trader. The decisive question becomes “What outcome do the contract’s rules establish?” rather than “What price can I get now?” The market title is only the starting point for that assessment.

• Check whether “home team wins” means regulation time only or includes extra time and penalties.
• Check which result source determines the outcome.
• Check how postponements, cancellations, abandoned matches and other exceptions are handled.
• Check the resolution process and any relevant timing conditions before entering.

An oracle is part of the process for bringing an external event outcome into contract settlement. UMA’s Optimistic Oracle documentation gives an event-based prediction-market example in which settlement requests are submitted at deployment and a proposer network identifies settlement events and proposes outcomes. That example illustrates the mechanism; it does not establish every Polymarket sports market’s resolution configuration or timing.

Under our example’s payout rules, a Yes resolution pays $200 for your 200 Yes shares, producing an $80 profit against the $120 entry cost. A No resolution pays those Yes shares $0, producing a $120 loss. Both figures exclude costs. A match ending is not, by itself, confirmation that the contract has completed resolution and its payout is available.

How is selling different from receiving a settlement payout?

• Selling requires matching buying interest; settlement pays according to the resolved contract outcome.
• Selling uses an executable market price; settlement uses the contract’s payout rules.
• Selling closes the shares sold; holding retains their outcome exposure through resolution.

Choose which route fits your plan before entering. A trader seeking to exit before kickoff needs buyers and sufficient liquidity at that time. A trader planning to hold needs to understand the outcome rules and accept the losing-outcome risk. Neither route guarantees a better result, and an intended early exit can fail to fill.

Where does OddsFantasy automation fit into this process?

Automation belongs after you understand what you own and how you intend to exit. The OddsFantasy Polymarket trading terminal lists live and pre-match sports prediction-market events. Its market views show charts, the order book, available liquidity and the current spread, helping you assess execution rather than relying on a headline price.

• Market orders prioritize execution and can carry optional take-profit and stop-loss instructions.
• Limit orders enter only at your chosen odds and remain open until matched, cancelled or expired.
• Quote orders place both sides of a market, calculating quote levels and stake split from capital and a target profit percentage. The target is not a guaranteed return.

The OddsFantasy trading guide explains these order choices. Order instructions do not create liquidity or guarantee an exit price. Decide how much exposure you can accept if a planned sale is incomplete or cannot execute as intended.

Open positions can be closed with a market close, a limit close at chosen odds or a time close scheduled for a set time, such as before kickoff. Scheduled time orders appear on the Orders page, where you can edit their execution time or cancel them. Scheduling an exit is different from confirming that it filled.

OddsFantasy also supports redeeming resolved positions from the Positions page. It is non-custodial: users connect their own wallet and their funds stay in it. Keep the workflow clear: placing an order requests a trade, receiving a fill establishes or closes exposure, and redeeming a resolved position collects its available settlement payout.

What should you check before your first trade?

1. Read the exact outcome definition and exception rules.
2. Check executable prices, available quantity and the spread.
3. Calculate the total entry cost and losing-outcome exposure.
4. Decide whether you intend to sell early or hold through resolution.
5. After submitting, verify fills and remaining orders rather than assuming the request completed.