How Polymarket Works: Share Price, Profit and a Comparison with intrade.bar

You bought an outcome at 60 cents, the card now shows 65%, and it feels as if the profit is already clear. But 65% may be the market’s estimate, not the price at which you can actually sell your whole position. To understand how Polymarket works, we’ll separate buying, selling and final settlement. Then we’ll compare that chain with intrade.bar: to forecast the direction of a price there, you just choose the amount and the expiry, and the potential profit is already expressed as a clear percentage.

Read the question first, then look at the percentages

A Yes contract refers to a precise condition. “Bitcoin will go up” may mean a price above a reference at the end of a window, a touch of a certain level or some other event. Before judging whether a share is a good deal, find the time, the starting point, the settlement source and the rule for a tie.

State your own view separately. For example: “the contract checks the price at 18:00 against the level at the start of the window; I expect this outcome for the following reasons.” This separation seems like a formality — until you discover that you correctly guessed the direction after buying, but bought a contract with a different starting reference.

On intrade.bar, the reference for a price trade is its opening quote. That is convenient when your idea is specifically about movement from the moment of entry. Still, you check the percentage and the expiry before confirming: a simple form does not remove the need to understand your own condition.

How to work out the cost of 100 shares

In the standard model, a winning share pays out $1 and a losing one pays $0. If you buy 100 shares at 0.60, you spend $60 before costs. If the outcome wins, you receive 100, of which 40 is profit. If it loses, the payout is zero and the loss is 60.

The number of shares is not the amount invested. 100 shares at 0.40 cost 40; at 0.80, they cost 80. To double-check, multiply the filled quantity by the average price and add the costs related to the transaction. That is the number to compare with the amount debited, not the quantity shown next to the outcome’s name.

The return on a successful settlement in the first example is 40 / 60 × 100% ≈ 66.7%. The total payout of 100 is 166.7% of the amount invested, but you cannot call all of it profit: it already includes your original 60. This kind of arithmetic mix-up can make even a perfectly ordinary trade look spectacular.

The price on the card and the fill price

The estimate Polymarket displays is usually calculated from the midpoint of the best bid and ask. When the spread is wide, the last trade price is used instead. What decides your money result is the actual fill: how many shares you managed to buy and at what prices.

Suppose the best buyer bids 0.58 and the seller asks 0.60. The 0.59 midpoint helps describe the market, but an immediate purchase of the available volume goes through at 0.60. If you then sold right away with the book unchanged, the available 0.58 bid would give you a $2 loss on 100 shares, even before any separate fees. The difference between bid and ask is called the spread.

So a rise in the estimated value of a position is not always the profit available on exit. Check whether there is a buyer for your whole volume at the price you want. The on-screen estimate is useful for watching; the fill history is for tracking money. It is best not to mix up these roles.

Why volume changes the average price

Say you want 100 shares, but only 60 are offered at 0.60 and the next 40 are available at 0.62. If your order accepts both levels, the cost will be 60 × 0.60 + 40 × 0.62 = $60.80. The average price is 0.608, and the possible profit on a payout of 100 is 39.20 before costs.

A limit order capped at 0.60 may fill only the available part, or wait for a matching offer according to its terms. It controls the price but does not promise a complete fill. An order that takes the currently available offers solves a different problem: getting filled matters more than one fixed price for the whole volume.

After acting, check what is left of the order. It may fill later, when you already consider the decision finished. This is an extra thing to keep an eye on in a share market. In a digital trade on intrade.bar, you don’t need to build a position level by level through an order book: you see the amount and the percentage of a specific trade in advance.

Selling early: working the result out to the end

Back to 100 shares at 0.60. If the whole position is sold to a buyer at 0.65, the proceeds are 65, the profit is 5 before costs, and the return is about 8.3%. You cannot expect another 100 when the event settles: the shares now belong to another participant. The sale closed this particular position.

Selling 40 shares at 0.65 brings in 26. Those 40 shares cost 24, so the realized profit is 2. The remaining 60 shares cost 36 and still depend on the event. If they lose, the overall money result is 26 − 60 = −34. A profitable partial sale did not make the whole sequence profitable.

If the remaining 60 shares win, the receipts are 26 + 60 = 86, a profit of 26 before costs. Had you held all 100 winning shares, the profit would have been 40. The difference is the price of the early exit you chose for part of the position. This is not a platform error: you traded future uncertainty for interim proceeds.

It helps to check such calculations two ways: add up the results of the parts, and separately calculate all receipts minus all costs. If the answers differ, you have usually forgotten the remaining position, counted a purchase twice, or taken an estimated value for money actually received.

When a sale may not happen

The sell button does not create a buyer at your price. A limit order may go unfilled, and a quick exit using the available volume may go through at less attractive levels. This matters if your plan rests on the thought “if I need to, I’ll get out right away”: you first need to check the available liquidity.

Holding until regular settlement, however, does not require reselling the share. The winning payout is determined by the event’s rules. So it would be wrong to compare Polymarket and intrade.bar as “there you always have to find a buyer, here you don’t.” A buyer is needed specifically for an early sale.

intrade.bar has no early closing at all. For a short expiry chosen in advance, this gives a simple sequence: open, wait for expiry, check the result. If the ability to change your mind and sell the position is an essential part of your approach, take this difference into account before you enter.

Costs: count each cash flow once

Fees and other costs are checked for the specific market and transaction. Don’t apply an old claim that “everything is free” to whatever the terms are today. For a training example, let the difference between purchase and sale be $5, with related costs of 1. The net profit is then 4; the number 1 here does not represent Polymarket’s fee schedule.

The spread is already reflected in the actual purchase and sale prices. Once you have calculated from the filled transactions, you cannot subtract it again as yet another fee. Likewise, check whether the fee is included in the total cost shown. Your records should reflect real movements of money, not the sum of every cost label you came across.

When comparing with intrade.bar, keep the result of the trade itself separate from deposits and withdrawals. The terms of a payment method may affect the overall money result. A trading percentage shown in advance makes a specific contract clearer, but it does not mean that every related transaction is always free.

What intrade.bar simplifies for a price forecast

If you want an answer to the question “will the asset be above my entry price after the chosen expiry,” you can do without shares, an average cost of building a position and leftover orders. On intrade.bar you choose an available asset, the direction, the amount and the expiry, and see the payout percentage before confirming.

Say the form shows a hypothetical 85% and the amount is 100 units. If the outcome is successful, the profit is 85 and the total return is 185; if not, 100 is lost; if the opening and closing quotes are exactly equal, the amount is refunded. This is a transparent money scenario you can write down in one line. Take the actual percentage from the form; it is not always 85%.

A share at 0.50 offers a possible profit of 100% on a payout of 1, and a share at 0.80 offers 25%. Compare percentages under the same forecast conditions. intrade.bar’s advantage here is the direct link between the amount and the profit shown, plus the familiar TradingView chart for analyzing the very question you opened the terminal for.

A practical test of both approaches

Take a paper example of buying 100 shares at 0.60, and separately a training digital trade of 60 at a hypothetical 85%. Write down both outcomes: for the shares, a profit of 40 or a loss of 60; for the digital trade, a profit of 51 or a loss of 60, not counting extra costs. Then ask whether the starting reference, the source and the deadline match. Without that, you cannot declare one option better than the other.

Now, on the intrade.bar demo, choose one available asset and an expiry that fits your training hypothesis. Before opening, save the amount, the direction, the time and the actual percentage. After expiry, check the result against the history. The practical goal here is to go through the whole chain without any vague numbers, not to win on the first try.

If you get lost between probability, quantity and price when looking at a share market, this exercise is especially useful. It shows whether a format with a fixed expiry and a result you can read in advance suits you. The forecast itself, of course, remains your own separate job.

How to stay in control of a series of decisions

Carefully tracking one purchase does not stop you from opening ten more on emotion. Decide in advance on an overall participation limit and a stopping rule. Be especially careful with several outcomes tied to the same Bitcoin move: different cards do not necessarily mean different risks.

intrade.bar has voluntary daily loss and profit limits. You can keep No limits or set boundaries; once set, they can only be changed for the next day, and a limit that has been reached stops new trades until the end of the day, Moscow time (MSK). This is useful when you want to back up your trading plan with a technical setting in advance.

Start with one reproducible trade on the demo and a full review of it. Once the opening price, the expiry and the money outcome are clear, it is harder to mistake a temporary peak on the screen for profit already earned. That kind of clarity is what makes choosing a trading format meaningful.

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