How spreads and fees affect profit

By the Cent Signals editorial desk. Reviewed June 17, 2026.

Two costs shape who ends a year of trading in the black on Polymarket, and neither shows up as a line item the way a stock commission does. The first is the bid-ask spread, the quiet gap between the best resting buy and sell prices. The second is the taker fee, which Polymarket applied to only a handful of categories until early 2026. Drawing on Akey, Gregoire, Harvie, and Martineau, "Who Wins and Who Loses in Prediction Markets? Evidence from Polymarket" (2026), this guide describes how those costs fall on different participants, and how much they move the line between winners and losers. Like everything on this site it is description, not direction.

The spread is the quiet cost

On any market the order book carries a best resting buy price and a best resting sell price, and the gap between them is the bid-ask spread. A participant who crosses the book to fill an order immediately, a taker, pays roughly half that spread on entry and again on exit, because the taker is meeting prices that already sit away from the midpoint. A participant who instead posts a resting order, a maker, waits to be met and sits on the receiving side of the same gap.

For most of the period the study examined, Polymarket charged no explicit trading fee. That makes the spread the dominant transaction cost on the platform: it is the price of demanding immediacy, paid by whoever crosses the book rather than waits.

How much it moves outcomes

The study put a number on the spread's effect. Removing even the minimum-tick spread cost would move about 18.5 percent of losing traders, roughly one in five, into non-negative profit. For that band of marginal participants, the spread was the line between a small loss and breaking even.

The same exercise had a clear limit. It could not rescue the worst performers, whose losses came from systematic forecasting errors rather than from transaction costs; stripping out the spread left them roughly where they started. The split runs along role as well: winning traders were net earners of the spread, while losing traders paid it.

The tick and the grid

The smallest possible spread is set by the price grid. Polymarket's minimum tick is one cent across most of the range, so two adjacent resting prices can sit no closer than a penny apart through the bulk of a market. The grid is finer in the tails: below four cents and above ninety-six cents it steps in increments of a tenth of a cent.

The practical effect is that spreads can be narrower in the deep tails, where the grid allows resting prices to sit closer together, than they can in the middle of the range. The minimum-tick spread the study removed reflects that floor.

Where fees now apply

The no-fee picture has changed at the edges. In early 2026 Polymarket added category-based taker fees on some market types, for example certain crypto, NCAA basketball, and Serie A markets. The charge falls on takers; makers are not charged, which keeps the maker and taker roles on opposite sides of the cost structure.

Because the schedule is category-specific and has shifted over time, the current detail lives on its own page. See Polymarket fees explained for which categories carry a fee and at what rate.

Why costs compound

A single cost of half a spread looks trivial, and on one trade it is. The arithmetic changes when the same small cost is paid repeatedly across many orders. A participant who turns over a position dozens or hundreds of times pays the spread on every crossing, and the sum can outrun the edge that motivated the activity. This is part of why high-frequency takers can transact large volume yet still finish behind on the year.

The role split runs through the whole picture, which is why it sits at the center of makers vs takers and informs the broader question of who actually wins on Polymarket. Across all of it the finding stays descriptive: costs accrue to the side that demands immediacy, and they accumulate with frequency.

Frequently asked questions

What is the bid-ask spread on Polymarket?

It is the gap between the best resting buy price and the best resting sell price on a market's order book. A taker who crosses the book to fill immediately pays roughly half that gap on the way in and again on the way out, while a maker who posts a resting order sits on the receiving side of it. The spread is therefore a transaction cost paid by the side that demands immediacy.

Does the spread really affect who profits?

The 2026 study by Akey, Gregoire, Harvie, and Martineau found that removing even the minimum-tick spread cost would move about 18.5 percent of losing traders, roughly one in five, into non-negative profit. It could not rescue the worst performers, whose losses traced to systematic forecasting errors rather than to costs, but for a large band of marginal losers the spread was the difference between red and flat.

Does Polymarket charge trading fees?

For most of the study period Polymarket charged no explicit trading fee, so the spread was the dominant transaction cost. In early 2026 the platform added category-based taker fees on some market types, such as certain crypto, NCAA basketball, and Serie A markets, while makers are not charged. The current schedule is covered on the Polymarket fees explained guide.

Do makers pay the spread?

No. A maker posts a resting order and waits to be filled, so the maker is on the receiving side of the spread rather than the paying side. The taker who crosses the book to fill against that resting order is the one who pays. This is why the maker and taker roles sit on opposite sides of the same transaction cost.