Two ways to send the same trade. One protects your price and risks not filling, the other fills now and risks the price. Knowing which you are using is the difference between a clean entry and an expensive surprise.
A market order trades right now against whatever prices are resting in the book, so it almost always fills but you accept the price the book gives you. A limit order names the worst price you will accept and waits, so you keep control of the price but may never fill. The choice is a trade off between certainty of price and certainty of execution, and the right answer depends on how deep the book is, what the venue charges for each, and which kind of certainty matters more for that trade.
A market order says fill me now at the best prices available. It crosses the spread immediately and matches against the orders resting on the other side of the book. A limit order does the opposite. It posts your price into the book and sits there until another participant chooses to trade against it. The market order is impatient and pays for speed. The limit order is patient and pays for that patience with the risk of never being filled. In exchange language the impatient side is the taker and the patient side is the maker, and that single distinction drives most of what follows.
A market order fixes execution and leaves price uncertain. You will almost certainly get filled, but the final average price depends on what the book holds at the moment you click. A limit order fixes price and leaves execution uncertain. You know you will never pay worse than your limit, but you might wait, fill only in part, or not fill at all. You cannot lock down both at once, and pretending otherwise is how people get surprised.
If your order is bigger than the size sitting at the best price, a market order walks up or down the book and fills the next levels at worse prices. That gap between the price you saw and the price you paid is slippage, and in a thin book it can be large. A limit order cannot slip past your limit, because the limit is a hard ceiling on a buy or floor on a sell. The protection is real, but it comes with the risk that the rest of your order simply does not fill.
When you post a limit order you add a resting price to the book that someone else can trade against, which is what makes a market liquid for everyone. When you send a market order you remove a resting order by trading against it. This is why many venues charge differently for the two, and why a book full of patient limit orders tends to have tighter spreads. The structure rewards the side that supplies liquidity, though that patience is not free when the market moves away from you before your order fills.
Say a yes contract shows a best ask of fifty six cents with only forty contracts there, and the next level is fifty nine cents. You want one hundred. A market order fills forty at fifty six and sixty at fifty nine, an average near fifty eight, more than the price you first saw. A limit order at fifty six fills the forty available and rests for the other sixty, which may or may not arrive. Same intention, very different results, decided entirely by which order you chose.
Numbers are an example to show the trade off, not a quote and not a prediction. Fees are excluded.
Order choice is not only about price and certainty. On most order book venues the fee itself depends on whether you make liquidity with a resting limit order or take it with an order that fills now. The table below sets out the published position on two of the larger order book platforms. Figures are taken from each platform's own fee documentation on the dates shown and can change, so confirm the current schedule before you trade.
| Platform | Maker (resting limit order) | Taker (market order, or a limit that crosses) | As of |
|---|---|---|---|
| Kalshi | 25 percent of the taker fee per its published schedule | Taker fee of about 7c times C times (1 minus C) per contract, where C is the price; highest near 50c, smallest near 1c or 99c | Feb 2026 |
| Polymarket | Zero trading fee, and makers share a daily rebate funded by taker fees | Category based, up to about 0.75 dollars per 100 shares on sports rising to about 1.80 dollars per 100 shares on crypto; some categories listed as fee free | 2026 |
Methodology: figures summarised from the Kalshi fee schedule (as of February 2026) and the Polymarket fee documentation (as of 2026). Both use a formula in which the fee is largest at a 50c price and shrinks toward the ends of the scale. We track fees across all 16 platforms in the cross platform fees dataset; this table is the order type slice of it. Always check the live schedule before trading, as terms change.
The clearest way to see the difference is to look at how a regulated exchange prices it. On Kalshi, an order that adds a resting price to the book is a maker order, and an order that fills against an order already resting there is a taker order. Per Kalshi's published fee schedule, as of February 2026, the taker fee is calculated from a formula of roughly 7 cents times the price times one minus the price per contract, and the maker fee is set at 25 percent of that taker fee. Because the formula peaks at a price of 50 cents and falls toward either end, both fees are largest on a contract priced like a coin flip and smallest on a near certain one. There is no fee simply for resting a limit order that you later cancel; the fee attaches when a trade actually executes.
Polymarket frames the same split even more sharply. Per its fee documentation, as of 2026, a resting limit order that supplies liquidity is a maker order and pays no trading fee at all, while also sharing in a rebate pool funded from taker fees and paid daily. An order that fills immediately is a taker order and pays a fee that varies by market category, described as up to around 0.75 dollars per 100 shares on sports and rising toward 1.80 dollars per 100 shares on crypto, with some categories listed as fee free. A limit order priced aggressively enough to cross the spread and fill on the spot counts as a taker too, which is a useful reminder that the label follows the behaviour, not the order ticket you clicked.
Two lessons follow for anyone choosing between the orders. First, on these venues the patient choice is usually the cheaper one, sometimes dramatically so, which quietly tilts the maths toward limit orders for traders who can wait. Second, the price level matters because the fee is not flat. A market order on a 50 cent contract carries the heaviest fee and, in a thin book, the widest scope for slippage at the same time, so the two costs stack. Not every platform uses an order book or a maker and taker model, and a few use an automated market maker or a fixed structure instead, so treat the figures above as the position on these two named venues rather than a universal rule.
The reason this choice matters so much on prediction markets is that many contracts trade thinly. In a deep, busy contract the spread is narrow and there is plenty of size at the top of the book, so a market order fills close to the quoted price and slippage is small. In a thin contract the spread is wide and there is very little size resting at any level, so the same market order can fill at a noticeably worse average than the screen suggested. The order type that is harmless in one market can be costly in another, and the only way to tell the difference is to look at the depth before you trade.
A useful habit is to ask what you actually care about for a given trade. If you have a clear view and you want to control the price, a limit order lets you name your number and wait, accepting that you might not get filled. If you need to be in or out right now, for example to close a position before a result lands, certainty of execution can matter more than a cent or two, and a market order does that job. Neither is the smart choice in the abstract. The skill is matching the order to the moment.
Partial fills are part of the picture too. A limit order does not promise to fill all at once. If only some size is willing to meet your price, you can end up holding a smaller position than you intended, with the remainder resting in the book. That is not necessarily a problem, but it is something to expect rather than be surprised by, because a half filled order can leave you with a different risk than you planned. Whether and how a venue handles partial fills varies, so it is worth checking the platform before you rely on the behaviour.
Fees sit on top of the order choice and can tilt it, as the table above shows. Some venues charge a maker fee on resting orders and a higher taker fee on orders that fill now, and a few pay makers a rebate, so the patient choice is often the cheaper one. Any per contract fee then compounds with the spread you cross. When you add the spread, the fee, and any slippage in a thin book, the true cost of a market order can be well above the headline price, while a patient limit order can lower that cost at the price of uncertainty. Estimating the full cost of each path before you commit is what separates a considered trade from a reflexive one.
None of this tells you whether a trade is worth making. The order type controls how you enter and exit, not whether the outcome goes your way. A contract can resolve against you no matter how cleanly you filled, and a perfectly placed limit order on a losing position still loses. We never name a contract to buy or predict a result. The value of understanding these two orders is narrower and more honest, which is to avoid paying more than you meant to and to know exactly what you are risking before you risk it.
You can fold all of this into a short check that takes seconds. First, look at the depth at the best price and the size of the gap to the next level. If your order is smaller than the size at the top and the gap is narrow, a market order will fill near the screen price and the choice barely matters. If your order is larger than the top level, or the next level is far away, a market order will walk into worse prices and a limit order starts to look better.
Second, ask whether speed or price matters more for this particular trade. If you must be in or out before something happens, accept that a market order trades certainty of execution for an uncertain price. If you can wait, a limit order trades certainty of execution for a known price and, on many venues, a lower fee. Third, check the fee for each path on your platform, because as the table shows the maker and taker fees can differ by a wide margin and that difference is part of the true cost. Answer those three and the right order usually picks itself.
Most venues offer more than the bare choice between fill now and name a price. The two ideas behind the extra settings are the same two we have been weighing all along, certainty of price and certainty of execution, so once you understand the core pair the variants are easy to read. A common setting is time in force, which tells the venue how long a resting limit order should live. A good til cancelled order stays in the book until it fills or you remove it, while a day order expires at the close of the trading day if it has not filled. The setting does not change the price you named; it changes how long you are willing to wait for it.
You may also see instructions that govern partial fills directly. An immediate or cancel order takes whatever size is available at your limit right now and cancels the unfilled remainder rather than resting it, which suits a trader who wants the price protection of a limit but does not want a leftover order sitting in the book. A fill or kill order goes further and asks for the entire size at the limit or nothing at all, so it either completes in full at your price or does not trade. Both are simply ways of pairing the price control of a limit order with a tighter rule about execution, and not every platform offers each one, so check what your venue actually supports.
A word of caution applies to anything that triggers automatically. Some platforms offer orders that turn into a market order once a price level is reached, which can be useful for managing a position but reintroduces the very slippage a limit order was meant to avoid, because the resulting order takes whatever the book offers at that moment. The neutral point to hold onto is that none of these settings change the underlying bargain. Every order on a prediction market is still trading certainty of price against certainty of execution, and the extra controls only let you tune where on that line you sit. They do nothing to change whether the contract resolves for you or against you.
A carefully chosen order does not make a trade safe. It controls your price or your speed, not the outcome, and any position can lose. Prediction markets can lose you money, and a thin market can move against you fast. Stake only what you can afford to lose, never to chase a loss, and never on borrowed money. If it stops feeling like a free choice, step back. In the United States you can call or text the helpline on 1-800-GAMBLER or visit ncpgambling.org.
A market order trades immediately against the best prices resting in the book, so it gives near certainty of filling but an uncertain final price. A limit order names the worst price you will accept and rests until someone meets it, so it gives a known price but no guarantee of a fill.
There is no single right answer. Many careful traders prefer limit orders because they protect against paying far more than the screen suggested in a thin book. The cost is that a limit order can sit unfilled while the market moves away. The better choice depends on whether price or certainty matters more for that trade.
Slippage is the gap between the price you expected and the price you got because your order was larger than the size at the best level. A market order is exposed to slippage because it takes whatever the book offers. A limit order caps your price, so it cannot slip past the limit, though it may only fill in part.
Often, yes. Several venues charge a maker fee on resting limit orders and a higher taker fee on orders that fill immediately. On Polymarket, makers paid zero trading fees while takers paid a category based fee as of 2026. On Kalshi, the maker fee was set at 25 percent of the taker fee per its published schedule as of February 2026. Always check the current schedule.
Yes. If there is not enough size willing to trade at your limit price, you can receive a partial fill, with the rest of the order resting until more interest arrives or you cancel it. Whether and how a venue supports partial fills varies, so check the platform.
No. Order type controls how you enter and exit, not whether the outcome goes your way. A contract can resolve against you regardless of how skilfully you placed the order. The money at stake is genuinely at risk, and we never name a contract to buy or predict a result.
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