A partial fill is when only part of your order executes because there is not enough size willing to trade at your price, leaving you with a smaller position than you intended.
Last reviewed 3 December 2025 · Educational, not advice
When you place an order to buy or sell a number of contracts, it can only execute against the size other participants are willing to trade at your price. If that available size is smaller than your order, only part of it executes. That is a partial fill. You wanted one hundred contracts, the book offered forty at your price, so forty fill and sixty do not, at least not yet. You are left holding a smaller position than you set out to take.
Partial fills happen because depth at any single price level is limited, and they are most common in thin markets where only a little size rests at each level. A busy, liquid contract may have enough resting interest to fill a normal order in full at the top of the book, while a quiet contract may only fill a fraction before running out of willing counterparties. This is one of the practical reasons that reading the depth of the order book matters before you trade, since it tells you whether the size you want is actually available.
What happens to the unfilled portion depends on the order type and the platform. A standard limit order usually leaves the remainder resting in the book at your price, where it waits until more interest arrives or you cancel it. Some order instructions instead cancel any unfilled part immediately, so you keep only what filled in that instant. Because venues differ in how they handle the leftover and in which order instructions they support, it is worth checking the specific platform rather than assuming one behaviour everywhere.
A partial fill is not necessarily a problem, but it is something to expect rather than be caught out by. It leaves you with a different position than you planned, which changes your risk. If you intended a larger stake and only part filled, you are less exposed than you thought, and trying to force the rest in by crossing the spread or chasing a moving price can be a costly reflex. Knowing that partial fills exist, and deciding in advance how you will handle the remainder, keeps the surprise from turning into a hasty decision.
You place a buy limit order for one hundred contracts at fifty cents. Only forty are offered at fifty cents, so forty fill at once and the other sixty rest in the book at your price. If new sellers come in at fifty cents, the rest fills over time. If the market trades up and never returns to fifty cents, the remaining sixty simply never fill, and you hold a forty contract position rather than the hundred you intended.
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A partial fill leaves you with a different position than you planned, and forcing the rest in can be costly. Prediction markets can lose you money. 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.
It is when only part of your order executes because there is not enough size willing to trade at your price. You end up with a smaller position than you intended, and depending on the order and the venue, the remainder either rests in the book waiting to fill or is cancelled.
Because the size available at a given price is limited. If you want one hundred contracts but only forty are offered at your price, you can fill forty and no more until additional interest arrives. Partial fills are most common in thin markets where depth at each price level is shallow.
It depends on the order type and the platform. A limit order usually leaves the unfilled remainder resting in the book until it fills or you cancel it. Some order instructions cancel any unfilled portion immediately instead. Always check how a given venue handles the leftover before relying on the behaviour.
Not necessarily, but it can leave you with a different position than you planned, which changes your risk. If you intended a larger stake and only part filled, you are less exposed than expected, and chasing the rest at a worse price can be costly. It is something to expect rather than be surprised by.
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