What is a fill
A fill is the execution of an order: your buy or sell request is matched with the other side and becomes a completed trade. A partial fill means only part of the requested volume was executed, and the rest is still waiting, was cancelled, or was rejected.
So "order filled" means the full volume was traded. "Partially filled" means some of it was traded and some was not.
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Formal definition and how fills work
In exchange and broker terms, an order has a requested volume and a filled volume. Each match with a counterparty creates a deal (also called an execution or trade). An order can be filled:
- In full, at once, through a single deal.
- In full, in several pieces, through several deals, often at different prices. The average of these prices is the average fill price.
- In part, where the filled volume is less than the requested volume and the remainder is handled by the order's fill policy.
The fill policy decides what happens to the unfilled remainder:
| Policy | What happens to the remainder |
|---|---|
| Fill or Kill (FOK) | The whole order fills at once or is cancelled. A partial fill is not allowed. |
| Immediate or Cancel (IOC) | Whatever can fill now fills. The rest is cancelled. |
| Return / good for the session | The rest stays as a working order until it fills, expires or you cancel it. |
You can read more on Fill or kill and IOC and Day order.
Worked example (hypothetical)
A trader places a buy limit order on a share CFD. A limit order sets the worst price the trader accepts. At that price, the market only has sellers for part of the requested volume.
- With IOC, the available part fills and the rest is cancelled. The position is smaller than planned.
- With FOK, nothing fills and the order is cancelled.
- With a return policy, the available part fills now, and the remainder stays in the order book. It may fill later at the limit price, or never.
To see how a smaller filled volume changes margin, pip value or risk, use the tools on the Calculators page with the volume that actually filled, not the volume you requested.
Where you see the term
- MetaTrader 5: the History tab shows orders, deals and positions separately. A single order can show several deals, and the volume column can show filled volume against requested volume. See MetaTrader 5 and MT WebTerminal.
- MetaTrader 4: orders and trades are shown together, so partial fills are less visible. See MetaTrader 4.
- Statements and reports: an account statement lists each deal with its price and volume.
- News and market commentary: phrases like "orders were filled at worse prices" usually describe thin liquidity, fast moves or a flash crash.
Edge cases experienced traders should know
- Slippage: a market order can fill at a price different from the quote you saw. A limit order avoids a worse price but may not fill at all.
- Thin liquidity: large volumes, illiquid instruments, session opens and opening and closing auctions make partial fills more likely.
- Stop orders: once triggered, a stop becomes a market order and fills at the next available price, which can be far from the stop level after a gap.
- Market maker execution: when a dealer takes the other side, you may see full fills more often. Whether partial fills are possible depends on the execution model and the account's fill policy.
- Minimum volume and contract size: the remainder of a partial fill can fall below the minimum tradable volume, so it gets cancelled.
Leveraged CFD and forex trading can lose money fast. A fill at a worse price or with an unexpected volume changes your risk. See Risk management.
Related terms
Trading glossary · Trading basics · Fill or kill and IOC · Day order · Dealer · Counterparty · Exposure
Frequent questions
What does "order filled" mean?
The full requested volume was executed and the trade is complete.
What is the meaning of a partial fill?
Only part of the requested volume was executed. The rest depends on the fill policy: it is cancelled, kept as a working order, or the whole order is rejected under FOK.
Do I pay costs on a partially filled order?
Costs such as spread or commission normally apply to the filled volume. Check the conditions of your own account for the exact terms.
Why did my market order fill at a different price?
Prices moved, or the volume at the quoted price was not enough. The order then filled at the next available prices. This is called slippage.
