Partial Fill
When only part of an order is executed — common with large orders or low-liquidity conditions.
A partial fill occurs when the exchange matches only a portion of your order. For example, you order 500 shares but only 200 are available at your limit price right now — those 200 fill and 300 remain working (or are canceled, depending on time-in-force).
Partial fills are normal with limit orders in thinner markets. They increase the number of transactions and therefore commission costs if your broker charges per trade rather than per share.
Orders with FOK or AON constraints explicitly avoid partial fills at the cost of lower fill probability.
Related Terms
All or None (AON)
An order that must fill completely or not at all, but unlike FOK it can wait for a full match.
IntermediateFill
A confirmed execution of an order — the trade happened, shares changed hands at a specific price and time.
BeginnerFill or Kill (FOK)
An order that must be filled in its entirety immediately or canceled outright — no partial fills, no waiting.
IntermediateImmediate or Cancel (IOC)
An order that executes as much as possible immediately, then cancels any unfilled portion.
IntermediateLimit Order
An order to buy or sell only at a specified price or better. Guarantees price but not execution.
Beginner