Definition
An order is partially filled if some quantity has traded while a remainder is still unexecuted. This often happens when available counterparties at acceptable prices cannot satisfy the whole order at once. The executed portion is a real trade, not a provisional reservation.
How It Works
If a hypothetical buy order requests 10 units but only 4 execute, 6 remain. Under a resting time-in-force instruction, those 6 may wait for later trades. An immediate-or-cancel instruction instead cancels the unfilled remainder, while fill-or-kill requires immediate full execution or none.
Key Considerations
The filled portion creates exposure even if the remainder is canceled. Review actual quantity, average price, and fees before replacing an order or adjusting a hedge. A “partially filled, then canceled” order can therefore leave a real holding or position; cancellation does not erase the earlier trade.