· EXECUTION
Partial fills and how platforms display them
A partial fill trades only part of a limit order. One 10 lot MES bid on the Liquivue DOM shows how the working order, the position and the bracket change.
SHORT ANSWER
A partial fill happens when the exchange fills only part of an order's size, and the rest keeps working at the same price. A platform then shows two numbers, the filled position and the unfilled working order. In Liquivue the DOM keeps the unfilled part as a working order, and position tracking shows size, entry, profit and loss, and each fill.
A partial fill is an order that the exchange fills for only part of its size. The unfilled part stays in the book as a working order at the same price. Partial fills are common with limit orders. A limit order waits in a queue, and the trades at its price can stop before they reach the end of it. This note follows one invented 10 lot bid on the Liquivue DOM and shows what the screen displays after each fill.
Why limit orders fill in pieces
At CME, most futures contracts match orders at one price in time order. The first order to arrive at a price fills first. The note on where your stop sits in the queue explains that queue.
Your limit order fills only when sellers trade through every contract ahead of you. If they trade 30 more contracts than the queue ahead holds and your order is 10, you get 10. If they trade 4 more, you get 4, and the other 6 keep waiting.
Market orders can also fill in pieces, but they fill at several prices in one go. The note on why market orders fill at several prices covers that case. This note covers the limit order case, where the pieces arrive at one price over time.
One 10 lot bid, fill by fill
All numbers below are invented. The contract is MES, the Micro E-mini S&P 500 future. One tick is 0.25 points and is worth US$1.25 per contract.
At 10:30:00 the trader places a buy limit for 10 MES at 5,050.00 from the Liquivue DOM, with a bracket attached. The stop sits 8 ticks below at 5,048.00 and the target sits 12 ticks above at 5,053.00. The DOM shows 60 contracts already bid at 5,050.00 ahead of the order.
| Time | Sellers trade at 5,050.00 | Ahead in queue after | Trader filled | Still working |
|---|---|---|---|---|
| 10:30:20 | 45 | 15 | 0 | 10 |
| 10:31:02 | 19 | 0 | 4 | 6 |
| 10:31:09 | 3 | 0 | 7 | 3 |
| 10:31:15 | 0 | 0 | 7 | 3 |
At 10:31:15 the ask moves up to 5,050.50 and the trading at 5,050.00 stops. The trader holds 7 contracts and still has a working order for 3.
What the screen shows after each fill
On the Liquivue DOM, the working order at 5,050.00 drops from 10 to 6, then to 3. The working order stays on the ladder until the last 3 fill or the trader cancels them.
Liquivue position tracking changes at the same moments. After 10:31:02 it shows a size of 4 and an entry of 5,050.00. After 10:31:09 it shows 7 at 5,050.00. The fills list holds two rows, one for 4 and one for 3. Both fills are at one price, so the average entry is 5,050.00.
The trade bubbles on the Liquivue heatmap show the sell trades that filled the order. The bid band at 5,050.00 also gets dimmer as the 60 contracts ahead of the trader trade away.
The bracket on a partial fill
The trader sized the bracket for 10 contracts. With 7 filled, the stop and target need to cover 7.
- With 7 filled, a stop at 5,048.00 risks 7 times 8 ticks times US$1.25, or US$70.
- With all 10 filled, the same stop would risk US$100.
The working order for 3 is still at the exchange. If price falls back and fills it, the position grows to 10 and the risk returns to US$100. Platforms handle bracket sizes on partial fills in different ways, so check the stop and target quantities on your own DOM after the first fill, not after the last.
If you do not want the last 3, cancel the working order. The position then stays at 7. Liquivue session risk controls add another limit. A maximum contracts setting per instrument caps the position size on that contract for the session.
How other platforms compare
Live futures order entry needs a specific plan on some platforms. Bookmap adds live futures execution with Global+ at US$99 a month. ATAS allows futures order management on its Pro and Ultra plans, from €69.95 a month. Liquivue includes chart and DOM order entry with brackets, OCO and trailing stops in its €20 a month workspace, and it starts with a 7-day trial. The vendor says live-account acceptance on the NinjaTrader bridge is unverified, so test partial fills in simulation first.
A check you can run
In a simulation account, place a limit order for 5 contracts at the best bid when the DOM shows at least 50 contracts ahead of it. Write down the size of each fill, the time, and the working quantity left after each one. Then check the stop and target quantities in your bracket after the first fill and compare them with the filled size.
Questions
What is a partial fill?
A partial fill is an order that the exchange has filled for part of its size. The unfilled part stays in the book as a working order until it fills, you cancel it, or it expires.
Why did only part of my limit order fill?
The trades at your price ran out before they reached the end of your order. At CME most contracts fill in time order, so the contracts queued ahead of you filled first and the sellers stopped before all of yours traded.
Does a partial fill cost more in commission?
Futures commissions are usually charged per contract, so 7 contracts filled in two pieces cost the same as 7 filled at once. Check your broker's fee schedule, because some brokers add a charge per order or per fill.
How does Liquivue show a partially filled order?
Liquivue position tracking shows the filled size, entry, profit and loss, and the fills. The unfilled contracts stay on the DOM as a working order at their price, and you can cancel them from there.
Educational content about market data and charting software. It is not trading or investment advice. Trading involves risk.