Limit orders

Use a limit order to choose your price. Pick Limit on the ticket, enter a price and a size, and send. The order waits on the exchange, so it keeps working while Mirrorlane is closed.

The exchange matches by price, then by time. Your order first fills against any resting orders that already meet your price, at their prices, as a taker. What’s left joins the book at your price, behind the orders already there, and fills as a maker when the market comes to it.

Before you send, Fills as reads “Maker, rests on the book” or “Taker, crosses the spread”. Under the Price field, a line shows how far your price sits from the mark price, such as “−0.42% from mark”, so a slipped digit shows up before anything goes.

A button under the size slider, at the right, shows the order’s time in force. Press it to go from GTT to IOC to Post only.

Time in force	What it does
GTT	The default. Good till time: the order rests for 28 days, and the exchange cancels whatever hasn’t filled by then.
IOC	Immediate or cancel: the order fills what it can at once, and the rest is cancelled. It never rests.
Post only	The order only ever rests. If it would cross the book when it arrives, the exchange cancels it, so every fill pays the maker fee. It rests for 28 days, as GTT does.

Setting	What it does
Price	Your limit. Bid on a buy, or Ask on a sell, and Mid put that price from the book in the field. ↑ and ↓ step it by one tick, ten with Shift.
Size	In the market’s asset by default, or in dollars, with the slider and the % box.
Size by	Size by default. Risk, on perpetuals, works out the size from the most you’ll lose if your stop is hit, as on a market order.
TP / SL	Off by default. Adds a take profit and a stop loss for what this order fills. See TP / SL. Perpetuals only.
Reduce only	Off by default. The order can only make your position smaller. Perpetuals only.
Time in force	GTT by default, as above.

Clicking a price in the order book also puts a limit at that price in the ticket.

• Minimum size. An order that rests must be at least the market’s minimum: the larger of its minimum size and its minimum value at your price. Below it, the ticket gives the minimum size at that price.
• Price band. A buy can’t be priced more than 5% above the lower of the mark price and the best ask. A sell can’t be priced more than 5% below the higher of the mark price and the best bid.
• Steps. Prices go in the market’s tick and sizes in its size step.
• Open orders. Plus accounts hold up to 750 open limit orders, at most 250 in one market. Premium accounts hold up to 1,500, at most 1,000 in one market.

The part that fills at once pays the taker fee, and the part that rests and fills later pays the maker fee. The Fees row shows the estimate in dollars before you send. See The fee.

• The price crosses the book. The order fills at once as a taker, at the resting orders’ prices. The ticket warns first, “This price crosses the book, so it fills at once as a taker.” Choose Post only if it must rest.
• Post only would take liquidity. The exchange cancels the order with nothing filled, and the order button says “Post only would take liquidity”.
• The price is outside the band. The ticket warns “Outside the price band around the mark price, so it would be refused.” If the exchange refuses it, the ticket says how far a buy can go up, or a sell down, right now.
• There isn’t enough margin. The order button offers the largest size that fits, as on a market order.
• Your position closes first. A reduce-only order larger than what’s left fills down to zero, and the exchange cancels the rest.
• It meets your own order. When a new order of yours would trade with one of your resting orders, the exchange cancels the resting one in full.
• It expires. After 28 days, the exchange cancels a GTT or post-only order that hasn’t filled, and a notice says so.

Open orders lists the order with its price, size, how much has filled, and Reduce only.

• Edit changes its price and size while nothing has filled. On the chart, drag its line to a new price. A move that would leave it under the market’s minimum at the new price is refused before it goes.
• Cancel on its row cancels it at once. Right-click the row, or press and hold it on a touch screen, for its menu, where Cancel asks first.
• Cancel all cancels every open order, or the ones you select or filter to. The dialog warns when reduce-only orders are among them.

Cancelling stops what hasn’t filled; what has filled stays filled.