Articles on: Trading Essentials

Smart Order Options: Post Only and Time in Force

Add Order options to your Smart Orders for full control over execution.
These options are found under the buttons to place or cancel an order.

Two options are available:
Time in Force

Post Only

Available as an additional option to Limit or Stop Limit Orders, Post Only Orders ensure that your Limit Orders will be placed in the Order Book (OB) and be eligible for a Maker fee or rebate when executed. If this option is selected and it would be executed immediately upon the order placement (as a Taker Order), the exchange will automatically cancel the limit order.
This option gives the trader more control over their trading fees, which is particularly relevant for large volumes and scalping.

Post Only is ignored on Market and Stop Market Orders.

Post Only example

The Trader prepares an order at 497, expecting it to be placed in the OB, and to be eligible for the Maker fee (or Rebate).
However, the OB is moving quickly and by the time the order is submitted looks like this:

Post only is only used with Time in Force of GTC.
If Post Only is added to a Market Order it will be ignored.
If Post Only is used on a Limit Order that would result in a Taker Order (where the buy price is equal to or above the Lowest Ask, or the sell price is equal to or below the highest Ask) the exchange will reject the order with an error.

Time In Force

Altrady offers three 'Time in Force' order execution strategies for limit orders.
Good till cancelled (GTC)
The order will remain open until it is fully filled or cancelled by the trader. GTC is suitable for traders who are willing to wait for the full order to be filled at a specified price. They can cancel the remaining unfilled order at any time. GTC can be used with Limit or Market Orders, although it is irrelevant for a Market order since by definition a Market order is immediately matched to the Order Book.

Fill or Kill (FOK)
The order must be immediately executed at the order price or better, otherwise, it will be completely cancelled. Partially filled orders are not allowed.
FOK is only used with Limit Orders with a price "above the Book", i.e. for a Buy order, the price would need to be >= the lowest Ask price.

Immediate or Cancel (IOC)
The order must be filled immediately at the order limit price or better. If the order cannot be filled immediately, the unfilled portion of the order will be cancelled.
IOC is ionly used with Limit Orders with a price "above the Book", i.e. for a Buy order, the price would need to be >= the lowest Ask price.

Time in Force Example

A trader wants to buy 100 coins immediately, and the execution price cannot exceed USD 500.
The current market situation is shown in the following figure.

If the trader uses GTC to execute the order, then 60 coins will be purchased immediately, and the remaining order for 40 coins will be entered into the order book to wait for fulfilment.
If the trader uses FOK to execute the order, and since there are currently less than 100 coins in the OB at that price or better, no coins will be purchased and the order will be cancelled.
If the trader uses IOC to execute the order, 60 coins will be bought at $ 500 and the remaining unfilled order for 40 coins will be cancelled.

Updated on: 28/03/2023

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