What is a Post-Only order?
A Post-Only (PO) order is submitted only if it enters the order book without triggering an immediate trade. If you submit a Post-Only order that would cross the order book (i.e., a buy order that is higher than the last price), the order will be cancelled.
Post-Only orders are useful if you wish to pay maker fees only.
What are the limitations of Post-Only orders?
If a Post-Only order’s price matches or crosses the best price on the opposite side, it is rejected. This forces you to manually adjust and resubmit orders, reducing efficiency in fast-paced markets.
What is a Smart Post-Only order?
A Smart Post-Only (SPO) order improves on the standard Post-Only order by automatically adjusting prices to ensure you enter the order book as maker orders to avoid cancellation.
Currently, SPO orders can only be placed via Exchange API.
How do I submit an SPO order?
Submit a Post-Only order via Exchange API with the SPO flag enabled. The system will check if the price triggers an immediate trade.
If it doesn’t, the submission will enter the order book. If it does, the price is automatically adjusted by a single tick, or US$0.01, to qualify it as a maker order.
The adjusted order is then added to the order book
How are SPO orders adjusted?
If the order placed triggers an immediate trade, the price is adjusted by one tick
Buy orders are adjusted below the best ask price
Sell orders are adjusted above the best bid price
The adjusted order is then placed as a maker order
What are the benefits of SPO orders?
Efficiency: You do not need to manually adjust and resubmit orders after a Post-Only order is rejected
Cost Savings: Your trades are executed as maker orders, ensuring you pay only maker fees
Note: SPO orders will be rejected if the margin requirement from the adjusted order exceeds the available margin.
Example:
On the sell side of the order book, the best ask price is $100.00, and the second best ask price is $100.01.
The submitted Buy order is $100.03 with SPO order enabled.
The system flags the trade as a taker order, adjusts the price by one tick ($0.01) and places it as a maker order at $99.99.
Notes
When placing trades via API, you can specify SMART_POST_ONLY in the exec_inst field to enable SPO orders
SMART_POST_ONLY cannot be used together with REDUCE_ONLY
Support for this feature on the Crypto.com Exchange Web and App will be added later