When placing market order, you can indicate additional conditions in the "Fill Policy" field of the trade page:
● Immediate or Cancel (IOC)
In this case, an order will be filled with the quantity maximally available in the market for the quantity indicated in the order. In case the order cannot be filled completely, the order will be partially filled with available quantity, and the unfulfilled part of order will be canceled.
● Fill or Kill (FOK)
This fill policy means that an order can be filled only with the specified quantity. If the specified quantity is currently unavailable in the market, the order will be canceled.