An order (limit order) that is not revealed to the public- i.e., it is not displayed in the market system. However, dark orders remain placed for potential execution against all incoming orders until executed in full or cancelled. An example of such an order is the minimum quantity orders (which, once posted on the exchange book, remain always non-displayed). Dark orders are not displayed in the central limit order book (hence, are not visible) but are fully integrated into the existing order book on each exchange, where the new dark orders will be allowed to interact with lit order (displayed orders) and other dark orders.

Dark orders can be in the form of undisclosed orders pegged to the mid-point of the national best bid or offer (dark midpoint) or limit orders where price and volume are undisclosed (dark limit orders, or dark limit).

Dark orders are also known as non-displayed orders.