A trading algorithm that seeks and searches for non-displayed liquidity (dark liquidity). In order to reduce impact (aggression), the algorithm only targets market liquidity that has lower potential impacts. Additionally, it may trade lit (seeking lit liquidity) with a minimum participation rate. This algorithm operates on the so-called passive liquidity aggregation, taking a more passive approach to liquidity aggregation, seeking to place orders in dark pools and searching for hidden liquidity between the spread on exchanges and electronic communication networks (ECNs). Aggression level or degree can determine the types of venues accessed by a shadow.

The algorithm does not post bid or offers in public, and therefore it does not interact with visible top-of-book liquidity. In the meantime, it attempts to optimize venue selection in order to reduce opportunity cost and gaming risk to the extent possible.