Regulators are concerned that large volumes of trading outside lit venues (i.e., dark trading) harms the functioning of financial markets. In contrast, regulators are neutral about hidden-order trading as these occur on lit venues and are associated with positive effects on market quality. An unanswered economic question concerns the interrelation between these two types of opaque trading, i.e., hidden orders and dark trading. Employing two different empirical methodologies we find that dark and hidden-order trading are substitutes. We also show that both types of opaque trading increase when markets are volatile and fewer algorithmic trading occurs. Smart order routing increases dark trading but reduces hidden-order activity.

监管机构担心在照明场所外的大量交易（即暗交易）会损害金融市场的运作。相比之下，监管机构对隐藏订单交易持中立态度，因为这些交易发生在照明场所，并对市场质量产生积极影响。一个悬而未决的经济问题涉及这两种不透明交易，即隐藏订单和暗交易之间的相互关系。采用两种不同的经验方法，我们发现暗交易和隐藏订单交易是替代品。我们还表明，当市场波动且算法交易较少时，两种类型的不透明交易都会增加。智能订单路由增加了暗交易，但减少了隐藏订单活动。