The Benefits of Volume-Conditional Order-Crossing∗

We assess the role and viability of an order-crossing or market-clearing mechanism that is automatically triggered only when a minimum number of shares can be crossed. Such a mechanism is naturally more attractive to traders who do not require much immediacy for their trades, as liquidity is cheaper in this market than in a continuous-auction market. The volume condition that we propose is crucial to the effectiveness with which this market complements the continuous-auction market in two important ways. First, when appropriately set, the volume condition endogenously adjusts the probability that market-clearing is triggered and so keeps impatient traders and highly informed traders away. Second, because market-clearing with a large volume condition reduces the effects of adverse selection in this market, patient traders are more willing to place orders in it. As we show, these effects often combine into a Pareto-dominating equilibrium when the continuous-auction market and the crossing mechanism with the right volume condition are both open.