The tendency to introduce anonymity into financial markets apparently runs counter to the theory supporting transparency. This paper studies the impact of pre-trade transparency on liquidity in a market where risk-averse traders accommodate the liquidity demand of noise traders. When some risk-averse investors become informed, an adverse selection problem ensues for the others, making them reluctant to supply liquidity. Hence the disclosure of traders' identities improves liquidity by mitigating adverse selection. However, informed investors are effective liquidity suppliers, as their adverse selection and inventory costs are minimized. With endogenous information acquisition, transparency reduces the number of informed investors, thus decreasing liquidity. The type of information that traders hold and the effectiveness of insider trading regulation are crucial to distinguish between equilibria.

Reserve orders enable traders to hide a portion of their orders and now appear in most electronic limit order markets. This paper outlines a theory to determine an optimal submission strategy in a limit order book, in which traders choose among limit, market, and reserve orders and simultaneously set price, quantity, and exposure. We show that reserve orders help traders compete for the provision of liquidity and reduce the friction generated by exposure costs. Therefore, total gains from trade increase. Large traders always benefit from reserve orders, whereas small traders benefit only when the tick size is large.

We show that when a continuous dark pool is added to a limit order book that opens illiquid, book and consolidated fill rates and volume increase, but spread widens, depth declines, and welfare deteriorates. The adverse effects on market quality and welfare are mitigated when book-liquidity builds but so are the positive effects on trading activity. All effects are stronger when traders’ valuations are less dispersed, access to the dark pool is greater, horizon is longer, and relative tick size larger.

We study the effects of the introduction of a closing auction (CA) on the microstructure on the continuous trading phase in Borsa Italiana and Paris Bourse. We postulate and compare several empirical predictions based on both standard Kyle-type models and more recent models of limit order book. We find that while the CA has no effect during most of the day, its effect on the last minutes of trading is dramatic. We document a sharp decline in volume, associated with a significant reduction in spread and volatility, and an increase in aggressiveness of liquidity suppliers during the last minutes. We show that the differences in the Reference Price algorithm between Milan and Paris have a significant effect: the CA attracts greater volumes when the Reference Price is equated to the CA price.