Welfare and Optimal Trading Frequency in Dynamic Double Auctions

This paper studies the welfare consequence of increasing trading speed in financial markets. We build and solve a dynamic trading model, in which traders receive private information of asset value over time and trade strategically with demand schedules in a sequence of double auctions. A stationary linear equilibrium and its efficiency properties are characterized explicitly in closed form. Slow trading (few double auctions per unit of time) serves as a commitment device that induces aggressive demand schedules, but fast trading allows more immediate reaction to new information. If all traders have the same speed, the socially optimal trading frequency tends to be low for scheduled arrivals of information but high for stochastic arrivals of information. If traders have heterogeneous trading speeds, fast traders prefer the highest feasible trading frequency, whereas slow traders tend to prefer a strictly lower frequency.