We model endogenous technology adoption and competition among liquidity providers with access to High-Frequency Trading (HFT) technology. HFT technology provides speed and information advantages. Information advantages may restore excessively toxic markets. Speed advantages may reduce resource costs for liquidity provision. Both effects increase liquidity and welfare. However, informationally advantaged HFTs may impose a winner’s curse on traditional market makers, who in response reduce their participation. This increases resource costs and lowers the execution likelihood for market orders, thereby reducing liquidity and welfare. This result also holds when HFT technology dominates traditional technology in terms of costs and informational advantages.

Traders may run on financial markets merely out of fear of future liquidity shocks. We present a model that shows that adequately calibrated circuit breakers can prevent such coordination failures by curbing excessive trading. It suggests a novel, forward-looking circuit breaker that becomes most restrictive in cases when expected welfare losses of inefficient market runs are largest. The probabilities of current and future liquidity shortages are important determinants for such welfare-optimized circuit breakers. We empirically illustrate how to calibrate these parameters. We also determine under which economic conditions circuit breakers damage welfare and should not be implemented.

We analyze a dynamic microstructure model in which a dealer market (DM) and a crossing network (CN) interact for three informational settings. A key result is that coexistence of trading systems generates systematic patterns in order flow, which depend on the degree of transparency. Further, we study overall welfare, measured by the gains from trade of all agents, and compare it with the maximum overall welfare. The discrepancy between both measures is attributable to two inefficiencies. Due to these inefficiencies, introducing a CN next to a DM, as well as increasing the transparency level, not necessarily produces greater overall welfare.