In many jurisdictions, equity market regulation requires traders to honor the best quotes on all marketplaces, often forcing brokers to split client trades across multiple markets.Markets react strongly: we show that such split trades have double the price impact of single-market trades. The...

By employing a dynamic model with two limit order books, we show that fragmentation is associated with reduced competition among liquidity suppliers and lower picking-o↵ risk of limit orders. Due to these countervailing channels, the impact of fragmentation on liquidity and welfare di↵ers...

I model a market in which a trader with superior information about an asset is subject to careful scrutiny by another agent who immediately observes the trading decisions of the informed agent with some noise and engages in (klepto)parasitic behavior by imicking the informed trader and trading...