We study fragmentation of equity trading using a model of imperfect competition among exchanges. In the model, increased competition drives down trading fees. However, additional arbitrage opportunities arise in fragmented markets, intensifying adverse selection. These opposing forces imply that...

We study liquidity provision in fragmented markets. Market makers intermediate heterogeneous order flows, trading off expected spread revenue and inventory costs. Portfolio considerations to diversify inventory risk reveal that market makers have an incentive to siphon certain orders, thus...