| Abstract: | This article presents a microstructure model of liquidity provisionin which a specialist with market power competes against a competitivelimit order book. General solutions, comparative statics andexamples are provided first with un-informative orders and thenwhen order flows are informative. The model is also used toaddress two optimal market design issues. The first is the effectof 'tick' size - for example, eighths versus decimal pricing- on market liquidity. Institutions trading large blocks havea larger optimal tick size than small retail investors, butboth prefer a tick size strictly greater than zero. Second,a hybrid specialist/limit order market (like the NYSE) providesbetter liquidity to small retail and institutional trades, buta pure limit order market (like the Paris Bourse) may offerbetter liquidity on mid-size orders. |
