Mechanisms according to which private intermediaries or governments chargetransaction fees or indirect taxes are prevalent in practice. We consider a setup withmultiple buyers and sellers and two-sided independent private information aboutvaluations. We show that any weighted average of revenue and social welfare can bemaximized through appropriately chosen transaction fees and that in increasinglythin markets such optimal fees converge to linear fees. Moreover, fees decrease withcompetition (or the weight on welfare) and the elasticity of supply but decreasewith the elasticity of demand. Our theoretical predictions fit empirical observationsin several industries with intermediaries.
展开▼
