Banking,incentive constraints,and demand deposit contracts with nonlinear returns

Summary This paper presents two results regarding banking theory: (1) demand deposit contracts are essential in providing insurance against preferences shocks, as in Diamond and Dybvig (1983), if and only if the incentive compatibility conditions bind at the social optimum; and (2) for additively separable preferences with random discount factors, demand deposit contracts have the realistic feature that the interest rate paid is an increasing function of deposit balance.This paper is based on Chapter 2 of my Ph.D. dissertation submitted to the Graduate School of The University of Minnesota. I am indebted to Neil Wallace for his advice and guidance. I thank an anonymous refree for comments on a previous version of the paper. The comments from Edward Green, Nobuhiro Kiyotaki, Antonio Merlo, and Arijit Mukherji are appreciated.