TY - JOUR AU - Bonaparte,Yosef AU - Cooper,Russell TI - Costly Portfolio Adjustment JF - National Bureau of Economic Research Working Paper Series VL - No. 15227 PY - 2009 Y2 - August 2009 UR - http://www.nber.org/papers/w15227 L1 - http://www.nber.org/papers/w15227.pdf N1 - Author contact info: Yosef Bonaparte Claremont Graduate University Claremont, CA 91711 E-Mail: bonaparte20@gmail.com Russell Cooper Department of Economics The Pennsylvania State University 611 Kern State College, PA 16802 E-Mail: russellcoop@gmail.com AB - This paper studies the dynamic optimization problem of a household when portfolio adjustment is costly. The analysis is motivated by the observation that on an annual basis, less than 71% of stockholders typically adjust their portfolio of common stocks. We use this, and related observations, to estimate the parameters of household preferences and portfolio adjustment costs. We find significant adjustment costs, beyond the direct costs of buying and selling assets. These adjustment costs and the consequent inactivity in portfolio adjustment imply that inferences drawn about household risk aversion and the elasticity of intertemporal substitution are biased: household risk aversion is lower compared to other estimates and it is not equal to the inverse of the elasticity of intertemporal substitution. ER -