Institution: | (1) Graduate School of Business, The University of Chicago, 1101 East 58th Street, Chicago, IL 60637, USA (e-mail: gmc@gsb.chicago.edu) , US;(2) The National Bureau of Economic Research, 1050 Massachusetts Avenue, Cambridge, MA 02138, USA , US;(3) School of Business and Department of Mathematics, University of Wisconsin, Madison, WI 53706, USA , US |