1. Johns Hopkins Institute for Applied Economics, 3400 North Charles Street, Gilman Hall, Room 301, Baltimore, MD 21218, and Swiss Finance Institute (email: )
2. Federal Reserve Board, 20th and C Street NW, Washington, DC 20551 (email: )
3. Booth School of Business, University of Chicago, 5807 South Woodlawn Avenue, Chicago, IL 60637, NBER, and CEPR (email: )