[1
]McMaster University, 1280 Main Street West Hamilton, ON L8S 4M4, Canada (email: )
[2
]Toulouse School of Economics, University of Toulouse Capitole, 21 Allée de Brienne,
31000 Toulouse, France (email: )
[3
]University of Leuven, Naamsestraat 69, B-3000 Leuven, Belgium, and C.E.P.R. London
(email: )