1. RiskLab, Department of Mathematics, ETH Zurich, 8092 Zurich, Switzerland; and Swiss Finance Institute, 8006 Zurich, Switzerland
2. Department of Mathematics and Department of Statistics and Probability, Michigan State University, East Lansing, Michigan 48824
3. Department of Statistics and Actuarial Science, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada