1. Department of Statistical Sciences, University of Toronto, Toronto, Ontario, M5G 1Z5, Canada.
2. Department of Statistical Sciences, University of Toronto, Toronto, Ontario, M5G 1Z5, Canada; and Oxford-Man Institute of Quantitative Finance, Oxford, OX2 6ED, United Kingdom.
3. Oxford-Man Institute of Quantitative Finance & Mathematical Institute, University of Oxford, Oxford, OX2 9HB, United Kingdom.