1. Mathematical Institute, University of Oxford, Woodstock Road, Oxford OX2 6GG, UK
2. Oxford-Man Institute of Quantitative Finance, Eagle House, OX2 6ED, UK
3. Department of Statistical Sciences, University of Toronto, 100 St. George St, Toronto, ON, Canada M5S 3G3, Canada
4. Department of Mathematics, Imperial College London, South Kensington Campus, London SW7 2AZ, UK