1. Finance Department, The Wharton School, University of Pennsylvania, Philadelphia, Pennsylvania, USA
2. National Bureau of Economic Research, Cambridge, Massachusetts, USA
3. HKU Business School, The University of Hong Kong, Hong Kong SAR, China
4. Sloan School of Management, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA;
5. Laboratory for Financial Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
6. Computer Science and Artificial Intelligence Laboratory, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
7. Santa Fe Institute, Santa Fe, New Mexico, USA
8. Kenneth C. Griffin Department of Economics, University of Chicago, Chicago, Illinois, USA