1. Department of Stats & Maths, Shanghai Lixin University of Accounting & Finance, Shanghai 201620, P. R. China
2. Department of Maths, Shanghai JiaoTong University, Shanghai 200240, P. R. China
3. Guiyang Institute for Bigdata & Finance, Guizhou University of Finance & Economics, Guiyang 550025, P. R. China
4. School of Financial Technology, Shanghai Lixin University of Accounting & Finance, Shanghai 201209, P. R. China
5. Center for Financial Engineering, Soochow University, Suzhou 215008, P. R. China
6. Business School & Advanced Institute of Finance, Sun Yat-Sen University, Guangzhou 510275, P. R. China