1. Division of Banking and Finance, Nanyang Business School, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798
2. College of Mathematics and Statistics, Shenzhen University, Nanhai Ave 3688, Shenzhen, Guangdong 518060, China
3. Shenzhen Key Laboratory of Advanced Machine Learning and Applications, Shenzhen University, Shenzhen, Guangdong 518060, China
4. Department of Finance, Southern University of Science and Technology, 1088 Xueyuan Avenue, Shenzhen, Guangdong 518055, China