Alibaba Group sign is seen at the World Artificial Intelligence Conference (WAIC) in Shanghai HONG KONG (Reuters) – The Hong Kong-listed shares of China's Alibaba Group fell more than 4% on Monday after the surprise departure of outgoing Alibaba CEO Daniel Zhang from the company's cloud computing business. The company announced Zhang's decision to depart the unit in an internal letter to staff seen by Reuters. Zhang had been scheduled to hand over the role of group CEO to Eddie Wu on Sunday. The letter said Wu will also take charge of the cloud business after Zhang's departure. The unit…