Jack Ma expresses his gratitude to employees at a function to mark the 20th anniversary of Alibaba Group in Hangzhou, capital of east China's Zhejiang Province, Sept. 10, 2019. Jack Ma officially stepped down as group chairman of Alibaba Tuesday, handing over the position to the company CEO Daniel Zhang. It is a special day for both the Chinese billionaire and the e-commerce giant he co-founded. Ma, a former English teacher, turns 55 Tuesday, which also marked the 20th anniversary of Alibaba Group and coincided with Teachers' Day. Ma handed over the CEO position in 2013 and made an announcement in an open letter on Sept. 10, 2018, saying that he would step down in a year, with Zhang taking over. Yet his retirement is not a goodbye. He will continue to serve on Alibaba's board of directors until the general meeting of shareholders in 2020 and remain a permanent member of Alibaba's partners and employee No. 1. (Xinhua/Jin Liangkuai)