Citing “lots of dreams to pursue,” the billionaire will step down as executive chairman of the global e-commerce giant on his 55th birthday next September. He’s tapped CEO Daniel Zhang, 46, to replace him. Ma says he’ll pursue philanthropic opportunities and return to his professional roots as an educator. The success of Alibaba, which became a leading Chinese success story after its launch in 1999, has made Ma the country’s richest man — as well as a symbol of China’s economic development. He’ll remain on the company’s board until 2020.