Jack Ma, who founded e-commerce giant Alibaba Group and helped launch China’s online retailing boom, announced Monday that he will step down as the company’s chairman next September.

In a letter released by Alibaba, Ma said he will be succeeded by CEO Daniel Zhang, an 11-year veteran of the company. Ma handed over the CEO post to Zhang in 2013 as part of what he said was a long-planned succession.

Ma, a former English teacher, founded Alibaba in 1999 in an apartment in the eastern city of Hangzhou to connect Chinese exporters with foreign retailers. It expanded into consumer retailing, becoming the world’s biggest e-commerce company by total value of goods sold, as well as online finance, cloud computing and other services.

AP reports that, Alibaba said Ma will remain a member of the Alibaba Partnership, a group of 36 people with the right to nominate a majority of its board of directors. That arrangement limits shareholder control, but Ma has defended it as a way to keep Alibaba focused on long-term development.

“This transition demonstrates that Alibaba has stepped up to the next level of corporate governance from a company that relies on individuals, to one built on systems of organizational excellence and a culture of talent development,” said Ma’s letter.

Ma said he wants to “return to education” but gave no details.