In a letter sent to customers, employees, and shareholders, Ma explained that in exactly one year, on September 10, 2019—which is also Alibaba’s 20th anniversary—Alibaba Group CEO Daniel Zhang will replace him as chairman of the board. Ma will remain on the board of directors until the company’s annual shareholders meeting in 2020.

So who is Zhang, Ma’s replacement?

Zhang has served as CEO of Alibaba since 2015 and worked at the Alibaba Group more broadly for 11 years. Ma expressed confidence in his CEO, writing that “the company has run smoothly for five years on the back of these institutional ingredients,” and highlighting that China’s business news media named him the top CEO of 2018.

Zhang is a Shanghai-educated certified accountant. He joined Taobao, an e-commerce site owned by Alibaba, as chief financial officer in 2007. He has been credited as the “key architect” of Singles’ Day, turning it into the world’s biggest shopping day, outpacing Black Friday and Cyber Monday combined. Last year, Singles’ Day, which falls on November 11, topped $25 billion in sales.

Ma first turned over the position of CEO in 2013, to Jonathan Lu. But 46-year-old Zhang took over as CEO from Lu after Ma announced that it was time for the company to be run by people born in the 1970s and after. At the time, Zhang was serving as COO.

In the years since, Zhang has been responsible for managing 13 consecutive quarters of “consistent and sustainable growth,” Ma wrote in Monday’s letter. Alibaba’s stock has grown 87% during Zhang’s tenure and has a market value of around $420 billion, which is bigger than rival Tencent Holdings.

“Teachers always want their students to exceed them,” Ma wrote, “so the responsible thing to do for me and the company to do is to let younger, more talented people take over in leadership roles so that they inherit our mission ‘to make it easy to do business anywhere.’”

But, Ma added, “The one thing I can promise everyone is this: Alibaba was never about Jack Ma, but Jack Ma will forever belong to Alibaba.”