Ma said he would name a successor by May 10, when he switches to the role of executive chairman. He said most of Alibaba's leaders "born in the 1960s" would also pass their leadership responsibilities to younger colleagues.

"As a founder CEO, stepping down ... is a difficult decision. It's not because I wanted to take things easy (though the job of Alibaba CEO is no easy task), it's because I see that Alibaba's young people have better, more brilliant, dreams than mine, and they are more capable of building a future that belongs to them," Ma wrote in an e-mail to employees. Reuters obtained the letter on Tuesday from a source close to Alibaba.

The shift is a significant one for Alibaba and follows moves announced last week to chop the group into 25 smaller divisions — to give managers more flexibility.

It also comes after a transformative deal Alibaba struck with Yahoo Inc last year, in which the Chinese company agreed to buy back about half of the stake in itself held by its U.S. partner. Alibaba had long sought to buy back the shares to help regain control over its own corporate destiny.

In an interview with The New York Times, 48-year-old Ma acknowledged he was feeling the strain. "When I was 35, I was so energetic and fresh-thinking. I had nothing to worry about," he said, adding the role of executive chairman would let him focus on broad strategic issues, as well as corporate development and social responsibility.

"I will still be very active," he said. "It is impossible for me to retire."

Alibaba Group includes Alibaba.com, an online market for small businesses; Taobao, a consumer shopping site; and Alipay, an online payment platform.

(Reporting by Lee Chyen Yee; Editing by Ian Geoghegan)

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