(Yicai Global) March 15 -- Jack Ma and Joseph Tsai, two of Alibaba's billionaire co-founders, plan to sell as much as USD5.5 billion of stock they hold in the Chinese e-commerce giant to fulfill their commitments to charitable causes.

Ma, who is executive chairman, will sell up to 21.4 million shares within the 12 months starting April, while Tsai, executive vice chairman, will sell a maximum of 9.2 million by the end of this year, Chinese online news outlet Sina reported yesterday. It did not say which charities would receive the money.

The pair set up a charitable trust focusing on the environment, healthcare, and education before Hangzhou-based Alibaba went public in 2014, and gave it 2 percent of the company's outstanding shares. The donation is now worth over CNY60 billion (USD8.9 billion) based on the firm's market capitalization.

Ma, who has a net worth of USD39 billion, announced last September that he would step down as executive chairman in a year and be replaced by Chief Executive Daniel Zhang. Ma plans to devote himself to education and charity.

Alibaba [NYSE:BABA] closed 0.2 percent down yesterday at USD180.36, valuing the company at USD467.5 billion.

Editor: Emmi Laine