Alibaba co-founder Jack Ma cut his holdings in the e-commerce company to 4.8% from 6.2% over the past year, according to the company's annual report released on Friday. At the current share price, the stake he sold would be worth around $8.2 billion. Ma, who is currently China's second-richest person, with a net worth of $47.8 billion according to Forbes, retired from being Alibaba's chairman last year to focus on philanthropy.