Alibaba co-founder Joe Tsai, the billionaire owner of the Brooklyn Net, will take over as chairman of the Chinese e-commerce giant, the company said Tuesday. Tsai, a Taiwanese-Canadian billionaire with a reported net worth of $7.7 billion, replaces Daniel Zhang, who stepped down to focus on Alibaba’s “crown jewel” cloud division. Tsai, a Yale graduate, helped launch the company in 1999 and served as the company’s chief financial officer until 2013 before stepping into the executive vice chairman role. In 2017, he paid $1 billion for a 49% stake in the Nets and forked over an additional $1.35 billion over...