Among other buyers, Ark Investment Management, led by noted investor Cathie Wood, is doubling on Alibaba and Baidu. Ark bought Alibaba stock for the first time in four years last week and started a position in Baidu earlier this year. It increased its holdings over multiple transactions this week, including the purchase of $5.4 million worth of Alibaba shares and $2.9 million worth of Baidu shares on Wednesday.