Chinese microblog portal Weibo’s profit more than doubled in the latest period, helping internet company Sina post double-digit profit and revenue increases. Sina spun out Weibo in 2014 but kept a 50% equity stake. In addition, Sina holds a stake in Alibaba, which in turn holds a stake in Weibo and has been driving advertising to the microblog, according to The Wall Street Journal. In the most recent quarter, Sina reported a 21% increase in advertising revenue, with Weibo offsetting a nearly $12 million decline in portal advertising revenue. Over all, Sina’s fourth-quarter profit rose 37% to $19.9 million, or 27 cents a share. Excluding stock-based compensation and other items, profit rose to 63 cents a share from 35 cents a share a year earlier. Meanwhile, Weibo’s profit more than doubled to nearly $43 million, or 19 cents a share.