Do WeChat or do Weibo in China’s febrile social media market? We do neither. At least, neither network is a reason to buy its owner – Tencent and Sina, respectively – even as it becomes clearer that WeChat’s private messaging service is pulling ahead of Weibo’s public microblogging model.

Weibo, China’s Twitter, seems to be becoming its MySpace. Sina’s Nasdaq-listed shares are down a fifth so far this year. Weibo’s user numbers would make any western social network envious but they fell 9 per cent last year – from 2012’s 308m – and risk being overtaken by WeChat’s 272m. A study from Britain’s Daily Telegraph has also suggested that the most active Weibo users dropped off even faster, by almost three-quarters. This is a sign that “Big Vs” – accounts of famous bloggers with millions of followers – have felt the chill of the government crackdown on public spreading of “rumours”. So it might appear WeChat’s relatively private, politics-free approach is a safer bet.

The reality is more subtle. Sina has been hard-pressed to profit from its users, whatever their number. Weibo’s high-margin mobile services, such as music, have failed to take over from low-margin, distracting online advertising. Services as a share of revenue fell to 11 per cent in the first nine months of 2013, from 16 per cent in 2012. The amount of advertising on each Weibo page is a reason for users to leave.