One company launches a games centre and mobile payment system, the other counters with a surprise rise in users. In one corner is Tencent’s WeChat, the smartphone messaging app, and in the other Sina’s Weibo, the microblogging service. Both Chinese internet groups have – thankfully – just reported progress in making money from their social networking powerhouses.

This year investors have backed them both. Tencent is the Hang Seng’s best performer, up almost 50 per cent this year. Sina is nowhere near the top of the Nasdaq’s leaderboard but had rallied 60 per cent even before its results this week. Both have just reported higher sales, including hefty jumps in advertising revenues – and also higher marketing costs from chasing new users. Both missed expectations for profits, but then, the investment case here is about the future. Sina is trading on about 90 times forecast 2013 earnings (Facebook: 45), versus 30-odd for Tencent. Still, against, say, the 2015 earnings forecasts from Barclays, investors can squint and say both are only trading on 19 times. Phew.

The problem is reliably mapping out that future. The sales mix and potential success of new projects is anyone’s guess. And that is before having to factor in new, untested, seasonal trends such as Tencent blaming school exams for slower games sales growth. Different platforms use different metrics, too. WeChat has 236m active monthly users (Twitter: 200m-plus), Weibo has 54m active daily users but does not provide monthly data. Then there is the existing market excitement. Average price targets of analysts – a group known for their optimism – have been struggling to keep up with the rally in both stocks. There are a great many expectations and estimates already priced into both.