The mainland's leading internet portal Sina on Tuesday came in with some impressive results - revenue up 203 per cent year on year for the quarter to US$31.9 million. It comes on the heels of rival Sohu, who last week also announced triple-digit gains. Along with NetEase, the trio has been basking in a return from the dead last year to be among only a handful of profitable portals globally. Yet with the share prices of all three already up more than 400 per cent this year, the question has to be asked: Is it really going to be different this time? Or are we heading for a repeat of the dotcom bubble of 2000 that will once again end in tears? While growth rates remain in triple digits year on year, the three are still making less than US$10 million net a quarter - while market caps range from $1.3 billion to $2 billion. It certainly looks like we are approaching some of the stratospheric valuations of 2000. Those who follow technical charts can also point to similar patterns developing. Of course, this time there are some important differences. The portals are making money as no one gives credit anymore for eyeball hits. It is difficult to ignore the fact that earnings have staged a stunning turnaround this year. Most of the credit can go to an item classified as non-advertising revenue - applications linked to SMS (short message service). Crucially this has extended the portals' customer base to include the mainland's 220 million-plus mobile users, not just the 60 million Chinese with online access. The portals have also proved to be imaginative content developers of anything that can be billed or downloaded - in fact, you could say the portals have made the leap to 3G well ahead of the mobile operators - but these Gs are games, gambling and girls. Online advertising also seems resilient - a generic trend as advertisers learn how to use this medium. But while this positive news is welcome, it is a mistake, one often repeated, to get carried away with the unlimited potential of the China market. For one, it is always easier to get annualised growth rates looking good from a low base - Sohu and Sina's recent quarter-on-quarter numbers are not quite so flattering - third quarter gains of 14.5 per cent and 23 per cent, respectively. The mainland market's capacity to generate cut-throat competition, whether it be telecommunications, televisions or pagers, should not be underestimated. Here the portals' business model can look more than a little vulnerable given their reliance on China Mobile and China Unicom to bill and carry their SMS services. If these Nasdaq stars become too successful, you can expect the mobile heavyweights to try and muscle in on a bigger share of the SMS pie. It is no secret the carriers are already trying to renegotiate a revenue share arrangement that currently works 85-15 in favour of the portals. It is also a concern that the very public success of Sina, Sohu and NetEase might also be their undoing. While imitation is often said to be the sincerest form of flattery - reports that a host of new portals are lining up to come to the market are not the best news for future share price performance. Hutchison's Tom.com leads the way - opportunistically seeking to reverse its reincarnation as a media conglomerate. With a raft of new portal equity to choose from, it might seem inevitable that some of the rarity premium attached to Sohu, Sina and Netease will be diluted. Forecasting whether next year might see a repeat of 2000 might still need a crystal ball but a far easier wager would be a bet that these portals will have a much harder task repeating this year's banner performance.