Despite the dramatic run on Wall Street that China's Internet portals have enjoyed, with shares in companies like Sina and Sohu.com trading over 25 times their lows of last summer, there is concern that such times may be coming to an end, given the unpredictable business climate.

Charles Zhang, CEO of sohu.com, seems at ease: "When I started the climb, Sohu's stock price was still very low," he says. "But when I came back from the climb, the price went very high."

Since April, shares have climbed three-fold and Sohu, once a fledgling dotcom, is now profitable and popular, thanks mainly to SMS mobile messaging, from which more than 50% of its revenue comes, and rivals Sina and Netease.com have also enjoyed the SMS boost.

One main concern, however, is the possibility of China Mobile changing its deal with the portals in the wake of these share increases ¨C currently they give about 85 percent of value-added content revenues to the portals, but they could try to change that deal. Another concern is perception of the Internet in the government's eyes after 3,000 cyber cafes were closed a few months ago during a national safety campaign.

It is understandable, therefore, why Sohu and its rivals are now racing to diversify into the next big thing that has nothing to do with mobile phones ¨C online gaming.