The share price of Sina Corporation (NASDAQ:SINA) slid all the way from the peak price of $147 in 2011 to hitting a 52-week low of $41.25 per share on December 5. Over 70 percent of the market value of Sina has evaporated over the year.

Rumors that Alibaba would invest into Sina Weibo encouraged a 5 percent increase in Sina’s share price last month. However, with the death of this rumor, the share price quickly dropped again.

Moreover, Sina’s operating revenue in the fourth quarter is expected to be $132 to $136 million yuan, decreasing from the $147.7 million in the third quarter this year.

According to Zhang Yi, founder and CEO of Iimedia Research, Sina’s main source of income is advertisement, which heavily depends on the market environment and has a low resistance to risk.

Two years ago, when the user numbers and visiting traffic of Sina Weibo (micro-blog) rocketed, both capital markets and ordinary Internet users believed that Sina, one traditional Chinese web portal with a unitary profit pattern, had found a new growth area.

However, two years later, the profit model of Sina Weibo is increasingly confusing instead of gradually clearer. At present, Sina has over 400 million registered users to become one of the largest social media platforms in the world. However, Sina still has not found its profit model. Sina spent $110 to $200 million in 2011 for its Weibo platform and is expected to invest another $160 million in 2012.