Sina Corp's management says it's cautious about the outlook for next year's ad market, because of an expected slowdown in Chinese economic growth.[Photo / China Daily]

BEIJING - Sina Corp, the operator of China's largest Internet portal, swung to a third-quarter loss due to hefty write-downs on investments in two online businesses, and the company said it does not expect a significant increase in advertising spending next year.

China's online advertisement market grew 54.9 percent in the third quarter to 13.7 billion yuan ($2.2 billion) with Sina ranking fourth in the overall market behind Google China, Taobao and Baidu Inc, according to Beijing-based consultancy iResearch.

On an earnings call on Wednesday, Sina's management gave a cautious outlook on next year's ad market as China's economic growth is expected to cool.

Advertising trends are largely tied to macroeconomic conditions.

"Overall, sentiment is good but not great based on our assessment ... There may be some increase (in advertising spending) but not significant," Sina's chief executive Charles Chao said.

Sina booked non-cash impairment charges - essentially write-offs of intangible assets - of $350.1 million in the third quarter due to write-downs on investments in China Real Estate Information Corp (CRIC) and Mecox Lane Ltd.

Shares in loss-making Mecox, an online retailer in which Sina bought a stake in March, have fallen 77.7 percent so far this year, while shares in CRIC, an Internet real estate information and consultancy company, have fallen about 45 percent.

Excluding one-off items, Sina posted an adjusted profit that beat market expectations helped by strong growth in ad revenue and user additions on its Weibo platform.

"On the impairment charges, there's really nothing you can do. They've made some bad investments.

Mecox Lane was a bad investment for them," said Hong Kong-based Paul Wuh, head of telecoms and Internet research at Samsung Securities.

For the fourth quarter, Sina expects revenue of $128 million to $131 million.

For the third quarter, Sina posted a loss of $336.3 million, or $5.10 a share, compared with a profit of $31.3 million, or 48 cents a share, a year earlier.

The last time it posted a quarterly loss was in the fourth quarter of 2010.

Excluding one-off items, it earned 26 cents a share, beating the average forecast for earnings of 23 cents a share.

Revenue, excluding Sina's separate real-estate advertising business, rose 20 percent to $130.3 million, beating its forecast of $123 million to $126 million.

Sina rolled out specialized Weibo accounts for government officials and a functionality that allows businesses to set up accounts on the platform in the quarter.

Analysts said doubts lingered over when and how the company would monetize its Twitter-like Weibo platform.

Chao said the focus on Weibo is not monetization but continuing to enhance user experience.

The company is testing and developing an advertising system for Weibo to be rolled out in the second quarter next year and will continue to enhance its micro-payment platform, he said.

"Our focus now turns to adding more social networking features to Weibo to increase user stickiness," Chao said in a statement.

However, not all analysts agree on the monetization potential of the user base.

"I'm still cautious about the potential of Weibo right now. This is a social media platform; Twitter is a social media platform that has had problems monetizing its platform, that's one of the biggest concerns I have," said Wuh, who has a "sell" rating on Sina.