Baidu, China's equivalent of Google, could report fourth-quarter earnings up about 70 percent due to strong growth in usage and ad sales, analysts estimate.

The Beijing-based online service is scheduled to report results Thursday. The consensus estimate is for net income of 91 cents a share, about 70 percent ahead of the year-earlier amount.

Baidu's American Depositary Receipts trade in the U.S. in dollars. Baidu's 2005 initial public offering, exactly a year after Google's, raised $109 million and was one of the most successful Chinese IPOs.

Baidu shares Thursday rose $2.09 to $140.41 in afternoon trading Thursday, giving the Chinese Web site a market capitalization of $49.1 billion. By contrast, Google's is $19  billion.

Analysts, such as Jefferies' Cynthia Meng in Hong Kong, expect Baidu to report fourth quarter revenue jumped 81 percent to RMB 4.4 billion (US $698 million) from RMB 2.4 billion a year ago. She estimates earnings of 91 cents, along with the consensus.

Meng said she was bullish on Baidu because traffic rose in the fourth quarter. Search ads rose more than 50 percent and query traffic rose 17 percent. That should leave Baidu with about 82 percent market share in China.

Google had 65 percent share of the U.S. search market in the third quarter of 2011, ComScore estimated. Yahoo held 15.5 percent followed by Microsoft's Bing with 14.7 percent.

Challenges remain. Catherine Leung, of Goldman Sachs, noted Baidu could face a new threat in mobile search from Google, owner of the Android OS. Google's acquisition of Motorola Mobility is expected to close this week following regulatory approvals. That's expected to bolster Google's share in the mobile market.

Google's better presence in search through Android could make it a more formidable challenger in China, where smartphones are also wildly popular, Leung wrote this week.

Brean Murran Caret's Fawne Jiang, who raised a price target on Baidu to $200 from $185, said the search engine will enjoy robust growth due to strong consumer buying over the next 12 months.

Baidu shares have gained 21 percent this year. Over the past 52 weeks, though, the gain is only 9.4 percent.