Firms count cost of new regulation

Analysts estimate the additional 3% tax will hit bottom line profits of Baidu and Alibaba

Some of China's biggest internet companies may see their earning taking a hit from a new regulation, as the country takes a firmer grip on search advertising.

The State Administration for Industry and Commerce on Friday released the new regulation, which for the first time classifies paid searches as internet advertising. Analysts said that the revenue could be subject to an additional 3 percent culture-cultivation tax.