French advertising company Publicis Group (PUB.EPA) said Monday it bought Beijing-based digital-marketing company Longtuo for an undisclosed amount, Publicis’s fourth purchase in as many months as it seeks to make China its second-largest market by 2015, The Wall Street Journal reported. Longtuo will operate under Publicis’ digital arm, Razorfish. Industry insiders said Publicis is looking to establish itself in China’s online space, as stricter regulations on Chinese television continue to push more advertising online. Longtuo’s client list includes some of China’s largest e-commerce sites, including Alibaba Group’s Taobao.com and Beijing Jingdong Century’s 360buy.com. China’s ad market grew 15% last year to an estimated US$54.6 billion, according to GroupM, the ad-buying unit of Publicis competitor WPP (WPP.LON). Online advertising made up nearly US$6 billion of that total, up 26% from a year earlier, according to Beijing-based ad company Charm Communications.