China's second and third largest operators — China Unicom and China Telecom — have swapped chairmen effective today, while market leader China Mobile has named an official with the Ministry of Industry and Information Technology (MIIT) as its new chairman. Shang Bing, a vice-minister at the regulator, has replaced Xi Guohua as head of China Mobile, the company said in a statement. Meanwhile, Unicom's chairman Chang Xiaobing has taken the helm at Telecom, while his counterpart at Telecom, Wang Xiaochu, has become chairman of Unicom. Both executives have stepped down as executive directors of their previous companies. Announcements on China Unicom's and Telecom's websites offered no explanation for the sudden change. But the move is not unprecedented. Back in 2004, Wang Jianzhou, at the time president and CEO of Unicom, took over as general manager of China Mobile (he later become chairman).