Leading Chinese Internet-search firm Baidu announced that there had been several personnel changes at management level, including the resignation of its chief operating officer.

Dr. Ye Peng stepped down, with immediate effect, for what the firm described as “personal reasons.” It did not name a successor in the statement announcing Ye’s resignation.

Additionally, the company promoted Shen Haoyu to the position of senior vice president and Zhan Wang to vice president. They had previously been vice president of business operations and senior director of business products, respectively.

Shen joined Baidu in 2007 and has led the planning and execution of the firm’s search engine marketing platform and associated business alliances. Wang joined Baidu in 2000 and has been a key driver of the company’s commercial product developments.

Baidu, which has a dominant share of the Internet-search market in China, said in October its third-quarter earnings had leapt up by 42 percent, due largely to increased advertising revenue from large clients. However, the company’s projection of fourth-quarter revenue was much more conservative than Wall Street’s expectation then.