The chief operating officer of Tudou Holdings (TUDO.NASDAQ) resigned, leading to a 6.6% drop in the share price of China’s second largest video hosting website on Thursday, Bloomberg reported. China Business News Daily reported Wednesday that Tudou confirmed the departure of Xiangyun Wang, the company’s COO. Wang’s resignation is the first by a senior manager at the company since the March announcement that it would be purchased by larger rival Youku (YOKU.NYSE) for $925 million. Wang’s departure may be a sign that the transition is not progressing smoothly, said analyst Henry Guo of ThinkEquity Partners in San Francisco. The news also sent shares of Youku tumbling 4.5% to their lowest level since January. The Bloomberg China-US Equity Index which tracks the most-traded Chinese stocks in the US showed little change.