From 2000 to 2002, Zhou was the chairman of the China Securities Regulatory Commission. While there, he earned the nickname Zhou "Bapi" (), Zhou "the flayer". He targeted corruption in listed companies, angering many small shareholders, who saw their shares fall. In July 2001, Zhou declared his intention to reduce state ownership in the stock market. The stock market quickly went into freefall, forcing him to abandon his plans that October. He emphasized the role of market mechanisms, worked to reduce red tape and aimed to protect retail investors.