Abstract: The stock market downturn, small and medium investors suffered heavy This departure from this phenomenon of the tragic status of medium and small shareholders come to a concrete analysis of the situation first, five of China's stock market is not perfect, government supervision is not enough, and second, the value of the capital, three medium and small investors errors, four is the market risk, 5 the unreasonable pricing of stock issuance, distribution prices are generally too high, the stock issue price and the value of a serious departure small and medium investors; fiduciary duty; government regulation; economic fundamentals; issue price