The change of the index is caused by the overall change of the stock market, so the fundamental reason for the rise of the stock market is that the stock market is rising as a whole, and its influencing factors are generally national policies or economic situation.

Stock index generally refers to the stock price index (an indicator describing the overall price level change of the stock market)

Stock index is an index that describes the changes of the overall price level of the stock market. It is to select a group of representative stocks, weight and average their prices, and get them through certain calculation. The specific stock selection and calculation methods of various indexes are different.

20 15 1 19 Due to the supervision of two financial institutions, except Hongyuan Securities, stocks in the brokerage sector fell across the board. In terms of individual stocks, Founder Securities, Shaanxi Securities, Guohai Securities, Guo Jin Securities, Northeast Securities, CITIC Securities and China Merchants Securities 19 shares collectively fell. The Shanghai Composite Index plunged 7.7%, the biggest one-day drop in seven years.

The Shanghai Composite Index is referred to as the "Shanghai Composite Index" for short, and its sample stocks are all listed stocks, including A shares and B shares, reflecting the changes in the prices of listed stocks on the Shanghai Stock Exchange. It was officially released on July 199 15.