The stock price index is a statistical relative number of stock prices compiled to measure and reflect the overall price level and change trend of the stock market. Usually, the average stock price or stock market value in the reporting period is compared with the average stock price or stock market value in the selected base period, and the ratio between the two is multiplied by the index value in the base period, which is the stock price index for the reporting period.

When the stock price index rises, it indicates that the average price level of stocks has increased; when the stock price index falls, it indicates that the average price level of stocks decreases; it is a sensitive reflection of the society and politics of the country (or region) where the market is located. , a barometer of economic changes.

On January 19, 2015, due to the supervision of financial institutions and financial institutions, all stocks in the brokerage sector, except Hongyuan Securities, were suspended from trading. In terms of individual stocks, 19 stocks including Founder Securities, Shanxi Securities, Guohai Securities, Guojin Securities, Northeast Securities, CITIC Securities, and China Merchants Securities collectively fell to the limit. The Shanghai Composite Index fell 7.7 points, its largest single-day drop in seven years.

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Calculate index

The following four points are often considered when calculating the stock price average or index:

(1) Sample stocks It must be typical and common. To this end, the selection of samples should comprehensively consider factors such as industry distribution, market influence, stock grade, appropriate quantity, etc.

(2) The calculation method should be highly adaptable and can make corresponding adjustments or corrections to the stock price index in response to the changing stock market conditions, so that the stock index or average has better sensitivity.

(3) There must be scientific calculation basis and means. The caliber of the calculation basis must be unified. Generally, the closing price is used as the basis for calculation. However, as the calculation frequency increases, some calculations are based on hourly prices or even shorter time prices.

(4) The base period should be well balanced and representative.

Baidu Encyclopedia - Stock Price Index