Select some stocks in the GEM as samples to calculate, generally choose high-quality and representative ones, and because the performance of each company is changing, it is a sample adjustment of the GEM index.

First, the index effect refers to the abnormal reaction in terms of price and trading volume when the index constituent stocks are adjusted. To put it simply, when the index is transferred to the stock, the stock price rises and the trading volume rises; For the stocks transferred by the index, the share price fell and the trading volume increased. This has certain guiding significance for investors and friends in practice. Index funds are passive investment funds. According to the composition of the securities index, it copies and tracks the benchmark index by means of indexed investment, so that the fund's own income is basically the same as that of the benchmark index.

Second, simply put, index funds take sample stocks of the index as investment targets. When a stock is transferred out or transferred in by the index, many institutional investors such as funds, futures and options with the index as the investment target have to readjust their investment portfolios to keep the tracking error to a minimum, hold new shares and lighten their positions to sell the transferred shares. Because these institutional investors have strong financial strength, their trading operations will have an impact on the original stock prices of these stocks in a very short time, making the stock prices fluctuate abnormally.

3. At present, there are over 1 000 index funds in China's market, with a total scale of over 900 billion yuan, including 475 passive index funds. With the growing ranks of index funds in China, the index effect deserves every investor's attention. Of course, the exchange of sample stocks by index funds will not happen overnight, and there will be a window period, which is possible within a few weeks from the announcement to the implementation. Interested partners can choose the target and focus on tracking.

It is a normal operation to adjust the sample stocks of the index. For example, the sample stocks of the famous Dow Jones Industrial Average will also change due to the market environment, and the proportion of individual stocks will be adjusted.