To ensure the objectivity and impartiality of the component sample shares, Shenzhen Stock Exchange regularly inspects the performance of the component shares, timely replaces that of the lower performance. Of course, the replacement will not be too frequent, usually January, March and September each year.

According to the basic principles of component index adjustment, in the light of international practice, Shenzhen Stock Exchange has established scientific standards and the method of systematic sample Shares selection, that is, using the standards of primary selection to decide the candidate shares in all the listed companies, and then choose the sample shares from the preliminarily selected sample component shares.

Step One. Determine the shortlist companies. The set standards for shortlist companies include three main areas: listing time, market size, and liquidity.

1. In general, the transaction time should be more than three months.
2. From high to low, list the front listed companies according to the proportion of transaction value to market value (3-month average) and cumulate them, and the selected ones shall be in the 90% coverage.
3. From high to low, list the front listed companies according to the proportion of turnover value to market value (3-month average) and cumulate them, and the selected ones shall be in the 90% coverage.

Step Two. Decide sample shares. After the shortlist companies have been chosen according to the above criteria, the sample shares are determined by the combination of the following factors:

1. transaction market value and turnover amount;
2. industry representativeness and growth potential;
3. financial condition and operating performance (over the past three years);
4. standardized operations in two years.