The Shanghai Stock Exchange Index is a weighted composite stock price index calculated using the Paasche formula, with the number of shares issued during the reporting period as the weight. Among them, the CSI 300 is the most representative and widely used. The calculation method is as follows:

Total market value = ∑ (market price × number of shares issued);

Reporting period index = (Adjusted market value of constituent stocks in the reporting period / Adjusted market value of constituent stocks on the base day) × 1000;

Adjusted market value = ∑ (market price × adjusted number of shares). The adjusted market value of constituent stocks on the base day is also called the divisor. The adjusted number of shares is determined using a tiered approach to adjust the share capital of constituent stocks.

(I) Adjustment Formula

The Shanghai Stock Exchange Index series uses the "divisor adjustment method" for adjustments. When the list of constituent stocks changes, the capital structure of constituent stocks changes, or the market value of constituent stocks changes due to non-trading factors, the "divisor adjustment method" is used to adjust the original fixed divisor to ensure the continuity of the index. The adjustment formula is:

Adjusted market value before adjustment / Original divisor = Adjusted market value after adjustment / New divisor

Here, the adjusted market value after adjustment = Adjusted market value before adjustment + Newly added (or subtracted) market value.

This formula yields the new divisor (i.e., the adjusted divisor, also called the new base period), which is then used to calculate the index going forward.

(II) Situations Requiring Adjustments

1. New listings. For composite indices (SSE Composite Index and New SSE Composite Index) and sector indices (A-share Index, B-share Index, and industry classification indices), newly listed constituent securities are included in the index on the 11th trading day after listing.

2. Ex-dividend. When a constituent stock goes ex-dividend (distributes dividends), the index is not adjusted and is allowed to naturally decline.

3. Ex-rights. When a constituent stock issues bonus shares or rights offerings, the index is adjusted before the ex-rights date of the constituent stock.

Adjusted market value = Ex-rights price × Number of shares after ex-rights + Adjusted market value before adjustment (excluding the ex-rights stock).

4. Exchange rate changes. On the last trading day of each week, the index is adjusted based on the RMB/USD central parity rate published by the China Foreign Exchange Trade System on that day.

5. Trading suspension. When a constituent stock is suspended from trading, its last normal closing price is used to calculate the index.

6. Delisting. When a constituent stock is delisted (trading is terminated), the index is adjusted before the delisting date.

7. Share capital changes. When other share capital changes occur for a constituent stock (e.g., an increase in tradable shares due to a new share issuance), the index is adjusted before the share capital change date.

Adjusted market value = Closing price × Adjusted number of shares + Adjusted market value before adjustment (excluding the affected stock).

8. Market suspension. When part of the A-share or B-share market is suspended, the index is calculated as usual. When the entire A-share and B-share markets are suspended, index calculation is halted.