Stock index funds are index funds. You can buy it by opening a stock account, or you can buy ETF-linked funds in brokers and banks. Generally speaking, stock index funds can consider the following factors:

1, fund rate: the rate of index funds is relatively low, but there are still differences between different index funds before. Without considering other factors, choose index funds with low rates;

2. Tracking error: index funds generally choose smaller tracking error, and the smaller the tracking error, the closer it is to the index;

3. Fund size: The larger the fund size, the more difficult it is for fund managers to manage, and the smaller the fund size, the greater the risk of liquidation.