The main reason is that the shares of stocks or closed-end funds are fixed, unless dividends are distributed. In the secondary market, no matter which shareholder is sold to which shareholder, no matter how the price of the fund changes, his total share capital remains unchanged.

Open-end funds are different. Their total shares are not fixed. For example, when an open-end fund was first raised, its total share capital was 2 million. If it operates well and many people subscribe, its total share capital will become 3 million or even more. If the business is not good, it will encounter a large redemption. The total shares are getting less and less until the listing is suspended.

For this reason, stocks are bought and sold, while open-end funds are subscribed, purchased and redeemed.