Umbrella fund, also known as "series fund", is a management model (or organizational structure) of the fund. Under the organizational structure of open-end funds, fund sponsors initiate the establishment of multiple sub-funds according to a general fund prospectus, and each sub-fund makes investment decisions independently. Its main feature is that it can provide investors with a variety of investment options within the fund, and the sub-funds can be converted to each other. Open-end funds include general open-end funds and special open-end funds. After the issuance of listed open-end funds, investors can purchase and redeem fund shares at designated outlets or buy and sell funds on exchanges. However, if investors want to sell the fund shares purchased at designated outlets, they must go through certain transfer custody procedures; Similarly, if you want to redeem the fund shares you bought online on the exchange and redeem them at designated outlets, you must also go through certain transfer custody procedures.