Securities are all kinds of economic rights and interests certificates, and also refer to specialized products. It is a legal document used to prove that the holder enjoys certain rights. Securities investment fund: it is a collective securities investment model with portfolio investment, professional management, benefit sharing and risk sharing, that is, by issuing fund shares, investors' funds are concentrated, managed by fund custodians, and fund managers manage and use funds to invest in financial instruments such as stocks and bonds. It is an indirect investment tool for the public and an important financial intermediary.