The three main bodies of securities investment funds (fund investors, fund managers and fund custodians) operate according to the trust relationship. Fund investors, also known as fund share holders or fund beneficiaries, are the subject of rights and obligations to purchase fund shares, become the owner of fund assets and enjoy the right to distribute fund investment income. The promoters or investors' representatives assume the duties of trustees, pool the funds in the hands of investors to form a fund collection, and then entrust the manager with management and the trustee with custody. In the fund operation relationship, the sponsor is the principal or the trustee, and the manager and the custodian are the trustees.