Some investors may ask, since securities investment funds also invest in stocks and bonds, why don't we buy and sell directly in the stock and bond markets, but invest in funds and "indirectly invest" in related securities through the intermediary of fund management companies? This involves the role of fund management companies. The function of fund management companies is that, as experts, they can pool investors' idle funds and make investment decisions according to the scientific portfolio principle, which truly embodies the biggest feature of securities investment funds-expert financial management. The role of fund management companies is first determined by their "innate development". According to the relevant regulations, when a fund management company is established, it must be equipped with a high-quality fund manager with rich securities experience, a clear and feasible fund management plan and a scientific division of labor. At the same time, they must also establish and improve the internal management system and equip them with advanced technical facilities, so as to lay a solid foundation for their effective management and use of fund assets in the future. The role of fund management companies is mainly reflected in the process of effectively using fund assets for securities investment. Researchers and analysts of fund management companies can collect detailed information from the international and domestic macroeconomic situation to the specific operating conditions of listed companies in time for fund managers to refer to when making investment decisions. Fund managers use their rich knowledge and experience in investment analysis and portfolio management to buy and sell stocks and bonds in a planned way, thus increasing investors' wealth. The fund management company has set up a supervision and audit department to regularly check the internal work of the fund manager's investment decision-making, so as to reduce the risks in the fund operation. Fund managers should also hold regular investment review meetings to discuss the gains and losses of investment decisions made, sum up experiences and lessons, and serve future work. In addition, fund managers should regularly publish information such as fund net asset value and price, fund investment portfolio and fund financial report, so as to increase the transparency of fund management and operation and facilitate investors to buy and sell funds. Finally, externally, the fund management company should also accept the supervision of the fund custodian bank to see whether it has followed the relevant provisions of the fund contract and custody agreement, and whether it has really managed and used the fund assets honestly and diligently.