The minimum investment amount required by American Century Investments can vary depending on the specific fund and type of account. Generally, many of their mutual funds have a minimum initial investment requirement ranging from one thousand to three thousand dollars. However, certain funds may offer lower minimums, especially for retirement accounts, where the initial investment can be as low as five hundred dollars. Additionally, American Century may have specific minimums for subsequent investments. It is important to check the details for each fund as they can provide specific information regarding the investment options. For the most accurate and up-to-date information, it is recommended to visit their official website or consult the fund prospectus, which outlines the necessary investment amounts and other key details.