The American Century High-Yield Municipal Fund - I Class (AYMIX) is a mutual fund that primarily invests in high-yield municipal bonds issued by state and local governments. These bonds typically offer higher yields than investment-grade municipal bonds, but also carry a higher risk of default. The fund aims to provide investors with a steady stream of tax-free income while also seeking to preserve capital. As an "I Class" fund, it may have a higher minimum investment requirement and lower fees compared to other share classes of the same fund.