The PIMCO Mortgage-Backed Securities Fund Class I-3 (PSANX) is a mutual fund that primarily invests in mortgage-backed securities, which are bonds that are backed by a pool of mortgages. This fund is managed by PIMCO, a global investment management firm known for its expertise in fixed income investments. The Class I-3 shares of this fund are designed for institutional investors and have a lower expense ratio compared to other share classes. This fund aims to provide investors with a steady stream of income through its investments in mortgage-backed securities, while also seeking to preserve capital and achieve long-term growth.