The Nuveen Select Tax-Free Income Portfolio (NXP) is a mutual fund that focuses on providing tax-free income to its investors. It invests in a variety of tax-exempt bonds, such as municipal bonds, to generate income that is not subject to federal income tax. This fund is managed by Nuveen, a leading investment management firm, and aims to provide a steady stream of tax-free income while also preserving capital for its investors. With a diverse portfolio of tax-free bonds, the Nuveen Select Tax-Free Income Portfolio offers a potential solution for investors looking to minimize their tax burden while still earning income from their investments.