Nuveen Select Tax-Free Income Portfolio is a US-based company operating in industry. The company is headquartered in Chicago, Illinois. Nuveen Select Tax-Free Income Portfolio (the Fund) is a diversified closed-end management investment company. The Fund’s investment objective is to provide current income exempt from regular federal income tax, consistent with preservation of capital. The Fund will invest at least 80% of its Assets in municipal securities and other related investments, the income from which is exempt from regular federal income tax and federal alternative minimum tax. The Fund may invest up to 20% of its Managed Assets in municipal securities that at the time of investment are rated below investment grade or are unrated. The company may invest up to 15% of its Managed Assets in inverse floating rate securities. The Fund may invest up to 10% of its Managed Assets in securities of other open-or closed-end investment companies (including ETFs) that invest primarily in municipal securities of the types in which the Fund may invest directly. The Fund's investment advisor is Nuveen Fund Advisors, LLC.