Nuveen Select TaxFree Income Portfolio is a closedended fixed income mutual fund launched by Nuveen Investments Inc The fund is comanaged by Nuveen Fund Advisors LLC and Nuveen Asset Management LLC It invests in the fixed income markets of United States The fund invests in the investmentgrade municipal securities rated Baa and BBB or better It benchmarks the performance of its portfolio against the Standard Poors SP National Municipal Bond Index and Lipper General and Insured Unleveraged Municipal Debt Funds Average Nuveen Select TaxFree Income Portfolio was formed on March 19 1992 and is domiciled in the United States