Nuveen Municipal High Income Opportunity Fund is a closed-end fixed income mutual fund launched by Nuveen Investments Inc. The fund is co-managed by Nuveen Fund Advisors LLC and Nuveen Asset Management, LLC. It invests in the fixed income markets of the United States. The fund primarily invests in investment grade tax-exempt municipal securities. The fund was formerly known as Nuveen Municipal High Yield Opportunity Fund. Nuveen Municipal High Income Opportunity Fund was founded in November 19, 2003 and is based in the United States.