 Moodys Investors Service, Moodys has assigned a Aa3 rating to new preferred securities issued by Nuveen Municipal Credit Opportunities Fund ticker: NMCO, a closed-end fund registered under the Investment Company Act of 1940 with approximately 835 million of net assets under management. NMCOs primary investment objective is to provide a high level of current income exempt from regular U.S. federal income tax. The fund seeks to achieve its investment objectives by investing primarily in high yielding, low- to medium-quality municipal securities. 