Nuveen California Municipal Market Opportunity Fund, Inc. (the Fund) is a closed-end management investment company. The Fund seeks to provide current income exempt from both regular federal and California state income taxes by investing primarily in a portfolio of municipal obligations issued by state and local government authorities within the state of California or certain United States territories. It invests primarily in tax-exempt California municipal obligations rated within the four highest grades (Baa/BBB or better). Up to 20% of the Fund's assets may be invested in unrated municipal bonds that are considered to be of comparable quality. The Fund is authorized to invest in inverse floating-rate securities and zero coupon securities. It invests in sectors, such as transportation, water and sewer, healthcare and others. The Fund's investment advisor is Nuveen Asset Management, a wholly owned subsidiary of Nuveen Investments, Inc.