BlackRock Municipal Income Investment Quality Trust (the Trust), formerly BlackRock Insured Municipal Income Investment Trust, is a non-diversified perpetual closed-end management investment company. The trust's investment objective is to provide current income exempt from federal income tax, including the alternative minimum tax and Florida intangible property tax. The Trust invests at least 80% of its assets in municipal bonds exempt from federal income taxes, including the alternative minimum tax. The Trust also invests primarily in municipal bonds that are investment grade quality at the time of investment. The Trust may invest directly in such securities or synthetically through the use of derivatives. The trust invests in sectors, such as county/city/special district/school district, utilities, transportation, health, education, housing and tobacco. BlackRock Advisors, LLC is the Trust's investment advisor. Its sub-advisor is BlackRock Financial Management, Inc.