 First Trust Advisors LP lowered its holdings in shares of BlackRock MuniHolding Insured Investm NYSE:MFL by 7.0 during the 4th quarter, Holdings Channel.com reports. The firm owned 48,036 shares of the investment management companys stock after selling 3,605 shares during the quarter. First Trust Advisors LPs holdings in BlackRock MuniHolding Insured Investm were worth 638,000 ... 