(a) A Massachusetts trust is an unincorporated business association created at common law by an instrument under which property is held and managed by trustees for the benefit and profit of such persons as may be or may become the holders of transferable certificates evidencing beneficial interests in the trust estate, the holders of which certificates are entitled to the same limitation of personal liability extended to stockholders of private corporations.
(b) Nothing contained in this chapter shall be construed or held to authorize the levy of any tax on earnings or distributions from an investment fund organized as a unit investment trust taxable as a grantor trust under 26 U.S.C. §§ 671-677 (whether or not such trust would otherwise constitute a business trust); provided, that not less than seventy-five percent (75%) of the value of the investments of such investment fund shall be in any combination of bonds of the United States, state of Tennessee, or any county or any municipality or political subdivision of the state, including any agency, board, authority, or commission of the state or its subdivisions.