In towns which have chosen a single trustee of trust funds such funds shall be invested only by deposit in any federally insured bank authorized to accept deposits under N.H. Rev. Stat. § 6:8, I and I-a, or in state, county, town, city, school district, water and sewer district bonds and the notes of towns or cities in this state and when so invested the trustee shall not be liable for the loss thereof; and in any common trust fund established by the New Hampshire Charitable Foundation in accordance with N.H. Rev. Stat. § 292:23; or in obligations fully guaranteed as to principal and interest by the United States government. The obligations may be held directly or in the form of securities of or other interests in any open-end or closed-end management-type investment company or investment trust registered under 15 U.S.C. § 80a-1 et seq., if the portfolio of the investment company or investment trust is limited to such obligations and repurchase agreements fully collateralized by such obligations. Deposits in a federally insured bank shall be made in the name of the town which holds the same as a trust, and it shall appear upon the books thereof as a trust fund. Any person who directly or indirectly receives any such trust funds for deposit or for investment in securities of any kind shall, prior to acceptance of such funds, make available at the time of such deposit or investment an option to have such funds secured by collateral having value at least equal to the amount of such funds. Such collateral shall be segregated for the exclusive benefit of the town depositing or investing such funds. Only securities defined by the bank commissioner as provided by rules adopted pursuant to N.H. Rev. Stat. § 383-B:3-301(e) shall be eligible to be pledged as collateral. The trustee may retain investments as received from donors until the maturity thereof.