1. The board of trustees shall be the trustees of all the funds of the system and shall have full power to invest and reinvest such funds, and such trustees shall have full power to hold, purchase, sell, assign, transfer or dispose of any of the securities and investments in which such funds shall have been invested, as well as of the proceeds of such investments and any moneys belonging to such funds.

2. The board of trustees shall annually credit each member’s individual account with interest on the largest balance remaining in each account for the entire year and at the rate determined by the board.

3. The board of trustees may employ a bank having fiduciary powers for the provision of such custodial or clerical services as the board may deem appropriate. Disbursement of funds of the retirement system shall be under the general supervision of the board of trustees and shall be in accordance with procedures established or approved by the board of trustees with the concurrence of the system’s auditors.

4. For the purpose of meeting disbursements for pensions and other payments, there may be kept available cash on deposit in one or more banks or trust companies in the school district, organized under the laws of the state of Missouri, or of the United States; provided, that the amount on deposit in any one bank or trust company shall not exceed twenty-five percent of the paid-up capital and surplus of such bank or trust company, and for all deposits the board of trustees shall require of the banks or trust companies as security for the safekeeping and payment of the deposits securities of a like kind and character as may be required by law for the safekeeping and payment of deposits made by the state treasurer.

5. Except as herein provided, no trustee, member of the board of education or employee of either the board of trustees or the board of education shall have any direct interest in the gains or profits of any investment made by the board of trustees. Nor shall any of them directly or indirectly for himself or as an agent in any manner use the assets of the retirement system except to make such current and necessary payments as are authorized by the board of trustees, nor shall any of said persons become an endorser or surety or become in any manner an obligor for moneys loaned by or borrowed from the board of trustees.

6. No member of the board of education shall be interested in any contract with or claim against the public school retirement system in his school district. If at any time after the election of any member of the board he becomes interested in any contract or claim against said retirement system, either directly or indirectly, or as agent or employee of any individual, firm or corporation, which is so interested, he shall thereupon be disqualified to continue as a member of the board.