The State Treasurer is the custodian of: the accumulation, annuity savings, and expense funds of the several systems; and the assets of the Board of Trustees. The State Retirement Agency shall make all payments from the accumulation, annuity savings, and expense funds of the several systems in accordance with regulations that the Board of Trustees adopts with the approval of the State Treasurer. The State Treasurer may make arrangements with one or more duly qualified banks or trust companies in this State, organized under the laws of this State or of the United States, for: banking services; and any other function that the State Treasurer considers necessary to safeguard physically the assets that the Board of Trustees manages. The State Treasurer: may deposit any of the securities that the Board of Trustees purchases in vaults or in other safe depositories outside the office of the State Treasurer, whether or not in this State; and shall deliver to the Board of Trustees a safekeeping receipt that: describes the securities that the State Treasurer deposits; and is payable on demand and without conditions to the Board of Trustees, to any designated fund of the several systems that the Board of Trustees controls, or to the State Treasurer. The Board of Trustees shall keep on file any safekeeping receipt that the State Treasurer delivers. Subject to paragraph (2) of this subsection, to make disbursements, the State Treasurer may keep cash on deposit in one or more duly qualified banks or trust companies in this State that are organized under the laws of this State or of the United States. The State Treasurer may not: keep more than 10% of the total amount in the funds of the several systems on deposit as cash; or keep cash that exceeds 25% of the paid–up capital and surplus of the bank or trust company in that bank or trust company.