Sec. 4. (a) Any balance in the operations fund may be invested in the manner provided for investment of money by a political subdivision. The net proceeds from the investment become a part of the operations fund.
(b) Any balance, or a part of the balance, remaining in the operations fund at the end of a year may be:
(1) retained in the operations fund; or
(2) transferred to the school corporation's rainy day fund.