The governing board of a school district which has placed funds in the Foundation Fund is hereby authorized to invest all or any part of those funds as it deems wise and expedient as follows:
(a) In the securities, warrants, or instruments of indebtedness specified by Section 53601 of the Government Code.
(b) In corporate securities other than corporate shares, provided that the amount of investment under this subdivision shall not exceed 50 percent of the amount invested under subdivision (a).
Any security, warrant, or instrument of indebtedness purchased pursuant to this section may be sold and the proceeds reinvested in similar securities, warrants, or instruments, or placed in the Foundation Fund.