The State Board of Education may account for the exchange of permanent school fund securities in a closely related sale and purchase transaction in a manner in which the gain or loss on the sale is deferred as an adjustment to the book value of the security purchased, if:
(1) the security sold and the security purchased have a fixed maturity value;
(2) the board is authorized by law to invest the permanent school fund in the security purchased;
(3) the sale is made in clear contemplation of reinvesting substantially all of the proceeds;
(4) substantially all of the proceeds are reinvested;
(5) the transaction is completed within a reasonable time after the sale, not to exceed 30 business days; and
(6) the transaction results in an improvement in effective income yield, taking into consideration the deferral of any gain or loss on the sale.