Mont. Code Ann. § 17-5-305

The refunding bonds or debentures that may be issued under the provisions of this part must be sold by the board of examiners in a manner that the board considers to be in the best interests of the state. However, if the state holds any bonds or debentures to be refunded by an issue of refunding bonds or debentures as investments of institutional or other funds, the original bonds or debentures may be exchanged for the refunding bonds or debentures if the exchange is authorized by the proper state officers or board.