Haw. Rev. Stat. § 39-69: Investment of reserves, etc.

The director of finance, with the approval of the department, may invest any money held as reserves or in sinking funds or not required for immediate disbursement, including proceeds of the revenue bonds, which in the department's judgment are in excess of the amounts necessary for the meeting of immediate requirements, in securities permitted by the resolution or certificate and which constitute legal investments for public funds. Income derived therefrom shall be treated as revenue of the undertaking or loan program; expenses of purchase, safekeeping, sale, and redemption, and all other expenses attributable to the investments shall be proper expenses of the undertaking or loan program. Securities so purchased shall be considered as being deposited in the custody or control of the director of finance by the department, and shall be legally secured as provided in section 38-3.