Colo. Rev. Stat. § 15-1-308
In the absence of an express provision to the contrary, any fiduciary is authorized, whenever a governing instrument or order requires or permits investment in United States government obligations which are backed by the full faith and credit of the United States government, to invest in such obligations, either directly or in the form of the securities of or other interests in any open-end or closed-end management type investment company or investment trust registered under the federal "Investment Company Act of 1940", 1 5 U.S.C. sec. 80(a)-1 et seq., if the portfolio of such investment company or investment trust is limited to United States government obligations which are backed by the full faith and credit of the United States government and to repurchase agreements fully collateralized by such obligations and if any such investment company or investment trust actually takes delivery of such collateral, either directly or through an authorized custodian.
C.R.S. § 15-1-308