Colo. Rev. Stat. § 32-4-544
It shall be legal for any bank, trust company, banker, savings bank, or banking institution; any building and loan association, savings and loan association, or investment company; any other person carrying on a banking or investment business; any insurance company, insurance association, or other person carrying on an insurance business; and any executor, administrator, curator, trustee, or other fiduciary to invest funds or moneys in their custody in any of the securities authorized to be issued pursuant to the provisions of this part 5. Public entities, as defined in section 24-75-601 (1), C.R.S., may invest public funds in such bonds only if said bonds satisfy the investment requirements established in part 6 of article 75 of title 24, C.R.S. Such securities shall be authorized security for all public deposits. Nothing in this section with regard to legal investments shall be construed as relieving any public body or other person of any duty of exercising reasonable care in selecting securities.
C.R.S. § 32-4-544