Mo. Rev. Stat. § 108.210

Whenever the county commission or the governing authorities of any county, city, incorporated town or village, school district, or other political corporation or subdivision of the state shall deem it to be for the best interest of such county, city, incorporated town or village, school district, or other political corporation or subdivision of the state, to sell any bond, note, certificate, or security, so held by it, and to invest the proceeds derived therefrom in other bonds, notes, certificates, or securities authorized by law, they may order their treasurer to make such sale and collect the proceeds therefrom and to invest the same, within the limitations authorized by law, upon such terms and conditions as said county commission or said governing authorities may authorize; provided, that such sale may be ordered without ordering the purchase of any other bonds, notes, certificates or securities.