Colo. Rev. Stat. § 40-2-102
Each commissioner, before entering upon the duties of his office, shall take the constitutional oath of office. No person in the employ of or holding any official relation to any corporation or person, which said corporation or person is subject in whole or in part to regulation by the commission, and no person owning stocks or bonds of any such corporation or who is in any manner pecuniarily interested therein shall be appointed to or hold the office of commissioner or be appointed or employed by the commission; but if any such person becomes the owner of such stocks or bonds or becomes pecuniarily interested in such corporation otherwise than voluntarily, he shall divest himself of such ownership or interest within six months; failing to do so, his office or employment shall become vacant.
C.R.S. § 40-2-102
For the oath of office, see § 8 of article XII of the Colorado Constitution.