S.D. Codified Laws § 47-1A-120.2
If a provision of a filed document is made dependent on a fact ascertainable outside of the filed document, and that fact is not ascertainable by reference to a source described in subsection 47-1A-120.1(2)(a) or a document that is a matter of public record, or the affected shareholders have not received notice of the fact from the corporation, the corporation shall file with the Office of the Secretary of State articles of amendment setting forth the fact promptly after the time when the fact referred to is first ascertainable or thereafter changes. Articles of amendment under this section are deemed to be authorized by the authorization of the original filed document or plan to which they relate and may be filed by the corporation without further action by the board of directors or the shareholders.
SDCL 47-1A-120.2