SDCL § 47-1A-627: Restriction on transfer of shares or registration of transfer of shares in articles, bylaws, or agreements--Effect on shares.

The articles of incorporation, bylaws, an agreement among shareholders, or an agreement between shareholders and the corporation may impose restrictions on the transfer or registration of transfer of shares of the corporation. A restriction does not affect shares issued before the restriction was adopted unless the holders of the shares are parties to the restriction agreement or voted in favor of the restriction.