S.D. Codified Laws § 58-6-9
Any mutual and stock insurer authorized on July 1, 1966, to transact insurance in this state shall be eligible to continue such authorization if otherwise in compliance with this title and its charter provisions. As to any such domestic insurer, each holder of a policy of insurance who is entitled to participate in profits and savings, shall be entitled to participate and vote at all meetings of stockholders and to cast the same number of votes which he was entitled to cast under the articles of incorporation and bylaws of such insurer on July 1, 1966. At all such meetings, to constitute a quorum of such participating policyholders, there shall be present in person or by proxy at least ten percent of the total of such participating policyholders. Solicitation of proxies from such participating policyholders shall be subject to the same regulations and restrictions as apply to a domestic mutual insurer. Except as hereinbefore otherwise provided, such an insurer shall in all respects be subject to all laws regulating stock companies.
Any mutual and stock company authorized and doing business pursuant to this section may issue nonvoting participating policies. The issuance of such nonvoting participating policies may not affect the voting rights of holders of participating policies issued by a mutual and stock company pursuant to the first paragraph of this section.
SDCL 58-6-9