S.D. Codified Laws § 47-1A-863.1
Quorum of qualified shareholders
A majority of the votes entitled to be cast by the holders of all qualified shares constitutes a quorum for purposes of action that complies with § 47-1A-863 . Subject to the provisions of §§ 47-1A-863.2 and 47-1A-863.3 , shareholders' action that otherwise complies with § 47-1A-863 is not affected by the presence of holders, or the voting, of shares that are not qualified shares.
Source: SL 2005, ch 239, § 191.