S.D. Codified Laws § 55-4-6
Voting of corporate stock owned by trustee
A trustee owning corporate stock may vote it by proxy, but shall be liable for any loss resulting to the beneficiaries from a failure to use reasonable care in deciding how to vote the stock and in voting it.
Source: SL 1943, ch 308, § 8; SDC Supp 1960, § 59.0508.