S.D. Codified Laws § 55-1A-9

A trustee may invest and reinvest trust assets in any property or in an undivided interest in any property, wherever located, including bonds, debentures, secured or unsecured notes, preferred or common stock of corporations, real estate or improvements thereon or any interest therein, oil and mineral leases or royalty or similar interests, and interests in trusts including investment trusts and common trust funds maintained by a corporate trustee and any affiliated investments as defined in § 55-1A-9.1. Any such investments may be made, regardless of any lack of diversification.