S.D. Codified Laws § 60-13-2

No rule of law against perpetuities or suspension of the power of alienation of the title to property may operate to invalidate any trust created or attempted to be created, prior to July 1, 1955, by an employer as part of a stock bonus, pension, disability, death benefit, insurance, endowment, annuity or profit sharing plan for the benefit of some or all of the employer's employees to which contributions are made by the employer or employees, or both, for the purpose of distributing to the employees earnings or principal, or both earnings and principal of the fund held in trust.