Any national or state chartered bank, or trust company, authorized to do business in this state shall be exempt from the provisions of this chapter; provided, however, that no national or state bank or trust company shall purchase agricultural lands in South Dakota through a pooled investment fund formed from assets from retirement, pension, profit sharing, stock bonds or other trusts. Source: SL 1974, ch 294 , § 9; SL 1977, ch 383 .