Any bank holding company owned by a charitable trust that sells, assigns, merges, or transfers the stock of any bank or bank holding company pursuant to this chapter shall communicate to and offer to purchase the stock of any minority stockholder of the bank or bank holding company. The offer must be made to minority stockholders at least sixty days before the date of the sale and must extend thirty days after the sale of the bank or bank holding company. The offer must remain open for at least ninety days or for the same period as that which is offered to minority stockholders of the company’s banks located in other states, whichever period is greater. The offer to purchase minority stock in banks in this state must be based on at least the same criteria, standards, and formula as may be used by the bank holding company in computing an offer to purchase the minority stock of its banks in other states. The resulting offer to purchase must be on the same or better terms as any previous offer made by the bank holding company except for those previous offers made by reason of repurchase options between the bank holding company and the stockholder. Such repurchase options may not be used as a basis for determining the offer to purchase other minority stock.