STOCK COOPERATIVE. A corporation formed or availed of primarily for the purpose of holding title to, either in fee simple or for a term of years, improved real property, if all or substantially all of the shareholders of such corporation receive a right of exclusive occupancy in a portion of the real property, title to which is held by the corporation, which right of occupancy is transferable only con-currently with the transfer of the share or shares of stock in the corporation held by the person having such right of occupancy.