Any bank may subscribe to, invest in, buy, own, and sell the common stock, obligations, and other securities of one or more bank subsidiaries organized under the laws of the State of Nebraska. A bank shall not obligate more than thirty-five percent of its paid-up capital stock, surplus, undivided profits, capital reserves, and capital notes and debentures for such purposes. An additional percentage of its paid-up capital stock, surplus, undivided profits, capital reserves, and capital notes and debentures may be invested with written approval of the director. The subscription, investment, possession, or ownership is not subject to sections 8-148, 8-149, and 8-150.