If any part of the capital of a bank consists of preferred stock, the determination of whether or not the capital of such bank is impaired and the amount of such impairment shall be based on the value of its stock as established at the time it was issued, or its par value, if any, even though the amount which the holders of such preferred stock shall be entitled to receive in the event of retirement or liquidation shall be in excess of the originally established value or the par value of such preferred stock.