Notwithstanding any other provision of law, any national banking association may, with the approval of the Comptroller of the Currency and by vote of shareholders owning a majority of the stock of such association, upon not less than five days’ notice, given by registered mail or by certified mail pursuant to action taken by its board of directors, issue preferred stock of one or more classes, in such amount and with such par value as shall be approved by said Comptroller, and make such amendments to its articles of association as may be necessary for this purpose; but, in the case of any newly organized national banking association which has not yet issued common stock, the requireme