At no time shall the total obligations of the corporation exceed ten times the amount of paid-in capital and surplus, not including therein the earned surplus. This limitation shall not apply with respect to that portion of the corporation’s obligations incurred with respect to assets or investments to the extent that they are secured or covered by guaranties or by commitments or agreements to take over, or purchase, made by the United States of America, or by any department, bureau, agency, board, commission or establishment of the United States including any corporation, wholly owned, directly or indirectly, by the United States, pursuant to the authority of an act of Congress heretofore or hereafter adopted or amended or pursuant to the authority of any executive order of the President of the United States heretofore or hereafter made or amended under the authority of any act of Congress, heretofore or hereafter adopted or amended.