There are authorized to be appropriated to the Corporation, to remain available until expended, such amounts as may be necessary from time to time to replenish or increase the noncredit account revolving fund, to discharge the liabilities under insurance, reinsurance, or guaranties issued by the Corporation or issued under predecessor guaranty authority, or to discharge obligations of the Corporation purchased by the Secretary of the Treasury pursuant to this subsection. However, no appropriations shall be made to augment the noncredit account revolving fund until the amount of funds in the noncredit account revolving fund is less than $25,000,000. Any appropriations to augment the noncredit account revolving fund shall then only be made either pursuant to specific authorization enacted after August 27, 1974, or to satisfy the full faith and credit provision of section
2197
(c) of this title. In order to discharge liabilities under investment insurance or reinsurance, the Corporation is authorized to issue from time to time for purchase by the Secretary of the Treasury its notes, debentures, bonds, or other obligations; but the aggregate amount of such obligations outstanding at any one time shall not exceed $100,000,000. Any such obligation shall be repaid to the Treasury within one year after the date of issue of such obligation. Any such obligation shall bear interest at a rate determined by the Secretary of the Treasury, taking into consideration the current average market yield on outstanding marketable obligations of the United States of comparable maturities during the month preceding the issuance of any obligation authorized by this subsection. The Secretary of the Treasury shall purchase any obligation of the Corporation issued under this subsection, and for such purchase he may use as a public debt transaction the proceeds of the sale of any securities issued under chapter
31 of title
31 after August 27, 1974. The purpose for which securities may be issued under such chapter shall include any such purchase.