an account balance greater than zero, upon receipt of notification of such individual’s death, the Executive Director shall close the account and shall transfer the balance in such account to the AO account of such account holder’s surviving spouse or, if there is no such account of a surviving spouse, to the duly appointed legal representative of the estate of the deceased account holder, or if there is no such representative, to the person or persons determined to be entitled thereto under the laws of the domicile of the deceased account holder. 6. Rules governing AO accounts relating to investment, accounting, and reporting (a) Investment program (1) In general The American Opportunity Fund Board shall invest amounts in the American Opportunity Fund in securities of the United States Government issued as provided in paragraph (2). (2) Securities (A) In general The Secretary of the Treasury is authorized to issue special interest-bearing obligations of the United States for purchase by the American Opportunity Fund. (B) Investment (i) Obligations issued for the purpose of this paragraph shall have maturities fixed with due regard to the needs of the American Opportunity Fund as determined by the Executive Director, and shall bear interest at a rate equal to the average market yield (computed by the Secretary of the Treasury on the basis of market quotations as of the end of the calendar month next preceding the date of issue of such obligations) on all marketable interest-bearing obligations of the United States then forming a part of the public debt which are not due or callable earlier than 10 years after the end of such calendar month. (ii) Any average market yield computed under clause (i) which is not a multiple of one-eighth of 1 percent, shall be rounded to the nearest multiple of one-eighth of 1 percent. (b) Independent public accountant (1) In general Under regulations which shall be prescribed by the Executive Director, and subject to the provisions of this title, section 8439(b) of title 5, United