Ala. Code § 23-1-315
Any funds held as the proceeds of obligations issued by the authority under this article and any funds held by the State Treasurer in the sinking fund provided for the payment of such obligations shall be invested in obligations of the United States of America or in certificates of deposit secured by a deposit of obligations of the United States of America to the full amount of such certificates of deposit, and in investment agreements, repurchase agreements, or other investment arrangements fully collateralized by any of the foregoing, and the interest to be earned on such investment of funds may be pledged by the authority to the payment of the principal of and interest on the obligations issued by the authority under this article.
Ala. Code § 23-1-315 (1975)