12 U.S.C. § 83: Loans by bank on its own stock

(a) General prohibitionNo national bank shall make any loan or discount on the security of the shares of its own capital stock. (b) ExclusionFor purposes of this section, a national bank shall not be deemed to be making a loan or discount on the security of the shares of its own capital stock if it acquires the stock to prevent loss upon a debt previously contracted for in good faith.