When an association with preferred capital stock shall purchase the stock or any property or interest, it may discharge the obligation so incurred, wholly or in part, by exchanging for the acquired interest shares of its preferred capital stock to an amount which at par value would equal the fair market value of the stock, property, or interest so purchased, as determined by the board of directors. In that case the transfer to the association of the stock or interest purchased shall be equivalent to payment in cash for the shares of stock issued.