; (B) paid-in share capital, paid in cash; and (C) the United States Treasury, as on-call subscriber to the Bank, in an amount up to $100,000,000,000 in 30-year United States Treasury Bonds. (3) Limitation The Bank shall not purchase public debt of the United States, as newly issued, except for the purpose of rolling over the existing Treasury holdings of the Bank. (c) Preferred stock (1) In general All subscribed capital shall be exchanged for an equivalent in preferred stock, or shares, in the Bank, callable only by the Bank during a period of 20 years following finalization of a stock purchase agreement. Notwithstanding any other provision of law, a guarantee of redemption, to be included in the stock purchase agreement, shall impose upon the United States a contractual obligation to fund the redemption. Preferred shareholders shall have no voting rights in the Bank. (2) Dividends on preferred stock The Bank shall pay dividends, semiannually, at a rate of 2 percent per annum plus the annual rate of the Treasury security exchanged for the stock or 2 percent per annum for paid-in capital. The stock purchase agreement shall impose upon the United States a contractual obligation to fund the 2 percent portion of the dividend payment. (d) Borrowed capital The Bank is further authorized to raise medium- to long-term, borrowed capital for projects needs, and short-term capital to meet its cash flow needs, by, respectively— (1) issuing Bonds, with a fixed 5 to 10 year maturity