Vietnam\'s five-year bonds rose for a second week as the government continued to lower the coupon at debt auctions. The dong gained. Vietnam\'s State Treasury sold 1.75 trillion dong (Dh312.3 million) of three-year notes at 12.2 per cent on Friday, compared with 12.3 per cent at the previous auction, according to a statement on the Hanoi Stock Exchange\'s website. Demand for the debt has also increased recently due to banks having more cash available, said Hanoi-based Do Thi Phuong Trang, a trader at Bank for Investment and Development of Vietnam. \"When coupon rates in the primary market drop, yields in the secondary market normally also fall,\" Trang said. The dong rose 0.1 per cent last week and from Thursday to 20,575 per dollar in Hanoi on Friday, according to prices from banks.