The daily reference exchange rate was at 23,138 VND per USD on June 4 (Photo: VNA) Hanoi (VNA) - The State Bank of Vietnam set the daily reference exchange rate at 23,138 VND per USD on June 4, up 7 VND from the previous day. With the current trading band of +/- 3 percent, the ceiling rate applied to commercial bank during the day is 23,832 VND/USD and the floor rate 22,443 VND/USD. The rates listed at commercial banks saw slight rises. At 8:20 am, Vietcombank listed the buying rate at 22,920 VND/USD and the selling rate at 23,150 VND/USD, both up 10 VND from June 3. BIDV raised both rates by 5 VND to 22,945 (buying)