It fell 0.47% to VND24,615 at unofficial exchange points.
Most banks kept the rate unchanged. Vietcombank sold the dollar at VND24,240, same as Friday.
Eximbank sold the greenback at VND24,330.
But Techcombank lowered the rate down 0.53% to VND24,290.
The State Bank of Vietnam (SBV)’s reference rate is at VND23,660, down 0.01%.
The dollar has gained over the dong by 5.76% since the beginning of the year.
The U.S. Dollar Index, which measures the greenback’s strength against major currencies, continued its fall to 104.51 points, lowest since the end of June.