Vietcombank sold the dollar at VND24,730 Tuesday, up 0.02% from Monday.
The State Bank of Vietnam lowered its reference rate by 0.04% to VND24,087.
The dollar was kept stable at VND24,600 on the black market.
It has increased over the dong by 4.21% since the beginning of the year.
Globally, the yen weakened on Tuesday after the Bank of Japan (BOJ) stuck to its dovish stance in a keenly-awaited policy decision, disappointing speculators who had expected the central bank to start tightening its ultra-loose monetary policy settings, Reuters reported.
That sent the yen sliding nearly 0.7% against the dollar, past the 150 per dollar threshold to hit an intraday low of 150.12, before steadying to 149.93 per dollar.
The euro similarly jumped roughly 0.5% against the yen following the decision. The single currency last bought 158.87 yen.