Vietcombank sold the dollar at VND24,720, down 0.2% from the weekend.
At unofficial exchange points, the greenback rose 0.04% to VND25,080.
The State Bank of Vietnam lowered its reference rate by 0.05% to VND24,134.
The dollar has risen against the dong by 1.23% since the beginning of the year.
Globally, the dollar drooped on Wednesday after weak U.S. macroeconomic data overnight boosted the case for a second super-sized interest rate cut at the Federal Reserve's next meeting, Reuters reported.
The yen retreated about 0.17% to 143.47 per dollar, reversing earlier gains amid broad dollar weakness.
The euro ticked up to $1.11915 after earlier pushing as far as $1.1194 for the first time in a month.