Vietcombank sold the dollar at VND25,506, down 0.01% from the weekend.
At unofficial exchange points, the greenback rose 0.35% to VND25,840.
The State Bank of Vietnam raised its reference rate by 0.01% to VND24,292.
The dollar has risen against the dong by 4.45% in the year to date.
Globally, the dollar retreated against rivals on Monday as bond yields slid following the selection of fund manager Scott Bessent as the next U.S. Treasury secretary, with investors expecting he will be a voice for markets in Washington, Reuters reported.
The dollar dropped 0.7% against the yen and 0.6% versus the euro as traders snapped up Treasuries, sending the benchmark U.S. long-term yield down some 7 basis points to as low as 4.341% on Monday.
The yen last stood at 153.76 per dollar. The currency pair tends to closely follow moves in Treasury yields.
The euro changed hands at $1.0477, rebounding from Friday's two-year trough at $1.03315.
Sterling climbed 0.5% to $1.2592. On Friday, it slumped to the weakest since early May at $1.2475.