Vietcombank sold the dollar at VND24,420, down 0.25% from Wednesday.
The State Bank of Vietnam raised its reference rate by 0.08% to VND23,904.
The dollar fell 0.20% to VND24,770 on the black market.
It has gained over the dong by 2.91% since the beginning of the year.
The dollar fell across the board on Thursday with the Japanese yen, euro, and pound all at their strongest against the greenback in five months as bets the Federal Reserve will cut rates sharply in 2024 continued to drive markets, Reuters reported.
The dollar index, which measures the U.S. currency against six rivals, fell to a fresh five-month low of 100.76. The index is on course for a 2.6% decline this year, snapping two straight years of strong gains.