Vietcombank sold the greenback at VND25,035, up 0.02% from Tuesday.
The greenback increased by 0.31% to VND25,400 on the black market.
The State Bank of Vietnam raised its reference rate by 0.02% to VND24,229.
Since the beginning of the year, the dollar has increased against the dong by 2.52%.
Globally, the safe-haven Japanese yen rallied on Wednesday while riskier currencies like the Australian dollar and sterling languished as traders ducked for cover following the worst sell-off in almost a month on Wall Street and big losses for Asian stocks, Reuters reported.
The yen strengthened as much as 0.4% to 144.89 per dollar before last trading up about 0.1% at 145.37, following a 1% rally overnight against a broadly stronger dollar.
The dollar, though, was firm against most other major peers, as it tends to draw safety bids even when the U.S. economy is the locus of concern.
Sterling edged down to $1.3111, after weakening 0.23% overnight. The euro rose 0.1% to $1.1054, following a 0.26% decline in the previous session.