The benchmark VN-Index on the Ho Chi Minh Stock Exchange was down 0.27 per cent to close at 966.77 points.
The VN-Index lost a total of 0.60 per cent in the previous three trading days.
More than 65.3 million shares were traded on the southern market, worth VND1.24 trillion (US$61 million).
Petroleum stocks were the worst-performing in the morning session, following a tumble of oil prices on Thursday night.
Brent crude dipped 0.94 per cent to end Thursday at $69.45 a barrel.
On the Vietnamese stock market, PetroVietnam Gas (GAS) edged down 0.9 per cent and PetroVietnam Drilling and Well Services (PVD) declined by 2.8 per cent.
The negative performance of the energy sector also pulled down other industries such as banking, insurance, securities, healthcare and pharmaceuticals, and seafood processing.
Data on vietstock.vn showed the sector indices were down between 0.1 per cent and 0.4 per cent.
On the Ha Noi Stock Exchange, the HNX-Index fell 0.66 per cent to end at 104.62 points.
The northern market index ended flat on Thursday at 105.32 points.
More than 14 million shares were traded on the northern bourse, worth VND165 billion.
The afternoon trading session starts at 1pm.