The benchmark VN-Index on the Ho Chi Minh Stock Exchange fell 0.71 per cent to close at 947.44 points.
The southern market index lost 0.82 per cent on Wednesday.
More than 66.8 million shares were traded on the southern bourse, worth VND1.38 trillion (US$59.5 million).
The market was weighed down by pessimism following the escalation of the US-China trade war.
Declining stocks outnumbered gainers by 159 to 101 on the southern market while 52 others were unchanged.
The large-cap VN30-Index was down 0.59 per cent to 860.35 points with 20 of the 30 largest stocks by market value and trading liquidity falling.
Among large-cap decliners were property firm Vinhomes (VHM), dairy producer Vinamilk (VNM), DHG Pharmaceutical JSC (DHG) and budget airline Vietjet (VJC).
The fall of crude prices also put pressure on petroleum, oil and gas stocks such as PetroVietnam Gas (GAS) and Petrolimex (PLX).
On the Ha Noi Stock Exchange, the HNX-Index edged down 0.09 per cent to end at 103.46 points.
The HNX-Index shed 0.38 per cent in the previous day.
More than 10.6 million shares were traded on the northern market, worth VND120.6 billion.
The afternoon trading session starts at 1pm.