The index lost 1.55 points after closing 6.34 points lower in the last session.
Trading on the Ho Chi Minh Stock Exchange (HoSE) fell 5.6% to VND9.13 trillion ($388.83 million).
The VN-30 basket, comprising the 30 largest capped stocks, saw 14 tickers drop.
MSN of conglomerate Masan Group lost 4.1%, followed by GAS of state-owned Petrovietnam Gas with a 2.4% fall.
MWG of electronics retail chain Mobile World fell 2.3% and BID of state-owned lender BIDV closed 1.1% lower.
Fourteen blue chips rose, led by NVL of property developer Novaland Group with a 3.3% rise.
TCB of the largest private lender Techcombank gained 2.8% and POW of electricity producer Petrovietnam Power Corporation rose 1.6%.
Foreign investors were net buyers to the tune of VND259 billion, mainly buying Vietnam Maritime Commercial Joint Stock Bank (MSB) and HPG of steelmaker Hoa Phat Group.
The HNX-Index at the Hanoi Stock Exchange, where mid and small caps list, was down 0.08% while the UPCoM-Index at the Unlisted Public Companies Market was down by 0.12%.