The index closed 4.06 points lower after losing 4.79 points on Tuesday.
Trading on the Ho Chi Minh Stock Exchange (HoSE) increased by 7.07% to VND13.77 trillion ($586.76 million).
The VN-30 basket, comprising the 30 largest capped stocks, saw 15 tickers gain.
STB of Ho Chi Minh City-based lender Sacombank fell 2%, followed by GVR of Vietnam Rubber Group and HPG of steelmaker Hoa Phat Group, both with a 1.8% decline.
TCB of the largest private lender Techcombank also closed 1.8% lower.
Five blue chips gained, led by MSN of conglomerate Masan Group with a 2% rise.
VHM of property giant Vinhomes closed 1.5% higher.
Foreign investors were net sellers to the tune of VND569.87 billion, mainly selling HPG and VNM.
The HNX-Index at the Hanoi Stock Exchange, where mid and small caps list, was up 0.08% while the UPCoM-Index at the Unlisted Public Companies Market was down by 0.09%.