The index closed 22.9 points lower after losing 7.8 points on Tuesday.
Trading on the Ho Chi Minh Stock Exchange (HoSE) increased by 11% to VND11.78 trillion ($495.53 million).
The VN-30 basket, comprising the 30 largest capped stocks, saw 24 tickers dropped.
GAS of state-owned Petrovietnam Gas plunged 6.7%, followed by VIC of biggest private conglomerate Vingroup with a 5.7% drop.
VHM of property giant Vinhomes fell 5.4%, and MSN of conglomerate Masan Group went down 5.2%.
Other declining tickers included FPT of IT giant FPT Corporation, MWG of electronics retail chain Mobile World and HPG of steelmaker Hoa Phat Group.
Five blue chips gained, led by VPB of private lender VPBank with a 1.4% rise, followed by SSI of leading brokerage SSI Securities Corporation, up 1%.
Foreign investors were net sellers to the tune of VND4.79 billion, mainly selling VNM of dairy giant Vinamilk and NVL of real estate developer Novaland Group.
The HNX-Index at the Hanoi Stock Exchange, where mid and small caps list, was down 1.24% while the UPCoM-Index at the Unlisted Public Companies Market was down by 1%.