The index closed 0.01 points lower after gaining 4.11 points on Tuesday.
Trading on the Ho Chi Minh Stock Exchange (HoSE) increased by 9.16% to VND12.65 trillion ($539.51 million).
Foreign investors were net sellers to the tune of VND341.75 billion, mainly selling CTG of state-owned lender VietinBank and KBC of industrial real estate developer Kinh Bac City.
The VN-30 basket, comprising the 30 largest capped stocks, saw 15 tickers gain.
NVL of property developer Novaland Group led with a 6% rise, followed by PDR of Phat Dat Real Estate Development, up 4.8%, and MSN of conglomerate Masan Group up 2.1%.
POW of electricity producer Petrovietnam Power Corporation rose 1.9% and TCB of the largest private lender Techcombank closed 1% higher.
Fourteen blue chips dropped.
SSI of leading brokerage SSI Securities Corporation fell 2.7% and VJC of budget airline Vietjet lost 2.5%.
The HNX-Index at the Hanoi Stock Exchange, where mid and small caps list, was down 0.19% while the UPCoM-Index at the Unlisted Public Companies Market was up by 0.43%.