The index closed 4.79 points lower after gaining 3.57 points on Monday.
Trading on the Ho Chi Minh Stock Exchange (HoSE) increased by 2.62% to VND12.86 trillion ($548.05 million).
The VN-30 basket, comprising the 30 largest capped stocks, saw 15 tickers gain.
MSN of conglomerate Masan Group lost 2.2%, followed by VNM of dairy giant Vinamilk with a 1.8% decline.
GAS of state-owned Petrovietnam Gas fell 1.6% and BCM of Becamex Investment and Industrial Development dropped 1.4%.
Six blue chips closed in the green, led by BVH of insurance company Bao Viet Holdings with a 1.8% rise.
PDR of Phat Dat Real Estate Development closed 1.5% higher.
Foreign investors were net sellers to the tune of VND604.97 billion, mainly selling VNM and MSN.
The HNX-Index at the Hanoi Stock Exchange, where mid and small caps list, was down 0.05% while the UPCoM-Index at the Unlisted Public Companies Market was down by 0.26%.