The index closed 7.25 points lower after gaining 8.57 points in the previous session.
Trading on the Ho Chi Minh Stock Exchange increased by 2% to VND24.897 trillion (US$1 billion).
The VN-30 basket, comprising the 30 largest capped stocks, saw 22 tickers fell.
VRE of retail real estate arm Vincom Retail slid 3.2% while GVR of rubber company Vietnam Rubber Group declined by 2.7%.
Eight blue chips gained, led by SAB of leading beer producer Sabeco with a 4.1% surge, MSN of conglomerate Masan Group with a 1.6% rise, and GAS of gas company PVGas, up 1.4%.
Foreign investors were net seller to the tune of VND162 billion, mainly selling VHM of property giant Vinhomes and SSI of leading brokerage SSI Securities Corporation.
The HNX-Index for stocks on the Hanoi Stock Exchange, home to mid and small caps, fell 0.80%, while the UPCoM-Index for the Unlisted Public Companies Market went down 0.59%.