The index closed 14.08 points lower after losing 2.84 points on Friday.
Trading on the Ho Chi Minh Stock Exchange (HoSE) increased by 3.44% to VND16.04 trillion ($678.22 million).
The VN-30 basket, comprising the 30 largest capped stocks, saw 25 tickers dropped.
PDR of Phat Dat Real Estate Development fell 4.8%, and NVL of property developer Novaland Group lost 3.8%.
VIC of biggest private conglomerate Vingroup 3.3% and GVR of Vietnam Rubber Group lost 3.2%.
Other decliners were POW of electricity producer Petrovietnam Power Corporation (down 3.1%) and VPB of private lender VPBank (down 3%).
Four blue chips gained, led by VRE of retail real estate arm Vincom Retail with a 4.2% rise.
MSN of conglomerate Masan Group went up 1.6%.
Foreign investors were net buyers to the tune of VND108.72 billion, mainly buying STB of Ho Chi Minh City-based lender Sacombank and SHB of Saigon Hanoi Commercial Bank.
The HNX-Index at the Hanoi Stock Exchange, where mid and small caps list, was down 0.35% while the UPCoM-Index at the Unlisted Public Companies Market was down by 0.10%.