The index closed 4.36 points lower after losing 1.2 points on Friday.
Trading on the Ho Chi Minh Stock Exchange (HoSE) increased by 39.64% to VND15.06 trillion ($642.33 million).
The VN-30 basket, comprising the 30 largest capped stocks, saw 20 tickers dropped.
HPG of steelmaker Hoa Phat Group fell 2.4% and PDR of Phat Dat Real Estate Development lost 2.2%.
BID of state-owned lender BIDV closed 2.1% lower and VHM of property giant Vinhomes lost 1.8%.
Five blue chips gained, led by MWG of electronics retail chain Mobile World with a 5.1% gain.
POW of electricity producer Petrovietnam Power Corporation rose 2.3%, and TCB of the largest private lender Techcombank went up 2.2%.
Foreign investors were net sellers to the tune of VND305.36 billion, mainly HPG of steelmaker Hoa Phat Group and STB of Ho Chi Minh City-based lender Sacombank.
The HNX-Index at the Hanoi Stock Exchange, where mid and small caps list, was up 0.19% while the UPCoM-Index at the Unlisted Public Companies Market was down by 0.22%.