The index closed 0.28 points lower after gaining 2.51 points in the previous session.
Trading on the Ho Chi Minh Stock Exchange decreased by 10% to VND21.467 trillion (US$843.3 million).
The VN-30 basket, comprising the 30 largest capped stocks, saw 7 tickers gained.
PLX of fuel distributor Petrolimex went up 2.4%, followed by SSB of SeABank with a 2.2% growth and FPT of IT giant FPT Corporation, up 2.1%.
Eighteen blue chips fell. POW of electricity producer Petrovietnam Power Corporation lost 2.6%, HDB of private lender HDBank dropped 1.9%, and VJC of low-cost airline VietJet Air went down 1.3%.
Foreign investors were net seller to the tune of VND1008 billion, mainly selling FPT of FPT Corporation and NVL of property developer Novaland.
The HNX-Index for stocks on the Hanoi Stock Exchange, home to mid and small caps, rose 0.16%, while the UPCoM-Index for the Unlisted Public Companies Market went up 1.32%.