The index closed 4.52 points lower after gaining 18.33 points in the previous session.
Trading on the Ho Chi Minh Stock Exchange decreased by 29% to VND17.09 trillion ($703.93 million).
The VN-30 basket, comprising the 30 largest capped stocks, saw 26 tickers fell.
VHM of property giant Vinhomes dropped 1.9%, and VPB of private lender VPBank closed 1.8% lower.
SHB of Saigon Hanoi Commercial Bank and STB of Ho Chi Minh City-based lender Sacombank both fell 1.4%.
Four blue chips gained. BCM of Becamex Investment and Industrial Development led with a 6.9% rise, followed by FPT of IT giant FPT Corporation, up 1.3%.
Foreign investors were net sellers to the tune of VND1555 billion, mainly selling VHM and HPG of steelmaker Hoa Phat Group.
The HNX-Index for stocks on the Hanoi Stock Exchange, home to mid and small caps, rose 0.01%, while the UPCoM-Index for the Unlisted Public Companies Market went up 0.05%.