The index closed 1.54 points lower after gaining 5.19 points in the previous session.
Trading on the Ho Chi Minh Stock Exchange decreased by 20% to VND11.299 trillion (US$441.9 million).
The VN-30 basket, comprising the 30 largest capped stocks, saw 14 tickers dropped.
MBB of lender MB Bank slipped 1.3%, BID of state-owned lender BIDV closed 1.1% lower, and HPG of steelmaker Hoa Phat Group fell 1.0%.
Eleven blue chips rose. BVH of insurance company Bao Viet Holdings went up 3.2%.
VNM of dairy giant Vinamilk gained 1.0%, and LPB of Lien Viet Post Bank saw a 0.9% increase.
Foreign investors were net seller to the tune of VND409 billion, mainly selling MWG of electronics retail chain Mobile World and FPT of IT giant FPT Corporation.
The HNX-Index for stocks on the Hanoi Stock Exchange, home to mid and small caps, rose 0.20%, while the UPCoM-Index for the Unlisted Public Companies Market went up 0.02%.