The index closed 6.35 points lower after dropping 2.28 points in the previous session.
Trading on the Ho Chi Minh Stock Exchange increased by 6% to VND17.084 trillion (US$668.3 million).
The VN-30 basket, comprising the 30 largest capped stocks, saw 18 tickers fell.
PLX of fuel distributor Petrolimex saw the biggest drop of 2.8%, followed by HDB of HDBank with a 1.8% decline and FPT of tech giant FPT Corporation, down 1.7%.
Six blue chips gained, with VIC of private conglomerate Vingroup rising by 1.6%.
LPB of Fortune Vietnam Bank went up 1.4% and BVH of insurance company Bao Viet Holdings closed 0.6% higher.
Foreign investors were net seller to the tune of VND407 billion, mainly selling PNJ of Phu Nhuan Jewelry and VNM of dairy giant Vinamilk.
The HNX-Index for stocks on the Hanoi Stock Exchange, home to mid and small caps, fell 0.56%, while the UPCoM-Index for the Unlisted Public Companies Market went down 0.40%.