The index closed 21.11 points lower after gaining 5.73 points in the previous session.
Trading on the Ho Chi Minh Stock Exchange increased by 30% to VND32.502 trillion (US$1.32 billion).
The VN-30 basket, comprising the 30 largest capped stocks, saw 29 tickers fell and only one tickers gained - BCM of industrial property developer Becamex IDC with a 0.4% growth.
Ten blue chips fell. BID of state-owned lender BIDV went down 4.1%, TCB of private lender Techcombank slid 3.8%, and CTG of lender VietinBank, down 3.6%.
Foreign investors were net seller to the tune of VND667 billion, mainly selling MWG of electronics retail chain Mobile World and VNM of dairy giant Vinamilk.
The HNX-Index for stocks on the Hanoi Stock Exchange, home to mid and small caps, fell 0.44%, while the UPCoM-Index for the Unlisted Public Companies Market went down 0.38%.