The index fluctuated in the 1,350-range throughout the day and closed with a near five-point loss.
Trading value on the Ho Chi Minh Stock Exchange (HoSE), on which the index is based, fell nearly 14 percent to VND22.68 trillion ($997 million). The bourse saw 185 tickers gain and 183 lose.
The VN30 basket, comprising the 30 largest capped stocks, was dominated by red with 20 tickers falling, led by MWG of electronics retail chain Mobile World, down 2.9 percent.
STB of Ho Chi Minh City-based lender Sacombank lost 2.6 percent, and FPT of IT giant FPT Corporation, 2.4 percent.
FPT of IT giant FPT Corporation fell 2.4 percent to its lowest this month, while ACB of Asia Commercial Bank dropped 1.9 percent.
Seven blue chip tickers gained, led by BVH of insurance company Bao Viet Holdings with a 2-percent increase.
VPB of private lender VPBank went up 1.1 percent.
Foreign investors were net sellers for the third straight session to the tune of VND143 billion, with strongest pressure on VNM of dairy giant Vinamilk and VRE of retail real estate arm Vincom Retail.
The HNX-Index for stocks on the Hanoi Stock Exchange, home to mid and small caps stayed unchanged, while the UPCoM-Index for the Unlisted Public Companies Market fell 0.03 percent.