The index stayed in the green in the morning but fluctuated in the afternoon to close four points lower after scoring 55 points in the last three sessions.
Trading value on the Ho Chi Minh Stock Exchange (HoSE), on which the index is based, surged 17.9 percent to VND23 trillion ($1 billion).
The VN30 basket, comprising the 30 largest capped stocks, saw 20 tickers in the red.
VIC of biggest private conglomerate Vingroup posted the biggest fall this session at 3.6 percent. It was also the biggest contributor to VN-Index’s fall, pulling it down by 3.8 points.
GAS of state-owned Petrovietnam Gas dropped 2.1 percent after three sessions in the green.
NVL of real estate developer Novaland Group lost 1.7 percent, while PLX of fuel distributor Petrolimex fell 1.5 percent.
Ten blue chip tickers bucked the trend, with POW of electricity producer Petrovietnam Power Corporation rising 5.2 percent in its fifth green session.
Other gainers included BVH of insurance company Bao Viet Holdings, up 1.7 percent, and TPB of private TPBank, up 1.6 percent.
Foreign investors were net sellers to the tune of VND474 billion, with strongest focus on HPG of steelmaker Hoa Phat Group and TCH of real estate company Hoang Huy Investment Financial Services.
The HNX-Index for stocks on the Hanoi Stock Exchange, home to mid and small caps, fell 0.39 percent while the UPCoM-Index for the Unlisted Public Companies Market lost 0.09 percent.