The index rose to 10 points at some point in the afternoon but quickly fell to close with a two-point gain.
Trading value on the Ho Chi Minh Stock Exchange (HoSE), on which the index is based, rose nearly 23 percent to VND23.3 trillion ($1.02 billion).
The VN30 basket, comprising the 30 largest capped stocks, saw 14 tickers in the green, led by MWG of electronics retail chain Mobile World with a 5 percent gain.
The ticker is now at a new peak, having ended in the green for three sessions in a row.
TPB of private TPBank rose 3.6 percent, also to a new peak.
GAS of state-owned Petrovietnam Gas rose 2.5 percent, and VHM of real estate giant Vinhomes, 1.7 percent.
Thirteen blue chip tickers ended in the red, with BVH of insurance company Bao Viet Holdings down 2 percent and MSN of conglomerate Masan Group down 1.4 percent.
Foreign investors were net sellers for the third session in a row to the tune of VND374 billion, with strongest pressure on HPG of steelmaker Hoa Phat Group and KBC of industrial real estate developer Kinh Bac City.
The HNX-Index for stocks on the Hanoi Stock Exchange, home to mid and small caps, fell 0.66 percent while the UPCoM-Index for the Unlisted Public Companies Market gained 0.74 percent.