The index shot up 15 points in the morning but gradually fell throughout the rest of the day to close with a 4-point gain.
Trading value on the Ho Chi Minh Stock Exchange (HoSE), on which the index is based, rose nearly 15 percent to VND18.5 trillion ($803 million), the highest in the last six sessions.
Foreign investors were net buyers to the tune of VND339 billion, with strongest pressure on AGG of real estate developer An Gia and NVL of real estate developer Novaland Group.
The VN30 basket, comprising the 30 largest capped stocks, saw 19 tickers in the green, led by MSN of conglomerate Masan Group, up 3.6 percent to a new peak.
TPB of private TPBank gained 3.3 percent to a near two-week high, while VRE of retail real estate arm Vincom Retail rose 3.4 percent.
POW of electricity producer Petrovietnam Power Corporation rose 2.9 percent, while SSI of leading brokerage SSI Securities Corporation gained 2.4 percent.
On the losing side, VHM of real estate giant Vinhomes and VNM of dairy giant Vinamilk led with a 1.6 percent drop.
The HNX-Index for stocks on the Hanoi Stock Exchange, home to mid and small caps, rose 1.03 percent while the UPCoM-Index for the Unlisted Public Companies Market gained 1.07 percent.