The index closed 4.43 points lower after losing 2.35 points Wednesday.
Trading on the Ho Chi Minh Stock Exchange rose by 30.46% to VND18.78 trillion ($802.8 million).
The VN-30 basket, comprising the 30 largest capped stocks, saw 17 tickers drop.
NVL of property developer Novaland led with a 2.3% lost.
It was followed by VNM of diary giant Vinamilk, down 1.9%, and HPG of steelmaker Hoa Phat, down 1.7%.
Other losers included VPB of private lender VPBank, down 1.7%, and MBB of MBBank, down 1.5%.
Eleven blue chips gained, with GAS of Petrovietnam Gas closing 1.9% higher.
VIC of the biggest conglomerate Vingroup rose 1.5%, and VRE of its mall operator arm Vincom Retail gained 1.8%.
Foreign investors were net buyers to the tune of VND73.9 billion.
The HNX-Index at the Hanoi Stock Exchange, where mid and small caps list, was down 1.11 percent while the UPCoM-Index at the Unlisted Public Companies Market was down by 0.42 percent.