The index closed 8.57 points lower after losing 34.23 points Wednesday. It is now at its lowest since Aug. 2.
Trading on the Ho Chi Minh Stock Exchange fell by 29.1% to VND14.42 trillion ($612.8 million).
The VN-30 basket, comprising the 30 largest capped stocks, saw 18 tickers drop.
VIB of Vietnam International Bank fell 3.7% to a 10-week low.
It was followed by GVR of Vietnam Rubber Group, down 3.1%.
Tickers of the two largest lenders, BID of BIDV and VCB of Vietcombank, were also among top losers with 2.5-2.9% losses.
Eleven blue chips gained, led by MSN of conglomerate Masan Group at 2.7%.
SAB of brewer Sabeco rose 2%, while NVL of property developer Novaland ended 1.4% higher.
Foreign investors were net buyers for the first time since Aug. 26 to the tune of VND74.35 billion, focusing on HPG of steelmaker Hoa Phat, DGC of Duc Giang Chemicals, and NLG of property developer Nam Long Group.
The HNX-Index at the Hanoi Stock Exchange, where mid and small caps list, fell 0.67% while the UPCoM-Index at the Unlisted Public Companies Market dropped by 0.08%.