The index closed 1.6 points lower after losing 3.6 points Wednesday.
Trading on the Ho Chi Minh Stock Exchange (HoSE) increased by 1.43% to VND8.39 trillion ($341.75 million).
The VN-30 basket, comprising the 30 largest capped stocks, saw 14 tickers fall.
TCB of the largest private lender Techcombank dropped 2.4%, and VIB of Vietnam International Commercial Bank fell 2.2%.
GVR of Vietnam Rubber Group declined by 2.1% and MBB of lender MB lost 2%.
Other decliners were HPG of steelmaker Hoa Phat Group, KDH of real estate firm Khang Dien House and POW of electricity producer Petrovietnam Power Corporation.
14 blue chips gained, led by FPT of IT giant FPT Corporation with a 3% rise.
VCB of state-owned lender Vietcombank rose 1.9% and GAS of state-owned Petrovietnam Gas went up 1.6%.
Foreign investors were net buyers to the tune of VND183.49 billion, mainly buying VNM of dairy giant Vinamilk and MSN of conglomerate Masan Group.
The HNX-Index at the Hanoi Stock Exchange, where mid and small caps list, was down 0.89% while the UPCoM-Index at the Unlisted Public Companies Market was up by 0.14%.