The index closed 8.3 points lower after losing 45.67 points on Monday.
Trading on the Ho Chi Minh Stock Exchange (HoSE) increased by 4.5% to VND12.05 trillion ($504.55 million).
The VN-30 basket, comprising the 30 largest capped stocks, saw 14 tickers fall.
GVR of Vietnam Rubber Group dropped 6.2%, followed by HPG of steelmaker Hoa Phat Group, down 4.6%.
CTG of state-owned lender VietinBank fell 3.9%, and MSN of conglomerate Masan Group was down 3.7%.
Other declining tickers were SSI of leading brokerage SSI Securities Corporation, BVH of insurance company Bao Viet Holdings and ACB of Asia Commercial Bank.
Fifteen blue chips gained, led by SAB of brewer Sabeco with a 3.2% rise to the highest in two weeks.
Other gainers include VIC of biggest private conglomerate Vingroup, up 2.7%, and VJC of budget airline Vietjet, 2.6%.
Foreign investors were net sellers to the tune of VND471.31 billion, mainly selling BSR of Binh Son Refining and Petrochemical and VTP of logistics firm Viettel Post.
The HNX-Index at the Hanoi Stock Exchange, where mid and small caps list, was down 1.07% while the UPCoM-Index at the Unlisted Public Companies Market was down by 0.46%.