The index was in the red throughout the day and closed with a near 11-point fall. This ended three consecutive sessions in the green.
Trading value on the Ho Chi Minh Stock Exchange (HoSE), on which the index is based, fell 4 percent to VND23.4 trillion ($1.02 billion), the lowest since June 1. The bourse saw 176 tickers gain and 222 lose.
The VN30 basket, comprising the 30 largest capped stocks, saw 20 tickers in the red, led by SSI of leading brokerage SSI Securities Corporation with a 5 percent fall.
This ended a chain of four sessions in the green for the ticker.
CTG of state-owned lender VietinBank fell 3.1 percent, its third losing session in a row.
TCB of the largest private lender Techcombank also dropped 3.1 percent.
Other major losers include STB of Ho Chi Minh City-based lender Sacombank, down 3 precent, and HDB of HDBank, down 2.7 percent.
Foreign investors were net sellers to the tune of VND76.46 billion.
The HNX-Index for stocks on the Hanoi Stock Exchange, home to mid and small caps, fell 1.46 percent while the UPCoM-Index for the Unlisted Public Companies Market dropped 0.06 percent.