The index closed 2.9 points lower after gaining over eight points on Thursday.
Trading on the Ho Chi Minh Stock Exchange (HoSE) increased by nearly 20 percent to VND13.12 trillion ($559.49 million), highest since July 5.
The VN-30 basket, comprising the 30 largest capped stocks, saw 22 tickers dropped.
BVH of insurance company Bao Viet Holdings fell 2.4 percent.
SSI of leading brokerage SSI Securities Corporation lost 1.9 percent.
Other losers included MWG of electronics retail chain Mobile World, PNJ of Phu Nhuan Jewelry and VJC of budget airline Vietjet.
Six blue chips gained, led by HPG of steelmaker Hoa Phat Group with a 4.5 percent rise.
TPB of private TPBank and VPB of private lender VPBank both rose 0.7 percent.
Foreign investors were net sellers to the tune of VND496.85 billion, mainly selling FUEVFVND of Dragon Capital Vietfund Management and UIC of Idico Urban & House Development Jsc.
The HNX-Index at the Hanoi Stock Exchange, where mid and small caps list, was down 0.12 percent while the UPCoM-Index at the Unlisted Public Companies Market was up by 0.15 percent.
Source: VnExpress
