The index closed 11.4 points lower after gaining 4.2 points on Thursday.
Trading on the Ho Chi Minh Stock Exchange (HoSE) fell by 3.2% to VND11.29 trillion ($476.23 million).
The VN-30 basket, comprising the 30 largest capped stocks, saw 27 tickers dropped.
VCB of state-owned lender Vietcombank dropped 2.7% to the lowest in nearly two months.
STB of Ho Chi Minh City-based lender Sacombank fell 2.3% to a three-month low.
Other losers included SSI of leading brokerage SSI Securities Corporation, down 2.1%, and VJC of budget airline Vietjet, down 1.9%.
Only two blue chips gained: BVH of insurance company Bao Viet Holdings, up 5.8%, and GAS of state-owned Petrovietnam Gas, up 1.4%.
Foreign investors were net sellers to the tune of VND330.98 billion.
The HNX-Index at the Hanoi Stock Exchange, where mid and small caps list, was down 0.45% while the UPCoM-Index at the Unlisted Public Companies Market was up by 0.05%.