The index closed nearly 37 points lower after losing 19 points on Friday.
Trading on the Ho Chi Minh Stock Exchange (HoSE) fell by 10.9 percent to VND15.44 trillion ($664.52 million).
The VN-30 basket, comprising the 30 largest capped stocks, saw 27 tickers dropped, with five of them hitting floor prices.
GAS of state-owned Petrovietnam Gas, HPG of steelmaker Hoa Phat Group, STB of Ho Chi Minh City-based lender Sacombank, POW of electricity producer Petrovietnam Power Corporation and SSI of leading brokerage SSI Securities Corporation fell by 6.8-6.9 percent.
Other losers included BID of state-owned lender BIDV, PLX of fuel distributor Petrolimex and MSN of conglomerate Masan Group.
Two blue chips bucked the trend: VNM of dairy giant Vinamilk rose 3.4 percent, and VJC of budget airline Vietjet gained 1.7 percent.
Foreign investors were net sellers to the tune of VND604.62 billion.
The HNX-Index at the Hanoi Stock Exchange, where mid and small caps list, was down 4.33 percent while the UPCoM-Index at the Unlisted Public Companies Market fell by 1.91 percent.