The index dropped 39.8 points after falling 19.7 points Friday. This was its third losing session in a row.
Trading on the Ho Chi Minh Stock Exchange (HoSE), on which the index is based, dropped 27% to VND23.49 trillion ($963.49 million).
The VN30 basket, comprising the 30 largest capped stocks, saw 26 tickers fell.
VIC of private conglomerate Vingroup dropped 7%, followed by GVR of Vietnam Rubber Group with a 6.9% decline.
SSI of leading brokerage SSI Securities Corporation 6.9% while MSN of conglomerate Masan Group closed 6.8% lower.
Only three blue chips gained. SSB of Southeast Asia Commercial Bank (SeABank) rose 2%, followed VJC of budget airline Vietjet with a 0.4% increase and VNM of dairy giant Vinamilk, up 0.1%.
Foreign investors were net buyers to the tune of VND708 billion, mainly buying HPG of steelmaker Hoa Phat Group and SSI.
The HNX-Index for stocks on the Hanoi Stock Exchange, home to mid and small caps, dropped 4.79% while the UPCoM-Index for the Unlisted Public Companies Market fell 2.27%.