The index closed 8.75 points lower after losing 4.48 points on Friday.
Trading on the Ho Chi Minh Stock Exchange (HoSE) fell by 0.55% to VND14.84 trillion ($633.89 million).
The VN-30 basket, comprising the 30 largest capped stocks, saw 25 tickers dropped.
HDB of HDBank lost 3%, followed by VIC of biggest private conglomerate Vingroup with a 2.8% decline.
VIB of Vietnam International Bank fell 2.7%, and KDH of real estate firm Khang Dien House lost 2.6%.
Four blue chips gained, with MWG of electronics retail chain Mobile World rising 3.7%.
Foreign investors were net sellers to the tune of VND229.24 billion, mainly selling KBC of industrial real estate developer Kinh Bac City and SSI of leading brokerage SSI Securities Corporation.
The HNX-Index at the Hanoi Stock Exchange, where mid and small caps list, was down 1.08% while the UPCoM-Index at the Unlisted Public Companies Market was down by 0.59%.