The index closed 14.50 points lower after gaining 20.18 points in the previous session.
Trading on the Ho Chi Minh Stock Exchange decreased by 14% to VND12.12 trillion ($492.48 million).
The VN-30 basket, comprising the 30 largest capped stocks, saw 28 tickers fell.
MSN of conglomerate Masan Group dropped 4.3%, followed by MWG of electronics retail chain Mobile World, down 3.8%.
GVR of Vietnam Rubber Group fell 3.7% and GAS of state-owned Petrovietnam Gas lost 3.1%.
Two blue chips gained. SSB of Southeast Asia Commercial Bank (SeABank) rose 1.4% and VIC of private conglomerate Vingroup closed 0.1% higher.
Foreign investors were net buyers to the tune of VND85 billion, mainly buying VHM of property giant Vinhomes and IDC of construction firm Idico Corporation.
The HNX-Index for stocks on the Hanoi Stock Exchange, home to mid and small caps, fell 0.96% while the UPCoM-Index for the Unlisted Public Companies Market dropped 0.41%.