The index closed 37.15 points lower after gaining 1.10 points in the previous session.
Trading on the Ho Chi Minh Stock Exchange increased by 83% to VND21.065 trillion ($863.29 million).
Foreign investors were net seller to the tune of VND154 billion, mainly selling CTG of state-owned lender VietinBank and VPB of private lender VPBank.
The HNX-Index for stocks on the Hanoi Stock Exchange, home to mid and small caps, dropped 4.24% while the UPCoM-Index for the Unlisted Public Companies Market fell 2.27%.
