The index closed 0.5 points lower after slipping 0.2 points Tuesday as investors chose to observe the market amid uncertainties about the impact of the Omicron variant.
Trading value on the Ho Chi Minh Stock Exchange (HoSE), on which the index is based, fell 6 percent to VND25.92 trillion ($1.13 billion).
The VN30 basket, comprising the 30 largest capped stocks, saw 12 tickers in the red, with POW of electricity producer Petrovietnam Power Corporation falling 3 percent.
VIC of biggest private conglomerate Vingroup fell 2.4 percent to a near three-week low.
SSI of leading brokerage SSI Securities Corporation fell 1.9 percent in its second session in the red.
GVR of Vietnam Rubber Group and VPB of private lender VPBank both lost 1 percent.
Sixteen blue chip tickers gained, led by TPB of private TPBank, up 3 percent.
MSN of conglomerate Masan Group rose 2.7 percent to a new peak in its third gaining session.
Foreign investors were net sellers for the fourth session in a row to the tune of VND143 billion, with focus on VPB and NLG of real estate developer Nam Long Investment Corp.
The HNX-Index for stocks on the Hanoi Stock Exchange, home to mid and small caps, lost 0.22 percent while the UPCoM-Index for the Unlisted Public Companies Market fell 0.33 percent.