The index mostly stayed in the green in the morning but started to fall after lunch, closing 0.93 points lower and ending its three-session winning streak.
It surged 6 percent this week thanks to a 56.4-point rise Tuesday, but has dropped over 18 percent since the beginning of 2022.
Trading on the Ho Chi Minh Stock Exchange fell marginally to VND12.46 trillion.
The VN-30 basket, comprising the 30 largest capped stocks, saw 17 tickers lose, led by SAB of brewery Sabeco with a 3.9 percent loss.
MSN of conglomerate Masan Group dropped 2.4 percent and ended its 21-percent gain over the last three sessions.
VNM of dairy giant closed 1.3 percent lower, and GAS of Petrovietnam Gas fell 1.2 percent.
Other losers included three lenders: VCB of largest player Vietcombank, down 0.9 percent, CTG of VietinBank, down 0.8 percent, and STB of Sacombank, down 0.7 percent.
Ten blue chips gained, with PNJ of Phu Nhuan Jewelry rising 3.8 percent and GVR of Vietnam Rubber Group closing 3.3 percent higher.
ACB of lender Asia Commercial Bank surged 1.6 percent, and MBB of MBBank gained 0.9 percent.
Foreign investors were net sellers to the tune of VND423.46 billion, highest in five weeks, focusing on SSI of leading brokerage SSI Securities, HPG of steelmaker Hoa Phat, and STB.
The HNX-Index at the Hanoi Stock Exchange, where mid and small caps list, lost 0.32 percent while the UPCoM-Index at the Unlisted Public Companies Market dropped by 0.64 percent.