The index started off in the green before dipping by nearly 28 points starting at around 10.40 a.m. while a slight recovery in the afternoon was unable to bring it back to the starting point. It closed with a 18.43-point drop, ending a chain of five consecutive gaining sessions.
Trading value on the Ho Chi Minh City Stock Exchange (HoSE), on which the index is based, rose 9.8 percent to VND16.8 trillion ($728.4 million), the highest since February 1. The bourse saw 95 stocks gain and 362 lose.
Many investors reported overloads on the bourse even in the morning. There were times when buy orders were delayed for two or three minutes, they said.
The VN30 basket, comprising the 30 largest capped stocks on the HoSE, saw 29 stocks in the red. VIC of biggest conglomerate Vingroup was the only ticker with no price change at VND106,900.
Losing blue chips were led by TCH of real estate company Hoang Huy Investment Financial Services JSC, down 4.2 percent, and SSI of SSI Securities Corporation, down 4 percent.
They were followed by five banks, including TPB of private TPBank, down 3.7 percent, STB of Ho Chi Minh City-based lender Sacombank, down 3.4 percent and TCB of the largest private lender Techcombank, down 3.2 percent.
Foreign investors were net sellers for the 10th session in a row to the tune of VND229.6 billion, with the strongest pressure on VNM of dairy giant Vinamilk, VIC and VCB of state-owned lender Vietcombank.
The HNX-Index for stocks on the Hanoi Stock Exchange, home to mid and small caps, gained 0.66 percent, while the UPCoM-Index for stocks on the Unlisted Public Companies Market fell 0.18 percent.