The index closed 2.79 points lower after gaining 4.63 points on Monday.
Trading on the Ho Chi Minh Stock Exchange (HoSE) fell by 18.40% to VND19.21 trillion ($801.58 million).
The VN-30 basket, comprising the 30 largest capped stocks, saw 17 tickers dropped.
VIC of private conglomerate Vingroup fell 3.5%, followed by SSI of leading brokerage SSI Securities Corporation with a 1.5% drop.
BID of state-owned lender BIDV and STB of Ho Chi Minh City-based lender Sacombank both closed 1.3% lower.
Eleven blue chips gained. VRE of retail real estate arm Vincom Retail went up 3.3% and TPB of private TPBank rose 1.9%.
Foreign investors were net sellers to the tune of VND540.08 billion, mainly selling VPB of private lender VPBank and VIC of private conglomerate Vingroup.
The HNX-Index at the Hanoi Stock Exchange, where mid and small caps list, was up 0.40% while the UPCoM-Index at the Unlisted Public Companies Market was down by 0.03%.