The index closed 2.05 points lower after gaining 2.03 points in the previous session.
Trading on the Ho Chi Minh Stock Exchange increased by 38% to VND18.282 trillion (US$735.6 million) .
The VN-30 basket, comprising the 30 largest capped stocks, saw 19 tickers fell.
VJC of budget airline Vietjet saw the biggest drop of 1.5%, followed by FPT of IT giant FPT Corporation with a 1.43% fall and MWG of electronics retail chain Mobile World, down 1.4%.
Eight blue chips gained. VHM of property giant Vinhomes VHM went up 4%, GVR of Vietnam Rubber Group rose 2.3%, and POW of electricity producer Petrovietnam Power Corporation closed 1.6% higher.
Foreign investors were net seller to the tune of VND615 billion, mainly selling FPT and VPB of private lender VPBank.
The HNX-Index for stocks on the Hanoi Stock Exchange, home to mid and small caps, fell 0.28%, while the UPCoM-Index for the Unlisted Public Companies Market went down 0.24%.
Globally, stock markets held below last month's record highs on Monday, while the Chinese yuan and oil prices weakened as China's broad economic stimulus promises made over the weekend failed to inspire investors across the globe, Reuters reported.
U.S. stock futures and European shares were a touch higher on the day, with focus turning to the third quarter earnings season and a key European Central Bank rate decision later in the week.
The MSCI's World Stock Index was flat on the day, below record highs hit last month.