The index closed 7.59 points lower after dropping 8.07 points in the previous session.
Trading on the Ho Chi Minh Stock Exchange increased by 6% to VND16.59 trillion (US$671 million).
The VN-30 basket, comprising the 30 largest capped stocks, saw 27 tickers fell.
GVR of Vietnam Rubber Group plunged 2.3%, followed by PLX of fuel distributor Petrolimex, down 2%.
FPT of IT giant FPT Corporation and MBB of lender MB both fell 1.8%.
Three blue chips gained, led by VHM of property giant Vinhomes, up 2.9%, and VIC of private conglomerate Vingroup, up 2.4%.
Foreign investors were net sellers to the tune of VND684 billion, mainly selling FPT and HPG of steelmaker Hoa Phat Group.
The HNX-Index for stocks on the Hanoi Stock Exchange, home to mid and small caps, fell 0.50%, while the UPCoM-Index for the Unlisted Public Companies Market went down 0.30%.
Asian shares were subdued on Thursday, with Japanese stocks sliding to their lowest in three weeks as investors sought safety, pushing the yen to a one-month high while U.S. economic worries boosted prospects for the Federal Reserve to cut rates, Reuters reported.
Amid the fragile sentiment, Japan's benchmark Nikkei slid more than 1% to its lowest in three weeks, while stocks in tech-heavy Taiwan and South Korean stood slightly higher on the day, giving up earlier gains.
The MSCI's broadest index of Asia-Pacific shares outside Japan up 0.25%, subdued after having tumbled nearly 3% during a three-day losing streak. The index had risen more than 0.6% but gave up those gains.