The index closed 1.5 points lower. It has stayed in the 1,390-range for the past eight sessions.
Trading value on the Ho Chi Minh Stock Exchange (HoSE), on which the index is based, surged 17 percent to VND23.78 trillion ($1.04 billion).
The VN30 basket, comprising the 30 largest capped stocks, saw 17 tickers in the red, led by SAB of brewer Sabeco with a 2.1 percent drop.
The fall brought SAB to a two-week low. It has been on a downward trend since the beginning of this year.
HDB of HDBank and PLX of fuel distributor Petrolimex both dropped 1.6 percent.
Eight blue chip tickers bucked the trend, with PDR of Phat Dat Real Estate Development gaining 3.1 percent to a new peak.
VRE of retail real estate arm Vincom Retail rose 2.1 percent to the highest since July 7.
Foreign investors were net sellers for the third straight session to the tune of VND1.36 trillion, highest in over a month.
They focused on selling HPG of steelmaker Hoa Phat Group, and NLG of real estate developer Nam Long Investment Corp.