The market plummeted suddenly in the last 20 minutes of trading yesterday despite rising for almost the entire trading time. The VN-Index lost nearly 14 points, or 2.74 per cent, to close at 496.50 points.

An unexpected reduction of the gasoline price Tuesday evening helped lift shares on the HCM City Stock Exchange in the morning, but massive sell-offs of blue chips towards the end of the afternoon pulled the market down.

The VN30, tracking the top 30 shares by market capitalisation and liquidity, fell by a more significant 3.05 per cent to stand at 558.37 points.

Five of the top 30 shares dropped to the floor price, including Bao Viet Holdings (BVH), PetroVietnam Finance (PVF), Ocean Group (OGC), Vietcombank (VCB) and Southern Rubber Industry (CSM).

Other heavyweight shares such as Vinamilk (VNM), Hoa Phat Group (HPG) and FPT Corp (FPT) also fell hard.

"The sharp drop of blue-chips came as a surprise to most investors, as the market stayed above the neutral line most of the time after petroleum traders cut retail prices," analysts at FPT Securities Co commented on their website.

Analysts had doubts that exchange traded funds (ETFs) were responsible for these sell-offs, as most of the shares that suffered steep plunges yesterday were on the Market Vectors Viet Nam and FTSE Viet Nam Index lists.

Foreign investors concluded yesterday as sellers on the southern market, unloading VND65.23 billion (US$3.1 million) worth of shares.

Trading improved with 69 million shares exchanged, worth over VND1.43 trillion ($68.1 million) – an increase of 10 per cent in volume and 30 per cent in value compared to Tuesday's levels.

Tan Tao Investment Industry (ITA) was still the most active code by the end of the session with over 3.4 million shares exchanged. It fell 4.23 per cent to close at VND6,800 a share.

On the Ha Noi Stock Exchange, the HNX-Index also went down 1.69 points to close at 60.33 points, with total trading value of VND445 billion ($21.2 million).

Sai Gon-Ha Noi Bank (SHB) shares continued to be traded actively with nearly 15 million shares changing hands. The stock decreased 5.5 per cent to settle at VND6,900 a share.