The State Securities Commission has urged investors to keep calm and careful following the plunge in the stock market on May 8.
It said it would keep an eye on unusual transactions and crack down on anybody trying to take advantage of the situation to control the market or rig prices.
Despite the sharp fall, liquidity had improved and some large investors continued to buy, the commission said.
The economy is stable and improving since the start of the year. Listed companies are performing better and the number of loss-making companies is falling, it added.
Foreign investors have been net buyers in recent days.
The VN-Index lost a whopping 32.88 points to close at 527.09 points on May 8 as 258 shares declined, 13 gained, and 17 remained unchanged.
The VN30-Index fell by 34.2 points to 575.31 with all 30 shares losing.