A rule of thumb is to not buy more than 20% of average daily turnover (ADTO) in a stock in a single day to avoid moving the price.
An ADTO of US$0.5m would then allow for buying US$100,000 worth of shares in a single day.
At cutoff 3-month ADTO of US$0.5m, only 80 stocks or 10% are liquid in Vietnam with an average market cap of US$1.4bn.
While Vietnam has become a hot and interesting market with about 800 listed stocks, virtually 90% of stocks have almost no trading.