The Shanghai Stock Exchange has said it will begin suspend trading of stocks it deems particularly volatile, the Wall Street Journal reported. The move is aimed at reducing insider trading and speculation on new shares. The exchange said it would suspend trading on a stock for up to half an hour if its price more than doubles or if it drops below half its opening price. Prices of new stocks are not limited on their first day of trading, although subsequent sessions are restricted to a 10% band. Once a stock is suspended, trading can only resume if the company's explanation for the volatility is approved by the exchange. The suspension program will start September 1.