Chinese regulators are instructing quantitative trading funds to phase out a strategy that has been criticized for exacerbating stock market turmoil. The move aims to scale back quantitative trading, with funds told to stop accepting new inflows and to phase out existing products. The strategy, which helped boost returns in 2023, is estimated to have stood at as much as 200 billion yuan ($27.8 billion) at the beginning of the year. China's securities regulator is tightening control on this highly leveraged trading approach, including banning a top-performing quant fund from the stock-index futures market and increasing oversight on high-speed trading.