In a significant regulatory move, China's financial authorities have suspended a major quantitative (quant) fund for dumping $350 million worth of shares in just one minute, sparking a broader crackdown on quant trading practices. The China Securities Regulatory Commission (CSRC) has introduced stringent changes, including prohibiting selling within the first and last 30 minutes of the trading session and banning short selling by certain accounts. These measures come in response to recent market volatility attributed to aggressive quant fund activities, with quant funds' stampeding exit exacerbating an equity rout. China's two main stock exchanges have also pledged to enhance supervision over quant trading, requiring new funds to disclose their investment strategies before commencing trading, and freezing accounts for three days. This tightening of regulations follows an incident where the stock market was significantly impacted by the automated selling of shares, leading to a three-day ban on the involved fund. The CSRC is now investigating all Chinese quant trading firms, particularly after models used by quant hedge funds went haywire, resulting in unprecedented failures during a tumultuous two-week period in the market, described by some as the industry's 'biggest black swan event.'