Eight mainland China-based companies – five of them biotech firms – passed listing hearings on the Hong Kong stock market in April, clearing the way for them to tap the city’s deep liquidity.The influx, including an AI-driven drug discovery firm, a driverless technology developer and a maker of industrial robots, comes as the China Securities Regulatory Commission (CSRC) has been pushing private firms to list in Hong Kong. The market regulator has required companies that established so-called...