Two listings of Chinese tech businesses added new members to the country’s billionaire ranks on Friday. Memory chip supplier Shenzhen Longxi Electronics rose 77.8% to 99 yuan on the Shenzhen Stock Market. The company’s chairman, Cai Huabo, held at least $2.1 billion worth of shares on Friday. Longsys is relatively well-known in the chip business, having acquired the Lexar brand from Micron in 2017. Semitronics Corp., a provider of chip-related software, rose nearly 156 percent to close at 148.35 yuan in Shenzhen debut. That makes its chairman, Zheng Yongju, worth $1 billion. China is home to the second largest number...