HONG KONG • Mom-and-pop investors who put in bids worth a record US$3 trillion (S$4.1 trillion) in China's Ant Group were stunned after regulators abruptly suspended what would have been the world's largest stock market debut. China blocked the fintech giant's US$37 billion listing on Tuesday, thwarting its debut in Hong Kong and Shanghai and dealing a blow to the company founded by Alibaba's billionaire co-founder Jack Ma. Retail investors in the two markets - from taxi drivers to students to young professionals - used their savings and borrowed heavily from banks and brokerages for what many saw as a once-in-a-lifetime investment opportunity. "I feel like I made a very wrong decision," said 21-year-old Hong Kong resident and Cambridge student Vincent Tse, who applied for 2,000 shares worth around HK$160,000 (S$28,000), a sum he earned doing a part-time job. "This situation really reveals a deep problem in the Chinese market and shows a lack of experience in holding such a large (initial public offering)," he said, adding that he will no longer invest in Ant and will instead reinvest in US, European or Japanese stock markets. In China, investors cited the changing business environ...