From classroom to billion-dollar fortune: How Chinese siblings struck gold in the stock market

A stock market debut has delivered a billion-dollar glow-up for a former elementary school teacher and his sister in China, turning them into billionaires after shares of their adhesive products company skyrocketed nearly eightfold on their first day of trading.Michael Mai, 62, who once taught at an elementary school in the southern Chinese city of Zhongshan, now has an estimated fortune of $2.5 billion following the listing of Crown New Materials Technology on the Shenzhen Stock Exchange on Tuesday.His sister, Mai Huixia, 64, who serves as the company’s vice-chairperson, has also made it to the billionaire club, with an estimated net worth of $2 billion.The company, which Mai chairs and leads as CEO, made its stock market debut at 16.98 yuan per share. Its shares subsequently jumped as much as 787%, according to the Shenzhen bourse, mainland China’s second-largest stock exchange. The estimated fortunes of the siblings are based on their respective stakes in the business, Forbes reported.Mai is an Australian citizen and permanent resident of Hong Kong. Crown New Materials Technology, founded in 2000, is headquartered in Zhongshan, the same city where he reportedly worked as a teacher.Crown New Materials Technology makes binding agents and other adhesive products used by major brands, including Tesla and Apple. Its products help hold together components used in a variety of retail products, ranging from vehicle roofs to semiconductors in smartphones, according to the company’s website.The business has expanded its manufacturing operations to five plants, with four located across China and one in Vietnam, CNN reported.The sharp rally in the company’s shares was followed by a correction on Wednesday morning, when they eased to around 77 yuan ($12) apiece. The surge on the previous day had prompted the company to issue a statement asking investors to “invest rationally.”The listing comes against the backdrop of a difficult spell for China’s stock markets. Weak consumer spending and concerns about a possible bursting of the AI bubble have weighed on equities in recent months.Key Chinese indexes have fallen more than 20% from their June peaks, entering bear market territory.Beijing responded two weeks ago by injecting $19 billion into exchange-traded funds, according to Bloomberg data. This was its biggest intervention since early 2025, when US President Donald Trump’s tariff offensive sent global markets into turmoil.