Chinese start-up X Square Robot has filed confidentially for an initial public offering (IPO) in Hong Kong, according to two sources familiar with the matter, joining a growing wave of domestic robot makers flocking to capital markets, despite new US trade restrictions. The Shenzhen-based firm has tapped Huatai Securities and Morgan Stanley as sponsors for the prospective float, one of the sources said. Besides X Square, AgiBot and Galbot have also filed confidentially for Hong Kong IPOs, the second person said. X Square and Morgan Stanley declined to comment, while the other companies and securities firms did not respond to requests for comment. This was up 92 per cent, while the number of new listings almost doubled to 87 from a year earlier, according to PwC Hong Kong.