Photo: Gilles Sabrie/Bloomberg

Beijing's cybersecurity probes into three Chinese tech companies that recently listed in the United States threaten to stem the flow of Chinese initial public offerings in the U.S., hampering the practices of the many global firms operating in Hong Kong and China that rely on IPOs and other capital markets work.

On Friday—two days after the popular ride-hailing app Didi Chuxing listed on the New York Stock Exchange in a $4.4 billion initial public offering—a new Chinese cybersecurity unit announced that it was reviewing Didi's data collection policies, citing national security concerns. Soon after, Didi's app became unavailable in Chinese app stores.

Then on Monday, the Cybersecurity Review Office doubled down, ordering similar reviews into two smaller Chinese tech companies—Full Truck Alliance Co. and Kanzhun Ltd.—both of which also went public in the U.S. in June.