China’s cyberspace regulator has ordered app stores to remove Didi Chuxing, dealing a major blow to a ride-hailing giant that just days ago pulled off one of the largest U.S. initial public offerings of the past decade.

The Cyberspace Administration of China announced the ban Sunday, citing serious violations on Didi Global Inc.’s collection and usage of personal information, without elaborating. That unusually swift decision came two days after the regulator said it was starting a cybersecurity review of the company.

That effectively requires the largest app stores in China, operated by the likes of Apple Inc. and smartphone makers Huawei Technologies Co. and Xiaomi Corp., to strike Didi from their offerings. But the current half-billion or so users can continue to order up rides and other services so long as they downloaded the app before Sunday’s order. Shares in SoftBank Group Corp., a major Didi shareholder, fell as much as 5.9% Monday, its biggest intraday fall since May 13.