China’s cyberspace regulator is clamping down on companies with data for more than one million users saying they must undergo a security review before listing its shares overseas.

China watchers say the new regulations have broadened Beijing’s clampdown on its large platform economy.

The Cyberspace Administration of China (CAC) said the security review would focus on risks of data being affected, controlled or manipulated by foreign governments after overseas listings.

The cyberspace regulators are imposing tighter restrictions on data collection and data storage. Authorities are also more broadly pushing for companies to list domestically.

China’s market regulator also said it would block Tencent Holdings plan to merge the country’s top two videogame streaming sites, Huya and DouYu on anti-competition grounds.

China tightening of oversight of data security and overseas listings has battered US-traded Chinese shares, already reeling from a security review by their internet regulator last week and a demand for app stores to remove Didi Chuxing. The crackdown came just days after Didi’s $4.4 billion initial public offering.