Shares in Fosun and HNA Group tanked on Thursday, while bonds of Fosun and Dalian Wanda were also hit. The three firms have just joined the unlisted insurance company Anbang and Zhejiang Rosserini Investment on a list of companies being targeted by the China Banking Regulatory Commission for greater scrutiny.

According to an email sent to banks and viewed by the Financial Times, the agency has told financial institutions to review their exposure to the five firms.

“This is a game changer for Chinese M&A and could pretty much stop all outbound dealmaking in its tracks,” Keith Pogson, EY’s senior partner for financial services in Asia was quoted by FT as saying. “The template was that if you did one deal and regulators didn’t like it, they told you and you stopped using that format. But if you didn’t get into trouble, then everyone would copy that structure. This has just taken out that certainty of precedent.”