America has recently signalled a further tightening of regulations on U.S.-listed Chinese companies and warned investors about the potential risks of investing in these companies. The Public Company Accounting Oversight Board (PCAOB) on Sept. 22 approved a new framework that requires  companies not audited by American audit firms (China Concepts Stocks) to disclose more information to help the PCAOB implement the Holding Foreign Company Accountability Act. The framework will become effective upon approval by the U.S. Securities and Exchange Commission (SEC). SEC chairman Gary Gensler stressed in late August, and again on Sept. 14, that if China Concepts Stocks do not abide by the rules and do not allow the United States to review their audit briefs within 3 years, they will be delisted from the U.S. stock market as early as 2024. On Sept. 20, the SEC warned people and institutions who invest in stocks, by pointing out that …