Arc Capital, the Chinese firm helping former President Donald Trump take his media company public, has been the subject of investigations by federal securities regulators. The Shanghai-based company has been under investigation for misrepresenting shell companies with no products and few employees as growth companies, the Washington Post reported Thursday. Arc Capital has repeatedly helped create or finance companies with little or no revenue or customers and listed office locations that are actually P.O. boxes, according to the Post's review of documents tied to the investigations. Earlier this year, Arc helped create Digital World Acquisition, an investment company that has…