Four listed companies announced on Friday that their independent director Song Chang is under investigation by the China Securities Regulatory Commission for suspected insider trading and short-swing trading. Song is a professor at Renmin University of China, who has been called "the busiest independent director" by the media, because he has been an independent director of more than 10 listed companies in the past.

1月22日，四家上市公司发布公告称，他们的独立董事宋常因涉嫌内幕交易和短线交易被证监会立案调查。宋常是中国人民大学的教授，曾因担任十多家上市公司的独立董事，被媒体称为“最忙独董”。

“最忙独董”（the busiest independent director）宋常因同时担任多家横跨多个行业及地区上市公司的独立董事，而被广泛质疑。董事分为执行董事（executive director）和“独董”（independent director），也称外部董事（outside director），是独立于公司股东且不在公司内部任职，与公司或公司经营管理者没有重要的业务联系或专业联系，并对公司事务作出独立判断的董事。