The idea, from the beginning at the SEC, was that insiders should not be allowed to trade on information that is not properly disclosed to the public.

证交会从成立开始就规定,局内人不得利用未公开披露的信息,进行内幕交易

耶鲁公开课 - 金融市场课程节选

Another important distinction in securities regulation is the distinction between insider and outsider.

证券监管另一个重要的划分是,局内人和局外人

耶鲁公开课 - 金融市场课程节选