I'm going to guess that insider trading is that top 1%, then, or most of it. Some trading on insider knowledge (such as when you sell a stock, depending) is perfectly legal, or at least wholly unpreventable or unprosecutable, of course.

Those in the bottom 99% of investors may still be capturing at least some of the increase in world wealth over time. Then again, maybe not: or not much. I'd have to read the article to know if the answer to that question is there, and I can't afford the extra time, alas.