Black and O’Rourke’s scheme was complex, but manipulation of so-called “penny stocks” to defraud Americans, particularly elderly ones, is hardly rare. One study found pump-and-dump schemes cost American investors between $3 billion and $10 billion annually, said James Cox, a professor of securities law at Duke University. “We ought to just shut the penny stock market down,” Cox told Quartz. “It’s a sad, sad part of our economy.”