It made headlines around the world: a New Jersey sandwich shop with a soaring stock price. Was it just speculation, or something stranger? To hear more audio stories from publications like The New York Times, download Audm for iPhone or Android. In a letter to his investors this April, David Einhorn, founder of the hedge fund Greenlight Capital and a well-known short-seller, complained that the stock market was in a state of “quasi anarchy.” As one piece of evidence, he pointed to Elon Musk, whose commentary on Twitter, Einhorn said, amounted to market manipulation.