The Journal has a nice article about David Einhorn today, making the point that he can move stocks with the sheer power of his disapproval. Not even disapproval, really; a raised eyebrow will suffice, as it did for HerbaLife. Imagine his parenting skills.
But you get the gist: on average (er, median), an Einhorn seal of disapproval lops 4.9% off a company’s market cap in one day, and 13% in a month. You can argue that he is just excellent at picking stocks that are about to drop precipitously, but the repeated one-day success seems like pretty clear evidence that the market is reacting to, rather than independently fulfilling, his predictions.
So, first off: this is a great skill to have! I think that in part because I am very lazy and have always imagined a hedge fund manager’s job as being to come into the office, point at a stock, say “that one,” and go home for the year while the stock he picked makes him rich. I don’t think it works that way, though; stocks tend to move for reasons in the external world unrelated to your simple desire to make yourself rich, so you have to spend your days, like, doing research and stuff. But when your desire to get rich off a stock pick makes it so, that is metaphysically delightful.