The public loves to hate short sellers, the investors who profit from declining securities’ values. Their bad reputation is mostly undeserved. In reality, many provide a valuable service, taking the other side of frauds and bubbles, and generally helping drive prices toward a semblance of fair value. What’s more, they do this despite inherently poor odds: Statistically speaking, the market goes up more than it goes down. A healthy market needs short sellers, and in recent years they have gone mi