It’s more difficult to study short-selling than long-only investing simply because of the difference in reporting requirements: short positions don’t show up in 13-F filings. But in November 2012 the EU started requiring funds to file whenever they built up short positions equivalent to 0.5% of outstanding shares, and then file again for every 0.1% change as long as they are above that threshold. Looking at this new data on significant short positions, finance professors Stephan Jank and Esad Smajlbegovic have found that short sellers earned between 5.46% and 7.53%. “The largest group of short-sellers, i.e. hedge funds, generate, on…