American Superconductor Co. (NASDAQ:AMSC – Get Rating) saw a significant decrease in short interest in May. As of May 31st, there was short interest totalling 640,700 shares, a decrease of 5.8% from the May 15th total of 680,000 shares. Based on an average daily volume of 163,000 shares, the days-to-cover ratio is presently 3.9 days. […]