lt's been awhile since we posted our lists of the stocks with the highest and lowest short interest, so below we provide an update of the numbers. As shown, First Solar (FSLR) is the S&P 500 stock currently with the highest short interest as a % of float at 30.87%. Mylan (MYL) ranks second at 26.1%, followed by AIG (25.92%), SHLD (24.16%), ZION (22.53%), and EK (21.92%). In a declining market, highly shorted stocks usually underperform, while in a rising market, they typically outperform since they not only have buyers but short coverers. Stocks with very low short interest typically hold up better during declining markets, but most are low beta names that won't outperform during a rising market.