S&P's Most Shorted By: CNBC.com News September 27, 2011 at 11:36 AM EDT Shares of Sears and AK Steel have seen a more than 50 percent jump in short-interest since early August. Read More >> Related Stocks: AK Steel Holding Corp First Solar GX Defense Tech ETF GameStop Corp J C Penney Company Inc Lennar Corp Netflix Urban Outfitters Vulcan Materials