Shares of RadioShack plunged on Tuesday after posting dismal first quarter results. The electronics retailer posted a loss of $0.97 a share compared to a loss of $0.28 a share in the same period last year. Analysts were expecting RadioShack to post a loss of $0.52 a share for the quarter. Sales slid 13% to $737 million. Comparable store sales -- those stores open a year or more -- were down 14% driven by lower traffic and "soft performance" in its mobile business as consumers went elsewhere for their smartphones and tablets. Strong promotional activities from competitors like Best Buy, Walmart, Target, Amazon as well as the wireless carriers hurt RadioShack's sales and gross margin performance.