RadioShack profit down 30% on costs

Fort Worth, Texas -- RadioShack Corp.'s first-quarter earnings fell 30% amid higher costs and lower margins. The company also lowered the high end of its full-year earnings estimate. RadioShack reported net income of $35.1 million, down from $50.1 million a year earlier. Revenue for the three months ended March 31 rose 2% to $1.06 billion, boosted by 11% growth in mobile devices.