A lender to bankrupt RadioShack Corp (RSHCQ.PK) told a U.S. judge on Friday it was prepared to present a new offer that was a “significant improvement” over a rival proposal that was selected as a winning bidder at an auction this week. Clark’s announcement came at the end of two days of hearings to consider the sale of the company to Standard General, a hedge fund. RadioShack’s advisers declared that Standard General had outbid Salus, RadioShack’s largest creditor, at a four-day auction that concluded Thursday morning.