Best Buy Co. plans to close all 257 of its stand-alone mobile phone stores in the United States, the company announced Wednesday. All stores, including a location at the Topanga Mall in Woodland Hills, will be shuttered by May 31. The mobile phone stores are much smaller than traditional Best Buy stores. In a Securities and Exchange Commission filing, the electronics retailer cited “changing economics in the mobile industry” since first opening the specialized stores in 2006, as the reason for the closures. It will continue to sell mobile phones at its core retail stores and online. The company on Thursday reported better-than-expected fourth quarter sales in its latest fiscal year. Same-store sales increased 9 percent thanks to a strong holiday shopping season. Excluding the negative impact from last year’s tax reform bill, non-diluted earnings per share were $2.42 for the quarter, up 25 percent from the same quarter a year earlier. Shares of Best Buy (BBY) rose $2.02 or 2.8 percent, to close at $75.06 on the New York Stock Exchange on Monday, a day when the major stock markets increased 1 percent or more.