Best Buy is planning to close all of its roughly 250 smaller-format mobile phone stores, CEO Hubert Joly said to employees Wednesday in an internal memo, which was reviewed by CNBC. From a report: The stores, which are about 1,400 square feet in size compared with Best Buy's bigger boxes of 40,000 square feet, are scheduled to close by the end of May, he said. The mobile stores are almost exclusively located within malls, with a few scattered throughout open-air strip centers. "We feel good about the opportunity to retain customers and transition them to another one of our sales channels," Joly wrote to workers. "85 percent of existing standalone Mobile stores are within three miles of a Big Box store."