Shares of Biomerica Inc. BMRA, -5.05% shot up 13.1% toward a 6-month high in active morning trading Friday, after the medical diagnostic products company said Walmart Inc. WMT, -0.82% will start selling its Aware Breast Self Exam device in about half its stores. Trading volume ballooned to 1.8 million shares, compared with the full-day average of about 57,200 shares. The stock had jumped 8.0% on July 14, after Walmart said it would start selling Aware online, but the discount retail behemoth will now also sell Aware in over 2,400 of its retail stores. Biomerica said the product, which retails for $19.95, should be on Walmart shelves “within weeks.” The stock has rallied 15.2% year to date, while the S&P 500 SPX, -1.20% has dropped 22.9%.