Your herbal supplements might be a sham By: MarketWatch February 03, 2015 at 09:30 AM EST Tests on some store-brand supplements from Target, Wal-Mart, GNC and Walgreen’s are unable to confirm plant materials on the labels 79% of the time. Read More >> Related Stocks: GNC Holdings Inc Target Corp Wal-Mart Stores, Inc. Walgreens Boots Alliance