Zynex (NASDAQ:ZYXI – Get Rating) was downgraded by Zacks Investment Research from a “hold” rating to a “sell” rating in a report released on Saturday, Zacks.com reports. According to Zacks, “Zynex, Inc. engineers, manufactures, markets, and sells medical devices for the electrotherapy, and stroke and spinal cord injury rehabilitation markets primarily in the United States. […]