Zynex, Inc. engages in the design, manufacture, and marketing of medical devices. It sells electrotherapy medical devices used for pain management and rehabilitation. Read More The company also develops a new blood volume monitor for use in hospitals and surgery centers. Zynex was founded by Thomas Sandgaard in 1996 and is headquartered in Englewood, CO. ZYXI is listed on the OTCQB market tier. OTC market data is provided by OTC Markets Group, Inc (otcmarkets.com).