Mannatech, Incorporated, is a multinational firm engaged in multi-level marketing , research, and distribution of glyconutrients. Its stock is traded on the Nasdaq exchange and as of 2006 has a market capitalization of about US $500 million, classifying it as a mid-cap corporation. Mannatech was founded in 1993 by Sam Caster and is headquartered in Coppell, Texas.