Mark Douglas was a renowned author and educator in the financial trading community, most famous for his work in the field of trading psychology. His most notable books include "The Disciplined Trader: Developing Winning Attitudes," published in 1990, and "Trading in the Zone: Master the Market with Confidence, Discipline, and a Winning Attitude," published in 2000. Douglas's writings focus on understanding and overcoming the psychological barriers that prevent traders from achieving success in the markets. He explores how traders' beliefs and mindset can shape their decision-making processes and often determine their level of success or failure in trading. His work has had a significant influence on traders and investors seeking to improve their mental approach to the financial markets. Mark Douglas passed away in 2015, leaving behind a legacy as one of the leading voices on the psychology of trading.