Today’s best managers know that TMX stands for team member exchange and refers to the quality of the relationship between team members. Team members who have high quality relationships with their team members tend to assist each other and share information more than teams with low TMX. Teams with higher TMX tend to have higher positive emotions, such as excitement, enjoyment, satisfaction, and enthusiasm, compared to teams with low TMX. This happens because over time teams become more experienced, and negative emotions are reduced due to familiarity and understanding among team members.
Source: Tse, H. H M., & Dasborough, M. T. 2008, April. A study of exchange and emotions in team member relationships. Group & Organization Management, 33, 194-215.