When imperfect collusion is profitable

This paper studies cartel stability under the assumption that member firms can choose intermediate degrees of collusion as well as the joint-profit-maximizing solution in determining the quota to be produced by each firm. After showing that firms can increase the number of participants by decreasing the degree of collusion, I prove that individual members' profits are maximized when firms choose a (possibly low) degree of collusion such that all firms in the industry want to take part in the cartel. More precisely, if the number of firms in the industry is four or less, then all of them want to take part in the cartel even if the maximum degree of collusion is chosen (i.e., the monopoly output is produced); if the number of firms is greater than four, firms will still create an industry-wide cartel but they will produce a higher quantity than the monopoly output.