Are leniency programs too generous?

I present a simple model of collusion in which the competition authority offers leniency rates contingent on the number of firms that report information. The optimal leniency policy involves what I refer to as a single informant rule-that is, leniency should be given only when a single firm reports information. The single informant rule allows to increase expected sanctions compared to the first informant rule, which overall improves cartel deterrence.