Leniency in antitrust investigations as a cooperative game

Leniency programs in antitrust investigations exist in Europe since the late nineties. They cover secret agreements and concerted practices between companies, and provide total or partial immunity to companies reporting evidence. This raises the question of assessing correctly the contribution of each company that take part in a leniency program. This question is formalized within a cooperative game with transferable utility. The resulting game being convex, its core is nonempty and contains the Shapley value in its center. It defines a reference allocation that treats the participants symmetrically. In practice, companies report sequentially leading to allocations that are vertices of the core.