Network Interventions: Targeting Agents or Targeting Links?

Consider a network game with linear best responses and spillovers between players, and let agents endogenously choose their links. A planner considers interventions to subsidize actions and/or links between players, aiming to maximize a welfare objective. The structure of an optimal intervention is shaped by the intrinsic value that links provide to agents. When this value is non-negative, it is optimal to focus only on subsidizing actions. When it is negative, we give conditions under which it is necessary to include link subsidies. This reverses the basic structure of the optimal intervention in settings with exogenous links.