We analyze the efficiency defense in merger control. First, we show that the relationship between exogenous efficiency gains and social welfare can be non-monotone. Second, we consider both endogenous mergers and endogenous efficiencies and find that merger proposals are largely aligned with a proper social welfare analysis which explicitly considers the without merger counterfactual. We demonstrate that the merger specificity requirement does not help much to select socially desirable mergers; to the contrary, it may frustrate desirable mergers inducing firms not to claim efficiencies at all.
Horizontal Mergers Efficiency Defense Merger Specific Efficiencies