M&A advisory and the merger review process

Two firms propose a merger to the antitrust authority. They are uninformed about the efficiencies generated by the merger, but can hire an expert to gather information on their behalf. The authority is also uninformed about the merger's efficiencies, but can run a costly internal investigation to learn them. We analyze the effect of the disclosure of the expert's contract on consumer welfare, and show that consumers are not necessarily better off with disclosure. This possibility result hinges on a free-riding problem between expert and authority in the information acquisition game, and is more relevant in highly competitive industries.