Selling certification of private and market information

We consider a monopolistic certifier selling certification services to a partially privately informed seller. The certifier can enable the seller to disclose her private information publicly, as well as gather additional market information about the good's quality publicly. We show that the certifier's optimal contract exhibits maximal disclosure but non-maximal information-gathering. Thus, optimal contracts eliminate private information but not market uncertainty; even though the latter would be costless, it is suboptimal as it requires excessive information rents to the seller. Thus, market inefficiencies remain due to market uncertainty but not due to private information.