  We consider the robust pricing problem of an advertising platform that
charges a producer for disclosing hard evidence of product quality to a
consumer before trading. Multiple equilibria arise since consumer beliefs and
producer's contingent advertisement purchases are interdependent. To tackle
strategic uncertainty, the platform offers each producer's quality type a menu
of disclosure-probability-and-price plans to maximize its revenue guaranteed
across all equilibria. The optimal menus offer a continuum of plans with
strictly increasing marginal prices for higher disclosure probabilities. Full
disclosure is implemented in the unique equilibrium. All partial-disclosure
plans, though off-path, preclude bad equilibrium play. This solution admits a
tractable price function that suggests volume-based pricing can outperform
click-based pricing when strategic uncertainty is accounted for. Moreover, the
platform prioritizes attracting higher types into service and offers them
higher rents despite symmetric information between the platform and the
producer.
