Platform-based information sharing among competing firms presents challenges for antitrust authorities, yet effective remedies remain unclear. Drawing inspiration from the Informed Sources retail gasoline antitrust case, we develop a theoretical model that offers policy guidance for disrupting anticompetitive coordination facilitated through price-sharing platforms. Removing only one firm from a platform may be ineffective for disrupting such coordination. However, competitive benefits can emerge if (i) at least two firms lack platform access, and (ii) the costs of price leadership are sufficiently high. More broadly, coordinating price increases becomes more difficult when multiple firms cannot quickly observe or respond to rivals' prices.

Using a natural experiment from a retail gasoline antitrust case, we study how asymmetric information sharing affects oligopoly pricing. Empirically, price competition softens when, following case settlement, information sharing shifts from symmetric to asymmetric, with one firm losing access to high-frequency granular rival price data. We provide theory and empirics illustrating how strategic ignorance creates price commitment, leading to higher price-cost margins. Using a structural model, we find substantial profit-enhancing effects of asymmetric information sharing. These results provide a cautionary tale for antitrust agencies regarding the potential unintended consequences of limiting price information sharing among firms.