Score contribution per author:
α: calibrated so average coauthorship-adjusted count equals average raw count
This study develops a stylized model in which a cross-market complementarity (e.g., volume discounts or rewards across categories) provided by a platform plays a role of anti-steering device. The complementarity across markets locks consumers into the platform and makes it hard for individual third-party sellers to divert consumers to direct channels. Accordingly, the platform can profitably raise the commission by increasing the cross-market complementarity. The platform’s incentive to invest in cross-market complementarity is excessive. The application to cross-market merger shows that a merger that generates a cross-market synergy may be harmful to consumers and welfare.