Loyalty discounts can wear different hats: they may function as ordinary price competition or as de facto exclusivity. Courts generally apply cost-based screens under the predatory pricing doctrine when the alleged competitive harm comes from low prices. Loyalty discounts can also become de facto exclusive dealing when they impose switching penalties, lock up demand, or deny rivals the scale necessary to compete. Two-sided transaction platforms after Ohio v. American Express Co. further complicate the loyalty discount doctrine because output is produced only through simultaneous participation on both sides of a platform, and foreclosure on one side may also reduce rivals’ access to the matched transactions necessary to compete on the other side.
This Comment argues that the loyalty discount doctrine is not cleanly applicable in two-sided transaction platforms because traditional price-cost tests may not sufficiently capture exclusionary effects caused by single-homing, routing restraints, and “chicken-and-egg” barriers to entry. Additionally, the Comment proposes a three-step framework that combines cost-based screens, non-price exclusion, and Amex’s instruction that competitive effects in transaction platforms should be evaluated as a whole. Courts should first consider whether the defendant has sufficient market power to make foreclosure plausible. They should then identify the mechanism of exclusion. Specifically, if price is clearly the predominant mechanism, a price-cost screen should be applied; if the challenged arrangement instead functions as de facto exclusivity, a foreclosure-based exclusive-dealing framework would be the more appropriate test. Finally, once exclusion is established, courts should assess competitive effects at the platform level under Amex. This three-step approach upholds the error-cost logic of cost-based rules while allowing courts to identify profitable, above-cost exclusion in two-sided transaction platforms in which denial of scale and matched transactions, rather than profit sacrifice, is the core competitive harm.