Currently, consumers must take multiple steps to make their Mastercard credit and debit cards the preferred payment mechanism when using a PayPal wallet for online payments because of PayPal’s practice of prompting consumers to make their checking account the default payment mechanism. A new U.S.–only agreement with Mastercard ends PayPal’s practice. With the change, Mastercard issuers and the Mastercard network will gain transactions at the expense of the Automated Clearing House (ACH) network, which currently settles checking account payments from PayPal wallets. Mastercard cardholders...