A transaction processing service operates as an intermediary between acquirers of financial transaction requests and issuing institutions that process the financial transaction requests. The intermediary receives an authorization request generated based on a transaction initiated by a customer at a point of purchase. The intermediary service then determines one or more stored value items that can be applied to the transaction. Stored value items may be determined based on the customer's identity or based on transaction characteristics, such as the point of purchase or the transaction items. The service sends a transaction notification to a mobile device associated with the customer to notify the customer of the available stored value items. The service then applies the stored value items to pay a portion of the transaction amount and initiates a payment process to pay the remainder of the transaction amount.