The present invention is generally directed to systems and methods for detecting unauthorized or fraudulent use of stored-value instruments. A stored-value instrument can be any instrument (tangible or intangible) that may be associated with a debit account and/or may otherwise be presented for payment for goods and/or services, used to transfer money, etc. The systems and methods of the invention generally involve processing request activity through a predetermined rule set to ascertain whether the activity is potentially unauthorized or fraudulent. The systems and methods of the invention allow for real-time monitoring of request activity for potentially unauthorized or fraudulent use of stored-value instruments.