Card issuers have massive computer systems that handle transaction processing. These companies also have some very advanced and large scale fraud detection systems.

Every time a credit card is reported as stolen, a huge amount of past data about that card is put into a big database. This database of pre-fraud activity is used in a large algorithm to look for similarities, which can signal the origination of stolen or lost credit card numbers. Since Visa and MasterCard have access to billions of transactions worth of information, they can screen for events that may signal that a business is losing card numbers. Read More »