This filter scans for repeated use of the same credit card account number. The specified action is taken when the account number is used a fifth time within a three-day (72-hour) period.
When triggered, this filter performs the action specified only on the transaction that triggered the filter. This filter does not retroactively hold or reject the previous four transactions.
In the risk management industry, velocity is a term that refers to the frequency in which an event occurs. Velocity could indicate that a fraudster is making repeated attacks on a system.
Fraudsters often make multiple purchases or attempts with a single account number within a short time period in order to "crack the system." A fraudulent credit card user may repeatedly attempt a transaction with the same card number in order to discover the card's valid billing address or card security code, or more simply the fraudster may attempt to make many small purchases to bypass item or price ceiling filters.
When set to Review, the Account Number Velocity filter sets aside the transaction so you can review it more closely, as well as track the preceding four transactions. Even though these preceding transactions have already passed through the filters, you should still review them and take action on them as needed.