CardSystems Solutions was a credit card processing company. In June 2005, the fact that 40 million credit cards had been stolen from CardSystems was discovered. This led to the discoveries that CardSystems had been keeping data in unencrypted form that it was contractually obligated to delete, and that its own network was vulnerable to infiltration by hackers. Visa and American Express subsequently dropped it as a credit card processing company. CardSystems was acquired by Pay By Touch. The buyout was completed on December 9, 2005. On March 19, 2008, Pay By Touch shut down.
At the time it was the largest computer hack in history. The hack would be surpassed by the Albert Gonzalez hacks in 2007 of TJX Companies in which 45.6 million cards were hacked and Heartland Payment Systems in which 130 million cards were hacked.