CardSystems Solutions was a

credit card A credit card is a payment card issued to users (cardholders) to enable the cardholder to pay a merchant for goods and services based on the cardholder's accrued debt (i.e., promise to the card issuer to pay them for the amounts plus the o ...

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 Visa most commonly refers to: *Visa Inc., a US multinational financial and payment cards company ** Visa Debit card issued by the above company ** Visa Electron, a debit card ** Visa Plus, an interbank network *Travel visa, a document that allows ...

and

American Express American Express Company (Amex) is an American multinational corporation specialized in payment card services headquartered at 200 Vesey Street in the Battery Park City neighborhood of Lower Manhattan in New York City. The company was found ...

subsequently dropped it as a credit card processing company. The data breach prompted controversy over regulation and triggered a federal investigation into the incident. CardSystems was acquired by Pay By Touch. The buyout was completed on December 9, 2005. All charges brought by the Federal Trade Commission against the company were settled in February 2006. On March 19, 2008, Pay By Touch shut down. At the time it was the largest computer hack in history.TJX data breach: At 45.6M card numbers, it's the biggest ever - Computerworld - March 29, 2007
The hack would be surpassed by two different Albert Gonzalez hacks discovered in 2007the 45.6 million cards hacked from TJX Companies, revealed in March, and the 130 million cards hacked from Heartland Payment Systems, revealed in July.

References

Defunct financial services companies of the United States {{US-finance-company-stub