One of the two banks suing Target and security vendor Trustwave over responsibility for one the largest data breaches in history has pulled out of the lawsuit.
Trustmark National Bank, of New York, filed a notice of dismissal of its claims on Friday in U.S. District Court for the Northern District of Illinois.
It had joined Green Bank of Houston in the class-action suit, which claims Target and Trustwave failed to stop the theft of 40 million payment card details and 70 million other personal records.
The suit may have wrongly named Trustwave as one of Target's IT security contractors. After the suit was filed on March 24, Trustwave said it would not comment on pending litigation and customarily does not identify its customers. Many agreements with IT vendors and customers are confidential.
But on Saturday, Trustwave's Chairman and CEO Robert J. McCullen added more clarity by writing a letter on its website saying Target did not outsource its data security or IT obligations to the company.
"Trustwave did not monitor Target's network, nor did Trustwave process cardholder data for Target," McCullen wrote.
Lawyers for Trustmark and Green Bank did not respond to an email asking for comment. It was unclear if Green Bank might take similar action or amend the suit. Trustmark could refile the suit and drop Trustwave as a plaintiff.
The lawsuit was notable for its aim to widen the circle of responsibility for a data breach, which burden banks with the cost of reissuing cards. The suit, which asks for a jury trial, seeks unspecified compensatory and statutory damages.
It was not clear from the class-action suit why the bank thought Trustwave was a supplier for Target, although the company has a large business advising companies on compliance issues related to payment card data.
The suit alleged that Trustwave scanned Target's network on Sept. 20, 2013, and told Target no vulnerabilities were found. It further maintained that Trustwave failed to bring Target's systems up to industry standards.
Card companies such as Visa and MasterCard require vendors to comply with PCI-DSS, which is a set of recommendations for preventing the loss of cardholder data.
Both Target and Neiman Marcus confirmed malicious software on their point-of-sale (POS) systems intercepted data after payment cards were swiped while it was briefly held unencrypted in the device's memory.