MasterCard announced Friday that it is conducting an ongoing investigation into a possible breach of cardholder data at Global Payments, one of the company’s payment processors. “MasterCard’s own systems have not been compromised in any manner,” a spokesman for MasterCard said. Visa is also reportedly affected by the breach. The possible extent of the breach at Global Payments has not yet been determined, but it could involve up to 50,000 cardholders. The breach was first reported Friday by the blog Krebs On Security.