Transaction Systems Architects to Acquire S2 Systems

OMAHA, NE – Transaction Systems Architects, Inc. (Nasdaq: TSAI), a leading global provider of enterprise e-payments solutions, today announced the signing of a definitive agreement to acquire substantially all of the assets of S2 Systems.

S2 Systems is a global provider of electronic payments and network connectivity software with significant presence in Europe, Middle East and Asia-Pacific. S2 Systems has more than 120 active customers and generates nearly half of its revenue from international markets. S2 primarily serves financial services and retail customers, which are homogeneous and complementary to the Company’s target markets.

“We welcome S2′s customers and its talented group of employees to TSA,” said Philip G. Heasley, CEO. “We believe this acquisition will enable us to leverage our combined expertise and strengthen our leadership position in the growing payments industry. The S2 acquisition will expand our presence in important markets and improve our cross-sell opportunities to customers around the globe.”

Under the terms of the agreement, Transaction Systems will acquire substantially all of the assets of S2 Systems in exchange for $35 million in cash, subject to certain holdbacks, and “earn-out” payments based on incremental performance criteria. The Company expects the transaction to be accretive to its financial performance. The acquisition, which has been approved by the boards of directors of both companies, is expected to close in late July 2005 subject to customary closing conditions.

Gregory D. Derkacht, Executive Vice President, will oversee the Company’s integration of S2′s business and key members from the Company and S2 have been identified to ensure effective integration of each functional area. Upon closing, Lynn Holland, S2 System’s Chief Technical Officer, is expected to serve as Vice President with ACI Worldwide.

The acquisition will add talented development and support personnel with open systems expertise and expand TSA’s global presence. S2 facilities in England and Australia will be integrated into ACI Worldwide offices, while other acquired locations will increase the Company’s presence in the Middle East and U.S.

Transaction Systems Architects will hold a conference call at 9:00 a.m. EDT (8:00 a.m. CDT) on June 30, 2005 to further discuss this transaction. Interested persons may access a real-time audio broadcast of the teleconference at: www.tsainc.com/investors.

Portico Capital Securities of Greenwich, CT advised S2 Systems on the transaction.