S1 Responds to ACI's Filing of Preliminary Proxy Materials

S1 Corporation (Nasdaq: SONE) today issued the following statement in response to the filing of preliminary proxy materials by ACI Worldwide, Inc. (Nasdaq: ACIW), to solicit votes in opposition of S1's proposed combination with Fundtech Ltd. (Nasdaq: FNDT):

"The S1 Board of Directors urges S1's stockholders to disregard ACI's voting recommendations and vote for all of the proposals associated with the combination with Fundtech when they receive S1's proxy solicitation material. S1's Board believes that the combination with Fundtech will establish a strong platform to accelerate revenue growth, increase earnings and generate significant value for stockholders.

"On August 2, 2011, S1 announced that its Board of Directors had rejected ACI's proposal to acquire S1 and had affirmed its commitment to S1's pending business combination with Fundtech. The S1 Board, in consultation with its financial and legal advisors, gave careful consideration to each of the proposed terms and conditions of ACI's proposal and determined that ACI's proposal is not in the best interests of S1 and its stockholders.

"S1 has set a Special Meeting of Stockholders for Thursday, September 22, 2011 to consider and vote on proposals related to the combination with Fundtech. S1 stockholders of record as of the close of business on Thursday, August 18, 2011 will be entitled to receive the notice of, and to vote at, the Special Meeting."