EXHIBIT 99.1

S1 Corporation Reports Fourth Quarter and Full Year 2010 Financial Results

Revenue Backlog in Payments and Banking: Large FI Segments Increased to
$62.8 Million, a 60% Increase Compared to December 31, 2009

Sales Bookings in Payments and Banking: Large FI Segments Increased to $68.3 Million in Six Months Ended December 31, 2010, a 74% Increase Compared to Six Months Ended December 31, 2009

Generated $37.2 Million in Net Cash From Operations in 2010, a 132% Increase Compared to 2009

Fourth Quarter 2010 Revenue Reduced by $5.0 Million Due to Change in Scope of Custom Project

Introduces 2011 Guidance: Expects to Generate Revenue of $225 to $235 Million and Adjusted EBITDA of $22 to $27 Million

NORCROSS, Ga., March 10, 2011 (GLOBE NEWSWIRE) -- S1 Corporation (Nasdaq:SONE), a leading global provider of payments and financial services software solutions, today announced financial results for the fourth quarter and the full year ended December 31, 2010:

Financial Results and Operating Highlights

• Total revenue decreased 12% to $52.5 million in the fourth quarter of 2010 compared with $59.5 million in the fourth quarter of 2009. As discussed in further detail below, revenue in the fourth quarter was reduced by $5.0 million due to a change in the scope of the project with the international branch customer that is one of our Custom Projects. Total revenue for the year ended December 31, 2010 decreased 12% to $209.1 million from $238.9 million in the year ended December 31, 2009. The decrease in revenue was primarily attributed to a $13.2 million reduction in professional services revenue from State Farm, an $11.6 million reduction in professional services revenue from an international branch customer (collectively, the "Custom Projects"), and the impact of recognizing a lower percentage of software licenses upon delivery due to an increase in projects where revenue is recognized using the percentage of completion method.
• U.S. GAAP net loss was $4.3 million, or ($0.08) per share, in the fourth quarter of 2010 compared with U.S. GAAP net income of $9.9 million, or $0.18 per share (diluted), in the fourth quarter of 2009. U.S. GAAP net loss was $6.3 million, or ($0.12) per share, in the year ended December 31, 2010 compared with U.S. GAAP net income of $30.4 million, or $0.55 per share (diluted), in the year ended December 31, 2009. These figures include stock-based compensation expense of $2.3 million and $1.2 million in the fourth quarter of 2010 and 2009, respectively, and stock-based compensation expense of $3.7 million and $1.6 million in the year ended December 31, 2010 and 2009, respectively.
• Adjusted EBITDA was $0.8 million in the fourth quarter of 2010 compared with $12.5 million in the fourth quarter of 2009. Adjusted EBITDA in the year ended December 31, 2010 was $10.4 million compared with $46.4 million in the year ended December 31, 2009. Adjusted EBITDA does not include stock-based compensation expense and is described below and reconciled to the most directly comparable financial measure calculated and presented in accordance with U.S. GAAP in Tables 4, 5, 6 and 7, provided below.
• Net cash provided by operating activities increased 132% to $37.2 million in the year ended December 31, 2010 compared with $16.0 million in the year ended December 31, 2009. The Company had cash and cash equivalents of $61.9 million as of December 31, 2010.
• Revenue backlog, which is discussed in further detail below, in the Company's Payments and Banking: Large FI segments increased to $62.8 million as of December 31, 2010, an 11% increase compared with $56.7 million as of September 30, 2010 and a 60% increase compared with $39.2 million as of December 31, 2009.
• The Company added 41 new customers in 2010.  
• Notable fourth quarter 2010 contract signings include:

• One of the 20 largest U.S. headquartered commercial bank holding companies for S1's payments solution;
• One of the top 20 banks in the world for S1's Corporate Banking and Trade Finance solutions;
• A top four bank in South Africa for S1's payments solution;
• A top supermarket chain in the United Kingdom for S1's payments solution;
• The leading independent global provider of fleet cards for S1's payments solution; and
• Two of the top five banks in the U.S. for S1's Trade Finance solution.

• In 2011, the Company expects to generate revenue of $225 to $235 million and Adjusted EBITDA of $22 to $27 million. 

Johann Dreyer, Chief Executive Officer, said, "Although our 2010 financial performance was impacted by the transition of our business model and a reduction in revenue from the Custom Projects, the fundamentals of our core businesses were strong as evidenced by the significant increases in revenue backlog, sales bookings, and cash flows.  We ended 2010 with another strong quarter of sales bookings and entered 2011 with a 60% increase in revenue backlog as compared to 2010. With the progress we made in the transition of our business model during 2010, and the greater visibility we have with the increase in revenue backlog, we have resumed providing annual financial guidance."

Custom Projects – International Branch Customer

During the fourth quarter of 2010, the scope of the project with the international branch customer that is one of our Custom Projects increased significantly.  Since we recognize revenue for this project using the percentage of completion method, our revenue in the fourth quarter was reduced by $5.0 million as a result of this change. However, we will recognize this amount as revenue over the remainder of the project, expected primarily in 2011 and 2012. In an effort to reduce the likelihood of any further increases in the scope of this project and accelerate cash flows from this customer, in February 2011 we amended certain agreements with this customer to (i) reduce the scope of the project, and (ii) revise billing milestones.

Conference Call, Webcast and Slide Information

Management will host a conference call to discuss its fourth quarter and full year 2010 results on Friday, March 11, 2011, at 8:30 a.m. ET. Participants may access the call by dialing (877) 899-9075 (United States) or (706) 758-0819 (International) and entering passcode 42730048. Investors also may access a slide presentation and live audio webcast of this conference call by visiting www.s1.com and entering the Investor Relations section under "About S1."

A replay of the webcast will be available approximately two hours after the conclusion of the call. A telephone replay will also be available approximately two hours after the conclusion of the call through March 25, 2011. To access the replay, please dial (800) 642-1687 or (706) 645-9291 and enter passcode 42730048.

Non-GAAP Measures and Reconciliation to U.S. GAAP

Our results of operations are based upon our consolidated financial statements, which have been prepared in accordance with accounting principles generally accepted in the United States of America ("U.S. GAAP"). In addition to U.S. GAAP financial measures, we use non-GAAP measures to evaluate our financial performance, assist management decisions, and in communications with our Board of Directors, stockholders, analysts and investors concerning our financial performance. Although we believe that our presentation of non-GAAP financial measures provides useful supplemental information to investors regarding our results of operations, our non-GAAP financial measures should only be considered in addition to, and not as a substitute for or superior to, our financial measures prepared in accordance with U.S. GAAP. The use of non-GAAP financial measures is subject to inherent limitations because they do not include all the expenses that must be included under U.S. GAAP and because they involve the exercise of management's judgment of which charges should properly be excluded from the non-GAAP financial measure. Management accounts for these limitations by not relying exclusively on non-GAAP financial measures, but only using such information to supplement U.S. GAAP financial results. Our non-GAAP financial measures may be different from such measures used by other companies.

We are presenting Adjusted EBITDA, a non-GAAP financial measure, below and reconciling to the most directly comparable U.S. GAAP equivalent of which is Net income for our consolidated results and Operating income for our segment results. We define Adjusted EBITDA as, in the case of our consolidated results, Net income plus interest and other expense (income), plus income taxes or, in the case of our segment results, Operating income, in each case adjusted for depreciation, amortization of intangibles, and stock-based compensation expense. We believe that excluding depreciation, amortization, stock-based compensation expense, interest and other expense (income) and income taxes provides supplemental information and an alternative presentation useful to investors understanding our core operating results and trends. Not only are depreciation and amortization expenses based on historical costs of assets that may have little bearing on present or future replacement costs, but they are also based on management's estimates of remaining useful lives. Additionally, while stock-based compensation is an important part of overall compensation expense, a portion of our stock-based compensation expense is the result of cash-settled stock appreciation rights that are revalued each quarter for U.S. GAAP earnings based in part on the closing price of our stock on the last day of the quarter. Consequently, fluctuations in our stock price can have a significant impact on our reported U.S. GAAP earnings. See Tables 4, 5, 6 and 7 for reconciliations of non-GAAP Adjusted EBITDA.

We are presenting Cash earnings per share, a non-GAAP financial measure, below and reconciling to the most directly comparable U.S. GAAP equivalent of which is Net income and earnings per share. We define Cash earnings as Net income plus amortization of intangibles, stock-based compensation and deferred income taxes. We calculate Cash earnings per share by adding back the per share impact of adjustments from diluted earnings per share. We believe Cash earnings per share is a useful financial measure which provides supplemental information and an alternative presentation useful to investors understanding trends of our income. Amortization of intangibles is generally expensed over several periods and may not be indicative of current cash expenditures. We believe the exclusion of stock-based compensation provides useful supplemental information to help understand the changes in our earnings per share due to the fluctuations of our cash-settled stock appreciation rights included in stock compensation. We exclude the impact of deferred income taxes on earnings as the temporary differences and the changes in valuation allowances may be misleading for trend analysis. See Table 1 for reconciliation of non-GAAP Cash earnings per share to U.S. GAAP Diluted earnings per share.

We are presenting an estimate of revenue backlog for our Payments and Banking: Large Financial Institution segments which is defined as an estimate of revenue for software licenses, including term licenses, professional services, and hosting services, in each case as specified in executed contracts that we believe will be recognized in revenue over the next 12 months. The portion of the estimate from our Banking: Large Financial Institution segment does not include revenue associated with the Company's Custom Projects. We believe that presenting this estimate provides supplemental information and an alternative presentation useful to investors understanding trends in our business including the shift we are experiencing toward recognizing more software license revenue using the percentage of completion method.

Our estimate of revenue backlog requires substantial judgment of our management, is based on a number of assumptions, which may turn out to be inaccurate or wrong, and is subject to a number of factors and uncertainties, many of which are outside of our control. Such assumptions, factors and uncertainties include, but are not limited to, the following:

• Revenue for term licenses and hosting services are the annualized amount expected over the next 12 months as of the date presented;
• Foreign currency exchange rates are assumed to remain constant over the 12 month period for contracts stated in currencies other than the U.S. Dollar;
• Perpetual licenses and professional services are based on current estimates of project completion over the next 12 months;
• Our customers may attempt to renegotiate or terminate their contracts for a number of reasons, including mergers, changes in their financial condition or general changes in economic conditions within their industries or geographic locations;
• We may experience delays in the development or delivery of products or services specified in customer contracts; and
• Our estimate is based on constant hosting transaction volumes, and changes in hosting transaction volumes may impact the amount of revenue actually recognized in future periods.

Estimates of future financial results are inherently unreliable. Accordingly, there can be no assurance that the amounts included in our estimate of revenue backlog will be recognized over the next 12 months, or at all. Additionally, because our estimate of revenue backlog is an operating metric, it is not subject to the same level of internal review or control as a U.S. GAAP financial measure.

About S1 Corporation

Leading banks, credit unions, retailers, and processors need technology that adapts to the complex and challenging needs of their businesses. These organizations want solutions that can respond quickly to changes in the marketplace and help grow their businesses.  For more than 20 years, S1 Corporation (Nasdaq:SONE) has been a leader in developing software products that offer flexibility and reliability. Over 3,000 organizations worldwide depend on S1 for payments, online banking, mobile banking, voice banking, branch banking and lending solutions that deliver a competitive advantage. More information is available at www.s1.com.

Forward-Looking Statements

This press release contains forward-looking statements within the safe harbor provisions of the Private Securities Litigation Reform Act. These statements include statements with respect to our financial condition, results of operations and business. The words "believes," "expects," "may," "will," "should," "projects," "contemplates," "anticipates," "estimates," "forecasts," "intends" or similar terminology identify forward-looking statements. Forward-looking statements may include projections of our revenue, expenses, Adjusted EBITDA, revenue backlog, capital expenditures, earnings per share, product development projects, future economic performance or management objectives. These statements are based on our beliefs as well as assumptions made using information currently available to us. Because these statements reflect our current views concerning future events, they involve risks, uncertainties and assumptions. Therefore, actual results may differ significantly from the results discussed in the forward-looking statements. The risk factors included in our reports filed with the Securities and Exchange Commission (and available on our web site at www.s1.com or the SEC's web site at www.sec.gov) provide examples of risks, uncertainties and events that may cause our actual results to differ materially from the expectations we describe in our forward-looking statements. Except as provided by law, we undertake no obligation to update any forward-looking statement for any reason, even if new information becomes available.

CONTACT: Investor Contact:
         Paul M. Parrish
         Chief Financial Officer
         404.923.3500
         paul.parrish@s1.com