ADVISORY/S1 Corporation Announces Catalyst 2002 Global Customer Forum in Atlanta.

Business Editors

ADVISORY...for Sept. 30 - Oct. 3, 2002 (Monday - Thursday)

--(BUSINESS WIRE)

Citizens Business Bank, JP Morgan, PNC Bank, Swiss

Reinsurance and U.S. Bank Among Others to Drive Industry

Dialogue and Share Best Practices

    Who:   S1 Corporation, (Nasdaq: SONE), a leading global provider
           of Enterprise solutions for the financial services industry

    What:  Catalyst 2002 Customer Forum, themed "Potential. Progress.
           Payoff." This forum will equip S1 customers with information
           on the measurable value of their current systems and how to
           execute short- and long-term integration strategies. Most
           importantly, participants will gain insight into how they
           can obtain a single holistic view of each customer that will
           empower them to solidify profitable relationships across all
           market segments.

    Where: Westin Peachtree Plaza, Atlanta, Ga.

    When:  September 30 - October 3, 2002

Catalyst 2002 will address issues facing institutions of all sizes and lines of business - How can I leverage customers' financial information, trends and demographic data to better market my institution's products and services? How can J2EE, Web Services and SOAP technologies help my institution offer consistent, personalized services to customers across multiple delivery channels? How can I better achieve return on my technology investments?

The forum will kick off with a presentation on "Harnessing, Delivering and Integrating Information Across Your Enterprise," by Jaime Ellertson, CEO of S1 Corporation. Keynote speakers featured on Wednesday, October 2 are Mark Lewis, vice president, financial services sector, Americas for IBM, and Cigdem Oktem, director of The Council on Financial Competition, who will present, "Two Perspectives - One Goal: Unrivaled Customer Loyalty."

Dr. Buzz Aldrin, renowned scientist and astronaut, will host Catalyst's closing session, "Steer for the Stars." With his stories of space adventures and his unique vision of the future, Dr. Aldrin ignites his listeners with the desire to push their potential and put their greatest aspirations into action.

The event will offer educational sessions and roundtables that focus on six different subject tracks: branch banking, online retail banking, online business banking, CRM, voice solutions, insurance and general topic sessions focused on how institutions can create meaningful interactions with their customers.

Catalyst will also feature sessions led by industry visionaries from financial institutions and industry analysts, including:

    --  John Collins, Vice President B2B Internet Window, U.S. Bank,
        "The Promise of J2EE";

    --  Rico Iacchetti, VP eCommerce, PNC Bank, "Winning the Battle
        for Small Business Customers";

    --  Adam Holt, Senior Analyst, JP Morgan - Equity Research,
        "Emerging Trends in Financial Services Technology"; and

    --  Marita Barker, Vice President, Citizens Business Bank and Elsa
        Zavala, Senior Vice President, Citizens Business Bank,
        "Turning Business Customer Interactions into Profits."

For registration information, please visit www.s1catalyst.com or contact Priscilla Cross, S1 Corporation, 404-923-3500. Attendees who register by August 30, 2002 will receive a $100 Early Bird discount.

For media inquiries, please contact Christopher Rogers, Sterling Hager, Inc., 617-393-4285.

About S1 Corporation

S1 (Nasdaq: SONE) is a leading global provider to more than 3,800 banks, credit unions, insurance providers, and investment firms of enterprise software solutions that turn customer interactions into profits. S1's Enterprise software solutions deliver a transactionable, customer-centric view across all delivery channels, resulting in a more compelling experience for the customers and a more profitable relationship for the financial institution. S1 is the only provider with the proven experience, breadth of products, and financial strength to empower financial services companies' Enterprise strategies. Additional information about S1 is available at www.s1.com.

Forward-Looking Statements

This press release contains forward-looking statements relating to results of operations; product features and benefits; market penetration and market strategies. Such statements are made based on management's beliefs as well as assumptions made by, and information currently available to, management, pursuant to "safe-harbor" provisions of the Private Securities Litigation Reform Act of 1995. While these statements reflect our best judgment, they are subject to risks and uncertainties that could cause a change in focus and direction. A discussion of certain risk factors that may cause actual results to differ from these forward-looking statements can be found in S1's Annual Report on Form 10-K for the period ended December 31, 2001, on file with the SEC.