ACI Worldwide Inc. will buy S1 Corp., the companies announcedMonday, and combine their global payments and online bankingpresence.

The deal is a stock and cash blend for about $520 million basedon ACI's stock price as of Friday. Both boards have approved thedeal, the companies said in a statement.

The price is an increase of 42 cents per share over the offerACI had made this summer when it launched a bid for S1 afterthat company had agreed to merge with Fundtech Ltd.

S1's board rejected that ACI offer and said it remainedcommitted to the Fundtech deal, which suddenly ended inmid-September when Fundtech instead was sold to a private equityfirm in Chicago.

S1 isan Atlanta-based provider of online banking and payments softwarewith more than 3,000 clients worldwide. It also is owner of PMSystems Corp., a South Carolina-based provider of online bankingand security services to about 175 credit unions.

ACI Worldwide has U.S. operations based in Elkhorn, Neb., andsaid it provides electronic payments to more than 800 financialinstitutions, retailers and processors globally and financial crimeprevention solutions to more than 160 organizations.

The company said it manages more than $12 trillion a day inwholesale payments and more than 90 billion consumer payments ayear.

“The combined company will have enhanced scale, breadth andadditional capabilities, as well as a complementary suite ofproducts that will better serve the entire spectrum of financialinstitutions, processors and retailers,” said Philip Heasley,president/CEO of ACI.

“With the significant improvements in the transaction terms andconditions, S1's Board of Directors unanimously concluded thatcombining with ACI is in the best interests of S1's stockholders,as it provides a substantial premium for their investment and theopportunity to participate further in this powerful combination,”said John Spiegel, chairman of S1.