The agreement, approved by both boards, has an enterprise value of approximately $263 million, which includes the redemption of Online Resources' preferred stock.

Online Resources provides electronic banking and bill payment technology to more than 1000 financial institutions and billers. The company processes over 245 million bill payment transactions annually.

The pro forma financial implications of the transaction are "compelling", says ACI, with annual cost savings of around $19.5 million. The deal is expected to be accretive to full year non-GAAP earnings in 2013.

Philip Heasley, president and CEO, ACI Worldwide, says: "Online Resources' robust product set and talented employee base of online banking and payment experts is well-aligned with this focus and our desire to lead in a category undergoing accelerating change."

ACI will commence a cash tender offer to purchase all outstanding shares of common stock of Online Resources no later than 15 February and the deal is expected to close by the end of the quarter.