Fidelity National Information Services is buying rival financial software company SunGard to bolster the services it can offer clients.
The deal, which is expected to close in the fourth quarter, is valued at $9.1 billion, if debt is included.
Shares of Fidelity National jumped to an all-time high Wednesday.
SunGard, based in Wayne, Pennsylvania, provides software and other services to financial companies and has annual revenue of $2.8 billion. Jacksonville, Florida-based Fidelity National provides banking and payment technology to financial institutions. The combined company will have more than 55,000 employees, Fidelity National said.
Shares of Fidelity National Information Services Inc. rose $4.89, or 7.5 percent, to $69.96 in afternoon trading Wednesday. Earlier, they touched an all-time high of $70.36.