Worldpay comprises the bulk of the FIS merchant business, which processes payments for companies.
GTCR's offer prevailed over Advent International, another buyout firm that was also vying for the business, the sources said.
If the negotiations conclude successfully in the coming days, FIS plans to keep a minority stake in the business, the sources said.
FIS, which started in 1968 and serves big financial services corporations, has cut thousands of jobs since the review began.
Chicago-based GTCR manages more than $35 billion in assets and invests across sectors, including financial services.
Persons:
GTCR, Johnson, Kellogg, Shaw, Jana, Anirban Sen, David French, Milana, Greg Roumeliotis, Richard Chang
Organizations:
YORK, GTCR, Fidelity National Information Services, FIS, International, Financial Times, General Electric Co, Toshiba Corp, Jana Partners, Reuters, Black Knight Inc, Global, Service, Thomson
Locations:
Worldpay, Jacksonville , Florida, Chicago, New York