Private equity firm GTCR LLC is in advanced talks to acquire a majority stake in the merchant business of payment processing company Fidelity National Information Services Inc in deal that values the division at between $15 billion and $20 billion, people familiar with the matter said on Monday.

The deal would be the largest in GTCR’s history and would enable FIS to undo its $43 billion acquisition of WorldPay, which it completed four years ago. WorldPay now comprises the bulk of the FIS merchant business.

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, which for the most part comprises of Worldpay, which it bought for $43 billion in 2019.

GTCR plans to finance the deal half through equity financing and half through borrowing, two of the sources said. The sources requested anonymity and cautioned that deal talks could collapse at the last minute.

GTCR and Advent declined to comment, while FIS did not immediately respond to requests for comment.

Reuters