Fiserv is battling with Amadeus IT Group to acquire payments processor Shift4 Payments, according to Reuters.
Publicly-listed Shift4, which has a market valuation of around $7 billion, has been running a sales process over recent months.
Fiserv and Amadeus have emerged as the main contenders, with final offers to be submitted in the coming weeks, says Reuters, citing sources.
In November, Shift4 CEO Jared Isaacman told shareholders the company was exploring "strategic opportunities and alternatives". Global Payments has previously been named as a suitor.
Shift4, processes over $200 billion worth of annual transactions for more than 200,000 merchants, including restaurants and hotels.