FleetCor Technologies Inc., the global provider of fuel cards and workforce payment products, has agreed to buy the electronic payment processing company Comdata Inc. from Ceridian LLC and Thomas H. Lee Partners for $3.45 billion. The deal—the biggest in FleetCor’s history—would help the company boost its expansion into virtual payment market.

Ceridian, a portfolio company of funds affiliated with Thomas H. Lee and Fidelity National Financial Inc., is the parent company of Comdata.