Fiserv

Fiserv is the bedrock of US payments, processing over 100 billion transactions annually through its banking and merchant networks. With $19B in revenue—nearly nine times that of Adyen—it powers core systems for 1,000+ banks and credit unions. The $22B acquisition of First Data in 2019 made it the largest payments technology company by scale, serving 1 million+ Clover POS merchant locations.