Square / Block

Square, now under Block Inc, generates $21B in revenue—40% more than Stripe—making it the largest fintech conglomerate on this list. Cash App alone has 57 million monthly active users, processing over 1 billion transactions per quarter. CEO Jack Dorsey's $500M Bitcoin treasury underscores Block's crypto-first strategy, while the $29B acquisition of Afterpay cemented its BNPL dominance. Square's Clover POS system competes directly with Fiserv's Clover, but its unified merchant and consumer ecosystem sets it apart. With revenue growth averaging 25% year-over-year, Square outperforms #5 Stripe in diversification, blending payments, banking, and investing into a single platform.