Nu Holdings (Nubank) is a digital-only financial services platform operating in Brazil, Mexico, and Colombia, serving over 131 million customers with no physical branches. Nubank started as a no-annual-fee, Mastercard-branded credit card managed entirely through a mobile app, and has since expanded into deposit accounts, personal loans, investments, insurance, and SME banking products. Brazil is the dominant market, representing roughly 91% of revenue, where Nubank has reached approximately 62% of the Brazilian adult population. Mexico is the primary growth frontier, with 14 million customers, and Colombia remains the earliest-stage market with 4 million customers. Nubank earns money primarily through net interest income on its credit portfolio, funded almost entirely by retail deposits gathered organically through the app, along with interchange fees, brokerage commissions, and other service fees. Customer acquisition is largely organic and word-of-mouth, keeping acquisition costs near zero. Nubank uses a proprietary machine learning-based credit engine and a "low-and-grow" underwriting approach — starting customers at low credit limits and expanding as behavioral data accumulates. A key metric is monthly average revenue per active customer (ARPAC), currently around $15/month versus $40+ for incumbent Brazilian banks, which Nubank views as its core monetization opportunity. The company's cost to serve is roughly $0.80 per active customer per month, enabled by its cloud-based, branchless model. Growth strategy centers on deepening monetization in Brazil, scaling Mexico following receipt of a full banking license, expanding into secured lending, and developing a proprietary AI foundation model ("nuFormer") trained on its transaction data to improve credit underwriting across all markets.