AU Small Finance Bank's business model is built on a fundamental arbitrage: borrowing cheaply through retail deposits and deploying those funds at premium rates to borrowers who are creditworthy but underserved by the formal banking system. This spread business, common to all banks, is executed at AU with specific structural choices that differentiate it from both large private sector banks and peer small finance banks. The liability side of the business — deposits — is the foundation of AU's long-term franchise value. AU raises deposits through its branch network, digital channels, and the distribution reach of its banking correspondents. Fixed deposits, which offer retail customers rates typically 25–50 basis points above large private sector bank rates, have been the primary vehicle for deposit mobilization. This pricing premium reflects both AU's need to establish a new deposit franchise and the reality that AU's customers — semi-urban and small-city depositors — are more rate-sensitive than metros where brand and convenience dominate. As the deposit franchise matures and brand trust compounds, AU's cost of funds should converge toward large bank benchmarks, expanding net interest margins. The CASA ratio — currently in the 23–25% range — is the single most watched metric for AU's business model evolution. CASA deposits are effectively zero-cost (current accounts) or near-zero-cost (savings accounts) liabilities. Large private sector banks like HDFC Bank have historically maintained CASA ratios of 40–45%, giving them structural cost-of-fund advantages. AU's path to HDFC Bank-like profitability runs directly through CASA ratio improvement, and the bank has invested heavily in salary account acquisition, corporate current account programs, and digital savings product features to accelerate this metric. On the asset side, AU's loan book is structured across several segments with distinct risk-return profiles. Vehicle finance — commercial vehicle loans, car loans, two-wheeler and three-wheeler finance — remains the largest segment, contributing approximately 35–40% of advances. This portfolio is secured (vehicles are tangible collateral), but carries higher credit costs than mortgage lending because vehicle values depreciate and repossession and liquidation involve operational costs. AU's underwriting advantage in this segment, built over 25 years as an NBFC, is real: its loan officers understand commercial vehicle borrower cash flows, seasonal patterns, and local transport market dynamics in ways that branch bankers without this specialized background cannot replicate quickly. MSME and business banking loans — working capital facilities, term loans, and business property loans for small enterprises — constitute the second major asset segment. These loans require judgmental underwriting: evaluating business cash flows from bank statements, GST returns, and field visits rather than relying solely on formal financial statements. AU's relationship-based lending model, where branch and field staff maintain ongoing contact with borrowers, enables early identification of stress and proactive restructuring — a risk management advantage over banks that originate remotely and manage collections centrally. The retail banking segment — personal loans, home loans, credit cards — is the newer and faster-growing component of the asset book. Home loans, launched as a natural extension of AU's customer relationships, target borrowers in semi-urban markets where formal sector mortgage penetration is low. The credit card business, while still subscale relative to private sector bank leaders, is strategically important as a customer engagement and cross-sell vehicle: a credit card customer generates fee income, deepens the banking relationship, and provides behavioral data that improves cross-sell conversion. Fee income — from account maintenance, transaction processing, third-party product distribution (insurance, mutual funds), and trade finance — is a growing component of AU's revenue mix. The bank has explicitly targeted fee income as a share of total income as a metric, recognizing that a banking franchise that generates 25–30% of revenue from non-interest sources is structurally more valuable than a pure spread business. Distribution of life and general insurance products through the branch network is particularly attractive: the semi-urban customer base is significantly underinsured, and AU's trusted branch relationships create a natural distribution channel. Treasury operations — managing the investment portfolio of government securities and other instruments that banks are required to hold under SLR norms, and actively managing interest rate and liquidity risk — contribute to overall profitability. AU's treasury function has grown in sophistication alongside the bank's balance sheet, though it remains smaller as a percentage of revenues than at large banks with deeper capital markets operations.