How Banks Make Money
Banks make money primarily through the spread between what they pay to borrow money (deposits and wholesale funding) and what they charge to lend it out — a margin that has historically been protected by limited competition and regulatory barriers.
How It Works
The core of banking profitability is the net interest margin (NIM). A bank takes in deposits at 0.5%, lends mortgages at 7%, and earns the 6.5% difference on the balance. On $100 billion in loans, a 6.5% NIM generates $6.5 billion in net interest income before overhead. This spread is the engine of bank earnings.
Banks also generate significant fee income. Credit card interchange fees (the 1.5 to 3% charged to merchants on every card transaction) flow to the card-issuing bank. Overdraft fees — charges for spending more than your balance — historically generated enormous revenue, though regulatory pressure has reduced them. Account maintenance fees, wire transfer fees, foreign exchange conversion fees, ATM fees, and loan origination fees all add to the fee income stream.
Investment banking and trading revenue are the third pillar for large banks. JPMorgan, Goldman Sachs, and Morgan Stanley earn significant revenue advising on mergers and acquisitions, underwriting stock and bond offerings, and trading financial instruments for their own accounts. These businesses are more volatile than retail banking but can generate enormous profits during active market cycles.
Wealthmanagement and asset management fees — charging clients a percentage of assets under management for investment advice and portfolio services — are increasingly important for large banks. As interest margins have been compressed in low-rate environments, banks have pushed into fee-based wealth management to diversify revenue.
Why It Matters
Understanding how banks make money explains why specific digital finance innovations threaten them so acutely. Stablecoin yield threatens net interest margin by competing for deposits. Stablecoin payments threaten interchange fee income. DeFi lending threatens loan revenue. Digital wallets threaten the gatekeeper role that generates account fees.
This threat landscape explains the intensity of banking lobbying in Washington. Each piece of financial regulation that permits digital finance to operate freely represents a specific threat to a specific revenue line in the bank income statement.
Real-World Example
A major US regional bank with $100 billion in assets might generate roughly: $4 billion in net interest income (earning 6% on assets, paying 2% on liabilities), $1.5 billion in service and fee income, and $500 million in other revenue — totaling $6 billion annually. If stablecoin competition erodes 10% of deposits (raising funding costs) and 10% of payment fee income, earnings drop by $500-800 million — a 10 to 15% decline that would cause significant stock market reaction and executive compensation impact. This quantifies why banks fight so hard.
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How Banks Use Deposits
When you deposit money in a bank, the bank does not keep it in a vault — it immediately puts your money to work by lending most of it to other customers at much higher interest rates, keeping only a small fraction in reserve.
Why Banks Pay Almost No Interest
Banks pay near-zero interest on checking and savings accounts because consumers historically had no convenient alternatives, and because banks have large overhead costs they cover by keeping the spread between deposit rates and lending rates as wide as possible.
Why Banks Are Worried About Stablecoins
Banks see stablecoins as a direct competitive threat to their most profitable business lines — specifically the cheap deposits they rely on, the payment fees they collect, and their role as the essential gatekeepers of the financial system.