Banks make most of their money the old-fashioned way: by charging borrowers more interest than they pay depositors. Interest on loans generates about 69% of all U.S. bank revenue. In the fourth quarter of 2025, FDIC-insured banks earned $193.7 billion in net interest income and $85.7 billion in noninterest income, for a combined $279.4 billion in net operating revenue.1Federal Deposit Insurance Corporation. FDIC Quarterly Banking Profile Fourth Quarter 2025 Everything else — account fees, card interchange, mortgage servicing, investment banking, trading — fills in the remaining third.
Interest on Loans Is the Main Engine
Banking’s core business hasn’t really changed in centuries. Pay depositors one rate, charge borrowers a higher rate, keep the difference. That gap is the net interest margin, and it reached 3.39% across the industry in the fourth quarter of 2025, the highest level since 2019.2Federal Deposit Insurance Corporation. FDIC Quarterly Banking Profile Fourth Quarter 2025 Three percentage points sounds thin. Applied across trillions of dollars in outstanding loans, it isn’t.
Consider a single loan. A bank pays 4% on a certificate of deposit and lends the same money to a homebuyer at 7%. On a $300,000 mortgage, that three-point spread throws off roughly $9,000 a year in gross interest income. Multiply that logic across a portfolio of mortgages, auto loans, credit cards, and commercial lines, and the scale becomes clear. The Truth in Lending Act requires banks to disclose the annual percentage rate on every loan, which lets borrowers compare costs and also shows exactly how much income the bank stands to collect.3Consumer Financial Protection Bureau. 12 CFR Part 1026 Regulation Z – General Disclosure Requirements
The mix of loan types matters. Commercial and business loans carry higher rates than residential mortgages because businesses default more often and their collateral is harder to liquidate. Credit cards sit at the top, often 20% or more, because the debt is unsecured. Each product occupies a different slot on the risk-return scale, but they all feed the same interest income line.
To keep this engine running, banks track their loan-to-deposit ratio, meaning the share of deposits actively out on loan. The median ratio at small banks has climbed from around 60% in the late 1980s to roughly 80% in recent years.4Federal Reserve Bank of Philadelphia. Banking Trends: The Rise in Loan-to-Deposit Ratios – Is 80 the New 60 Federal liquidity rules cap how aggressively banks can push that ratio, requiring them to hold enough high-quality liquid assets to cover stressed cash outflows.
Why Interest Rates Shape Bank Profits
The Federal Reserve’s target rate acts as a thermostat for the whole system. As of early 2026, that target sits at 3.5% to 3.75%.5Board of Governors of the Federal Reserve System. The Fed Explained – Accessible Version When the Fed raises rates, banks can charge more on new loans and on existing variable-rate debt like commercial credit lines and adjustable-rate mortgages. What they pay depositors rises too, but historically at a slower pace. That lag is where the extra profit lives.
During the 2015–2018 tightening cycle, net interest margins widened as rates climbed. For every 1 basis point increase in the fed funds rate, margins expanded by about 0.2 basis points, because loan income rose faster than deposit costs.6Board of Governors of the Federal Reserve System. Changes in Monetary Policy and Banks Net Interest Margins – A Comparison across Four Tightening Episodes Commercial and industrial loans with floating rates repriced upward almost immediately, while savings account yields moved slowly.
The reverse happens when rates fall. Loan income drops with the market, but banks can only cut deposit rates so far, because no one accepts a negative yield on their savings. That squeeze is why bank earnings tend to suffer in prolonged low-rate environments, and why bank stocks often jump on rate-hike news.
Mortgage Origination and Servicing
Banks don’t hold every mortgage they write. Many follow an “originate to distribute” model: underwrite the loan, collect the origination fee, then sell the mortgage to a government-sponsored enterprise like Fannie Mae or Freddie Mac. Selling frees up capital almost immediately, which the bank turns around and lends to the next borrower.
Even after the sale, the originating bank usually keeps the servicing rights, meaning the job of collecting monthly payments, managing escrow, and handling delinquencies. That work carries a servicing fee of at least 25 basis points of the unpaid principal balance for conventional mortgages sold to Fannie Mae or Freddie Mac, and between 19 and 69 basis points for government-backed loans pooled into Ginnie Mae securities.7Ginnie Mae. Servicing Transcript On a $300,000 mortgage, 25 basis points equals $750 a year, and it recurs for the life of the loan.
Banks record these servicing rights as assets and collect the associated cash flows for as long as they continue performing the duties.8Federal Housing Finance Agency. Valuation of Mortgage Servicing Rights for Managing Counterparty Credit Risk A single mortgage can generate revenue three separate ways: origination fees at closing, the interest spread while the bank holds the loan, and servicing income for years after selling it.
Account and Service Fees
Fee line items look small individually. Multiplied across millions of accounts, they add up. Monthly checking account maintenance fees run from about $5 to $35, though most banks waive them for customers who keep a minimum balance or set up direct deposit.9Federal Deposit Insurance Corporation. Deposit Products A $12 monthly fee that never gets waived is $144 a year per account.
Overdraft and NSF Fees
Overdraft and non-sufficient fund charges have historically been one of the most profitable fee categories. Before the pandemic, many large banks charged $34 to $37 per occurrence, and overdraft revenue across the industry topped $12 billion a year. That picture has shifted. By 2023, total overdraft and NSF revenue had dropped more than 50% from pre-pandemic levels, saving consumers over $6 billion annually, as major banks cut fees or eliminated them under public pressure and regulatory scrutiny.10Consumer Financial Protection Bureau. Overdraft NSF Revenue in 2023 Down More Than 50 Percent Versus Pre-Pandemic Levels The average overdraft fee dropped to about $27 by 2025, though some banks still charge as high as $37.
The CFPB finalized a rule in late 2024 that would have capped overdraft charges at $5 for banks with over $10 billion in assets, but Congress repealed the rule before it took effect.11Congress.gov. Congress Repeals CFPB Overdraft Rule A separate CFPB rule capping credit card late fees at $8 for large issuers remains stayed by a federal court.12Consumer Financial Protection Bureau. Credit Card Penalty Fees Final Rule For now, overdraft and late fee amounts are set by individual banks, not federal caps.
Wire Transfers, Cashier’s Checks, and ATMs
Domestic outgoing wire transfers typically cost $25 to $30, with some banks charging up to $40 for in-branch service. International wires often run $40 to $50. Cashier’s checks and money orders carry smaller fees, usually $5 to $15.
Out-of-network ATM withdrawals cost an average of about $4.86 per transaction, split between a surcharge from the machine’s owner and a fee from your own bank. Someone hitting an out-of-network ATM twice a week spends over $500 a year on withdrawal fees alone.
Card Interchange
Every card swipe at a store generates a small fee paid by the merchant, not the consumer. The bank that issued your card collects the bulk of this interchange fee. On the Visa network, credit card interchange ranges from about 1.18% for basic cards used at supermarkets up to 3.15% for premium cards or transactions that don’t qualify for lower tiers.13Visa USA. Visa USA Interchange Reimbursement Fees Other networks set their own schedules in comparable ranges.
Debit is different. The Durbin Amendment caps debit interchange for banks with more than $10 billion in assets at 21 cents plus 0.05% of the transaction, with an additional 1-cent fraud-prevention adjustment.14Office of the Law Revision Counsel. 15 USC 1693o-2 – Reasonable Fees and Rules for Payment Card Transactions Smaller banks are exempt and can charge higher rates. The Federal Reserve proposed lowering the cap in late 2023 to 14.4 cents plus 4 basis points, but that proposal has not been finalized.15Federal Register. Debit Card Interchange Fees and Routing The 21-cent cap remains in effect.
Even with the debit cap, the sheer volume makes interchange a substantial revenue line. Foreign transaction fees add another 1% to 3% on international purchases, going entirely to the card issuer. As consumers keep shifting from cash to cards, interchange revenue grows without the bank taking on any lending risk.
Advisory, Investment Banking, and Trading
Large universal banks don’t stop at deposits and loans. Their investment banking divisions earn fees helping companies raise capital, merge, and navigate public markets. When a company goes public, underwriting banks typically collect 5% to 7% of the total capital raised. On a $500 million offering, that’s $25 million to $35 million for a single deal. Debt issuance earns similar commissions at lower percentages. Mergers and acquisitions advisory earns success fees paid at closing, often as a percentage of deal value.
Wealth management divisions charge annual fees based on assets under management, typically around 1% for portfolios under $1 million and declining above that. Because these fees track market valuations rather than credit risk, they provide relatively stable income across rate cycles.
Banks that run trading desks earn revenue from market-making, meaning quoting both buy and sell prices for securities and profiting from the bid-ask spread. In the most liquid markets like government bonds, margins per trade are razor-thin, so profitability depends on volume and rapid inventory turnover.16Bank for International Settlements. Market-Making and Proprietary Trading – Industry Trends Drivers and Policy Implications Trading revenue is volatile, but it gives large banks a stream completely independent of consumer banking.
Disputing a Fee You Think Is Wrong
Banks have strong incentives to charge fees. Federal law gives you tools to push back when a charge is wrong, and the rules differ by transaction type.
For electronic fund transfers — debit card charges, ATM withdrawals, direct deposit errors, and overdrafts — Regulation E requires your bank to investigate any error you report within 60 days of the statement date. The bank has 10 business days to complete its investigation and one business day after that to correct any error it finds. If it needs more time, it can extend to 45 days, but only if it provisionally credits your account within 10 business days so you aren’t out the money while waiting.17eCFR. 12 CFR 1005.11 – Procedures for Resolving Errors If the bank concludes no error occurred, it must explain its findings in writing and tell you how to request the underlying documents.
Credit card billing disputes fall under the Fair Credit Billing Act, which requires card issuers to acknowledge your complaint promptly and investigate billing errors without damaging your credit standing during the process.18Federal Trade Commission. Fair Credit Billing Act Creditors must also post payments promptly and either refund overpayments or credit them to your account. If a fee looks wrong, dispute it quickly. Missing the 60-day window for electronic transfers or the billing cycle deadline for credit cards can cost you the right to a formal investigation.