Banks earn money by charging interest on loans and paying you less interest on savings

A bank's core business is simple: it borrows money from depositors (you, through your savings account) at a low interest rate, then lends that same money to borrowers at a higher interest rate. The difference between what the bank pays you and what it charges borrowers is called the interest spread, and that spread is the bank's primary source of profit.

When you deposit $10,000 in a savings account earning 0.01% annual interest, the bank pays you $1 per year. That same bank might lend $10,000 to a car buyer at 6% interest, earning $600 per year on that loan. The bank keeps the $599 difference. Multiply that across millions of customers and thousands of loans, and the spread becomes enormous.

This model only works if the bank can reliably collect on its loans. When borrowers default—stop paying—the bank loses money. Banks manage this risk by checking credit scores, requiring down payments, and setting interest rates higher for riskier borrowers. A person with poor credit might pay 12% on a loan while someone with excellent credit pays 4%, because the bank is pricing in the higher chance of default.

Key Takeaways

  • Banks profit from the gap between the interest rate they pay depositors and the rate they charge borrowers, a difference called the interest spread.
  • A bank lends out most of the money you deposit, keeping only a small reserve on hand to cover daily withdrawals.
  • Banks charge fees for services like overdrafts, wire transfers, account maintenance, and late payments, which add significantly to their revenue.
  • Banks invest deposited money in stocks, bonds, and other securities, and keep the returns as profit.
  • When interest rates rise, banks can charge more on new loans while still paying depositors the same low rate on old accounts, widening their profit margin.

How banks use your deposits to make loans

When you deposit money in a checking or savings account, the bank does not lock it away in a vault with your name on it. Instead, the bank treats your deposit as a loan to itself. The bank is now obligated to give you your money back on demand, but in the meantime, it lends most of that money out to other customers.

Banks are required to keep a reserve—a percentage of deposits on hand—to cover customer withdrawals. The Federal Reserve sets minimum reserve requirements, though these have been reduced in recent years. For most deposit accounts, banks must hold roughly 10% in reserve and can lend out the remaining 90%. If you deposit $1,000, the bank keeps $100 available and lends $900 to someone else.

This system works as long as not everyone withdraws their money at once. During a bank run—when many customers try to withdraw simultaneously—a bank can run out of cash even if it has plenty of assets. This is why the Federal Deposit Insurance Corporation (FDIC) insures deposits up to $250,000 per account holder per bank. The insurance protects you if the bank fails, and it also reassures depositors so they do not panic and trigger a run.

Fees are often larger than interest spread profit

Banks charge fees for almost every service beyond basic deposit-taking. These fees often generate more profit than the interest spread itself, especially in a low-interest environment.

Common bank fees include overdraft fees (charged when you spend more than your balance, typically $25 to $35 per transaction), monthly maintenance fees (usually $5 to $15 for checking accounts), wire transfer fees ($15 to $50 depending on direction), ATM fees (charged by banks that are not yours, typically $2 to $3), and late payment fees on credit products. A customer who overdrafts their account three times in a month might pay $105 in overdraft fees alone, far exceeding any interest they earn on their balance.

Banks also charge fees for services that cost them almost nothing to provide. A wire transfer takes seconds to process but costs you $20. A stop-payment order on a check costs the bank minimal effort but costs you $25 to $35. These fees are pure profit with virtually no cost to the bank.

Banks invest deposits in stocks, bonds, and securities

Beyond lending to individuals and businesses, banks invest deposited money in financial markets. A bank might use customer deposits to buy government bonds, corporate bonds, mortgage-backed securities, or stocks. Any returns the bank earns on these investments—dividends, interest, or capital gains—belong to the bank, not to the depositor.

This is where banks take on additional risk. If a bank invests heavily in mortgage-backed securities and the housing market crashes, the bank's investment portfolio loses value. The 2008 financial crisis happened partly because banks invested in complex securities tied to subprime mortgages that defaulted en masse. Banks that had invested heavily in these products failed or required government bailouts.

Banks manage investment risk by diversifying across many asset types and by holding some capital in reserve specifically to absorb losses. Regulators also impose rules on how much risk banks can take and require them to maintain minimum capital levels. These rules exist to prevent banks from gambling with customer deposits.

Interest rate changes shift bank profits dramatically

When the Federal Reserve raises interest rates, banks benefit in a specific way: they can charge more on new loans, but existing savings accounts often stay at the old low rate. A bank that was paying 0.01% on savings accounts before a rate increase might still pay 0.01% on old accounts while charging 7% on new loans. The spread widens, and bank profits rise.

The opposite happens when rates fall. If a bank locked in a 5% mortgage rate for a 30-year loan before rates dropped to 2%, the bank is stuck earning 5% while it might only be paying 0.5% on new deposits. The spread narrows, and profits fall. Banks also face refinancing risk: borrowers with high-rate mortgages may refinance into lower-rate mortgages elsewhere, forcing the bank to replace that income with new loans at lower rates.

This is why bank stocks often rise when the Federal Reserve signals it will raise rates, and fall when rate cuts are expected. Investors understand that higher rates mean wider spreads and higher bank profits.

Credit card companies and payment networks generate separate revenue

Many large banks own credit card divisions, which operate on a different model than deposit-taking. Credit card companies earn money from interchange fees—a percentage of every transaction that merchants pay. When you swipe a credit card at a store, the merchant pays roughly 1.5% to 3% of the purchase to the card network and the card issuer. On a $100 purchase, the merchant pays $1.50 to $3.00, and the bank keeps a portion of that.

Banks also earn interest on credit card balances. The average credit card interest rate is around 20% to 25%, far higher than any loan product. A customer carrying a $5,000 balance at 22% interest pays $1,100 per year in interest alone. Credit card companies also charge annual fees (on premium cards), late fees, and over-limit fees.

Credit card lending is riskier than mortgage lending because there is no collateral—if you stop paying your credit card, the bank cannot repossess anything. Banks price this risk into the high interest rates and fees.

Banks earn money from trading and financial services

Large banks operate trading desks that buy and sell securities, currencies, and derivatives for profit. A trader might buy a stock at $50 and sell it at $52, keeping the $2 spread. Multiply that across thousands of trades per day, and the profits add up. Banks also charge commissions on trades executed for customers.

Investment banking is another revenue stream. When a company wants to go public or issue bonds, it hires an investment bank to manage the process. The bank charges a fee—typically 3% to 7% of the money raised—for underwriting the offering and finding buyers. A company raising $100 million in an IPO pays the bank $3 to $7 million for the service.

Wealth management and advisory services are also profitable. Banks charge fees to manage investment portfolios for wealthy customers, typically 0.5% to 2% of assets under management per year. A bank managing $100 million in customer assets at a 1% fee earns $1 million annually with minimal cost.

Frequently Asked Questions

Do banks actually lend out all the money I deposit?

Banks lend out most of it, not all. Federal Reserve rules require banks to hold a reserve—roughly 10% for most deposit accounts—and keep it available for withdrawals. The remaining 90% can be lent out. If you deposit $1,000, the bank keeps about $100 on hand and lends $900 to other customers.

What happens to my money if the bank fails?

The Federal Deposit Insurance Corporation (FDIC) insures deposits up to $250,000 per account holder per bank. If your bank fails, the FDIC pays you back up to that limit. Amounts over $250,000 are at risk, though in practice large bank failures are rare because regulators intervene early.

Why do banks pay almost no interest on savings accounts?

Banks pay low interest on savings because they can. Depositors have few alternatives for keeping money safe and accessible, so banks face little pressure to raise rates. When the Federal Reserve raises its benchmark rate, some banks eventually raise savings rates, but they lag behind and by smaller amounts than loan rate increases.

Can I earn more interest by moving my money to a different bank?

Yes. Online banks and credit unions often pay higher interest on savings accounts than traditional brick-and-mortar banks because they have lower overhead costs. Rates vary widely—some accounts pay 4% to 5% annual interest while others pay 0.01%. Shopping around for the best rate takes minutes and can earn you hundreds of dollars per year on a large balance.

How do banks decide what interest rate to charge on a loan?

Banks base loan rates on the Federal Reserve's benchmark rate, plus a markup for risk and profit. A borrower with excellent credit and a large down payment might get a rate close to the Fed's rate plus 2%. A borrower with poor credit and no down payment might pay the Fed's rate plus 8% or more. The bank is pricing in the higher likelihood that the riskier borrower will default.