Banks lend out most of the money you deposit, and keep the difference between what they pay you and what borrowers pay them

When you deposit money into a checking or savings account, the bank does not lock it in a vault with your name on it. Instead, the bank uses that money to make loans to other customers—mortgages, car loans, business lines of credit, credit cards. You earn interest on your deposit (often very little). The borrower pays interest on the loan (much more). The bank keeps the spread as profit.

This is the core business of retail banking. A bank that takes in $100 million in deposits might lend out $85 million of it, keeping $15 million as a reserve. If depositors earn 0.5% annually and borrowers pay 6% on a mortgage, the bank earns roughly 5.5% on that $85 million in loans—minus the cost of running the bank, paying employees, and covering loan defaults. That spread is where the profit comes from.

The bank is legally required to keep some deposits on hand (called reserve requirements), though the Federal Reserve has relaxed these rules in recent years. The bank also has to be confident it can meet withdrawal requests on any given day. But beyond that safety margin, deposits are working capital. Your money is not sitting idle—it is out in the economy as someone else's debt.

Key Takeaways

  • Banks earn profit by lending deposits to borrowers at higher interest rates than they pay depositors, keeping the difference.
  • A bank does not hold your deposit in a separate account; it pools deposits and uses them to fund loans across its customer base.
  • Banks must keep a portion of deposits in reserve to cover withdrawals and meet regulatory requirements, but lend out the majority.
  • The interest rate spread—the gap between what the bank pays you and what it charges borrowers—is the primary source of bank profit.
  • Banks also generate revenue from fees, investment services, and trading, but lending deposits remains the largest profit driver for most retail banks.

The interest rate spread: where the actual profit lives

The spread is the difference between the rate a bank pays depositors and the rate it charges borrowers. On a savings account earning 4.5% annually, you might receive $45 on a $1,000 deposit. On a $1,000 mortgage at 7%, the borrower pays $70. The bank collects $70 and pays out $45, netting $25 on that pair of transactions (before operating costs).

The spread varies by loan type and market conditions. Mortgage spreads are typically 2% to 3%. Credit card spreads are much wider—a bank might pay 4% on a savings account and charge 18% to 24% on a credit card, creating a 14% to 20% spread. Unsecured personal loans sit somewhere in between. The riskier the loan, the wider the spread, because the bank is compensating itself for the possibility that the borrower will not repay.

When the Federal Reserve raises interest rates, the spread often narrows temporarily. Banks can raise deposit rates quickly to stay competitive, but they cannot when ready raise rates on existing fixed-rate loans. When the Fed cuts rates, the opposite happens—banks can lower deposit rates faster than they lower loan rates, widening the spread. This is one reason banks lobby heavily during rate-setting discussions.

How banks manage the risk of lending out deposits

A bank cannot lend out every dollar it takes in. It needs to keep enough cash on hand to cover daily withdrawals, and regulators require a minimum reserve. The reserve requirement varies by account type and has changed over time—during the pandemic, the Federal Reserve dropped it to zero for most banks, though some institutions maintain higher reserves voluntarily.

Beyond the reserve, banks use liquidity management to predict how much cash they will need. They study historical withdrawal patterns, seasonal trends, and economic conditions. A bank that expects a rush of withdrawals in December (holiday spending) will hold more cash in November. A bank facing economic uncertainty might hold larger reserves even when not required to do so.

Banks also manage risk by diversifying their loan portfolio. A bank that lends 80% of deposits to a single industry—say, commercial real estate—faces catastrophic loss if that sector collapses. Banks spread loans across mortgages, auto loans, business loans, and credit cards so that a downturn in one category does not wipe out the entire loan book. They also sell loans to other banks or to investment firms, converting a long-term loan into when ready cash when they need liquidity.

What happens when borrowers do not repay

When a borrower defaults on a loan, the bank loses the interest it expected to earn and may lose part or all of the principal. This is why the spread exists—it has to be wide enough to cover expected losses plus operating costs plus profit. A bank that expects 2% of its loans to default needs to earn enough on the remaining 98% to make up for it.

Banks set aside money in a loan loss reserve, an accounting category that estimates how much they will lose to defaults in the coming year. If a bank originates $100 million in mortgages and estimates 0.5% will default, it reserves $500,000. When a borrower actually defaults, the bank draws from this reserve. If defaults exceed the reserve, the bank's profit shrinks. If defaults are lower than expected, the bank releases the reserve as additional profit.

This is why bank profit is cyclical. During economic expansions, defaults fall, reserves shrink, and bank profits rise. During recessions, defaults spike, reserves are depleted, and bank profits fall sharply. A bank that was highly profitable in 2022 might report losses in 2023 if the economy turns and borrowers stop paying.

Fees and other sources of bank revenue

Interest on loans is the largest source of profit for most retail banks, but it is not the only one. Banks charge overdraft fees when an account goes negative, monthly maintenance fees on checking accounts, ATM fees when you use another bank's machine, and wire transfer fees. These fees are smaller individually but add up across millions of customers.

Banks also earn revenue from investment services—managing wealth, trading securities, underwriting bonds and stock offerings. They earn interchange fees when you use a debit or credit card (the merchant's bank pays the card issuer a small percentage of the transaction). They earn foreign exchange spreads when customers exchange currency. None of these match the profit from lending deposits, but together they can account for 20% to 40% of a bank's total revenue.

During periods of high interest rates, banks can also profit from their own investment portfolio. A bank holds Treasury bonds, municipal bonds, and other securities. When interest rates rise, the value of existing bonds falls, but the bank earns higher yields on new purchases. When rates fall, existing bonds become more valuable. Banks time these purchases to maximize returns, though they are constrained by regulations that limit how much risk they can take.

Why banks pay such low interest on deposits

If banks profit from the spread between deposit rates and loan rates, they have an incentive to pay depositors as little as possible. In a low-rate environment—when the Federal Reserve keeps rates near zero—banks can pay almost nothing on savings accounts because depositors have nowhere else to go. A savings account earning 0.01% is still better than cash under a mattress.

Competition changes this. When the Federal Reserve raised rates sharply in 2022 and 2023, online banks and credit unions began offering savings rates above 4%. Traditional banks lost deposits to these competitors and were forced to raise their own rates to keep customers. The spread narrowed, but banks still profited because loan rates rose even faster.

Banks also pay low rates because they have other ways to access funds. They borrow from the Federal Reserve's discount window, borrow from other banks in the federal funds market, and issue certificates of deposit (CDs) to customers willing to lock money away for a set term. These alternative funding sources are often cheaper than raising deposit rates, so banks use them when deposit rates get too high.

The role of capital requirements and regulation

Banks cannot straightforward lend out 95% of deposits and keep 5% in reserve. Regulators require banks to hold capital—shareholder equity and retained earnings—as a cushion against losses. The Basel III framework, adopted by most major economies, sets minimum capital ratios. A bank must hold capital equal to at least 10.5% of its risk-weighted assets (loans and investments weighted by how risky they are).

This means a bank with $100 million in deposits cannot lend out $95 million if it only has $5 million in capital. It would need roughly $10.5 million in capital to support $100 million in risk-weighted assets. Capital comes from shareholder equity (stock sales) and retained earnings (profit the bank keeps rather than paying out as dividends). A bank that wants to grow its lending has to either raise capital from shareholders or retain more profit.

These regulations exist because banks that fail can trigger financial crises. When a bank fails, depositors lose money (though the Federal Deposit Insurance Corporation insures up to $250,000 per account), and the bank's borrowers may not be able to refinance their loans. Regulators use capital requirements to force banks to absorb their own losses rather than passing them to the public.

Frequently Asked Questions

Where does my deposit actually go when I put money in the bank?

Your deposit enters the bank's general pool of funds. The bank does not set aside a specific account with your money in it. Instead, it uses deposits to fund loans to other customers. You have a claim on the bank for your deposit amount plus interest, but the actual cash is out in the economy as mortgages, car loans, and business credit.

What happens to my money if the bank fails?

The Federal Deposit Insurance Corporation (FDIC) insures deposits up to $250,000 per depositor per bank. If a bank fails, the FDIC pays depositors from its insurance fund. Deposits above $250,000 are not insured and may be lost, though in practice large depositors often recover some funds when the bank is sold or liquidated.

Why do banks pay almost nothing on savings accounts?

Banks pay low rates when they have excess deposits and few borrowers, or when the Federal Reserve keeps interest rates low. When rates rise or deposits become scarce, banks raise deposit rates to compete. The rate you earn depends on supply and demand for deposits in your market, not on what the bank thinks is fair.

Can a bank run out of money if too many people withdraw at once?

Yes, this is called a bank run. If depositors lose confidence and try to withdraw all their money at once, the bank may not have enough cash on hand because most deposits are lent out. Banks manage this risk by holding reserves, borrowing from other banks and the Federal Reserve, and selling loans quickly. The FDIC's insurance also prevents runs by assuring depositors their money is safe.

Do banks make more profit when interest rates are high or low?

Banks profit most when rates are rising and the spread widens—they can raise loan rates faster than deposit rates. When rates are falling, the spread narrows and profit falls. When rates are stable at any level, banks adapt their business model. The direction of rate change matters more than the absolute level.