Your bank lends most of it out

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 loans, credit cards. The bank keeps a portion in reserve (required by federal law) and lends out the rest. You earn interest on your deposit because the bank is earning more interest on the loans it makes with your money.

This is how banks make their primary income. A customer borrows $300,000 for a home at 6.5% interest. The bank paid you 0.01% on your savings account. The difference — roughly 6.49% — is the bank's profit on that transaction, minus their operating costs. The bank is essentially borrowing from you at a low rate and lending to someone else at a higher rate.

The system depends on most depositors not withdrawing all their money at once. Banks are required to keep enough cash on hand to cover daily withdrawals, but they do not keep 100% of deposits sitting idle. If a bank cannot meet withdrawal requests, it fails — which is why the Federal Deposit Insurance Corporation (FDIC) insures deposits up to $250,000 per account holder per bank.

Key Takeaways

  • Banks lend out the majority of customer deposits to borrowers, keeping only a federally required reserve amount in cash.
  • The interest rate you earn on savings is much lower than the rate the bank charges borrowers, and that gap is the bank's profit.
  • Your deposits are insured by the FDIC up to $250,000 per account type at each bank, protecting you if the bank fails.
  • Banks also earn money from fees — overdraft charges, monthly maintenance fees, wire transfer fees — which are separate from lending profits.
  • The Federal Reserve sets a baseline interest rate that influences how much banks pay you and how much they charge borrowers.

How reserve requirements limit what banks can lend

The Federal Reserve requires banks to hold a minimum percentage of customer deposits as reserves — money that must stay in the bank and cannot be lent out. As of 2023, this requirement is 0% for most deposit accounts, though banks still maintain reserves voluntarily to may support they can cover withdrawals and meet regulatory expectations.

Even without a hard requirement, banks cannot lend out every dollar you deposit. They need cash on hand for daily operations: when you withdraw $200 from an ATM, that money has to come from somewhere. Banks use historical data about withdrawal patterns to estimate how much cash they need to keep available. A bank that lends out too much and cannot cover withdrawals faces a liquidity crisis.

The amount a bank holds in reserve also depends on the type of account. Money market accounts and savings accounts typically have higher reserve ratios than checking accounts, because checking accounts see more frequent withdrawals. A bank's reserve strategy is part of its risk management — too little reserve and it cannot survive a sudden spike in withdrawals; too much reserve and it loses profit on money that could be lent.

The interest rate chain: Federal Reserve to your account

The Federal Funds Rate — set by the Federal Reserve's policy committee — is the interest rate at which banks lend money to each other overnight. When the Fed raises this rate, banks' cost of borrowing goes up, so they raise the rates they charge customers on loans. When the Fed lowers the rate, banks lower loan rates and sometimes raise savings rates to attract deposits.

Your savings account interest rate moves in the same direction as the Fed rate, but with a lag. When the Fed raises rates, banks take weeks or months to raise what they pay you on savings, because they want to lock in higher lending rates first. When the Fed cuts rates, banks drop savings rates quickly. This asymmetry is another source of bank profit.

The relationship is not one-to-one. If the Fed rate rises by 0.5%, your savings rate might rise by 0.1% or 0.3%, depending on how competitive your bank's market is and how much the bank needs deposits. Banks in areas with many competitors (online banks, credit unions) tend to raise savings rates faster because they need to attract deposits. Banks with less competition can move more slowly.

Fees: the second major source of bank income

Beyond lending profits, banks earn significant revenue from fees. An overdraft fee (charged when you spend more than your balance) can be $25 to $35 per transaction. Monthly maintenance fees on checking accounts range from $0 to $15 depending on the bank and account type. Wire transfer fees are typically $15 to $30. ATM fees at out-of-network machines are usually $2 to $3, though the bank you use may not charge you — the fee comes from the ATM operator's bank.

Some fees are avoidable: you can prevent overdraft fees by linking a savings account or setting up alerts. Many banks waive monthly fees if you maintain a minimum balance or set up direct deposit. Others are harder to avoid — if you travel and need to wire money internationally, you will pay a wire fee regardless of your account balance.

Overdraft fees are the most controversial. A customer with a $500 balance who makes a $510 debit card purchase can be charged $35, even though the overage is only $10. Some banks charge multiple overdraft fees per day on the same account, turning a small mistake into a large bill. Federal regulators have increased scrutiny of overdraft practices, and some banks have reduced or eliminated overdraft fees to stay competitive.

Investment and trading: what banks do with excess capital

Banks do not just lend deposits to individuals and businesses. Large banks also invest in stocks, bonds, and other securities using their own capital (money the bank owns, not customer deposits). These investments generate returns that add to bank profits. A bank might buy Treasury bonds, corporate bonds, or mortgage-backed securities — financial products that pay interest over time.

Banks also trade currencies and commodities for their own accounts. A large bank might buy euros when the exchange rate is favorable and sell them later at a profit. These trading operations are separate from customer banking services, but they are a significant profit center for major institutions.

The 2008 financial crisis exposed the risks of this activity. Banks had invested heavily in mortgage-backed securities that lost value when the housing market collapsed. Some banks failed; others required government bailouts. Regulations like the Dodd-Frank Act now limit how much risk banks can take with their own capital, though the rules remain complex and contested.

Payment processing and settlement: the infrastructure layer

When you swipe a debit card, the transaction does not settle when ready. Your bank receives the transaction request, checks your balance, and sends an authorization to the merchant's bank. The merchant's bank confirms the funds are available. Money does not actually move between accounts until settlement — typically one to two business days later.

During that gap, the bank holds the money in a clearing account. If thousands of transactions are settling simultaneously, the bank is temporarily holding millions of dollars in transit. Banks earn interest on these "float" balances, though the amounts are small compared to lending profits. More importantly, the delay gives the bank time to manage liquidity and may support funds are available.

Banks also charge merchants for processing debit and credit card transactions. A merchant pays roughly 1% to 3% of each transaction to the bank and payment processor. This fee is built into prices you pay at stores — it is not a direct charge to you, but it is a cost of the payment system you use.

How deposit insurance protects your money

The FDIC insures deposits up to $250,000 per depositor per bank per account type. This means if your bank fails, the FDIC will reimburse you for balances up to that limit. The insurance covers checking accounts, savings accounts, and money market accounts separately — so you could have $250,000 in each and be fully insured at a single bank.

The FDIC does not insure investment accounts, brokerage accounts, or money held in stocks and mutual funds. If you buy stock through your bank's brokerage arm and the bank fails, your stocks are protected (because they are your property, not the bank's), but the FDIC insurance does not explore. Similarly, if you hold a certificate of deposit (CD) at a bank, it is insured separately from your checking account.

The FDIC funds insurance through premiums paid by banks, not by taxpayers. Banks pay a small percentage of their insured deposits into the FDIC fund. When a bank fails, the FDIC uses this fund to reimburse depositors or arrange a merger with another bank. The system has worked since 1933, though the 2008 crisis strained it significantly.

Frequently Asked Questions

Can a bank go bankrupt and take my money with it?

A bank can fail, but your deposits up to $250,000 are protected by FDIC insurance. The FDIC will either reimburse you directly or transfer your account to another bank. Deposits over $250,000 at the same bank are not insured and could be lost if the bank fails, though in practice the FDIC often arranges mergers that protect all depositors.

Why do banks pay almost nothing on savings accounts?

Banks pay low rates on savings because they have many sources of funding — deposits are just one. When interest rates are low overall (set by the Federal Reserve), banks have less incentive to compete for deposits. Online banks and credit unions often pay higher rates because they have lower operating costs and need to attract deposits to grow.

Do banks make money if I never use my account?

Yes. Even if you never withdraw money or make purchases, the bank is earning interest on loans made with your deposit. You earn a small amount of interest on your balance, and the bank keeps the difference between what it earns on loans and what it pays you. The bank also profits if you pay monthly maintenance fees.

What happens to my money if I close my account?

When you close an account, the bank returns your balance to you (minus any outstanding fees or holds). The bank stops using that money for lending. If you have a negative balance — overdrafts or fees owed — the bank will deduct those amounts before returning the remaining balance.

Why do banks charge overdraft fees if they are lending me money anyway?

Overdraft fees are not interest on a loan — they are penalties for violating your account agreement. Banks argue the fee covers the cost of processing an unauthorized transaction and the risk of the account going negative. Critics argue the fees are excessive relative to the actual cost, and that banks deliberately process transactions in an order that maximizes overdraft fees.