Your bank lends out most of the money you deposit

When you put 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, personal loans, business loans. You earn interest on your deposit because the bank is earning more interest on the loans it makes with your money. The difference between what it pays you and what it collects from borrowers is the bank's profit.

The bank keeps a fraction of deposits on hand to cover withdrawals. This fraction is called the reserve requirement, and it varies by account type and by the Federal Reserve's rules. For most checking and savings accounts, the requirement is low—often 0 to 10 percent—which means the bank can lend out 90 percent or more of what you deposit. If many customers withdraw money at once, the bank borrows from other banks or the Federal Reserve to cover the gap.

This system is called fractional reserve banking, and it is how modern banking works everywhere. Your money is not sitting idle; it is working. That is also why banks fail when too many people withdraw at the same time—they do not have enough cash on hand because most of it is already lent out.

Key Takeaways

  • Banks lend out the majority of customer deposits to borrowers, earning interest on those loans and paying you a smaller interest rate on your account.
  • The bank keeps only a small reserve of your money on hand and borrows from other banks or the Federal Reserve if withdrawals exceed what they have available.
  • Your deposits are insured up to $250,000 per account type per bank by the FDIC, so you do not lose money if the bank fails.
  • Banks also earn money by charging fees for overdrafts, wire transfers, ATM use, and account maintenance, which is separate from lending profit.
  • The interest rate you earn depends on the bank's cost of borrowing and the current Federal Reserve rate, not on how much money you have deposited.

How the FDIC protects your money if the bank fails

Because banks lend out most deposits, the federal government created the Federal Deposit Insurance Corporation (FDIC) in 1933 to protect depositors. If a bank fails, the FDIC pays back depositors up to $250,000 per account type per bank. This means if you have $100,000 in a checking account and $100,000 in a savings account at the same bank, both are covered separately—you get all $200,000 back.

The FDIC does not use tax money to pay claims. Instead, banks pay insurance premiums into the FDIC fund based on the size of their deposits. When a bank fails, the FDIC either arranges for another bank to buy it (and your account transfers automatically) or pays depositors directly. The process usually takes a few weeks, though you may have temporary access to your money through the acquiring bank within one or two business days.

Coverage limits matter. If you have more than $250,000 at one bank, the amount over the limit is not protected. Some people spread large balances across multiple banks or use accounts registered in different names (like a joint account or a trust account) to increase coverage, since each registration type is insured separately.

Interest rates and how banks set them

The interest rate your bank pays on savings or money market accounts is not arbitrary. It is tied to the federal funds rate, which is the interest rate the Federal Reserve charges banks when they borrow from each other overnight. When the Federal Reserve raises this rate, banks' cost of borrowing goes up, so they raise the rates they pay depositors to attract and keep money. When the rate falls, banks lower deposit rates.

Banks also look at what competitors are offering. If another bank in your area is paying 4.5 percent on savings and yours is paying 2 percent, you might move your money. Banks balance the need to attract deposits against the need to keep profits high. Online banks often pay higher rates than brick-and-mortar banks because they have lower overhead costs.

Checking accounts typically pay little to no interest, even though the bank is using that money to lend. This is because checking accounts are more expensive for banks to maintain—they process more transactions, issue debit cards, and allow unlimited withdrawals. Savings accounts and money market accounts pay more because you agree to limit withdrawals or keep money there longer.

Fees: how banks make money beyond lending

Interest on loans is not the only way banks profit from your account. Banks charge fees for specific services and for account misuse. Common fees include overdraft fees (charged when you spend more than your balance), wire transfer fees, ATM fees if you use an out-of-network machine, monthly maintenance fees, and fees for stopping a check or requesting a copy of a statement.

Overdraft fees are the largest source of fee income for many banks. If you spend $50 more than your balance, the bank covers the transaction and charges you $25 to $35 for the overdraft. Some banks charge multiple overdraft fees in a single day if you make several transactions over your limit. Federal rules now require banks to let you opt in to overdraft coverage rather than forcing it on you, but many customers do opt in because the alternative is a declined transaction.

Some banks waive certain fees if you maintain a minimum balance, set up direct deposit, or use their credit card. Others charge fees on every account regardless. Reading the fee schedule before opening an account can save you hundreds of dollars per year, especially if you tend to overdraft or use ATMs frequently.

What happens to your money during a wire transfer or ACH payment

When you send money to another person or business, the path depends on the payment method. An ACH transfer (Automated Clearing House) is the slowest but cheapest. Your bank batches your payment with thousands of others, sends them to a clearing house, which sorts them and sends them to the receiving bank. This process takes one to three business days. During that time, your money is in transit through the Federal Reserve's system, not sitting in either bank's vault.

A wire transfer is faster but more expensive. Your bank sends the payment directly to the receiving bank using the SWIFT network (for international transfers) or the Federal Reserve's wire system (for domestic transfers). Wire transfers usually clear within hours, sometimes minutes. Your bank deducts the money from your account immediately, but the receiving bank may not credit it right away if the transfer arrives after business hours.

During both types of transfers, your bank is not holding your money in a separate account. The money leaves your account and enters the receiving bank's account. If something goes wrong—a wrong account number, a bank that no longer exists—the money can be stuck in limbo for days or weeks while banks trace it. This is why wire transfers are hard to reverse: the money has already left your bank's control.

Investment and trading: what banks do with excess reserves

Beyond lending to customers, large banks use some of their reserves to trade securities, buy bonds, and invest in other financial instruments. These activities generate additional profit but also carry risk. During the 2008 financial crisis, banks lost billions on mortgage-backed securities because they had invested heavily in loans that defaulted.

Banks are required to hold a certain amount of capital (their own money, not customer deposits) to cover potential losses. The more risky investments a bank makes, the more capital it must hold. Federal regulators set these requirements and conduct stress tests to make sure banks can survive a financial downturn. This is separate from FDIC insurance—it is a requirement that banks themselves stay solvent.

Smaller banks typically do less trading and investing because they lack the resources and expertise. They focus on lending to local customers and businesses. Larger banks have entire divisions dedicated to trading and investment management, which is why they can offer more products but also why they carry more risk.

How your data and account information are used

Banks collect detailed information about your spending, income, and financial behavior. They use this data to assess risk, set credit limits, and decide whether to offer you loans or credit products. Banks also sell anonymized data to third parties—not your name and account number, but patterns like "customers who spend heavily on groceries and utilities are less likely to default on auto loans."

Banks are required by law to protect your account information and to notify you if there is a data breach. They use encryption, multi-factor authentication, and fraud detection systems to prevent unauthorized access. If someone fraudulently uses your account, federal law limits your liability to $50 if you report it within 60 days, and $0 if the fraud is on a debit card and you report it quickly.

Your bank also shares information with the IRS, law enforcement, and other government agencies when required by law. Banks file reports on large cash deposits (over $10,000) and suspicious activity that might indicate money laundering. This is separate from your privacy rights—the bank is complying with federal reporting requirements, not selling your data to the government.

Frequently Asked Questions

What happens to my money if I do not use my account for a long time?

Nothing happens to the money itself—it stays in your account and earns interest if it is a savings account. However, if you do not make any deposits or withdrawals for several years, the account may be classified as dormant or abandoned. The bank may charge a monthly fee or close the account. If the account is closed, the bank sends your money to your state's unclaimed property program, where you can reclaim it at any time.

Can the bank use my money without my permission?

The bank can use your money to make loans, but it cannot take money out of your account without your authorization. If you authorize a recurring payment or overdraft coverage, the bank can charge fees or cover overdrafts. If the bank makes an unauthorized withdrawal, you can dispute it and the bank must investigate and return the money if it was truly unauthorized.

Why do banks pay almost no interest on checking accounts?

Checking accounts are expensive for banks to maintain because they process many transactions, issue debit cards, and allow unlimited withdrawals. Banks also cannot reliably lend out checking account money because customers may withdraw it at any time. Savings accounts and money market accounts pay more because you agree to keep money there longer and make fewer withdrawals, giving the bank more certainty about how much it can lend.

Is my money safer in a bank or under my mattress?

A bank is safer. Your money is insured up to $250,000 by the FDIC, so even if the bank fails, you get your money back. Under a mattress, your money can be stolen, lost in a fire, or damaged. You also earn interest in a bank account, even if the rate is low. The only reason to keep cash at home is for immediate access in an emergency.

What does the bank do with money from savings accounts that earn very low interest?

The bank lends it out at a higher rate. If your savings account earns 0.5 percent and the bank lends that money as a mortgage at 6 percent, the bank keeps the 5.5 percent difference. The bank also uses some of that money to pay for operations, employee salaries, and to cover loan defaults. The interest rate you earn reflects what the bank can afford to pay while still making a profit.