How Banks Work

Banks sit at the centre of the financial system, yet how they actually work is widely misunderstood. Many people picture a bank as a warehouse that stores deposited cash and lends out that same cash. The reality is more surprising and more important: when a bank makes a loan, it creates new money in the process.

Understanding this changes how you read the whole economy. It explains where most of the money in circulation comes from, why banks are so heavily regulated, and why confidence — not just capital — keeps a bank standing. This lesson describes the mechanics of the system, not what anyone should do with their own money.

Deposits and loans

A commercial bank has two basic activities. It accepts deposits from customers, which are recorded as balances people can spend or withdraw. And it makes loans to households, businesses, and others. The interest earned on loans, minus the interest paid on deposits and other costs, is a core part of how the bank earns its keep. In doing this, the bank acts as an intermediary, channelling funds from those who have more than they need now to those who need more than they have.

How lending creates money

Here is the counterintuitive part. When a bank grants a loan, it does not typically hand over a stack of someone else's cash. Instead, it credits the borrower's account with a new deposit. That deposit is newly created money — it did not exist a moment before. The borrower can now spend it. This is why economists say that in a modern economy, the bulk of money is created by commercial banks through lending, not printed by the government. The reverse also holds: when loans are repaid, that money is effectively extinguished. Lending is constrained by regulation, the need for profitable and creditworthy borrowers, and central bank policy — not by a simple pool of pre-existing cash.

Maturity transformation

Banks perform maturity transformation: they borrow short and lend long. Deposits can usually be withdrawn at any moment, while loans such as mortgages are repaid over many years. This mismatch is economically valuable — it lets savers keep easy access to their money while borrowers get long-term funding — but it creates a vulnerability. A bank cannot instantly turn its long-term loans back into cash. It relies on the reasonable assumption that not all depositors will ask for their money at once.

Suppose a bank grants a household a loan of 10,000 units to renovate a kitchen. Rather than moving cash from a vault, the bank simply increases the household's account balance by 10,000. New deposits — new money — have appeared in the economy. The household pays a builder, who deposits the funds at their own bank, and the money circulates. Over the following years the household repays the loan; as it does, the created money is gradually removed from circulation. This illustrative example shows lending expanding, and repayment contracting, the money supply.

Contrast this with a simple safety-deposit box. If you place gold coins in a box and the custodian merely guards them, no new money is created; the same coins sit untouched until you collect them. That is pure storage, not banking. The money-creating power comes specifically from the act of lending against deposits while promising depositors access to their funds — the very feature that also generates liquidity risk. Storage alone carries no such risk and no such power.

In 2014 the Bank of England published an article in its Quarterly Bulletin titled "Money creation in the modern economy," by Michael McLeay, Amar Radia and Ryland Thomas. It stated plainly that the majority of money in the modern economy is created by commercial banks making loans, and that each new loan creates a matching new deposit — challenging the older textbook picture of banks simply lending out savers' deposits. It is a widely cited, verifiable central-bank source.

The flip side of deposit banking is the bank run. Because banks lend out and cannot instantly repay every depositor, a loss of confidence can be self-fulfilling: if enough people rush to withdraw, even a fundamentally sound bank can fail. Waves of bank runs during the early 1930s in the United States are a well-documented example. Partly in response, many countries later introduced deposit insurance and stronger supervision to protect ordinary depositors and reduce the incentive to run.

• "Banks just lend out the cash people deposit." In a modern economy, banks create new deposits when they lend; they are not merely passing along existing cash.
• "Only the government or central bank creates money." Most money in circulation is created by commercial banks through lending, within limits set by regulation and policy.
• "A bank always holds all its depositors' money ready to withdraw." Through maturity transformation, much of it is lent out long-term; banks rely on the fact that not everyone withdraws at once.
• "A bank run only happens to badly run banks." Because of the liquidity mismatch, even a solvent bank can face a run if depositors lose confidence collectively.

Trace a single loan through the system. Start with a bank crediting a borrower's account, follow the money as it is spent and re-deposited elsewhere, and mark the moment new money entered the economy and the moment repayment removes it. Then ask what would happen if many depositors demanded cash at the same time. The exercise makes money creation and liquidity risk concrete.

Think Like a Maester: A bank does not lend out the money you deposited; it creates money when it lends, and stands only as long as trust does.

1. What are the two core activities of a commercial bank?
2. Explain how making a loan can create new money in the economy.
3. What is maturity transformation, and why does it create risk?
4. According to the Bank of England's 2014 article, where does most money in the modern economy come from?
5. Why can even a fundamentally sound bank be vulnerable to a bank run?

Banks take deposits and make loans, acting as intermediaries between savers and borrowers. Crucially, lending is not merely the recycling of existing cash: when a bank makes a loan it creates a new deposit, and most money in a modern economy arises this way — a point set out in the Bank of England's 2014 article on money creation. Banks also perform maturity transformation, borrowing short and lending long, which is useful but leaves them exposed to bank runs if confidence fails. That is why trust, regulation, and measures such as deposit insurance are central to how the banking system holds together.

• Debt and Credit
• Central Banks and the Economy