Money and Banking

Overview

Think of the monetary system as three layers. At the base is central bank money: currency in circulation plus reserves held by banks at the central bank. Above it is commercial bank money: deposits created when banks lend, which households and firms actually use for most payments. Above that is the wider financial system: non-bank lenders, bond and equity markets, and institutional investors that allocate long-term savings. Policy acts on the base layer and on interest rates, but its effects depend on how the upper layers respond: banks may hoard reserves, borrowers may be unwilling to borrow, and markets may already have anticipated the move. That layered view explains why the same policy rate cut can be powerful in one episode and weak in another, and why central banks monitor credit, asset prices and expectations, not just the policy rate.

Components of money supply

Money supply is measured by aggregates that differ in liquidity. Narrow money typically includes currency held by the public plus demand deposits that can be withdrawn on demand, the assets most directly usable for payments. Broad money adds time deposits, savings deposits and other near-money assets that can be converted into payments media at low cost but are not immediately spendable. Still broader measures may include deposits with non-bank institutions, money market fund shares and short-term securities. The choice of aggregate matters for policy: narrow money tracks transactions closely but is volatile when households shift between deposits and cash, while broad money tracks overall liquidity and credit conditions but responds more slowly to policy. Financial innovation constantly blurs boundaries, as new payment instruments, sweep accounts and digital wallets shift funds between categories without changing underlying liquidity, which is why central banks monitor several aggregates together rather than targeting one mechanically.

Money is defined functionally, not by physical form: anything generally accepted in payment, serving as a unit of account and a store of value, functions as money, whether it is coin, paper, a bank deposit entry or a digital balance. The demand for money, discussed in macroeconomics, interacts with supply to determine interest rates and prices. The supply side has two creators: the central bank creates base money, or high-powered money, consisting of currency plus bank reserves; commercial banks create deposit money when they make loans, crediting borrowers accounts and expanding both sides of their balance sheets. The money multiplier links the two: broad money equals the multiplier times base money, where the multiplier depends inversely on the reserve ratio and on the public preference for cash over deposits. If banks hold excess reserves or the public holds more cash, the multiplier falls and a given base expansion creates less broad money. This is why quantitative easing that expands reserves does not automatically expand lending by the same multiple, especially when banks are risk-averse or borrowers are deleveraging. Velocity, the ratio of nominal income to money supply, connects money to prices and output in the quantity theory, but velocity is not constant when interest rates, payment technology and expectations change, so money growth alone is an unreliable short-run guide to inflation.

Central bank

The central bank is the apex monetary authority, typically owned or chartered by the state and granted independence to pursue price stability without short-term political pressure. Its core functions begin with issuing currency, which gives it a monopoly over legal tender notes and coins and seigniorage revenue from issuing them. It acts as banker to the government, managing public accounts, debt issuance and payments, and as banker to banks, holding their reserves and operating the payments system through which banks settle with each other. As lender of last resort it lends to solvent but illiquid banks against good collateral in a crisis, preventing a liquidity shortage at one bank from becoming a system-wide panic; the classic prescription is to lend freely, at a penalty rate, against sound collateral, to distinguish illiquidity from insolvency. It also regulates and supervises banks, sets capital and liquidity standards, and manages foreign exchange reserves and the exchange rate regime where applicable.

Central bank independence is justified by time inconsistency: governments facing elections are tempted to expand money for short-term output gains at the cost of higher inflation later, and an independent bank with a clear mandate and accountability can commit credibly to low inflation. Independence is therefore paired with transparency: published mandates, inflation targets, minutes, forecasts and regular reports that let the public judge performance. The balance sheet is the policy tool: assets include government securities, foreign reserves and loans to banks, while liabilities include currency and bank reserves. Open market purchases expand assets and reserves together, while sales contract them. In a crisis the balance sheet can expand dramatically through lending facilities and asset purchases, raising questions about exit, fiscal interaction and distributional effects that go beyond textbook models. The central bank also plays a developmental role in many economies, promoting financial inclusion, payment system modernisation and priority sector credit, though these roles must be balanced against the primary stability mandate to avoid mission overload.

Commercial banking

Commercial banks accept deposits, make loans and provide payment services, transforming short-term liquid liabilities into longer-term illiquid assets. This maturity transformation is socially valuable because savers want instant access while borrowers want long-term funds, but it creates inherent fragility: if many depositors withdraw at once, a bank cannot liquidate long-term loans quickly without loss, which is the logic of bank runs. Banks manage this through liquid asset buffers, diversified loan portfolios, capital cushions that absorb losses before depositors, and access to central bank liquidity. The balance sheet identity is fundamental: assets, comprising cash, reserves, loans, securities and fixed assets, equal liabilities, comprising deposits and borrowings, plus capital. Capital adequacy, the ratio of capital to risk-weighted assets, measures loss absorption capacity, and regulators set minimum ratios with buffers that rise in good times to be drawn down in bad times, a macroprudential countercyclical design.

Credit creation is the most misunderstood banking function. When a bank makes a loan it does not simply lend out deposits it already holds; it creates a new deposit for the borrower, expanding the money supply, while the loan becomes an asset. The system as a whole is constrained by reserve requirements, capital requirements, the demand for loans from creditworthy borrowers, and the public cash-deposit ratio, not by any single bank reserve position in isolation. The credit creation process through successive rounds of lending and redepositing gives the deposit multiplier, the reciprocal of the reserve ratio in the simplest textbook case, and the full money multiplier once cash leakage and excess reserves are included. Banks also create risk through adverse selection and moral hazard in lending: they screen borrowers, monitor loans, demand collateral, use credit scoring and diversify across sectors and regions. Non-performing assets arise when borrowers default, eroding capital and constraining new lending, which can produce a credit crunch that amplifies a downturn. Deposit insurance protects small depositors and prevents panic runs, but it also creates moral hazard by weakening depositor discipline, which is why it is paired with supervision and risk-based premiums.

Instruments and working of monetary policy

Monetary policy aims typically at price stability, with support for growth and financial stability as secondary objectives, and it works through instruments that influence the cost and availability of money and credit. The policy interest rate, the rate at which the central bank lends to banks or remunerates reserves, is the primary signal: changes propagate to interbank rates, deposit and lending rates, bond yields and asset prices. Open market operations, purchases and sales of government securities, adjust reserves and short-term rates directly and are the most flexible day-to-day tool. Reserve requirements oblige banks to hold a fraction of deposits as reserves, and changes in the ratio alter the multiplier and lending capacity, though they are now used sparingly because they tax intermediation bluntly. Standing facilities, including a lending facility at a penalty rate and a deposit facility, bound overnight rates within a corridor and provide emergency liquidity. Cash reserve and statutory liquidity requirements in some systems oblige banks to hold specified assets, serving prudential as well as monetary purposes.

The transmission mechanism has several channels. The interest rate channel works through borrowing costs for consumption and investment. The credit channel works through bank lending capacity and borrower balance sheets: tighter policy reduces bank reserves and collateral values, constraining credit especially for small firms dependent on banks. The asset price channel works through equity and housing wealth and through Tobin q for investment. The exchange rate channel works through interest differentials and capital flows, affecting net exports and import prices. The expectations channel may be the most powerful: credible forward guidance about future policy shapes long-term rates and wage-price setting today. Transmission lags are long and variable, and it is weakened by broken banking systems, dollarisation, fiscal dominance where government borrowing forces monetary accommodation, or a liquidity trap where rates cannot fall further. Unconventional policies address those limits: quantitative easing expands the balance sheet through large-scale asset purchases to lower long-term yields, forward guidance commits to future rate paths, and negative policy rates attempt to push below the zero bound, each with side effects on bank profitability, asset bubbles and inequality that must be weighed.

Non-banking financial institutions and capital market

Non-banking financial institutions provide financial services without issuing demand deposits or, in many systems, without a full banking licence. They include finance companies that lend for vehicles, housing and consumer durables; leasing and hire-purchase companies; microfinance institutions serving borrowers excluded from banks; insurance companies that pool risks and invest premiums long-term; pension funds that collect retirement savings and invest in long-duration assets; and mutual funds that pool investor money into diversified portfolios. Development finance institutions were created to fund long-term industrial and infrastructure projects that commercial banks, with short-term deposits, are reluctant to finance. These institutions deepen finance and reach underserved segments, but they can also transmit risk: they borrow short-term in wholesale markets, lend long-term, and are interconnected with banks through funding lines and asset holdings, so distress can spill over even without deposit-taking.

The capital market is where long-term funds are raised and traded. The primary market issues new securities: initial public offers of equity, follow-on offers, rights issues, and bond issues by firms and governments. The secondary market, stock exchanges and bond markets, provides liquidity that makes primary issuance possible, because investors will only commit long-term funds if they can exit. Equity gives ownership and residual claims with variable dividends, while debt gives fixed contractual claims with priority in default, and the capital structure choice trades off tax advantages of debt against bankruptcy costs and agency problems. Market efficiency asks whether prices reflect available information: weak-form efficiency rules out profit from past prices, semi-strong form from all public information, and strong form from all information including private. Regulators oversee disclosure, prevent insider trading and market manipulation, protect investors, and ensure orderly trading, while clearing and settlement systems manage counterparty risk. A well-functioning capital market allocates savings to their most productive uses, diversifies risk, and provides price signals for investment, but it can also amplify cycles through leverage, herding and bubbles, which is why securities regulation and macroprudential oversight are complements to monetary policy, not substitutes for it.

Money aggregates by liquidity

Monetary policy instruments

Bank versus non-bank finance