Economics
Money Supply
Quick fact
The majority of money in modern economies is not physical cash but digital entries in bank accounts, created when banks make loans.
Why this is interesting
You carry money in your wallet, but have you ever wondered who decides how much total money exists in the entire economy—and what happens if that amount changes?
Read the full explanation
Understanding Money Supply
The money supply is the total stock of money circulating in an economy at a particular time. It includes not just physical cash and coins but also bank deposits that people can easily use for payments. Economists measure it in different ways: narrow measures like M1 include cash and checking accounts, while broader measures like M2 also include savings accounts and money market funds. This matters because changes in the money supply can affect spending, prices, and employment. For example, if the money supply grows faster than the economy's output, prices tend to rise (inflation). Central banks, like the Federal Reserve in the U.S., manage the money supply to keep inflation stable and support economic growth.
A deeper explanation
The money supply is primarily controlled by a central bank through three main tools: open market operations, reserve requirements, and the discount rate. Open market operations involve buying or selling government bonds to inject or withdraw money from the banking system. When a central bank buys bonds, it pays with new reserves, increasing the monetary base and enabling banks to create more money through lending (fractional reserve banking). Reserve requirements set the fraction of deposits banks must hold in reserve, limiting how much they can lend. The discount rate influences borrowing costs for banks. These tools affect the money multiplier—the ratio of the total money supply to the monetary base—which amplifies changes in reserves. Understanding this mechanism reveals why central bank decisions ripple through the entire economy, influencing everything from mortgage rates to business investment.