CONCEPTS · Money & Credit

Money Multiplier

The textbook equation is reserves times a multiplier equals deposits. The arithmetic works; the arrow runs backwards. Banks create the loan first and demand the reserves afterwards, which is why no fixed pool of reserves pins down the quantity of money.

The ratio, stated properly

The money multiplier is the ratio that converts a quantity of bank reserves into a quantity of broad money. In the textbook version, if banks must hold one dollar of reserves for every ten dollars of deposits, the reserve ratio is 0.10 and the multiplier is its reciprocal: 1 divided by 0.10 equals 10. Multiply a stock of base money by ten and you get the implied stock of deposits.

The arrow points the wrong way

The equation hides a claim about causation: that reserves are a fixed pool a bank lends out, so the pool sets the ceiling on deposits. In a modern system the central bank supplies reserves on demand, at the policy rate, to settle the payments banks make for one another. A bank makes the loan first, creating a deposit, and only then obtains the reserves to clear it.

That reverses the causality. The reserves follow the lending rather than funding it, and the multiplier becomes a ratio you observe after the fact. What sets the quantity of credit creation is demand for loans, the capital and risk appetite of the lender, and the price of the loan, not a fixed quantity of reserves.

What to do with it

Because reserves are supplied elastically, a central bank that targets the policy rate is controlling a price, not a quantity. That is the deep reason the money multiplier fails as a forecasting tool: with an elastic supply, no reserve number can determine the stock of broad money.

One checkable use: when a headline says the money multiplier has collapsed and therefore credit cannot expand, ask whether the central bank is supplying reserves on demand. If it is, the low ratio is a symptom of weak loan demand, not a cap on lending. Reverse the arrow and the story inverts.

IF YOU REMEMBER ONE THING

DefinitionThe ratio of broad money to base money, the reciprocal of the reserve ratio. On paper it converts a reserve quantity into a deposit quantity.

What it is notA causal mechanism. Reserves are supplied on demand after lending, not lent out from a fixed pool.

CheckAsk whether reserves are supplied elastically. If they are, the multiplier is an outcome of credit demand, not a constraint on it.

Next: Quantitative Easing