The money supply

"The money supply" sounds like a quantity somebody sets. It is better understood as an outcome, mostly of bank lending.

The two layers

Reserve money (M0) — currency in circulation plus banks' deposits with the RBI. This is central bank money, and it is the only money the RBI creates directly.

Broad money (M3) — currency with the public plus deposits with banks. This is the money the economy actually uses.

The crucial fact: M3 is many times M0, and the difference is bank deposits created by lending — chapter 2. Most of the money in the economy was created by a bank writing two entries when it made a loan, not by anybody printing anything.

The multiplier story, and why it runs backwards

The textbook version: the central bank injects reserves, banks lend a fraction, the deposit returns to the system, banks lend again, and the total expands by a multiplier determined by the reserve ratio.

The arithmetic is fine. The causation is backwards.

Banks do not wait for reserves and then lend. They lend when they find a creditworthy borrower and have the capital to support it, creating the deposit in the act — and acquire the reserves they need afterwards, from the market or from the central bank's facilities.

So reserves are not a binding constraint in normal conditions, because the central bank supplies them at the policy rate to keep the overnight rate inside its corridor (chapter 6). Refusing to supply them would mean losing control of the rate, which is the thing it is actually targeting.

The ratio of M3 to M0 is therefore a description, not a mechanism. It is an outcome worth measuring and a poor thing to reason forwards from.

Working the problem

₹10,000 crore of reserves injected.

Broad money could rise by far more if banks have creditworthy demand and capital to spare. The reserves were never the constraint; the injection simply lowered funding costs at the margin and lending expanded for its own reasons.

It could rise by far less, or not at all if banks cannot find borrowers worth lending to, or lack capital. The reserves then sit in the system, the overnight rate drifts to the SDF floor (chapter 8), and nothing reaches the real economy.

In a downturn, expect the second. This is chapter 2's point arriving with force: the binding constraint is creditworthy demand, and a downturn is precisely when that is scarce. Banks are simultaneously more cautious and facing weaker borrowers. Injecting reserves into that is pushing on a string — the classic description of why monetary policy is more effective at slowing an economy than at starting one.

That asymmetry is one of the strongest practical lessons in this subject.

What actually drives monetary growth

• Bank credit growth, which is the dominant component
• Government borrowing, when financed in ways that expand bank balance sheets
• Foreign exchange flows — RBI purchases of foreign currency inject rupees
• Currency preference — cash held outside banks does not support further deposit creation

The RBI influences all of these partially and controls none of them completely. The cash reserve ratio is the most direct lever, which is why it is moved rarely and taken seriously when it is: it changes what every bank must hold against every deposit, permanently.

Does money growth cause inflation?

The long-run relationship is one of the better-established regularities in economics: sustained, large monetary expansion beyond real output growth shows up in prices.

The short run is far weaker, for reasons worth naming:

Velocity is not stable. How often money changes hands moves, so a given stock of money supports different amounts of spending at different times.

It depends where the money goes. Credit flowing into asset purchases raises asset prices rather than consumer prices — which the consumer price index does not measure, and which is a live criticism of inflation targeting (chapter 9).

The lags are long and variable, which is why the MPC targets inflation directly rather than targeting money growth and hoping.

That last point is the historical conclusion: central banks tried targeting monetary aggregates and largely abandoned it, because the relationship between the aggregate and the goal proved too unstable to steer by.

The point

Reserve money is what the central bank creates; broad money is what the economy uses, and the gap between them is deposits created by bank lending. The money multiplier describes that ratio rather than explaining it, because banks lend first and obtain reserves afterwards — which the central bank supplies to keep its rate on target. Injecting reserves therefore expands money only when creditworthy demand and capital exist, and in a downturn neither does.