Five Percent Money Growth Rule
Use money growth and real-economy indicators to calibrate inflation policy
- Difficulty
- Advanced
- Time to result
- ~ongoing to results
- Steps
- 6
- Confidence
- 93%
The Five Percent Money Growth Rule treats money-supply expansion as a central policy indicator while checking it against credit, currency, real-rate, commodity, and housing data. Siegel argues that approximately five percent money growth is consistent with a two percent inflation objective. Growth far above that level signals excessive liquidity, but abruptly driving growth to zero or below after inflation appears can create an equally damaging contraction. Because monetary policy works with delays, officials should not repeatedly tighten merely because lagged service or housing statistics remain elevated. The process therefore compares the target path with current liquidity and forward-looking economic evidence, allows earlier actions time to work, and pauses when money contracts and interest-sensitive sectors deteriorate. Its goal is stable disinflation rather than alternating policy extremes.
Origin
Extracted from Masters in Business, where Jeremy Siegel contrasted the historic 2020-2021 money expansion with the subsequent contraction and criticized the Federal Reserve for reacting too late in both directions.
Core principles
- 01Monetary changes affect inflation with substantial delays
- 02Interest rates alone do not reveal the full degree of policy restraint
- 03Stable money growth is preferable to alternating stimulus and contraction
- 04Housing and service inflation measures can lag current conditions
- 05Policy should respond to multiple indicators rather than group consensus
How to run it
- 1
Set the monetary benchmark
Establish the money-growth rate considered consistent with the inflation target. Siegel uses roughly five percent money growth alongside a two percent inflation objective.
Pro tip Treat the benchmark as a policy guide rather than a mechanically exact monthly target.
Watch out A single observation can be distorted by financial flows or measurement changes.
- 2
Measure the liquidity gap
Compare actual money growth with the benchmark and determine whether liquidity is expanding excessively or contracting. Evaluate both the size and duration of the deviation.
Pro tip Review several months of data to identify a persistent direction.
Watch out Do not assume that correcting excessive past growth requires an equally extreme contraction.
- 3
Cross-check financial conditions
Inspect credit creation, deposit flows, the dollar, real interest rates, and borrowing conditions. These indicators reveal restraint that the policy rate alone may conceal.
Pro tip Pay special attention to rate-sensitive sectors such as housing and autos.
Watch out Looking only at the nominal policy rate can understate how tight conditions have become.
- 4
Correct for data lags
Distinguish current market prices from official measures that incorporate older rents or service costs. Give greater weight to leading evidence when lagged components are moving in the opposite direction.
Pro tip Compare real-time housing and commodity measures with their official inflation counterparts.
Watch out Waiting for every lagging measure to reach the target can extend tightening well beyond what current conditions justify.
- 5
Allow transmission time
Estimate whether previous rate changes have had enough time to affect credit, demand, and prices. Avoid escalating policy solely because the full effect is not visible within a few months.
Pro tip Record the dates of major policy changes and monitor their effects as a sequence.
Watch out Monetary policy does not deliver its complete result within six months.
- 6
Pause before contraction compounds
When money growth is near zero, liquidity is falling, and leading prices are weakening, pause additional tightening and observe the response. Resume only if forward evidence shows inflationary pressure rebuilding.
Pro tip A pause preserves the option to tighten later without committing to an immediate reversal.
Watch out Continuing to tighten into contracting liquidity can intensify recession and housing-market risks.
In the wild
Money supply grows at exceptional rates during 2020 and 2021, while policymakers initially describe inflation as temporary. Once inflation becomes undeniable, rates rise rapidly and money supply begins shrinking. Applying the rule would have called for earlier normalization during the expansion, followed by a pause as growth fell below the five percent benchmark.
→ Policy adjusts sooner but more gradually, reducing the risk of both runaway inflation and a subsequent recession.
Real-time home and rental indexes turn down while the official housing component continues accelerating because its methodology incorporates older observations. The framework flags that divergence, combines it with shrinking liquidity and weaker housing activity, and recommends waiting for existing tightening to transmit.
→ Officials avoid raising rates solely in response to inflation that reflects earlier housing conditions.
Common mistakes
Using only the policy rate
The nominal interest rate can miss contraction in money supply, credit, deposits, and broader liquidity.
Reacting to lagged inflation
Official housing and service measures may continue rising after current market prices have weakened.
Correcting one extreme with another
Moving from extraordinary money growth directly to zero or negative growth can convert disinflation into recession.
Is it for you?
Best for
It is best for macroeconomic analysts evaluating whether monetary policy is too loose, appropriately restrictive, or excessively tight.
Not ideal for
It is not ideal as a precise short-term market-timing signal or as a substitute for a complete economic forecast.
From the transcript
“what is consistent with a two percent inflation rate is five percent money growth.”
“but doesn't mean now you slam on the brakes and go to zero, because that could really precipitate a recession.”
“Well, it doesn't happen in six months, and in fact you are seeing if you're goods, good prices are way down and service prices take…”
From the episode
Siegel and Schwartz on Stocks for the Long Run