What it means
Monetary aggregates try to answer a slippery question: how much money does an economy actually have? Each measure draws the line somewhere, and MZM drew it at immediacy, counting every dollar that could be spent without notice, penalty or waiting.
The basket was broad and practical. Currency, current accounts, savings deposits and money market funds all qualified, because each can be converted to spending power instantly, while time deposits with maturity dates were excluded.
The concept is where the name comes from. A deposit you can tap today has zero maturity, and MZM, maintained by the Federal Reserve Bank of St.
Louis, summed exactly those zero-maturity balances as a gauge of truly liquid money. Economists liked MZM for its behavioural purity.
Unlike the narrower M1 and M2, it tracked money by what holders could do with it, not by the account label, which made it useful for studying how liquid wealth responds to interest rates. The series ended in February 2021.
When the Federal Reserve redefined its money stock measures, folding savings deposits into M1, the St. Louis Fed announced that MZM would be discontinued, and the aggregate now lives in the historical data rather than in current releases.
For a business owner, MZM is a footnote worth knowing rather than a dial to watch. Its history illustrates a durable lesson: monetary statistics are definitions, not facts of nature, and the definitions change when the financial system outgrows them.
The idea behind MZM survives the series itself. Economists still ask which balances are truly spendable, and measures such as the divisia monetary aggregates carry the same zero-maturity logic forward with more modern weighting.
Its rise also tells a story about innovation. MZM grew important precisely because money market funds and sweep accounts blurred the old account categories, and its discontinuation came when the categories blurred again.
In practice
Real-world examples.
Example
An economist studying the 1990s uses MZM to show liquid money growing faster than M1 as savers shifted into money market funds. The shift mattered for spending power even though M1 barely moved.
Example
A student downloads MZM for a thesis and finds the series stops in January 2021. The St. Louis Fed's announcement explains why, and she switches her analysis to the redefined M1 and M2.
Example
A bond fund manager once tracked MZM growth as a liquidity indicator. After its discontinuation, her team rebuilds the dashboard around money market fund assets and the new monetary aggregates.
Formula
Calculation
MZM = M2 - small-denomination time deposits + institutional money market funds, by its standard construction. The idea is to remove balances that carry a maturity penalty and add large pools of cash that can be moved instantly.
Worked example with round, purely illustrative numbers (not historical data). Suppose M2 is $19.0 trillion, small time deposits are $0.5 trillion and institutional money market funds are $2.5 trillion. MZM = $19.0 trillion - $0.5 trillion + $2.5 trillion = $21.0 trillion. The net adjustment is +$2.0 trillion, so MZM sits 2.0 / 19.0 = 10.5% above M2, and the gap is driven almost entirely by the institutional money funds. Real published figures differ, so always take actual values from the central bank's historical archive.Case study
Seen in the real world.
In this illustrative fictional case, Larisa, a doctoral researcher, builds her thesis around a forty-year MZM series to test whether liquid money predicts consumer spending. Midway through, the St. Louis Fed discontinues the aggregate, and her supervisor insists she treat the event as a research opportunity rather than a disaster. She reconstructs a synthetic continuation from its published components, validates it against the overlap period, and her chapter on measurement change becomes the thesis's most cited part. Her conference summary is dry but true: aggregates are conventions, and a good economist reads the definition before the number.
Watch out
Common mistakes.
- Citing MZM as a current statistic, when the St. Louis Fed discontinued the series in February 2021 and no new values exist beyond that date.
- Assuming MZM, M1 and M2 measure the same thing, when each draws the liquidity line differently and MZM uniquely counted every immediately spendable balance.
- Treating monetary aggregates as fixed facts, when central banks redefine them as finance evolves, as the 2021 redefinition of M1 demonstrated.
Questions
People also ask.
What did MZM include?
Every balance spendable without waiting: currency, current and savings deposits, and money market funds. It excluded time deposits, because those carry a maturity and cannot be tapped freely.
Why was MZM discontinued?
In February 2021 the Federal Reserve redefined its money stock measures, bringing savings deposits into M1. The St. Louis Fed discontinued MZM as part of that overhaul, since the new aggregates absorbed its role.
What should analysts use instead?
The current M1 and M2 series, plus money market fund data, cover most of what MZM tracked. Historical MZM data remains available in the St. Louis Fed's archive for research.
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