Central bankers spent the better part of four decades pretending money supply didn't matter. They were wrong, and the post-pandemic inflation shock proved it.
If you tracked central bank balance sheets and broad money metrics like M2 in 2020, the historic spike in global inflation wasn't a surprise. It was basic math. Yet, major policy institutions like the Federal Reserve and the European Central Bank dismissed early warnings, calling price increases "transitory." They focused on supply chain bottlenecks and labor shortages while ignoring the massive expansion of cash sloshing through the banking system.
Monetarism—the economic framework pioneered by Milton Friedman—is making a quiet, awkward comeback. You don't need to accept every monetarist axiom to see that completely decoupling interest rate policy from money growth was a massive mistake.
What Monetarism Got Right About Money Growth
The central premise of monetarism is remarkably straightforward. Inflation happens when the supply of money grows faster than the economy's capacity to produce goods and services. Friedman famously summed it up: "Inflation is always and everywhere a monetary phenomenon."
In the 1970s, as Keynesian models failed to explain stagflation, monetarism gained traction. Central banks, including Paul Volcker's Fed, shifted toward targeting money supply directly to tame runaway prices. It worked, but it created an unintended problem.
Financial deregulation in the 1980s and 1990s broke the stable relationship between money supply and GDP growth. New financial instruments appeared. Electronic banking accelerated how fast money changed hands. Economists call this the "velocity of money." When velocity became erratic, tracking broad aggregate measures like M1 or M2 suddenly stopped giving reliable policy signals.
Central banks abandoned monetary targeting. They moved toward direct inflation targeting using a single primary tool: short-term interest rates.
For thirty years, this shift seemed harmless. Inflation stayed low, anchored by globalization, technological advances, and demographic trends. Central bankers convinced themselves that money aggregates were relics of a bygone era. Jerome Powell even stated explicitly in testimony before Congress in 2021 that the relationship between money growth and economic outcomes had been severed for decades.
That assumption aged terribly.
The 2020 Liquidity Explosion and Its Fallout
When the pandemic hit, fiscal and monetary authorities coordinated an unprecedented response. Central banks bought government debt on a massive scale through quantitative easing (QE). Governments sent direct stimulus payments to households.
This wasn't typical post-2008 QE.
After the 2008 financial crisis, central bank asset purchases mostly sat in commercial bank accounts as excess reserves. The money stayed stuck in the financial system. Broad money supply growth remained subdued.
In 2020, things played out differently. Fiscal transfers placed cash directly into bank accounts of households and businesses. In the United States, broad money supply (M2) grew by more than 25% in a single year. That was the fastest expansion seen since World War II.
M2 Growth vs. Core CPI Spike (2020–2023)
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2020: M2 surges >25% ---> Bank deposits & liquidity flood real economy
2021: Velocity recovers ---> Demand spikes faster than output
2022: Inflation peaks ---> Central banks forced into aggressive rate hikes
Monetarists sounded the alarm immediately. Analysts like Steve Hanke from Johns Hopkins University warned that a major inflationary surge was coming within 12 to 18 months. Mainstream economists shrugged off those warnings, focusing instead on Phillips Curve dynamics and labor market slack.
We all know who ended up being right. The inflation wave hit hard, reaching multi-decade highs globally by mid-2022. Money supply growth led price increases with a classic 12- to 18-month lag.
The Flaws of Pure Monetarist Theory
Acknowledging that money supply matters doesn't mean monetarism is flawless. Pure monetarist doctrine relies on assumptions that rarely survive contact with modern financial markets.
First, defining what actually constitutes "money" is surprisingly tricky today. Should you look at M2, which includes savings deposits and money market funds? What about broader metrics like M3 or M4? Modern shadow banking creates credit outside traditional commercial bank channels, making broad liquidity hard to track accurately.
Second, the velocity of money remains highly unstable. If people choose to hoard cash rather than spend it—as they did during certain periods of economic uncertainty—an expansion in money supply won't automatically cause inflation.
Finally, strict monetary rules lack flexibility. Friedman advocated for a fixed monetary rule, where the central bank increases money supply at a constant percentage rate matching long-term GDP growth. Implementing a rigid rule like that in a dynamic, globalized financial system can trigger wild interest rate volatility and cause severe liquidity freezes during market panics.
Monetarism isn't a silver bullet. It's an indispensable diagnostic tool.
How Modern Central Banks Are Forced to Adapt
The debate isn't about choosing between strict monetarism and modern interest rate policy. It's about combining both.
Ignoring money supply metrics entirely creates huge blind spots for monetary policy. When broad money measures expand at historic rates, price stability is threatened regardless of where current interest rates sit.
Central banks are quietly bringing monetary analysis back into their decision-making frameworks. The Bank of England and the European Central Bank have both faced internal pressure from researchers urging a return to two-pillar strategies that formally track broad credit and monetary growth alongside standard economic indicators.
Understanding this shift gives investors and business leaders an edge:
- Track broad money trends, not just Fed funds rates. Watch annual M2 growth rates published by central banks. When broad money growth strays significantly from real GDP growth plus the inflation target, policy shifts usually follow.
- Differentiate between financial liquidity and real-economy liquidity. Quantitative easing that stays trapped in bank reserves inflates asset prices (stocks, real estate). Quantitative easing combined with fiscal stimulus floods the real economy and drives consumer price inflation.
- Monitor commercial bank credit creation. Central banks aren't the only entities that create money; commercial banks create money whenever they originate new loans. Credit growth data often reveals economic shifts months before official GDP reports come out.
Paying attention to money growth won't tell you where markets will head tomorrow, but it gives you a clearer view of economic trends over a 12- to 24-month horizon. Ignoring it is no longer an option.
