M2 Money Supply vs CPI

M2 is the broad measure of US money supply: currency in circulation, demand deposits and other checkable deposits, savings deposits, retail money market funds, and small-denomination time deposits under $100,000. It is published monthly by the Federal Reserve as series M2SL on a seasonally adjusted basis. M2 reached $22.44 trillion in January 2026, the latest available reading.

The series matters because, in the monetarist framing of MV=PQ, money supply (M) times velocity (V) equals price level (P) times real output (Q). When M grows faster than the economy can absorb, the residual shows up either in faster inflation or in faster velocity decline. The framework was central to mid-twentieth century macroeconomics, fell out of favor in the 1990s as velocity became unstable, and was rehabilitated by the 2020 to 2023 episode that produced the most extreme money supply movement in eighty years.

M2 rose from $15.41 trillion in February 2020 to $21.74 trillion at its peak in April 2022, a $6.33 trillion increase in 26 months. The annualized growth rate of M2 hit 27 percent in February 2021, more than four times the 6.7 percent annual average from 2010 to 2019. Three forces drove the expansion: Treasury direct deposits to households (three rounds of stimulus checks totaling roughly $850 billion), Paycheck Protection Program loans converted to grants ($800 billion), and the indirect monetization of Treasury issuance via Fed Treasury and MBS purchases.

Fiscal versus monetary attribution debates remain unresolved, but the aggregate effect on M2 is clear. Stimulus checks deposited to checking accounts directly increased M2. Fed asset purchases credited bank reserves, which then fed into M2 through bank deposit expansion. The 2020 to 2022 M2 expansion was unique in scale and unique in its joint fiscal-monetary mechanism.

Headline CPI ran below 2 percent through most of 2020 (1.4 percent in January 2021) before beginning to rise. By January 2022 it was 7.5 percent. June 2022 marked the cycle peak at 9.1 percent year-on-year, the highest reading since November 1981. The lag from M2 growth peak (February 2021) to CPI peak (June 2022) was approximately fifteen months, well within Milton Friedman's "long and variable" lag estimate of 6 to 24 months.

The transmission ran through demand: pandemic-affected consumers held excess savings, supply chains were constrained, and pent-up demand met limited supply at the precise moment the Fed kept rates near zero. CPI components tell the story: durable goods (used cars +45 percent in 2021) led, services (rents, restaurants) followed, and shelter CPI peaked last in March 2023 with the longest lag. Headline CPI then began descending as M2 stopped growing.

M2 fell from $21.74 trillion in April 2022 to $20.74 trillion in October 2023, a $1.0 trillion contraction over 18 months. Year-on-year M2 growth went negative for the first time since the series began in 1959, reaching minus 4.5 percent at the deepest point. The contraction was driven by Fed quantitative tightening (which drained bank reserves), Treasury General Account refills (which sterilized cash), and money market fund migration into the reverse repo facility.

In the entire post-1959 record, M2 had never contracted year-on-year in nominal terms. The five other instances of meaningful M2 contraction in 150 years (1878, 1893, 1921, 1931 to 1933, and 2022 to 2023) all coincided with deflationary depressions, except the most recent. The 2022 to 2023 contraction was the first M2 decline that did not accompany a depression, partly because it was modest in scale (4.5 percent peak decline versus 30+ percent in the 1930s) and partly because nominal GDP continued growing.

CPI fell from 9.1 percent year-on-year in June 2022 to 6.5 percent in December 2022, 3.0 percent in June 2023, and 3.1 percent at year-end 2023. By the second half of 2024 headline CPI was running 2.4 to 2.9 percent. The disinflation period ran roughly twelve months behind the M2 contraction trough, again consistent with the Friedman lag.

The disinflation was not pure monetarism. Energy prices fell sharply (WTI from $124 in June 2022 to $66 by April 2023). Goods inflation collapsed as supply chains repaired. Shelter CPI peaked late but then drifted down on rolling rent rolls. Wage growth decelerated as labor market slack increased. But all of these channels operated against a backdrop of contracting M2, and the joint outcome was consistent with the monetarist prediction. Money supply contraction need not cause deflation, but it strongly correlated with inflation declining to target.

M2 velocity, defined as nominal GDP divided by M2, fell from 2.19 in Q3 1997 to 1.13 in Q2 2020, the all-time low for the series. The 2020 reading reflected M2 expanding faster than GDP could absorb. By Q4 2025 velocity had recovered to roughly 1.41, well below the 1990s peak but rising as nominal GDP outpaced M2 growth.

Velocity matters because it modulates the M-to-CPI transmission. The same M2 expansion produces different inflation outcomes depending on whether velocity is rising or falling. The 2020 episode would have produced sharper inflation if velocity had not collapsed simultaneously. The 2010 to 2019 QE episodes, by contrast, did not produce inflation because new money was hoarded as bank reserves rather than circulating. Velocity is empirically unstable and structurally linked to interest rates, fiscal policy, and household savings rates, which is why monetarists eventually shifted toward focusing on broader credit aggregates rather than narrow money.

After the 2008 to 2009 financial crisis, the Fed expanded its balance sheet from $0.9 trillion to $4.5 trillion through three rounds of QE. Many monetarists predicted runaway inflation. CPI averaged 1.7 percent through the 2010 to 2019 period, well below the Fed's 2 percent target for most of the decade. Why did the prediction fail then?

The answer is that QE expanded bank reserves but did not expand M2 much. M2 grew 6.7 percent annually from 2010 to 2019, roughly in line with nominal GDP growth. New Fed-created reserves stayed at the Fed (paid IORB) rather than being lent out. The 2020 episode was different because the Fed expanded its balance sheet through Treasury purchases that funded direct fiscal transfers to households, which immediately boosted M2 through deposits, rather than funding bank lending into a slack economy. The mechanism, not the aggregate, mattered.

M2 reaccelerated through 2024 and 2025, rising from $20.74 trillion in October 2023 to $22.02 trillion in June 2025 and $22.44 trillion in January 2026. Year-on-year growth ran 4.0 to 4.5 percent through most of 2025, returning to the pre-2020 trend rate. The reacceleration coincided with the end of QT (Treasury runoff stopped December 1, 2025), the RRP drain returning cash to money markets, and modestly stronger bank lending.

CPI through the same period drifted from 2.4 percent in February 2026 to 3.3 percent in March 2026, but the March uptick was driven primarily by energy (gasoline +18.9 percent year-on-year, fuel oil +44.2 percent on Iran war effects) rather than by money supply transmission. Core CPI excluding energy ran roughly 2.7 to 2.9 percent through Q1 2026. The clean monetarist signal from M2 alone suggests inflation should stabilize in the 2.5 to 3 percent range through 2026, with the Iran energy shock layered on top.

The pair has clear failure modes. The first is supply shocks: oil embargoes (1973 to 1974), commodity spikes (2008), and energy wars (2026 Iran) push CPI without any M2 input. The second is exchange rate moves: a 20 percent depreciation in the dollar passes through to import prices and CPI within 12 to 18 months regardless of M2. The third is asset-versus-consumer-price divergence: 2010 to 2019 QE inflated equity, real estate, and bond prices substantially while leaving CPI flat.

The pair also breaks down at the high frequency end. Monthly M2 data is volatile and subject to revision. Monthly CPI prints can be dominated by single line items (used cars, airfares, hospital services). The relationship is most informative at year-on-year horizons, with a 12 to 18 month lag, and weakest at monthly horizons.

For practical use: the year-on-year change in M2 leads year-on-year CPI by roughly 12 to 18 months. M2 growth running below 5 percent has historically been consistent with CPI running 2 to 3 percent (the post-2009 norm). M2 growth above 10 percent has historically led to CPI running above 3 percent within two years. M2 contraction has historically preceded sharp CPI declines.

April 2026 M2 growth at roughly 4.5 percent year-on-year suggests headline CPI should stabilize in the 2.5 to 3 percent range through late 2026 and into 2027, absent further supply shocks. The Iran-driven energy spike adds 0.5 to 0.7 percentage points to headline CPI but should fade as base effects roll over. The Fed has cut rates 100 basis points from September to December 2024, holding the funds rate at 3.75 percent through Q1 2026. If M2 reaccelerates above 6 percent, the monetarist signal would suggest CPI heading to 3.5 percent or higher in 2027, a path the Fed would need to address with policy.