PMI - The Early Warning System for Recessions
The Purchasing Managers' Index is a diffusion index that measures the prevailing direction of economic trends in the manufacturing and services sectors. Published monthly, PMI surveys ask purchasing managers, the executives responsible for buying the materials and services companies need to operate, whether conditions are improving, stable, or deteriorating across several dimensions. Because purchasing managers sit at the nexus of supply and demand, their collective assessment provides one of the earliest and most reliable signals of economic turning points.
The ISM Manufacturing PMI, published on the first business day of each month by the Institute for Supply Management, has a track record dating to 1948. A reading above 50 indicates expansion in the manufacturing sector. A reading below 50 indicates contraction. The PMI has correctly signaled every U.S. recession since its inception, typically providing a lead time of several months. This track record, combined with its timeliness (the data is released before almost all other major economic indicators for the same period), makes PMI one of the most closely watched data releases on the economic calendar.
How PMI Surveys Work
The ISM Manufacturing PMI is a composite of five equally weighted sub-indices: New Orders, Production, Employment, Supplier Deliveries, and Inventories. Each sub-index is constructed as a diffusion index, meaning it measures the percentage of respondents reporting improvement minus the percentage reporting deterioration, plus 50. A reading of 55 means that 5% more respondents are reporting improvement than deterioration. A reading of 45 means that 5% more are reporting deterioration.
The approximately 400 purchasing managers who respond to the survey represent 18 manufacturing industries weighted by their contribution to GDP. The survey is conducted during the month and released on the first business day of the following month, giving it a timeliness advantage over many other economic indicators.
New Orders is the most forward-looking component because it measures demand that has not yet been fulfilled. Rising new orders signal that production, employment, and supplier activity will likely increase in the coming months. A sharp decline in new orders often precedes broader economic weakening. The New Orders sub-index has a particularly strong correlation with future industrial production and GDP growth.
Production measures current output levels and tends to move closely with industrial production data, which is released later in the month.
Employment indicates whether manufacturers are adding or reducing headcount. This sub-index correlates with the manufacturing component of the monthly payrolls report and provides an early read on the labor market in the goods-producing sector.
Supplier Deliveries is an inverted indicator: higher readings indicate slower deliveries, which paradoxically signals economic strength because it means demand is outstripping supply chain capacity. During the 2021 supply chain crisis, this sub-index spiked to levels consistent with the strongest manufacturing activity on record, even though the elevated readings reflected bottlenecks rather than healthy expansion.
Inventories measures whether manufacturers are building or drawing down stockpiles. Inventory cycles can amplify or dampen the business cycle, making this component important for understanding the underlying demand trend.
The 50-Line and Recession Thresholds
The 50-line is the demarcation between expansion and contraction, but a single month below 50 does not constitute a recession signal. The ISM has found that a reading of 48.7 sustained over time corresponds to a flat GDP economy (no growth, no contraction). Readings below approximately 42.5 have historically corresponded to negative GDP growth. The lower the reading falls below 50 and the longer it stays there, the stronger the recession signal. The economics guide covers these dynamics in greater depth.
The manufacturing PMI can remain below 50 while the broader economy continues to expand. This occurred from late 2022 through 2023, when the ISM Manufacturing PMI was below 50 for 16 consecutive months while GDP growth remained positive. The manufacturing sector was in a mild contraction while the larger services sector continued expanding, illustrating an important point: manufacturing represents only about 11% of U.S. GDP. A manufacturing recession does not necessarily mean an economy-wide recession.
The ISM Services PMI, published on the third business day of each month, covers the services sector that represents roughly 77% of GDP. When both the manufacturing and services PMIs are below 50 simultaneously, the recession signal is much stronger. This dual-contraction pattern has preceded or coincided with every recession in the data.
PMI and Market Reactions
Markets react to the ISM PMI within seconds of its 10:00 AM Eastern release. The reaction depends on the prevailing macro narrative and the specific components that drive the surprise.
In a "bad news is good news" environment (markets pricing in Fed rate cuts), a weaker-than-expected PMI can rally stocks because it increases the probability of monetary easing. In a "good news is good news" environment (markets pricing in a soft landing), a stronger PMI confirms the positive narrative and supports stocks.
The individual sub-indices often generate more sustained market reactions than the headline number. A significant decline in the Employment sub-index can trigger selling in industrial and manufacturing stocks. A spike in the Prices Paid sub-index can sell off rate-sensitive sectors because it implies persistent inflationary pressures. A collapse in New Orders can trigger a broad risk-off move because it signals a demand contraction that will eventually affect earnings across the manufacturing complex.
The relationship between PMI and future S&P 500 earnings growth is meaningful. Research from various investment banks has shown that the ISM Manufacturing New Orders minus Inventories spread is one of the better leading indicators for S&P 500 earnings per share growth. A positive spread (new orders exceeding inventories) suggests building demand relative to supply, which tends to precede earnings growth. A negative spread suggests demand is falling relative to stockpiled goods, which tends to precede earnings contraction.
Global PMIs
PMI surveys are conducted in virtually every major economy, and the global PMI data provides a comprehensive picture of worldwide manufacturing and services activity. The S&P Global (formerly IHS Markit) PMI surveys cover more than 40 countries and are released before the ISM data for the United States.
The JPMorgan Global Composite PMI aggregates these national surveys into a single global reading. Global PMI trends matter for U.S. investors because roughly 40% of S&P 500 revenue comes from outside the United States. When global manufacturing is expanding, multinational industrial, technology, and materials companies benefit from rising foreign demand. When global PMI contracts, these companies face revenue headwinds from their international operations.
China's manufacturing PMIs (both the official NBS survey and the Caixin survey) receive particular attention because China is the world's largest manufacturing economy. A significant downturn in Chinese manufacturing PMI typically signals weaker global demand for commodities, reduced orders for international suppliers, and potential weakness in the semiconductor, mining, and industrial sectors globally.
The eurozone manufacturing PMI from S&P Global is also closely watched. European manufacturing weakness has been a persistent feature of the post-2022 environment, contributing to euro depreciation and weakness in European equity markets relative to U.S. peers.
PMI's Predictive Power vs. Limitations
The PMI's strengths as an economic indicator include its timeliness, its long track record, and its diffusion index methodology, which captures the breadth of economic activity rather than the magnitude. A reading of 55 means that conditions are broadly improving across a wide range of companies, even if it does not tell you by how much.
The limitations are real and worth understanding.
Magnitude blindness. The diffusion index methodology means that a company reporting a 1% increase in orders counts the same as one reporting a 30% increase. The PMI captures direction, not intensity. An economy where most businesses are growing slowly produces the same reading as one where most businesses are growing rapidly.
Manufacturing bias. Despite the addition of services PMI surveys, the manufacturing PMI receives disproportionate attention relative to manufacturing's share of the economy. A manufacturing recession accompanied by healthy services growth, as occurred in 2023, can trigger misplaced recession fears.
Survey fatigue and response bias. The reliability of any survey depends on consistent, honest responses. If the same purchasing managers fill out surveys month after month, their responses may become formulaic. If response rates decline during economic disruptions, the sample may become less representative.
Seasonality and one-offs. Extreme weather, major holidays, natural disasters, and other one-time events can distort a single month's reading without representing a change in the underlying economic trend. The February PMI is frequently distorted by weather effects, and December readings can be affected by year-end inventory adjustments.
Despite these limitations, PMI remains one of the most useful tools in an investor's macroeconomic toolkit. Its ability to signal economic turning points months before they appear in lagging data like GDP and unemployment gives it genuine predictive value. The investor who tracks PMI trends, analyzes the sub-indices, and contextualizes the readings within the broader data picture has a meaningful informational advantage over one who waits for the "official" economic data to confirm what PMI suggested weeks or months earlier.
The practical application is straightforward: track the ISM Manufacturing and Services PMI monthly, pay special attention to New Orders and Employment, compare the U.S. data to global PMI trends, and use sustained moves below 50 in both surveys as a signal to evaluate portfolio positioning for a potential economic downturn.
Put these principles into practice. Track fundamentals, build portfolios, and analyze stocks with AI-powered insights.
Start Free on GridOasis →